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Versions: 00 01 02 03 04 draft-ietf-cellar-matroska

cellar                                                         S. Lhomme
Internet-Draft
Intended status: Standards Track                               M. Bunkus
Expires: July 7, 2018
                                                                 D. Rice
                                                         January 3, 2018


                        Matroska Specifications
                    draft-lhomme-cellar-matroska-04

Abstract

   This document defines the Matroska audiovisual container, including
   definitions of its structural elements, as well as its terminology,
   vocabulary, and application.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on July 7, 2018.

Copyright Notice

   Copyright (c) 2018 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.



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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   9
   2.  Status of this document . . . . . . . . . . . . . . . . . . .  10
   3.  Security Considerations . . . . . . . . . . . . . . . . . . .  10
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  10
   5.  Notation and Conventions  . . . . . . . . . . . . . . . . . .  10
   6.  Basis in EBML . . . . . . . . . . . . . . . . . . . . . . . .  11
     6.1.  Added Constraints on EBML . . . . . . . . . . . . . . . .  11
     6.2.  Matroska Design . . . . . . . . . . . . . . . . . . . . .  11
       6.2.1.  Language Codes  . . . . . . . . . . . . . . . . . . .  11
       6.2.2.  Physical Types  . . . . . . . . . . . . . . . . . . .  12
       6.2.3.  Block Structure . . . . . . . . . . . . . . . . . . .  12
       6.2.4.  Lacing  . . . . . . . . . . . . . . . . . . . . . . .  14
   7.  Matroska Structure  . . . . . . . . . . . . . . . . . . . . .  18
   8.  Matroska Schema . . . . . . . . . . . . . . . . . . . . . . .  26
     8.1.  Matroska Additions to Schema Element Attributes . . . . .  26
     8.2.  Matroska Schema . . . . . . . . . . . . . . . . . . . . .  27
       8.2.1.  EBMLMaxIDLength Element . . . . . . . . . . . . . . .  27
       8.2.2.  EBMLMaxSizeLength Element . . . . . . . . . . . . . .  27
       8.2.3.  Segment Element . . . . . . . . . . . . . . . . . . .  28
       8.2.4.  SeekHead Element  . . . . . . . . . . . . . . . . . .  28
       8.2.5.  Seek Element  . . . . . . . . . . . . . . . . . . . .  28
       8.2.6.  SeekID Element  . . . . . . . . . . . . . . . . . . .  29
       8.2.7.  SeekPosition Element  . . . . . . . . . . . . . . . .  29
       8.2.8.  Info Element  . . . . . . . . . . . . . . . . . . . .  30
       8.2.9.  SegmentUID Element  . . . . . . . . . . . . . . . . .  30
       8.2.10. SegmentFilename Element . . . . . . . . . . . . . . .  30
       8.2.11. PrevUID Element . . . . . . . . . . . . . . . . . . .  31
       8.2.12. PrevFilename Element  . . . . . . . . . . . . . . . .  31
       8.2.13. NextUID Element . . . . . . . . . . . . . . . . . . .  32
       8.2.14. NextFilename Element  . . . . . . . . . . . . . . . .  32
       8.2.15. SegmentFamily Element . . . . . . . . . . . . . . . .  33
       8.2.16. ChapterTranslate Element  . . . . . . . . . . . . . .  33
       8.2.17. ChapterTranslateEditionUID Element  . . . . . . . . .  33
       8.2.18. ChapterTranslateCodec Element . . . . . . . . . . . .  34
       8.2.19. ChapterTranslateID Element  . . . . . . . . . . . . .  34
       8.2.20. TimecodeScale Element . . . . . . . . . . . . . . . .  35
       8.2.21. Duration Element  . . . . . . . . . . . . . . . . . .  35
       8.2.22. DateUTC Element . . . . . . . . . . . . . . . . . . .  35
       8.2.23. Title Element . . . . . . . . . . . . . . . . . . . .  36
       8.2.24. MuxingApp Element . . . . . . . . . . . . . . . . . .  36
       8.2.25. WritingApp Element  . . . . . . . . . . . . . . . . .  37
       8.2.26. Cluster Element . . . . . . . . . . . . . . . . . . .  37
       8.2.27. Timecode Element  . . . . . . . . . . . . . . . . . .  37
       8.2.28. SilentTracks Element  . . . . . . . . . . . . . . . .  38
       8.2.29. SilentTrackNumber Element . . . . . . . . . . . . . .  38
       8.2.30. Position Element  . . . . . . . . . . . . . . . . . .  38



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       8.2.31. PrevSize Element  . . . . . . . . . . . . . . . . . .  39
       8.2.32. SimpleBlock Element . . . . . . . . . . . . . . . . .  39
       8.2.33. BlockGroup Element  . . . . . . . . . . . . . . . . .  40
       8.2.34. Block Element . . . . . . . . . . . . . . . . . . . .  40
       8.2.35. BlockVirtual Element  . . . . . . . . . . . . . . . .  40
       8.2.36. BlockAdditions Element  . . . . . . . . . . . . . . .  41
       8.2.37. BlockMore Element . . . . . . . . . . . . . . . . . .  41
       8.2.38. BlockAddID Element  . . . . . . . . . . . . . . . . .  41
       8.2.39. BlockAdditional Element . . . . . . . . . . . . . . .  42
       8.2.40. BlockDuration Element . . . . . . . . . . . . . . . .  42
       8.2.41. ReferencePriority Element . . . . . . . . . . . . . .  43
       8.2.42. ReferenceBlock Element  . . . . . . . . . . . . . . .  43
       8.2.43. ReferenceVirtual Element  . . . . . . . . . . . . . .  44
       8.2.44. CodecState Element  . . . . . . . . . . . . . . . . .  44
       8.2.45. DiscardPadding Element  . . . . . . . . . . . . . . .  44
       8.2.46. Slices Element  . . . . . . . . . . . . . . . . . . .  45
       8.2.47. TimeSlice Element . . . . . . . . . . . . . . . . . .  45
       8.2.48. LaceNumber Element  . . . . . . . . . . . . . . . . .  45
       8.2.49. FrameNumber Element . . . . . . . . . . . . . . . . .  46
       8.2.50. BlockAdditionID Element . . . . . . . . . . . . . . .  46
       8.2.51. Delay Element . . . . . . . . . . . . . . . . . . . .  47
       8.2.52. SliceDuration Element . . . . . . . . . . . . . . . .  47
       8.2.53. ReferenceFrame Element  . . . . . . . . . . . . . . .  48
       8.2.54. ReferenceOffset Element . . . . . . . . . . . . . . .  48
       8.2.55. ReferenceTimeCode Element . . . . . . . . . . . . . .  48
       8.2.56. EncryptedBlock Element  . . . . . . . . . . . . . . .  49
       8.2.57. Tracks Element  . . . . . . . . . . . . . . . . . . .  49
       8.2.58. TrackEntry Element  . . . . . . . . . . . . . . . . .  50
       8.2.59. TrackNumber Element . . . . . . . . . . . . . . . . .  50
       8.2.60. TrackUID Element  . . . . . . . . . . . . . . . . . .  50
       8.2.61. TrackType Element . . . . . . . . . . . . . . . . . .  51
       8.2.62. FlagEnabled Element . . . . . . . . . . . . . . . . .  51
       8.2.63. FlagDefault Element . . . . . . . . . . . . . . . . .  52
       8.2.64. FlagForced Element  . . . . . . . . . . . . . . . . .  52
       8.2.65. FlagLacing Element  . . . . . . . . . . . . . . . . .  53
       8.2.66. MinCache Element  . . . . . . . . . . . . . . . . . .  53
       8.2.67. MaxCache Element  . . . . . . . . . . . . . . . . . .  54
       8.2.68. DefaultDuration Element . . . . . . . . . . . . . . .  54
       8.2.69. DefaultDecodedFieldDuration Element . . . . . . . . .  54
       8.2.70. TrackTimecodeScale Element  . . . . . . . . . . . . .  55
       8.2.71. TrackOffset Element . . . . . . . . . . . . . . . . .  55
       8.2.72. MaxBlockAdditionID Element  . . . . . . . . . . . . .  56
       8.2.73. Name Element  . . . . . . . . . . . . . . . . . . . .  56
       8.2.74. Language Element  . . . . . . . . . . . . . . . . . .  57
       8.2.75. LanguageIETF Element  . . . . . . . . . . . . . . . .  57
       8.2.76. CodecID Element . . . . . . . . . . . . . . . . . . .  57
       8.2.77. CodecPrivate Element  . . . . . . . . . . . . . . . .  58
       8.2.78. CodecName Element . . . . . . . . . . . . . . . . . .  58



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       8.2.79. AttachmentLink Element  . . . . . . . . . . . . . . .  58
       8.2.80. CodecSettings Element . . . . . . . . . . . . . . . .  59
       8.2.81. CodecInfoURL Element  . . . . . . . . . . . . . . . .  59
       8.2.82. CodecDownloadURL Element  . . . . . . . . . . . . . .  60
       8.2.83. CodecDecodeAll Element  . . . . . . . . . . . . . . .  60
       8.2.84. TrackOverlay Element  . . . . . . . . . . . . . . . .  60
       8.2.85. CodecDelay Element  . . . . . . . . . . . . . . . . .  61
       8.2.86. SeekPreRoll Element . . . . . . . . . . . . . . . . .  61
       8.2.87. TrackTranslate Element  . . . . . . . . . . . . . . .  62
       8.2.88. TrackTranslateEditionUID Element  . . . . . . . . . .  62
       8.2.89. TrackTranslateCodec Element . . . . . . . . . . . . .  62
       8.2.90. TrackTranslateTrackID Element . . . . . . . . . . . .  63
       8.2.91. Video Element . . . . . . . . . . . . . . . . . . . .  63
       8.2.92. FlagInterlaced Element  . . . . . . . . . . . . . . .  63
       8.2.93. FieldOrder Element  . . . . . . . . . . . . . . . . .  64
       8.2.94. StereoMode Element  . . . . . . . . . . . . . . . . .  64
       8.2.95. AlphaMode Element . . . . . . . . . . . . . . . . . .  65
       8.2.96. OldStereoMode Element . . . . . . . . . . . . . . . .  65
       8.2.97. PixelWidth Element  . . . . . . . . . . . . . . . . .  66
       8.2.98. PixelHeight Element . . . . . . . . . . . . . . . . .  66
       8.2.99. PixelCropBottom Element . . . . . . . . . . . . . . .  66
       8.2.100. PixelCropTop Element . . . . . . . . . . . . . . . .  67
       8.2.101. PixelCropLeft Element  . . . . . . . . . . . . . . .  67
       8.2.102. PixelCropRight Element . . . . . . . . . . . . . . .  68
       8.2.103. DisplayWidth Element . . . . . . . . . . . . . . . .  68
       8.2.104. DisplayHeight Element  . . . . . . . . . . . . . . .  68
       8.2.105. DisplayUnit Element  . . . . . . . . . . . . . . . .  69
       8.2.106. AspectRatioType Element  . . . . . . . . . . . . . .  69
       8.2.107. ColourSpace Element  . . . . . . . . . . . . . . . .  70
       8.2.108. GammaValue Element . . . . . . . . . . . . . . . . .  70
       8.2.109. FrameRate Element  . . . . . . . . . . . . . . . . .  71
       8.2.110. Colour Element . . . . . . . . . . . . . . . . . . .  71
       8.2.111. MatrixCoefficients Element . . . . . . . . . . . . .  71
       8.2.112. BitsPerChannel Element . . . . . . . . . . . . . . .  72
       8.2.113. ChromaSubsamplingHorz Element  . . . . . . . . . . .  72
       8.2.114. ChromaSubsamplingVert Element  . . . . . . . . . . .  73
       8.2.115. CbSubsamplingHorz Element  . . . . . . . . . . . . .  73
       8.2.116. CbSubsamplingVert Element  . . . . . . . . . . . . .  73
       8.2.117. ChromaSitingHorz Element . . . . . . . . . . . . . .  74
       8.2.118. ChromaSitingVert Element . . . . . . . . . . . . . .  74
       8.2.119. Range Element  . . . . . . . . . . . . . . . . . . .  75
       8.2.120. TransferCharacteristics Element  . . . . . . . . . .  75
       8.2.121. Primaries Element  . . . . . . . . . . . . . . . . .  75
       8.2.122. MaxCLL Element . . . . . . . . . . . . . . . . . . .  76
       8.2.123. MaxFALL Element  . . . . . . . . . . . . . . . . . .  76
       8.2.124. MasteringMetadata Element  . . . . . . . . . . . . .  77
       8.2.125. PrimaryRChromaticityX Element  . . . . . . . . . . .  77
       8.2.126. PrimaryRChromaticityY Element  . . . . . . . . . . .  77



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       8.2.127. PrimaryGChromaticityX Element  . . . . . . . . . . .  78
       8.2.128. PrimaryGChromaticityY Element  . . . . . . . . . . .  78
       8.2.129. PrimaryBChromaticityX Element  . . . . . . . . . . .  79
       8.2.130. PrimaryBChromaticityY Element  . . . . . . . . . . .  79
       8.2.131. WhitePointChromaticityX Element  . . . . . . . . . .  79
       8.2.132. WhitePointChromaticityY Element  . . . . . . . . . .  80
       8.2.133. LuminanceMax Element . . . . . . . . . . . . . . . .  80
       8.2.134. LuminanceMin Element . . . . . . . . . . . . . . . .  81
       8.2.135. Projection Element . . . . . . . . . . . . . . . . .  81
       8.2.136. ProjectionType Element . . . . . . . . . . . . . . .  81
       8.2.137. ProjectionPrivate Element  . . . . . . . . . . . . .  82
       8.2.138. ProjectionPoseYaw Element  . . . . . . . . . . . . .  82
       8.2.139. ProjectionPosePitch Element  . . . . . . . . . . . .  83
       8.2.140. ProjectionPoseRoll Element . . . . . . . . . . . . .  84
       8.2.141. Audio Element  . . . . . . . . . . . . . . . . . . .  84
       8.2.142. SamplingFrequency Element  . . . . . . . . . . . . .  84
       8.2.143. OutputSamplingFrequency Element  . . . . . . . . . .  85
       8.2.144. Channels Element . . . . . . . . . . . . . . . . . .  85
       8.2.145. ChannelPositions Element . . . . . . . . . . . . . .  86
       8.2.146. BitDepth Element . . . . . . . . . . . . . . . . . .  86
       8.2.147. TrackOperation Element . . . . . . . . . . . . . . .  87
       8.2.148. TrackCombinePlanes Element . . . . . . . . . . . . .  87
       8.2.149. TrackPlane Element . . . . . . . . . . . . . . . . .  87
       8.2.150. TrackPlaneUID Element  . . . . . . . . . . . . . . .  88
       8.2.151. TrackPlaneType Element . . . . . . . . . . . . . . .  88
       8.2.152. TrackJoinBlocks Element  . . . . . . . . . . . . . .  89
       8.2.153. TrackJoinUID Element . . . . . . . . . . . . . . . .  89
       8.2.154. TrickTrackUID Element  . . . . . . . . . . . . . . .  89
       8.2.155. TrickTrackSegmentUID Element . . . . . . . . . . . .  90
       8.2.156. TrickTrackFlag Element . . . . . . . . . . . . . . .  90
       8.2.157. TrickMasterTrackUID Element  . . . . . . . . . . . .  91
       8.2.158. TrickMasterTrackSegmentUID Element . . . . . . . . .  91
       8.2.159. ContentEncodings Element . . . . . . . . . . . . . .  91
       8.2.160. ContentEncoding Element  . . . . . . . . . . . . . .  92
       8.2.161. ContentEncodingOrder Element . . . . . . . . . . . .  92
       8.2.162. ContentEncodingScope Element . . . . . . . . . . . .  93
       8.2.163. ContentEncodingType Element  . . . . . . . . . . . .  93
       8.2.164. ContentCompression Element . . . . . . . . . . . . .  94
       8.2.165. ContentCompAlgo Element  . . . . . . . . . . . . . .  94
       8.2.166. ContentCompSettings Element  . . . . . . . . . . . .  95
       8.2.167. ContentEncryption Element  . . . . . . . . . . . . .  95
       8.2.168. ContentEncAlgo Element . . . . . . . . . . . . . . .  95
       8.2.169. ContentEncKeyID Element  . . . . . . . . . . . . . .  96
       8.2.170. ContentSignature Element . . . . . . . . . . . . . .  96
       8.2.171. ContentSigKeyID Element  . . . . . . . . . . . . . .  97
       8.2.172. ContentSigAlgo Element . . . . . . . . . . . . . . .  97
       8.2.173. ContentSigHashAlgo Element . . . . . . . . . . . . .  97
       8.2.174. Cues Element . . . . . . . . . . . . . . . . . . . .  98



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       8.2.175. CuePoint Element . . . . . . . . . . . . . . . . . .  98
       8.2.176. CueTime Element  . . . . . . . . . . . . . . . . . .  99
       8.2.177. CueTrackPositions Element  . . . . . . . . . . . . .  99
       8.2.178. CueTrack Element . . . . . . . . . . . . . . . . . .  99
       8.2.179. CueClusterPosition Element . . . . . . . . . . . . . 100
       8.2.180. CueRelativePosition Element  . . . . . . . . . . . . 100
       8.2.181. CueDuration Element  . . . . . . . . . . . . . . . . 101
       8.2.182. CueBlockNumber Element . . . . . . . . . . . . . . . 101
       8.2.183. CueCodecState Element  . . . . . . . . . . . . . . . 101
       8.2.184. CueReference Element . . . . . . . . . . . . . . . . 102
       8.2.185. CueRefTime Element . . . . . . . . . . . . . . . . . 102
       8.2.186. CueRefCluster Element  . . . . . . . . . . . . . . . 102
       8.2.187. CueRefNumber Element . . . . . . . . . . . . . . . . 103
       8.2.188. CueRefCodecState Element . . . . . . . . . . . . . . 103
       8.2.189. Attachments Element  . . . . . . . . . . . . . . . . 104
       8.2.190. AttachedFile Element . . . . . . . . . . . . . . . . 104
       8.2.191. FileDescription Element  . . . . . . . . . . . . . . 105
       8.2.192. FileName Element . . . . . . . . . . . . . . . . . . 105
       8.2.193. FileMimeType Element . . . . . . . . . . . . . . . . 105
       8.2.194. FileData Element . . . . . . . . . . . . . . . . . . 106
       8.2.195. FileUID Element  . . . . . . . . . . . . . . . . . . 106
       8.2.196. FileReferral Element . . . . . . . . . . . . . . . . 106
       8.2.197. FileUsedStartTime Element  . . . . . . . . . . . . . 107
       8.2.198. FileUsedEndTime Element  . . . . . . . . . . . . . . 107
       8.2.199. Chapters Element . . . . . . . . . . . . . . . . . . 108
       8.2.200. EditionEntry Element . . . . . . . . . . . . . . . . 108
       8.2.201. EditionUID Element . . . . . . . . . . . . . . . . . 108
       8.2.202. EditionFlagHidden Element  . . . . . . . . . . . . . 109
       8.2.203. EditionFlagDefault Element . . . . . . . . . . . . . 109
       8.2.204. EditionFlagOrdered Element . . . . . . . . . . . . . 110
       8.2.205. ChapterAtom Element  . . . . . . . . . . . . . . . . 110
       8.2.206. ChapterUID Element . . . . . . . . . . . . . . . . . 110
       8.2.207. ChapterStringUID Element . . . . . . . . . . . . . . 111
       8.2.208. ChapterTimeStart Element . . . . . . . . . . . . . . 111
       8.2.209. ChapterTimeEnd Element . . . . . . . . . . . . . . . 112
       8.2.210. ChapterFlagHidden Element  . . . . . . . . . . . . . 112
       8.2.211. ChapterFlagEnabled Element . . . . . . . . . . . . . 113
       8.2.212. ChapterSegmentUID Element  . . . . . . . . . . . . . 113
       8.2.213. ChapterSegmentEditionUID Element . . . . . . . . . . 114
       8.2.214. ChapterPhysicalEquiv Element . . . . . . . . . . . . 114
       8.2.215. ChapterTrack Element . . . . . . . . . . . . . . . . 114
       8.2.216. ChapterTrackNumber Element . . . . . . . . . . . . . 115
       8.2.217. ChapterDisplay Element . . . . . . . . . . . . . . . 115
       8.2.218. ChapString Element . . . . . . . . . . . . . . . . . 116
       8.2.219. ChapLanguage Element . . . . . . . . . . . . . . . . 116
       8.2.220. ChapLanguageIETF Element . . . . . . . . . . . . . . 116
       8.2.221. ChapCountry Element  . . . . . . . . . . . . . . . . 117
       8.2.222. ChapProcess Element  . . . . . . . . . . . . . . . . 117



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       8.2.223. ChapProcessCodecID Element . . . . . . . . . . . . . 118
       8.2.224. ChapProcessPrivate Element . . . . . . . . . . . . . 118
       8.2.225. ChapProcessCommand Element . . . . . . . . . . . . . 118
       8.2.226. ChapProcessTime Element  . . . . . . . . . . . . . . 119
       8.2.227. ChapProcessData Element  . . . . . . . . . . . . . . 119
       8.2.228. Tags Element . . . . . . . . . . . . . . . . . . . . 120
       8.2.229. Tag Element  . . . . . . . . . . . . . . . . . . . . 120
       8.2.230. Targets Element  . . . . . . . . . . . . . . . . . . 120
       8.2.231. TargetTypeValue Element  . . . . . . . . . . . . . . 121
       8.2.232. TargetType Element . . . . . . . . . . . . . . . . . 121
       8.2.233. TagTrackUID Element  . . . . . . . . . . . . . . . . 122
       8.2.234. TagEditionUID Element  . . . . . . . . . . . . . . . 122
       8.2.235. TagChapterUID Element  . . . . . . . . . . . . . . . 122
       8.2.236. TagAttachmentUID Element . . . . . . . . . . . . . . 123
       8.2.237. SimpleTag Element  . . . . . . . . . . . . . . . . . 123
       8.2.238. TagName Element  . . . . . . . . . . . . . . . . . . 123
       8.2.239. TagLanguage Element  . . . . . . . . . . . . . . . . 124
       8.2.240. TagLanguageIETF Element  . . . . . . . . . . . . . . 124
       8.2.241. TagDefault Element . . . . . . . . . . . . . . . . . 125
       8.2.242. TagString Element  . . . . . . . . . . . . . . . . . 125
       8.2.243. TagBinary Element  . . . . . . . . . . . . . . . . . 126
   9.  Matroska Element Ordering Guidelines  . . . . . . . . . . . . 126
     9.1.  Top-Level Elements  . . . . . . . . . . . . . . . . . . . 126
     9.2.  CRC-32  . . . . . . . . . . . . . . . . . . . . . . . . . 127
     9.3.  SeekHead  . . . . . . . . . . . . . . . . . . . . . . . . 127
     9.4.  Cues (index)  . . . . . . . . . . . . . . . . . . . . . . 127
     9.5.  Info  . . . . . . . . . . . . . . . . . . . . . . . . . . 127
     9.6.  Chapters  . . . . . . . . . . . . . . . . . . . . . . . . 128
     9.7.  Attachments . . . . . . . . . . . . . . . . . . . . . . . 128
     9.8.  Tags  . . . . . . . . . . . . . . . . . . . . . . . . . . 128
     9.9.  Optimum layout from a muxer . . . . . . . . . . . . . . . 128
     9.10. Optimum layout after editing tags . . . . . . . . . . . . 129
     9.11. Optimum layout with Cues at the front . . . . . . . . . . 129
     9.12. Cluster Timecode  . . . . . . . . . . . . . . . . . . . . 129
   10. Chapters  . . . . . . . . . . . . . . . . . . . . . . . . . . 130
     10.1.  Edition and Chapter Flags  . . . . . . . . . . . . . . . 130
       10.1.1.  Chapter Flags  . . . . . . . . . . . . . . . . . . . 130
       10.1.2.  Edition Flags  . . . . . . . . . . . . . . . . . . . 130
     10.2.  Menu features  . . . . . . . . . . . . . . . . . . . . . 132
       10.2.1.  Matroska Script (0)  . . . . . . . . . . . . . . . . 132
       10.2.2.  DVD menu (1) . . . . . . . . . . . . . . . . . . . . 133
     10.3.  Example 1 : basic chaptering . . . . . . . . . . . . . . 134
     10.4.  Example 2 : nested chapters  . . . . . . . . . . . . . . 136
       10.4.1.  The Micronauts "Bleep To Bleep"  . . . . . . . . . . 136
   11. Attachments . . . . . . . . . . . . . . . . . . . . . . . . . 139
     11.1.  Introduction . . . . . . . . . . . . . . . . . . . . . . 139
     11.2.  Cover Art  . . . . . . . . . . . . . . . . . . . . . . . 139
   12. Cues  . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140



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     12.1.  Introduction . . . . . . . . . . . . . . . . . . . . . . 140
     12.2.  Recommendations  . . . . . . . . . . . . . . . . . . . . 140
   13. Matroska Streaming  . . . . . . . . . . . . . . . . . . . . . 141
     13.1.  File Access  . . . . . . . . . . . . . . . . . . . . . . 141
     13.2.  Livestreaming  . . . . . . . . . . . . . . . . . . . . . 142
   14. Menu Specifications . . . . . . . . . . . . . . . . . . . . . 142
     14.1.  Introduction . . . . . . . . . . . . . . . . . . . . . . 142
     14.2.  Requirements . . . . . . . . . . . . . . . . . . . . . . 143
       14.2.1.  Highlights/Hotspots  . . . . . . . . . . . . . . . . 143
       14.2.2.  Playback features  . . . . . . . . . . . . . . . . . 144
       14.2.3.  Player requirements  . . . . . . . . . . . . . . . . 144
     14.3.  Working Graph  . . . . . . . . . . . . . . . . . . . . . 144
     14.4.  Ideas  . . . . . . . . . . . . . . . . . . . . . . . . . 145
     14.5.  Data Structure . . . . . . . . . . . . . . . . . . . . . 145
   15. Unknown elements  . . . . . . . . . . . . . . . . . . . . . . 145
   16. Default Values  . . . . . . . . . . . . . . . . . . . . . . . 145
   17. DefaultDecodedFieldDuration . . . . . . . . . . . . . . . . . 145
   18. Encryption  . . . . . . . . . . . . . . . . . . . . . . . . . 146
   19. Image cropping  . . . . . . . . . . . . . . . . . . . . . . . 147
   20. Matroska versioning . . . . . . . . . . . . . . . . . . . . . 147
   21. MIME Types  . . . . . . . . . . . . . . . . . . . . . . . . . 148
   22. Segment Position  . . . . . . . . . . . . . . . . . . . . . . 148
     22.1.  Segment Position Exception . . . . . . . . . . . . . . . 148
     22.2.  Example of Segment Position  . . . . . . . . . . . . . . 148
   23. Linked Segments . . . . . . . . . . . . . . . . . . . . . . . 149
     23.1.  Hard Linking . . . . . . . . . . . . . . . . . . . . . . 149
     23.2.  Medium Linking . . . . . . . . . . . . . . . . . . . . . 150
     23.3.  Soft Linking . . . . . . . . . . . . . . . . . . . . . . 150
   24. Track Flags . . . . . . . . . . . . . . . . . . . . . . . . . 151
     24.1.  Default flag . . . . . . . . . . . . . . . . . . . . . . 151
     24.2.  Forced flag  . . . . . . . . . . . . . . . . . . . . . . 151
     24.3.  Track Operation  . . . . . . . . . . . . . . . . . . . . 151
     24.4.  Overlay Track  . . . . . . . . . . . . . . . . . . . . . 152
     24.5.  Multi-planar and 3D videos . . . . . . . . . . . . . . . 152
   25. Timecodes . . . . . . . . . . . . . . . . . . . . . . . . . . 153
     25.1.  Timecode Types . . . . . . . . . . . . . . . . . . . . . 153
     25.2.  Block Timecodes  . . . . . . . . . . . . . . . . . . . . 153
     25.3.  Raw Timecode . . . . . . . . . . . . . . . . . . . . . . 153
     25.4.  TimecodeScale  . . . . . . . . . . . . . . . . . . . . . 153
     25.5.  TimecodeScale Rounding . . . . . . . . . . . . . . . . . 154
     25.6.  TrackTimecodeScale . . . . . . . . . . . . . . . . . . . 156
     26.1.  URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 157
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . . 158








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1.  Introduction

   Matroska aims to become THE standard of multimedia container formats.
   It was derived from a project called MCF [1], but differentiates from
   it significantly because it is based on EBML [2] (Extensible Binary
   Meta Language), a binary derivative of XML.  EBML enables significant
   advantages in terms of future format extensibility, without breaking
   file support in old parsers.

   First, it is essential to clarify exactly "What an Audio/Video
   container is", to avoid any misunderstandings:

   o  It is NOT a video or audio compression format (codec)

   o  It is an envelope for which there can be many audio, video and
      subtitles streams, allowing the user to store a complete movie or
      CD in a single file.

   Matroska is designed with the future in mind.  It incorporates
   features like:

   o  Fast seeking in the file

   o  Chapter entries

   o  Full metadata (tags) support

   o  Selectable subtitle/audio/video streams

   o  Modularly expandable

   o  Error resilience (can recover playback even when the stream is
      damaged)

   o  Streamable over the internet and local networks (HTTP, CIFS, FTP,
      etc)

   o  Menus (like DVDs have)

   Matroska is an open standards project.  This means for personal use
   it is absolutely free to use and that the technical specifications
   describing the bitstream are open to everybody, even to companies
   that would like to support it in their products.








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2.  Status of this document

   This document is a work-in-progress specification defining the
   Matroska file format as part of the IETF Cellar working group [3].
   But since it's quite complete it is used as a reference for the
   development of libmatroska.  Legacy versions of the specification can
   be found here [4] (PDF doc by Alexander Noe -- outdated).

   For a simplified diagram of the layout of a Matroska file, see the
   Diagram page [5].

   A more refined and detailed version of the EBML specifications is
   being worked on here [6].

   The table found below is now generated from the "source" of the
   Matroska specification.  This XML file [7] is also used to generate
   the semantic data used in libmatroska and libmatroska2.  We encourage
   anyone to use and monitor its changes so your code is spec-proof and
   always up to date.

   Note that versions 1, 2 and 3 have been finalized.  Version 4 is
   currently work in progress.  There MAY be further additions to v4.

3.  Security Considerations

   Matroska inherits security considerations from EBML.

   Attacks on a "Matroska Reader" could include:

   o  Storage of a arbitrary and potentially executable data within an
      "Attachment Element".  "Matroska Readers" that extract or use data
      from Matroska Attachments SHOULD check that the data adheres to
      expectations.

   o  A "Matroska Attachment" with an inaccurate mime-type.

4.  IANA Considerations

   To be determined.

5.  Notation and Conventions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [8].

   This document defines specific terms in order to define the format
   and application of "Matroska".  Specific terms are defined below:



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   "Matroska": a multimedia container format based on EBML (Extensible
   Binary Meta Language)

   "Matroska Reader": A "Matroska Reader" is a data parser that
   interprets the semantics of a Matroska document and creates a way for
   programs to use "Matroska".

   "Matroska Player": A "Matroska Player" is a "Matroska Reader" with a
   primary purpose of playing audiovisual files, including "Matroska"
   documents.

6.  Basis in EBML

   Matroska is a Document Type of EBML (Extensible Binary Meta
   Language).  This specification is dependent on the EBML Specification
   [9].  For an understanding of Matroska's EBML Schema, see in
   particular the sections of the EBML Specification covering EBML
   Element Types [10], EBML Schema [11], and EBML Structure [12].

6.1.  Added Constraints on EBML

   As an EBML Document Type, Matroska adds the following constraints to
   the EBML specification.

   o  The "docType" of the "EBML Header" MUST be 'matroska'.

   o  The "EBMLMaxIDLength" of the "EBML Header" MUST be "4".

   o  The "EBMLMaxSizeLength" of the "EBML Header" MUST be between "1"
      and "8" inclusive.

6.2.  Matroska Design

   All top-levels elements (Segment and direct sub-elements) are coded
   on 4 octets, i.e. class D elements.

6.2.1.  Language Codes

   Matroska from version 1 through 3 uses language codes that can be
   either the 3 letters bibliographic ISO-639-2 [13] form (like "fre"
   for french), or such a language code followed by a dash and a country
   code for specialities in languages (like "fre-ca" for Canadian
   French).  The "ISO 639-2 Language Elements" are "Language Element",
   "TagLanguage Element", and "ChapLanguage Element".

   Starting in Matroska version 4, either "ISO 639-2" or BCP 47 [14] MAY
   be used, although "BCP 47" is RECOMMENDED.  The "BCP 47 Language
   Elements" are "LanguageIETF Element", "TagLanguageIETF Element", and



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   "ChapLanguageIETF Element".  If a "BCP 47 Language Element" and an
   "ISO 639-2 Language Element" are used within the same "Parent
   Element", then the "ISO 639-2 Language Element" MUST be ignored and
   precedence given to the "BCP 47 Language Element".

   Country codes are the same as used for internet domains [15].

6.2.2.  Physical Types

   Each level can have different meanings for audio and video.  The
   ORIGINAL_MEDIUM tag can be used to specify a string for
   ChapterPhysicalEquiv = 60.  Here is the list of possible levels for
   both audio and video :

   +----------------------+--------------+-----------+-----------------+
   | ChapterPhysicalEquiv | Audio        | Video     | Comment         |
   +----------------------+--------------+-----------+-----------------+
   | 70                   | SET /        | SET /     | the collection  |
   |                      | PACKAGE      | PACKAGE   | of different    |
   |                      |              |           | media           |
   | 60                   | CD / 12" /   | DVD / VHS | the physical    |
   |                      | 10" / 7" /   | /         | medium like a   |
   |                      | TAPE /       | LASERDISC | CD or a DVD     |
   |                      | MINIDISC /   |           |                 |
   |                      | DAT          |           |                 |
   | 50                   | SIDE         | SIDE      | when the        |
   |                      |              |           | original medium |
   |                      |              |           | (LP/DVD) has    |
   |                      |              |           | different sides |
   | 40                   | -            | LAYER     | another         |
   |                      |              |           | physical level  |
   |                      |              |           | on DVDs         |
   | 30                   | SESSION      | SESSION   | as found on CDs |
   |                      |              |           | and DVDs        |
   | 20                   | TRACK        | -         | as found on     |
   |                      |              |           | audio CDs       |
   | 10                   | INDEX        | -         | the first       |
   |                      |              |           | logical level   |
   |                      |              |           | of the          |
   |                      |              |           | side/medium     |
   +----------------------+--------------+-----------+-----------------+

6.2.3.  Block Structure

   Size = 1 + (1-8) + 4 + (4 + (4)) octets.  So from 6 to 21 octets.

   Bit 0 is the most significant bit.




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   Frames using references SHOULD be stored in "coding order".  That
   means the references first and then the frames referencing them.  A
   consequence is that timecodes MAY NOT be consecutive.  But a frame
   with a past timecode MUST reference a frame already known, otherwise
   it's considered bad/void.

   There can be many Blocks in a BlockGroup provided they all have the
   same timecode.  It is used with different parts of a frame with
   different priorities.

6.2.3.1.  Block Header

   +--------+--------+-------------------------------------------------+
   | Offset | Player | Description                                     |
   +--------+--------+-------------------------------------------------+
   | 0x00+  | MUST   | Track Number (Track Entry). It is coded in EBML |
   |        |        | like form (1 octet if the value is < 0x80, 2 if |
   |        |        | < 0x4000, etc) (most significant bits set to    |
   |        |        | increase the range).                            |
   | 0x01+  | MUST   | Timecode (relative to Cluster timecode, signed  |
   |        |        | int16)                                          |
   +--------+--------+-------------------------------------------------+

6.2.3.2.  Block Header Flags

   +--------+-----+--------+-------------------------------------------+
   | Offset | Bit | Player | Description                               |
   +--------+-----+--------+-------------------------------------------+
   | 0x03+  | 0-3 | -      | Reserved, set to 0                        |
   | 0x03+  | 4   | -      | Invisible, the codec SHOULD decode this   |
   |        |     |        | frame but not display it                  |
   | 0x03+  | 5-6 | MUST   | Lacing                                    |
   |        |     |        | *   00 : no lacing                        |
   |        |     |        | *   01 : Xiph lacing                      |
   |        |     |        | *   11 : EBML lacing                      |
   |        |     |        | *   10 : fixed-size lacing                |
   | 0x03+  | 7   | -      | not used                                  |
   +--------+-----+--------+-------------------------------------------+

6.2.3.3.  Laced Data

   When lacing bit is set.









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   +--------+--------+-------------------------------------------------+
   | Offset | Player | Description                                     |
   +--------+--------+-------------------------------------------------+
   | 0x00   | MUST   | Number of frames in the lace-1 (uint8)          |
   | 0x01 / | MUST*  | Lace-coded size of each frame of the lace,      |
   | 0xXX   |        | except for the last one (multiple uint8). *This |
   |        |        | is not used with Fixed-size lacing as it is     |
   |        |        | calculated automatically from (total size of    |
   |        |        | lace) / (number of frames in lace).             |
   +--------+--------+-------------------------------------------------+

   For (possibly) Laced Data

              +--------+--------+--------------------------+
              | Offset | Player | Description              |
              +--------+--------+--------------------------+
              | 0x00   | MUST   | Consecutive laced frames |
              +--------+--------+--------------------------+

6.2.4.  Lacing

   Lacing is a mechanism to save space when storing data.  It is
   typically used for small blocks of data (referred to as frames in
   Matroska).  There are 3 types of lacing:

   1.  Xiph, inspired by what is found in the Ogg container

   2.  EBML, which is the same with sizes coded differently

   3.  fixed-size, where the size is not coded

   For example, a user wants to store 3 frames of the same track.  The
   first frame is 800 octets long, the second is 500 octets long and the
   third is 1000 octets long.  As these data are small, they can be
   stored in a lace to save space.  They will then be stored in the same
   block as follows:

6.2.4.1.  Xiph lacing

   o  Block head (with lacing bits set to 01)

   o  Lacing head: Number of frames in the lace -1, i.e. 2 (the 800 and
      500 octets one)

   o  Lacing sizes: only the 2 first ones will be coded, 800 gives
      255;255;255;35, 500 gives 255;245.  The size of the last frame is
      deduced from the total size of the Block.




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   o  Data in frame 1

   o  Data in frame 2

   o  Data in frame 3

   A frame with a size multiple of 255 is coded with a 0 at the end of
   the size, for example 765 is coded 255;255;255;0.

6.2.4.2.  EBML lacing

   In this case, the size is not coded as blocks of 255 bytes, but as a
   difference with the previous size and this size is coded as in EBML.
   The first size in the lace is unsigned as in EBML.  The others use a
   range shifting to get a sign on each value:

   +----------------------------------+--------------------------------+
   | Bit Representation               | Value                          |
   +----------------------------------+--------------------------------+
   | 1xxx xxxx                        | value -(2^6-1) to 2^6-1 (ie 0  |
   |                                  | to 2^7-2 minus 2^6-1, half of  |
   |                                  | the range)                     |
   | 01xx xxxx  xxxx xxxx             | value -(2^13-1) to 2^13-1      |
   | 001x xxxx  xxxx xxxx  xxxx xxxx  | value -(2^20-1) to 2^20-1      |
   | 0001 xxxx  xxxx xxxx  xxxx xxxx  | value -(2^27-1) to 2^27-1      |
   | xxxx xxxx                        |                                |
   | 0000 1xxx  xxxx xxxx  xxxx xxxx  | value -(2^34-1) to 2^34-1      |
   | xxxx xxxx  xxxx xxxx             |                                |
   | 0000 01xx  xxxx xxxx  xxxx xxxx  | value -(2^41-1) to 2^41-1      |
   | xxxx xxxx  xxxx xxxx  xxxx xxxx  |                                |
   | 0000 001x  xxxx xxxx  xxxx xxxx  | value -(2^48-1) to 2^48-1      |
   | xxxx xxxx  xxxx xxxx  xxxx xxxx  |                                |
   | xxxx xxxx                        |                                |
   +----------------------------------+--------------------------------+

   o  Block head (with lacing bits set to 11)

   o  Lacing head: Number of frames in the lace -1, i.e. 2 (the 800 and
      400 octets one)

   o  Lacing sizes: only the 2 first ones will be coded, 800 gives 0x320
      0x4000 = 0x4320, 500 is coded as -300 : - 0x12C + 0x1FFF + 0x4000
      = 0x5ED3.  The size of the last frame is deduced from the total
      size of the Block.

   o  Data in frame 1

   o  Data in frame 2



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   o  Data in frame 3

6.2.4.3.  Fixed-size lacing

   In this case, only the number of frames in the lace is saved, the
   size of each frame is deduced from the total size of the Block.  For
   example, for 3 frames of 800 octets each:

   o  Block head (with lacing bits set to 10)

   o  Lacing head: Number of frames in the lace -1, i.e. 2

   o  Data in frame 1

   o  Data in frame 2

   o  Data in frame 3

6.2.4.4.  SimpleBlock Structure

   The "SimpleBlock" is inspired by the Section 6.2.3.  The main
   differences are the added Keyframe flag and Discardable flag.
   Otherwise everything is the same.

   Size = 1 + (1-8) + 4 + (4 + (4)) octets.  So from 6 to 21 octets.

   Bit 0 is the most significant bit.

   Frames using references SHOULD be stored in "coding order".  That
   means the references first and then the frames referencing them.  A
   consequence is that timecodes MAY NOT be consecutive.  But a frame
   with a past timecode MUST reference a frame already known, otherwise
   it's considered bad/void.

   There can be many "Block Elements" in a "BlockGroup" provided they
   all have the same timecode.  It is used with different parts of a
   frame with different priorities.

6.2.4.4.1.  SimpleBlock Header












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   +--------+--------+-------------------------------------------------+
   | Offset | Player | Description                                     |
   +--------+--------+-------------------------------------------------+
   | 0x00+  | MUST   | Track Number (Track Entry). It is coded in EBML |
   |        |        | like form (1 octet if the value is < 0x80, 2 if |
   |        |        | < 0x4000, etc) (most significant bits set to    |
   |        |        | increase the range).                            |
   | 0x01+  | MUST   | Timecode (relative to Cluster timecode, signed  |
   |        |        | int16)                                          |
   +--------+--------+-------------------------------------------------+

6.2.4.4.2.  SimpleBlock Header Flags

   +--------+-----+--------+-------------------------------------------+
   | Offset | Bit | Player | Description                               |
   +--------+-----+--------+-------------------------------------------+
   | 0x03+  | 0   | -      | Keyframe, set when the Block contains     |
   |        |     |        | only keyframes                            |
   | 0x03+  | 1-3 | -      | Reserved, set to 0                        |
   | 0x03+  | 4   | -      | Invisible, the codec SHOULD decode this   |
   |        |     |        | frame but not display it                  |
   | 0x03+  | 5-6 | MUST   | Lacing                                    |
   |        |     |        | *   00 : no lacing                        |
   |        |     |        | *   01 : Xiph lacing                      |
   |        |     |        | *   11 : EBML lacing                      |
   |        |     |        | *   10 : fixed-size lacing                |
   | 0x03+  | 7   | -      | Discardable, the frames of the Block can  |
   |        |     |        | be discarded during playing if needed     |
   +--------+-----+--------+-------------------------------------------+

6.2.4.5.  Laced Data

   When lacing bit is set.

   +--------+--------+-------------------------------------------------+
   | Offset | Player | Description                                     |
   +--------+--------+-------------------------------------------------+
   | 0x00   | MUST   | Number of frames in the lace-1 (uint8)          |
   | 0x01 / | MUST*  | Lace-coded size of each frame of the lace,      |
   | 0xXX   |        | except for the last one (multiple uint8). *This |
   |        |        | is not used with Fixed-size lacing as it is     |
   |        |        | calculated automatically from (total size of    |
   |        |        | lace) / (number of frames in lace).             |
   +--------+--------+-------------------------------------------------+

   For (possibly) Laced Data





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              +--------+--------+--------------------------+
              | Offset | Player | Description              |
              +--------+--------+--------------------------+
              | 0x00   | MUST   | Consecutive laced frames |
              +--------+--------+--------------------------+

7.  Matroska Structure

   A Matroska file MUST be composed of at least one "EBML Document"
   using the "Matroska Document Type".  Each "EBML Document" MUST start
   with an "EBML Header" and MUST be followed by the "EBML Root
   Element", defined as "Segment" in Matroska.  Matroska defines several
   "Top Level Elements" which MAY occur within the "Segment".

   As an example, a simple Matroska file consisting of a single "EBML
   Document" could be represented like this:

   o  "EBML Header"

   o  "Segment"

   A more complex Matroska file consisting of an "EBML Stream"
   (consisting of two "EBML Documents") could be represented like this:

   o  "EBML Header"

   o  "Segment"

   o  "EBML Header"

   o  "Segment"

   The following diagram represents a simple Matroska file, comprised of
   an "EBML Document" with an "EBML Header", a "Segment Element" (the
   "Root Element"), and all eight Matroska "Top Level Elements".  In the
   following diagrams of this section, horizontal spacing expresses a
   parent-child relationship between Matroska Elements (e.g. the "Info
   Element" is contained within the "Segment Element") whereas vertical
   alignment represents the storage order within the file.












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                       +-------------+
                       | EBML Header |
                       +---------------------------+
                       | Segment     | SeekHead    |
                       |             |-------------|
                       |             | Info        |
                       |             |-------------|
                       |             | Tracks      |
                       |             |-------------|
                       |             | Chapters    |
                       |             |-------------|
                       |             | Cluster     |
                       |             |-------------|
                       |             | Cues        |
                       |             |-------------|
                       |             | Attachments |
                       |             |-------------|
                       |             | Tags        |
                       +---------------------------+

   The Matroska "EBML Schema" defines eight "Top Level Elements":
   "SeekHead", "Info", "Tracks", "Chapters", "Cluster", "Cues",
   "Attachments", and "Tags".

   The "SeekHead Element" (also known as "MetaSeek") contains an index
   of "Top Level Elements" locations within the "Segment".  Use of the
   "SeekHead Element" is RECOMMENDED.  Without a "SeekHead Element", a
   Matroska parser would have to search the entire file to find all of
   the other "Top Level Elements".  This is due to Matroska's flexible
   ordering requirements; for instance, it is acceptable for the
   "Chapters Element" to be stored after the "Cluster Elements".

                    +--------------------------------+
                    | SeekHead | Seek | SeekID       |
                    |          |      |--------------|
                    |          |      | SeekPosition |
                    +--------------------------------+

                   Representation of a SeekHead Element.

   The "Info Element" contains vital information for identifying the
   whole "Segment".  This includes the title for the "Segment", a
   randomly generated unique identifier, and the unique identifier(s) of
   any linked "Segment Elements".







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                        +-------------------------+
                        | Info | SegmentUID       |
                        |      |------------------|
                        |      | SegmentFilename  |
                        |      |------------------|
                        |      | PrevUID          |
                        |      |------------------|
                        |      | PrevFilename     |
                        |      |------------------|
                        |      | NextUID          |
                        |      |------------------|
                        |      | NextFilename     |
                        |      |------------------|
                        |      | SegmentFamily    |
                        |      |------------------|
                        |      | ChapterTranslate |
                        |      |------------------|
                        |      | TimecodeScale    |
                        |      |------------------|
                        |      | Duration         |
                        |      |------------------|
                        |      | DateUTC          |
                        |      |------------------|
                        |      | Title            |
                        |      |------------------|
                        |      | MuxingApp        |
                        |      |------------------|
                        |      | WritingApp       |
                        |-------------------------|

         Representation of an Info Element and its Child Elements.

   The "Tracks Element" defines the technical details for each track and
   can store the name, number, unique identifier, language and type
   (audio, video, subtitles, etc.) of each track.  For example, the
   "Tracks Element" MAY store information about the resolution of a
   video track or sample rate of an audio track.

   The "Tracks Element" MUST identify all the data needed by the codec
   to decode the data of the specified track.  However, the data
   required is contingent on the codec used for the track.  For example,
   a "Track Element" for uncompressed audio only requires the audio bit
   rate to be present.  A codec such as AC-3 would require that the
   "CodecID Element" be present for all tracks, as it is the primary way
   to identify which codec to use to decode the track.






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        +------------------------------------+
        | Tracks | TrackEntry | TrackNumber  |
        |        |            |--------------|
        |        |            | TrackUID     |
        |        |            |--------------|
        |        |            | TrackType    |
        |        |            |--------------|
        |        |            | Name         |
        |        |            |--------------|
        |        |            | Language     |
        |        |            |--------------|
        |        |            | CodecID      |
        |        |            |--------------|
        |        |            | CodecPrivate |
        |        |            |--------------|
        |        |            | CodecName    |
        |        |            |----------------------------------+
        |        |            | Video        | FlagInterlaced    |
        |        |            |              |-------------------|
        |        |            |              | FieldOrder        |
        |        |            |              |-------------------|
        |        |            |              | StereoMode        |
        |        |            |              |-------------------|
        |        |            |              | AlphaMode         |
        |        |            |              |-------------------|
        |        |            |              | PixelWidth        |
        |        |            |              |-------------------|
        |        |            |              | PixelHeight       |
        |        |            |              |-------------------|
        |        |            |              | DisplayWidth      |
        |        |            |              |-------------------|
        |        |            |              | DisplayHeight     |
        |        |            |              |-------------------|
        |        |            |              | AspectRatioType   |
        |        |            |              |-------------------|
        |        |            |              | Color             |
        |        |            |----------------------------------|
        |        |            | Audio        | SamplingFrequency |
        |        |            |              |-------------------|
        |        |            |              | Channels          |
        |        |            |              |-------------------|
        |        |            |              | BitDepth          |
        |--------------------------------------------------------|


        Representation of the Tracks Element and a selection of its
                           Descendant Elements.




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   The "Chapters Element" lists all of the chapters.  Chapters are a way
   to set predefined points to jump to in video or audio.

  +-----------------------------------------+
  | Chapters | Edition | EditionUID         |
  |          | Entry   |--------------------|
  |          |         | EditionFlagHidden  |
  |          |         |--------------------|
  |          |         | EditionFlagDefault |
  |          |         |--------------------|
  |          |         | EditionFlagOrdered |
  |          |         |--------------------------------+
  |          |         | ChapterAtom | ChapterUID       |
  |          |         |             |------------------|
  |          |         |             | ChapterStringUID |
  |          |         |             |------------------|
  |          |         |             | ChapterTimeStart |
  |          |         |             |------------------|
  |          |         |             | ChapterTimeEnd   |
  |          |         |             |------------------|
  |          |         |             | ChapterFlagHidden |
  |          |         |             |---------------------------------+
  |          |         |             | ChapterDisplay   | ChapString   |
  |          |         |             |                  |--------------|
  |          |         |             |                  | ChapLanguage |
  +--------------------------------------------------------------------+

       Representation of the Chapters Element and a selection of its
                           Descendant Elements.

   "Cluster Elements" contain the content for each track, e.g. video
   frames.  A Matroska file SHOULD contain at least one "Cluster
   Element".  The "Cluster Element" helps to break up "SimpleBlock" or
   "BlockGroup Elements" and helps with seeking and error protection.
   It is RECOMMENDED that the size of each individual "Cluster Element"
   be limited to store no more than 5 seconds or 5 megabytes.  Every
   "Cluster Element" MUST contain a "Timecode Element".  This SHOULD be
   the "Timecode Element" used to play the first "Block" in the "Cluster
   Element".  There SHOULD be one or more "BlockGroup" or "SimpleBlock
   Element" in each "Cluster Element".  A "BlockGroup Element" MAY
   contain a "Block" of data and any information relating directly to
   that "Block".









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                       +--------------------------+
                       | Cluster | Timecode       |
                       |         |----------------|
                       |         | SilentTracks   |
                       |         |----------------|
                       |         | Position       |
                       |         |----------------|
                       |         | PrevSize       |
                       |         |----------------|
                       |         | SimpleBlock    |
                       |         |----------------|
                       |         | BlockGroup     |
                       |         |----------------|
                       |         | EncryptedBlock |
                       +--------------------------+

   Representation of a Cluster Element and its immediate Child Elements.

                   +----------------------------------+
                   | Block | Portion of | Data Type   |
                   |       | a Block    |  - Bit Flag |
                   |       |--------------------------+
                   |       | Header     | TrackNumber |
                   |       |            |-------------|
                   |       |            | Timecode    |
                   |       |            |-------------|
                   |       |            | Flags       |
                   |       |            |  - Gap      |
                   |       |            |  - Lacing   |
                   |       |            |  - Reserved |
                   |       |--------------------------|
                   |       | Optional   | FrameSize   |
                   |       |--------------------------|
                   |       | Data       | Frame       |
                   +----------------------------------+

              Representation of the Block Element structure.

   Each "Cluster" MUST contain exactly one "Timecode Element".  The
   "Timecode Element" value MUST be stored once per "Cluster".  The
   "Timecode Element" in the "Cluster" is relative to the entire
   "Segment".  The "Timecode Element" SHOULD be the first "Element" in
   the "Cluster".

   Additionally, the "Block" contains an offset that, when added to the
   "Cluster"'s "Timecode Element" value, yields the "Block"'s effective
   timecode.  Therefore, timecode in the "Block" itself is relative to
   the "Timecode Element" in the "Cluster".  For example, if the



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   "Timecode Element" in the "Cluster" is set to 10 seconds and a
   "Block" in that "Cluster" is supposed to be played 12 seconds into
   the clip, the timecode in the "Block" would be set to 2 seconds.

   The "ReferenceBlock" in the "BlockGroup" is used instead of the basic
   "P-frame"/"B-frame" description.  Instead of simply saying that this
   "Block" depends on the "Block" directly before, or directly
   afterwards, the "Timecode" of the necessary "Block" is used.  Because
   there can be as many "ReferenceBlock Elements" as necessary for a
   "Block", it allows for some extremely complex referencing.

   The "Cues Element" is used to seek when playing back a file by
   providing a temporal index for some of the "Tracks".  It is similar
   to the "SeekHead Element", but used for seeking to a specific time
   when playing back the file.  It is possible to seek without this
   element, but it is much more difficult because a "Matroska Reader"
   would have to 'hunt and peck' through the file looking for the
   correct timecode.

   The "Cues Element" SHOULD contain at least one "CuePoint Element".
   Each "CuePoint Element" stores the position of the "Cluster" that
   contains the "BlockGroup" or "SimpleBlock Element".  The timecode is
   stored in the "CueTime Element" and location is stored in the
   "CueTrackPositions Element".

   The "Cues Element" is flexible.  For instance, "Cues Element" can be
   used to index every single timecode of every "Block" or they can be
   indexed selectively.  For video files, it is RECOMMENDED to index at
   least the keyframes of the video track.

                  +-------------------------------------+
                  | Cues | CuePoint | CueTime           |
                  |      |          |-------------------|
                  |      |          | CueTrackPositions |
                  |      |------------------------------|
                  |      | CuePoint | CueTime           |
                  |      |          |-------------------|
                  |      |          | CueTrackPositions |
                  +-------------------------------------+

     Representation of a Cues Element and two levels of its Descendant
                                 Elements.

   The "Attachments Element" is for attaching files to a Matroska file
   such as pictures, webpages, programs, or even the codec needed to
   play back the file.





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            +------------------------------------------------+
            | Attachments | AttachedFile | FileDescription   |
            |             |              |-------------------|
            |             |              | FileName          |
            |             |              |-------------------|
            |             |              | FileMimeType      |
            |             |              |-------------------|
            |             |              | FileData          |
            |             |              |-------------------|
            |             |              | FileUID           |
            |             |              |-------------------|
            |             |              | FileName          |
            |             |              |-------------------|
            |             |              | FileReferral      |
            |             |              |-------------------|
            |             |              | FileUsedStartTime |
            |             |              |-------------------|
            |             |              | FileUsedEndTime   |
            +------------------------------------------------+

                 Representation of a Attachments Element.

   The "Tags Element" contains metadata that describes the "Segment" and
   potentially its "Tracks", "Chapters", and "Attachments".  Each
   "Track" or "Chapter" that those tags applies to has its UID listed in
   the "Tags".  The "Tags" contain all extra information about the file:
   scriptwriter, singer, actors, directors, titles, edition, price,
   dates, genre, comments, etc.  Tags can contain their values in
   multiple languages.  For example, a movie's "title" "Tag" might
   contain both the original English title as well as the title it was
   released as in Germany.




















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               +-------------------------------------------+
               | Tags | Tag | Targets   | TargetTypeValue  |
               |      |     |           |------------------|
               |      |     |           | TargetType       |
               |      |     |           |------------------|
               |      |     |           | TagTrackUID      |
               |      |     |           |------------------|
               |      |     |           | TagEditionUID    |
               |      |     |           |------------------|
               |      |     |           | TagChapterUID    |
               |      |     |           |------------------|
               |      |     |           | TagAttachmentUID |
               |      |     |------------------------------|
               |      |     | SimpleTag | TagName          |
               |      |     |           |------------------|
               |      |     |           | TagLanguage      |
               |      |     |           |------------------|
               |      |     |           | TagDefault       |
               |      |     |           |------------------|
               |      |     |           | TagString        |
               |      |     |           |------------------|
               |      |     |           | TagBinary        |
               |      |     |           |------------------|
               |      |     |           | SimpleTag        |
               +-------------------------------------------+

     Representation of a Tags Element and three levels of its Children
                                 Elements.

8.  Matroska Schema

   This specification includes an "EBML Schema" which defines the
   Elements and structure of Matroska as an EBML Document Type.  The
   EBML Schema defines every valid Matroska element in a manner defined
   by the EBML specification.

8.1.  Matroska Additions to Schema Element Attributes

   In addition to the EBML Schema definition provided by the EBML
   Specification, Matroska adds the following additional attributes:











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   +-----------+----------+--------------------------------------------+
   | attribute | required | definition                                 |
   | name      |          |                                            |
   +-----------+----------+--------------------------------------------+
   | webm      | No       | A boolean to express if the Matroska       |
   |           |          | Element is also supported within version 2 |
   |           |          | of the "webm" specification. Please        |
   |           |          | consider the webm specification [16] as    |
   |           |          | the authoritative on "webm".               |
   +-----------+----------+--------------------------------------------+

8.2.  Matroska Schema

   Here the definition of each Matroska Element is provided.

   % concatenate with Matroska EBML Schema converted to markdown %

8.2.1.  EBMLMaxIDLength Element

   name: "EBMLMaxIDLength"

   path: "1*1(\EBML\EBMLMaxIDLength)"

   id: "0x42F2"

   minOccurs: "1"

   maxOccurs: "1"

   range: "4"

   default: "4"

   type: "uinteger"

8.2.2.  EBMLMaxSizeLength Element

   name: "EBMLMaxSizeLength"

   path: "1*1(\EBML\EBMLMaxSizeLength)"

   id: "0x42F3"

   minOccurs: "1"

   maxOccurs: "1"

   range: "1-8"



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   default: "8"

   type: "uinteger"

8.2.3.  Segment Element

   name: "Segment"

   path: "1*1(\Segment)"

   id: "0x18538067"

   minOccurs: "1"

   maxOccurs: "1"

   type: "master"

   unknownsizeallowed: "1"

   minver: "1"

   documentation: The Root Element that contains all other Top-Level
   Elements (Elements defined only at Level 1).  A Matroska file is
   composed of 1 Segment.

8.2.4.  SeekHead Element

   name: "SeekHead"

   path: "0*2(\Segment\SeekHead)"

   id: "0x114D9B74"

   maxOccurs: "2"

   type: "master"

   minver: "1"

   documentation: Contains the Segment Position of other Top-Level
   Elements.

8.2.5.  Seek Element

   name: "Seek"

   path: "1*(\Segment\SeekHead\Seek)"



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   id: "0x4DBB"

   minOccurs: "1"

   type: "master"

   minver: "1"

   documentation: Contains a single seek entry to an EBML Element.

8.2.6.  SeekID Element

   name: "SeekID"

   path: "1*1(\Segment\SeekHead\Seek\SeekID)"

   id: "0x53AB"

   minOccurs: "1"

   maxOccurs: "1"

   type: "binary"

   minver: "1"

   documentation: The binary ID corresponding to the Element name.

8.2.7.  SeekPosition Element

   name: "SeekPosition"

   path: "1*1(\Segment\SeekHead\Seek\SeekPosition)"

   id: "0x53AC"

   minOccurs: "1"

   maxOccurs: "1"

   type: "uinteger"

   minver: "1"

   documentation: The Segment Position of the Element.






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8.2.8.  Info Element

   name: "Info"

   path: "1*(\Segment\Info)"

   id: "0x1549A966"

   minOccurs: "1"

   type: "master"

   minver: "1"

   definition: Contains general information about the Segment.

8.2.9.  SegmentUID Element

   name: "SegmentUID"

   path: "0*1(\Segment\Info\SegmentUID)"

   id: "0x73A4"

   maxOccurs: "1"

   range: "not 0"

   size: "16"

   type: "binary"

   minver: "1"

   definition: A randomly generated unique ID to identify the Segment
   amongst many others (128 bits).

   usage notes: If the Segment is a part of a Linked Segment then this
   Element is REQUIRED.

8.2.10.  SegmentFilename Element

   name: "SegmentFilename"

   path: "0*1(\Segment\Info\SegmentFilename)"

   id: "0x7384"




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   maxOccurs: "1"

   type: "utf-8"

   minver: "1"

   definition: A filename corresponding to this Segment.

8.2.11.  PrevUID Element

   name: "PrevUID"

   path: "0*1(\Segment\Info\PrevUID)"

   id: "0x3CB923"

   maxOccurs: "1"

   size: "16"

   type: "binary"

   minver: "1"

   definition: A unique ID to identify the previous Segment of a Linked
   Segment (128 bits).

   usage notes: If the Segment is a part of a Linked Segment that uses
   Hard Linking then either the PrevUID or the NextUID Element is
   REQUIRED.  If a Segment contains a PrevUID but not a NextUID then it
   MAY be considered as the last Segment of the Linked Segment.  The
   PrevUID MUST NOT be equal to the SegmentUID.

8.2.12.  PrevFilename Element

   name: "PrevFilename"

   path: "0*1(\Segment\Info\PrevFilename)"

   id: "0x3C83AB"

   maxOccurs: "1"

   type: "utf-8"

   minver: "1"





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   definition: A filename corresponding to the file of the previous
   Linked Segment.

   usage notes: Provision of the previous filename is for display
   convenience, but PrevUID SHOULD be considered authoritative for
   identifying the previous Segment in a Linked Segment.

8.2.13.  NextUID Element

   name: "NextUID"

   path: "0*1(\Segment\Info\NextUID)"

   id: "0x3EB923"

   maxOccurs: "1"

   size: "16"

   type: "binary"

   minver: "1"

   definition: A unique ID to identify the next Segment of a Linked
   Segment (128 bits).

   usage notes: If the Segment is a part of a Linked Segment that uses
   Hard Linking then either the PrevUID or the NextUID Element is
   REQUIRED.  If a Segment contains a NextUID but not a PrevUID then it
   MAY be considered as the first Segment of the Linked Segment.  The
   NextUID MUST NOT be equal to the SegmentUID.

8.2.14.  NextFilename Element

   name: "NextFilename"

   path: "0*1(\Segment\Info\NextFilename)"

   id: "0x3E83BB"

   maxOccurs: "1"

   type: "utf-8"

   minver: "1"

   definition: A filename corresponding to the file of the next Linked
   Segment.



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   usage notes: Provision of the next filename is for display
   convenience, but NextUID SHOULD be considered authoritative for
   identifying the Next Segment.

8.2.15.  SegmentFamily Element

   name: "SegmentFamily"

   path: "0*(\Segment\Info\SegmentFamily)"

   id: "0x4444"

   size: "16"

   type: "binary"

   minver: "1"

   definition: A randomly generated unique ID that all Segments of a
   Linked Segment MUST share (128 bits).

   usage notes: If the Segment is a part of a Linked Segment that uses
   Soft Linking then this Element is REQUIRED.

8.2.16.  ChapterTranslate Element

   name: "ChapterTranslate"

   path: "0*(\Segment\Info\ChapterTranslate)"

   id: "0x6924"

   type: "master"

   minver: "1"

   documentation: A tuple of corresponding ID used by chapter codecs to
   represent this Segment.

8.2.17.  ChapterTranslateEditionUID Element

   name: "ChapterTranslateEditionUID"

   path: "0*(\Segment\Info\ChapterTranslate\ChapterTranslateEditionUID)"

   id: "0x69FC"

   type: "uinteger"



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   minver: "1"

   documentation: Specify an edition UID on which this correspondance
   applies.  When not specified, it means for all editions found in the
   Segment.

8.2.18.  ChapterTranslateCodec Element

   name: "ChapterTranslateCodec"

   path: "1*1(\Segment\Info\ChapterTranslate\ChapterTranslateCodec)"

   id: "0x69BF"

   minOccurs: "1"

   maxOccurs: "1"

   type: "uinteger"

   minver: "1"

   documentation: The chapter codec

8.2.19.  ChapterTranslateID Element

   name: "ChapterTranslateID"

   path: "1*1(\Segment\Info\ChapterTranslate\ChapterTranslateID)"

   id: "0x69A5"

   minOccurs: "1"

   maxOccurs: "1"

   type: "binary"

   minver: "1"

   documentation: The binary value used to represent this Segment in the
   chapter codec data.  The format depends on the ChapProcessCodecID
   used.








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8.2.20.  TimecodeScale Element

   name: "TimecodeScale"

   path: "1*1(\Segment\Info\TimecodeScale)"

   id: "0x2AD7B1"

   minOccurs: "1"

   maxOccurs: "1"

   range: "not 0"

   default: "1000000"

   type: "uinteger"

   minver: "1"

   documentation: Timestamp scale in nanoseconds (1.000.000 means all
   timestamps in the Segment are expressed in milliseconds).

8.2.21.  Duration Element

   name: "Duration"

   path: "0*1(\Segment\Info\Duration)"

   id: "0x4489"

   maxOccurs: "1"

   range: "> 0x0p+0"

   type: "float"

   minver: "1"

   definition: Duration of the Segment in nanoseconds based on
   TimecodeScale.

8.2.22.  DateUTC Element

   name: "DateUTC"

   path: "0*1(\Segment\Info\DateUTC)"




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   id: "0x4461"

   maxOccurs: "1"

   type: "date"

   minver: "1"

   documentation: The date and time that the Segment was created by the
   muxing application or library.

8.2.23.  Title Element

   name: "Title"

   path: "0*1(\Segment\Info\Title)"

   id: "0x7BA9"

   maxOccurs: "1"

   type: "utf-8"

   minver: "1"

   documentation: General name of the Segment.

8.2.24.  MuxingApp Element

   name: "MuxingApp"

   path: "1*1(\Segment\Info\MuxingApp)"

   id: "0x4D80"

   minOccurs: "1"

   maxOccurs: "1"

   type: "utf-8"

   minver: "1"

   definition: Muxing application or library (example: "libmatroska-
   0.4.3").

   usage notes: Include the full name of the application or library
   followed by the version number.



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8.2.25.  WritingApp Element

   name: "WritingApp"

   path: "1*1(\Segment\Info\WritingApp)"

   id: "0x5741"

   minOccurs: "1"

   maxOccurs: "1"

   type: "utf-8"

   minver: "1"

   definition: Writing application (example: "mkvmerge-0.3.3").

   usage notes: Include the full name of the application followed by the
   version number.

8.2.26.  Cluster Element

   name: "Cluster"

   path: "0*(\Segment\Cluster)"

   id: "0x1F43B675"

   type: "master"

   unknownsizeallowed: "1"

   minver: "1"

   documentation: The Top-Level Element containing the (monolithic)
   Block structure.

8.2.27.  Timecode Element

   name: "Timecode"

   path: "1*1(\Segment\Cluster\Timecode)"

   id: "0xE7"

   minOccurs: "1"




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   maxOccurs: "1"

   type: "uinteger"

   minver: "1"

   documentation: Absolute timestamp of the cluster (based on
   TimecodeScale).

8.2.28.  SilentTracks Element

   name: "SilentTracks"

   path: "0*1(\Segment\Cluster\SilentTracks)"

   id: "0x5854"

   maxOccurs: "1"

   type: "master"

   minver: "1"

   documentation: The list of tracks that are not used in that part of
   the stream.  It is useful when using overlay tracks on seeking or to
   decide what track to use.

8.2.29.  SilentTrackNumber Element

   name: "SilentTrackNumber"

   path: "0*(\Segment\Cluster\SilentTracks\SilentTrackNumber)"

   id: "0x58D7"

   type: "uinteger"

   minver: "1"

   documentation: One of the track number that are not used from now on
   in the stream.  It could change later if not specified as silent in a
   further Cluster.

8.2.30.  Position Element

   name: "Position"

   path: "0*1(\Segment\Cluster\Position)"



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   id: "0xA7"

   maxOccurs: "1"

   type: "uinteger"

   minver: "1"

   documentation: The Segment Position of the Cluster in the Segment (0
   in live broadcast streams).  It might help to resynchronise offset on
   damaged streams.

8.2.31.  PrevSize Element

   name: "PrevSize"

   path: "0*1(\Segment\Cluster\PrevSize)"

   id: "0xAB"

   maxOccurs: "1"

   type: "uinteger"

   minver: "1"

   documentation: Size of the previous Cluster, in octets.  Can be
   useful for backward playing.

8.2.32.  SimpleBlock Element

   name: "SimpleBlock"

   path: "0*(\Segment\Cluster\SimpleBlock)"

   id: "0xA3"

   type: "binary"

   minver: "2"

   documentation: Similar to Block but without all the extra
   information, mostly used to reduced overhead when no extra feature is
   needed. (see SimpleBlock Structure)







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8.2.33.  BlockGroup Element

   name: "BlockGroup"

   path: "0*(\Segment\Cluster\BlockGroup)"

   id: "0xA0"

   type: "master"

   minver: "1"

   documentation: Basic container of information containing a single
   Block and information specific to that Block.

8.2.34.  Block Element

   name: "Block"

   path: "1*1(\Segment\Cluster\BlockGroup\Block)"

   id: "0xA1"

   minOccurs: "1"

   maxOccurs: "1"

   type: "binary"

   minver: "1"

   documentation: Block containing the actual data to be rendered and a
   timestamp relative to the Cluster Timecode. (see Block Structure)

8.2.35.  BlockVirtual Element

   name: "BlockVirtual"

   path: "0*1(\Segment\Cluster\BlockGroup\BlockVirtual)"

   id: "0xA2"

   maxOccurs: "1"

   type: "binary"

   minver: "0"




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   maxver: "0"

   documentation: A Block with no data.  It MUST be stored in the stream
   at the place the real Block would be in display order. (see Block
   Virtual)

8.2.36.  BlockAdditions Element

   name: "BlockAdditions"

   path: "0*1(\Segment\Cluster\BlockGroup\BlockAdditions)"

   id: "0x75A1"

   maxOccurs: "1"

   type: "master"

   minver: "1"

   documentation: Contain additional blocks to complete the main one.
   An EBML parser that has no knowledge of the Block structure could
   still see and use/skip these data.

8.2.37.  BlockMore Element

   name: "BlockMore"

   path: "1*(\Segment\Cluster\BlockGroup\BlockAdditions\BlockMore)"

   id: "0xA6"

   minOccurs: "1"

   type: "master"

   minver: "1"

   documentation: Contain the BlockAdditional and some parameters.

8.2.38.  BlockAddID Element

   name: "BlockAddID"

   path: "1*1(\Segment\Cluster\BlockGroup\BlockAdditions\BlockMore\Block
   AddID)"

   id: "0xEE"



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   minOccurs: "1"

   maxOccurs: "1"

   range: "not 0"

   default: "1"

   type: "uinteger"

   minver: "1"

   documentation: An ID to identify the BlockAdditional level.

8.2.39.  BlockAdditional Element

   name: "BlockAdditional"

   path: "1*1(\Segment\Cluster\BlockGroup\BlockAdditions\BlockMore\Block
   Additional)"

   id: "0xA5"

   minOccurs: "1"

   maxOccurs: "1"

   type: "binary"

   minver: "1"

   documentation: Interpreted by the codec as it wishes (using the
   BlockAddID).

8.2.40.  BlockDuration Element

   name: "BlockDuration"

   path: "0*1(\Segment\Cluster\BlockGroup\BlockDuration)"

   id: "0x9B"

   maxOccurs: "1"

   default: "DefaultDuration"

   type: "uinteger"




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   minver: "1"

   documentation: The duration of the Block (based on TimecodeScale).
   This Element is mandatory when DefaultDuration is set for the track
   (but can be omitted as other default values).  When not written and
   with no DefaultDuration, the value is assumed to be the difference
   between the timestamp of this Block and the timestamp of the next
   Block in "display" order (not coding order).  This Element can be
   useful at the end of a Track (as there is not other Block available),
   or when there is a break in a track like for subtitle tracks.

8.2.41.  ReferencePriority Element

   name: "ReferencePriority"

   path: "1*1(\Segment\Cluster\BlockGroup\ReferencePriority)"

   id: "0xFA"

   minOccurs: "1"

   maxOccurs: "1"

   default: "0"

   type: "uinteger"

   minver: "1"

   documentation: This frame is referenced and has the specified cache
   priority.  In cache only a frame of the same or higher priority can
   replace this frame.  A value of 0 means the frame is not referenced.

8.2.42.  ReferenceBlock Element

   name: "ReferenceBlock"

   path: "0*(\Segment\Cluster\BlockGroup\ReferenceBlock)"

   id: "0xFB"

   type: "integer"

   minver: "1"

   documentation: Timestamp of another frame used as a reference (ie: B
   or P frame).  The timestamp is relative to the block it's attached
   to.



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8.2.43.  ReferenceVirtual Element

   name: "ReferenceVirtual"

   path: "0*1(\Segment\Cluster\BlockGroup\ReferenceVirtual)"

   id: "0xFD"

   maxOccurs: "1"

   type: "integer"

   minver: "0"

   maxver: "0"

   documentation: The Segment Position of the data that would otherwise
   be in position of the virtual block.

8.2.44.  CodecState Element

   name: "CodecState"

   path: "0*1(\Segment\Cluster\BlockGroup\CodecState)"

   id: "0xA4"

   maxOccurs: "1"

   type: "binary"

   minver: "2"

   documentation: The new codec state to use.  Data interpretation is
   private to the codec.  This information SHOULD always be referenced
   by a seek entry.

8.2.45.  DiscardPadding Element

   name: "DiscardPadding"

   path: "0*1(\Segment\Cluster\BlockGroup\DiscardPadding)"

   id: "0x75A2"

   maxOccurs: "1"

   type: "integer"



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   minver: "4"

   documentation: Duration in nanoseconds of the silent data added to
   the Block (padding at the end of the Block for positive value, at the
   beginning of the Block for negative value).  The duration of
   DiscardPadding is not calculated in the duration of the TrackEntry
   and SHOULD be discarded during playback.

8.2.46.  Slices Element

   name: "Slices"

   path: "0*1(\Segment\Cluster\BlockGroup\Slices)"

   id: "0x8E"

   maxOccurs: "1"

   type: "master"

   minver: "1"

   documentation: Contains slices description.

8.2.47.  TimeSlice Element

   name: "TimeSlice"

   path: "0*(\Segment\Cluster\BlockGroup\Slices\TimeSlice)"

   id: "0xE8"

   type: "master"

   minver: "1"

   maxver: "1"

   documentation: Contains extra time information about the data
   contained in the Block.  Being able to interpret this Element is not
   REQUIRED for playback.

8.2.48.  LaceNumber Element

   name: "LaceNumber"

   path: "0*1(\Segment\Cluster\BlockGroup\Slices\TimeSlice\LaceNumber)"




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   id: "0xCC"

   maxOccurs: "1"

   default: "0"

   type: "uinteger"

   minver: "1"

   maxver: "1"

   documentation: The reverse number of the frame in the lace (0 is the
   last frame, 1 is the next to last, etc).  Being able to interpret
   this Element is not REQUIRED for playback.

8.2.49.  FrameNumber Element

   name: "FrameNumber"

   path: "0*1(\Segment\Cluster\BlockGroup\Slices\TimeSlice\FrameNumber)"

   id: "0xCD"

   maxOccurs: "1"

   default: "0"

   type: "uinteger"

   minver: "0"

   maxver: "0"

   documentation: The number of the frame to generate from this lace
   with this delay (allow you to generate many frames from the same
   Block/Frame).

8.2.50.  BlockAdditionID Element

   name: "BlockAdditionID"

   path:
   "0*1(\Segment\Cluster\BlockGroup\Slices\TimeSlice\BlockAdditionID)"

   id: "0xCB"

   maxOccurs: "1"



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   default: "0"

   type: "uinteger"

   minver: "0"

   maxver: "0"

   documentation: The ID of the BlockAdditional Element (0 is the main
   Block).

8.2.51.  Delay Element

   name: "Delay"

   path: "0*1(\Segment\Cluster\BlockGroup\Slices\TimeSlice\Delay)"

   id: "0xCE"

   maxOccurs: "1"

   default: "0"

   type: "uinteger"

   minver: "0"

   maxver: "0"

   documentation: The (scaled) delay to apply to the Element.

8.2.52.  SliceDuration Element

   name: "SliceDuration"

   path:
   "0*1(\Segment\Cluster\BlockGroup\Slices\TimeSlice\SliceDuration)"

   id: "0xCF"

   maxOccurs: "1"

   default: "0"

   type: "uinteger"

   minver: "0"




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   maxver: "0"

   documentation: The (scaled) duration to apply to the Element.

8.2.53.  ReferenceFrame Element

   name: "ReferenceFrame"

   path: "0*1(\Segment\Cluster\BlockGroup\ReferenceFrame)"

   id: "0xC8"

   maxOccurs: "1"

   type: "master"

   minver: "0"

   maxver: "0"

   documentation: DivX trick track extensions

8.2.54.  ReferenceOffset Element

   name: "ReferenceOffset"

   path:
   "1*1(\Segment\Cluster\BlockGroup\ReferenceFrame\ReferenceOffset)"

   id: "0xC9"

   minOccurs: "1"

   maxOccurs: "1"

   type: "uinteger"

   minver: "0"

   maxver: "0"

   documentation: DivX trick track extensions

8.2.55.  ReferenceTimeCode Element

   name: "ReferenceTimeCode"





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   path:
   "1*1(\Segment\Cluster\BlockGroup\ReferenceFrame\ReferenceTimeCode)"

   id: "0xCA"

   minOccurs: "1"

   maxOccurs: "1"

   type: "uinteger"

   minver: "0"

   maxver: "0"

   documentation: DivX trick track extensions

8.2.56.  EncryptedBlock Element

   name: "EncryptedBlock"

   path: "0*(\Segment\Cluster\EncryptedBlock)"

   id: "0xAF"

   type: "binary"

   minver: "0"

   maxver: "0"

   documentation: Similar to SimpleBlock but the data inside the Block
   are Transformed (encrypt and/or signed). (see EncryptedBlock
   Structure)

8.2.57.  Tracks Element

   name: "Tracks"

   path: "0*(\Segment\Tracks)"

   id: "0x1654AE6B"

   type: "master"

   minver: "1"





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   documentation: A Top-Level Element of information with many tracks
   described.

8.2.58.  TrackEntry Element

   name: "TrackEntry"

   path: "1*(\Segment\Tracks\TrackEntry)"

   id: "0xAE"

   minOccurs: "1"

   type: "master"

   minver: "1"

   documentation: Describes a track with all Elements.

8.2.59.  TrackNumber Element

   name: "TrackNumber"

   path: "1*1(\Segment\Tracks\TrackEntry\TrackNumber)"

   id: "0xD7"

   minOccurs: "1"

   maxOccurs: "1"

   range: "not 0"

   type: "uinteger"

   minver: "1"

   documentation: The track number as used in the Block Header (using
   more than 127 tracks is not encouraged, though the design allows an
   unlimited number).

8.2.60.  TrackUID Element

   name: "TrackUID"

   path: "1*1(\Segment\Tracks\TrackEntry\TrackUID)"

   id: "0x73C5"



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   minOccurs: "1"

   maxOccurs: "1"

   range: "not 0"

   type: "uinteger"

   minver: "1"

   documentation: A unique ID to identify the Track.  This SHOULD be
   kept the same when making a direct stream copy of the Track to
   another file.

8.2.61.  TrackType Element

   name: "TrackType"

   path: "1*1(\Segment\Tracks\TrackEntry\TrackType)"

   id: "0x83"

   minOccurs: "1"

   maxOccurs: "1"

   range: "1-254"

   type: "uinteger"

   minver: "1"

   documentation: A set of track types coded on 8 bits.

8.2.62.  FlagEnabled Element

   name: "FlagEnabled"

   path: "1*1(\Segment\Tracks\TrackEntry\FlagEnabled)"

   id: "0xB9"

   minOccurs: "1"

   maxOccurs: "1"

   range: "0-1"




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   default: "1"

   type: "uinteger"

   minver: "2"

   documentation: Set if the track is usable. (1 bit)

8.2.63.  FlagDefault Element

   name: "FlagDefault"

   path: "1*1(\Segment\Tracks\TrackEntry\FlagDefault)"

   id: "0x88"

   minOccurs: "1"

   maxOccurs: "1"

   range: "0-1"

   default: "1"

   type: "uinteger"

   minver: "1"

   documentation: Set if that track (audio, video or subs) SHOULD be
   active if no language found matches the user preference. (1 bit)

8.2.64.  FlagForced Element

   name: "FlagForced"

   path: "1*1(\Segment\Tracks\TrackEntry\FlagForced)"

   id: "0x55AA"

   minOccurs: "1"

   maxOccurs: "1"

   range: "0-1"

   default: "0"

   type: "uinteger"



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   minver: "1"

   documentation: Set if that track MUST be active during playback.
   There can be many forced track for a kind (audio, video or subs), the
   player SHOULD select the one which language matches the user
   preference or the default + forced track.  Overlay MAY happen between
   a forced and non-forced track of the same kind. (1 bit)

8.2.65.  FlagLacing Element

   name: "FlagLacing"

   path: "1*1(\Segment\Tracks\TrackEntry\FlagLacing)"

   id: "0x9C"

   minOccurs: "1"

   maxOccurs: "1"

   range: "0-1"

   default: "1"

   type: "uinteger"

   minver: "1"

   documentation: Set if the track MAY contain blocks using lacing. (1
   bit)

8.2.66.  MinCache Element

   name: "MinCache"

   path: "1*1(\Segment\Tracks\TrackEntry\MinCache)"

   id: "0x6DE7"

   minOccurs: "1"

   maxOccurs: "1"

   default: "0"

   type: "uinteger"

   minver: "1"



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   documentation: The minimum number of frames a player SHOULD be able
   to cache during playback.  If set to 0, the reference pseudo-cache
   system is not used.

8.2.67.  MaxCache Element

   name: "MaxCache"

   path: "0*1(\Segment\Tracks\TrackEntry\MaxCache)"

   id: "0x6DF8"

   maxOccurs: "1"

   type: "uinteger"

   minver: "1"

   documentation: The maximum cache size necessary to store referenced
   frames in and the current frame. 0 means no cache is needed.

8.2.68.  DefaultDuration Element

   name: "DefaultDuration"

   path: "0*1(\Segment\Tracks\TrackEntry\DefaultDuration)"

   id: "0x23E383"

   maxOccurs: "1"

   range: "not 0"

   type: "uinteger"

   minver: "1"

   documentation: Number of nanoseconds (not scaled via TimecodeScale)
   per frame ('frame' in the Matroska sense -- one Element put into a
   (Simple)Block).

8.2.69.  DefaultDecodedFieldDuration Element

   name: "DefaultDecodedFieldDuration"

   path: "0*1(\Segment\Tracks\TrackEntry\DefaultDecodedFieldDuration)"

   id: "0x234E7A"



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   maxOccurs: "1"

   range: "not 0"

   type: "uinteger"

   minver: "4"

   documentation: The period in nanoseconds (not scaled by
   TimecodeScale) between two successive fields at the output of the
   decoding process (see the notes)

8.2.70.  TrackTimecodeScale Element

   name: "TrackTimecodeScale"

   path: "1*1(\Segment\Tracks\TrackEntry\TrackTimecodeScale)"

   id: "0x23314F"

   minOccurs: "1"

   maxOccurs: "1"

   range: "> 0x0p+0"

   default: "0x1p+0"

   type: "float"

   minver: "1"

   maxver: "3"

   documentation: DEPRECATED, DO NOT USE.  The scale to apply on this
   track to work at normal speed in relation with other tracks (mostly
   used to adjust video speed when the audio length differs).

8.2.71.  TrackOffset Element

   name: "TrackOffset"

   path: "0*1(\Segment\Tracks\TrackEntry\TrackOffset)"

   id: "0x537F"

   maxOccurs: "1"




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   default: "0"

   type: "integer"

   minver: "0"

   maxver: "0"

   documentation: A value to add to the Block's Timestamp.  This can be
   used to adjust the playback offset of a track.

8.2.72.  MaxBlockAdditionID Element

   name: "MaxBlockAdditionID"

   path: "1*1(\Segment\Tracks\TrackEntry\MaxBlockAdditionID)"

   id: "0x55EE"

   minOccurs: "1"

   maxOccurs: "1"

   default: "0"

   type: "uinteger"

   minver: "1"

   documentation: The maximum value of BlockAddID.  A value 0 means
   there is no BlockAdditions for this track.

8.2.73.  Name Element

   name: "Name"

   path: "0*1(\Segment\Tracks\TrackEntry\Name)"

   id: "0x536E"

   maxOccurs: "1"

   type: "utf-8"

   minver: "1"

   documentation: A human-readable track name.




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8.2.74.  Language Element

   name: "Language"

   path: "0*1(\Segment\Tracks\TrackEntry\Language)"

   id: "0x22B59C"

   maxOccurs: "1"

   default: "eng"

   type: "string"

   minver: "1"

   documentation: Specifies the language of the track in the Matroska
   languages form.  This Element MUST be ignored if the LanguageIETF
   Element is used in the same TrackEntry.

8.2.75.  LanguageIETF Element

   name: "LanguageIETF"

   path: "0*1(\Segment\Tracks\TrackEntry\LanguageIETF)"

   id: "0x22B59D"

   maxOccurs: "1"

   type: "string"

   minver: "4"

   documentation: Specifies the language of the track according to BCP
   47 and using the IANA Language Subtag Registry.  If this Element is
   used, then any Language Elements used in the same TrackEntry MUST be
   ignored.

8.2.76.  CodecID Element

   name: "CodecID"

   path: "1*1(\Segment\Tracks\TrackEntry\CodecID)"

   id: "0x86"

   minOccurs: "1"



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   maxOccurs: "1"

   type: "string"

   minver: "1"

   documentation: An ID corresponding to the codec, see the codec page
   for more info.

8.2.77.  CodecPrivate Element

   name: "CodecPrivate"

   path: "0*1(\Segment\Tracks\TrackEntry\CodecPrivate)"

   id: "0x63A2"

   maxOccurs: "1"

   type: "binary"

   minver: "1"

   documentation: Private data only known to the codec.

8.2.78.  CodecName Element

   name: "CodecName"

   path: "0*1(\Segment\Tracks\TrackEntry\CodecName)"

   id: "0x258688"

   maxOccurs: "1"

   type: "utf-8"

   minver: "1"

   documentation: A human-readable string specifying the codec.

8.2.79.  AttachmentLink Element

   name: "AttachmentLink"

   path: "0*1(\Segment\Tracks\TrackEntry\AttachmentLink)"

   id: "0x7446"



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   maxOccurs: "1"

   range: "not 0"

   type: "uinteger"

   minver: "1"

   maxver: "3"

   documentation: The UID of an attachment that is used by this codec.

8.2.80.  CodecSettings Element

   name: "CodecSettings"

   path: "0*1(\Segment\Tracks\TrackEntry\CodecSettings)"

   id: "0x3A9697"

   maxOccurs: "1"

   type: "utf-8"

   minver: "0"

   maxver: "0"

   documentation: A string describing the encoding setting used.

8.2.81.  CodecInfoURL Element

   name: "CodecInfoURL"

   path: "0*(\Segment\Tracks\TrackEntry\CodecInfoURL)"

   id: "0x3B4040"

   type: "string"

   minver: "0"

   maxver: "0"

   documentation: A URL to find information about the codec used.






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8.2.82.  CodecDownloadURL Element

   name: "CodecDownloadURL"

   path: "0*(\Segment\Tracks\TrackEntry\CodecDownloadURL)"

   id: "0x26B240"

   type: "string"

   minver: "0"

   maxver: "0"

   documentation: A URL to download about the codec used.

8.2.83.  CodecDecodeAll Element

   name: "CodecDecodeAll"

   path: "1*1(\Segment\Tracks\TrackEntry\CodecDecodeAll)"

   id: "0xAA"

   minOccurs: "1"

   maxOccurs: "1"

   range: "0-1"

   default: "1"

   type: "uinteger"

   minver: "2"

   documentation: The codec can decode potentially damaged data (1 bit).

8.2.84.  TrackOverlay Element

   name: "TrackOverlay"

   path: "0*(\Segment\Tracks\TrackEntry\TrackOverlay)"

   id: "0x6FAB"

   type: "uinteger"




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   minver: "1"

   documentation: Specify that this track is an overlay track for the
   Track specified (in the u-integer).  That means when this track has a
   gap (see SilentTracks) the overlay track SHOULD be used instead.  The
   order of multiple TrackOverlay matters, the first one is the one that
   SHOULD be used.  If not found it SHOULD be the second, etc.

8.2.85.  CodecDelay Element

   name: "CodecDelay"

   path: "0*1(\Segment\Tracks\TrackEntry\CodecDelay)"

   id: "0x56AA"

   maxOccurs: "1"

   default: "0"

   type: "uinteger"

   minver: "4"

   documentation: CodecDelay is The codec-built-in delay in nanoseconds.
   This value MUST be subtracted from each block timestamp in order to
   get the actual timestamp.  The value SHOULD be small so the muxing of
   tracks with the same actual timestamp are in the same Cluster.

8.2.86.  SeekPreRoll Element

   name: "SeekPreRoll"

   path: "1*1(\Segment\Tracks\TrackEntry\SeekPreRoll)"

   id: "0x56BB"

   minOccurs: "1"

   maxOccurs: "1"

   default: "0"

   type: "uinteger"

   minver: "4"





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   documentation: After a discontinuity, SeekPreRoll is the duration in
   nanoseconds of the data the decoder MUST decode before the decoded
   data is valid.

8.2.87.  TrackTranslate Element

   name: "TrackTranslate"

   path: "0*(\Segment\Tracks\TrackEntry\TrackTranslate)"

   id: "0x6624"

   type: "master"

   minver: "1"

   documentation: The track identification for the given Chapter Codec.

8.2.88.  TrackTranslateEditionUID Element

   name: "TrackTranslateEditionUID"

   path: "0*(\Segment\Tracks\TrackEntry\TrackTranslate\TrackTranslateEdi
   tionUID)"

   id: "0x66FC"

   type: "uinteger"

   minver: "1"

   documentation: Specify an edition UID on which this translation
   applies.  When not specified, it means for all editions found in the
   Segment.

8.2.89.  TrackTranslateCodec Element

   name: "TrackTranslateCodec"

   path:
   "1*1(\Segment\Tracks\TrackEntry\TrackTranslate\TrackTranslateCodec)"

   id: "0x66BF"

   minOccurs: "1"

   maxOccurs: "1"




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   type: "uinteger"

   minver: "1"

   documentation: The chapter codec.

8.2.90.  TrackTranslateTrackID Element

   name: "TrackTranslateTrackID"

   path: "1*1(\Segment\Tracks\TrackEntry\TrackTranslate\TrackTranslateTr
   ackID)"

   id: "0x66A5"

   minOccurs: "1"

   maxOccurs: "1"

   type: "binary"

   minver: "1"

   documentation: The binary value used to represent this track in the
   chapter codec data.  The format depends on the ChapProcessCodecID
   used.

8.2.91.  Video Element

   name: "Video"

   path: "0*1(\Segment\Tracks\TrackEntry\Video)"

   id: "0xE0"

   maxOccurs: "1"

   type: "master"

   minver: "1"

   documentation: Video settings.

8.2.92.  FlagInterlaced Element

   name: "FlagInterlaced"

   path: "1*1(\Segment\Tracks\TrackEntry\Video\FlagInterlaced)"



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   id: "0x9A"

   minOccurs: "1"

   maxOccurs: "1"

   range: "0-2"

   default: "0"

   type: "uinteger"

   minver: "2"

   documentation: A flag to declare is the video is known to be
   progressive or interlaced and if applicable to declare details about
   the interlacement.

8.2.93.  FieldOrder Element

   name: "FieldOrder"

   path: "1*1(\Segment\Tracks\TrackEntry\Video\FieldOrder)"

   id: "0x9D"

   minOccurs: "1"

   maxOccurs: "1"

   range: "0-14"

   default: "2"

   type: "uinteger"

   minver: "4"

   documentation: Declare the field ordering of the video.  If
   FlagInterlaced is not set to 1, this Element MUST be ignored.

8.2.94.  StereoMode Element

   name: "StereoMode"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\StereoMode)"

   id: "0x53B8"



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   maxOccurs: "1"

   default: "0"

   type: "uinteger"

   minver: "3"

   documentation: Stereo-3D video mode.  There are some more details on
   3D support in the Specification Notes.

8.2.95.  AlphaMode Element

   name: "AlphaMode"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\AlphaMode)"

   id: "0x53C0"

   maxOccurs: "1"

   default: "0"

   type: "uinteger"

   minver: "3"

   documentation: Alpha Video Mode.  Presence of this Element indicates
   that the BlockAdditional Element could contain Alpha data.

8.2.96.  OldStereoMode Element

   name: "OldStereoMode"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\OldStereoMode)"

   id: "0x53B9"

   maxOccurs: "1"

   type: "uinteger"

   maxver: "0"

   documentation: DEPRECATED, DO NOT USE.  Bogus StereoMode value used
   in old versions of libmatroska.





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8.2.97.  PixelWidth Element

   name: "PixelWidth"

   path: "1*1(\Segment\Tracks\TrackEntry\Video\PixelWidth)"

   id: "0xB0"

   minOccurs: "1"

   maxOccurs: "1"

   range: "not 0"

   type: "uinteger"

   minver: "1"

   documentation: Width of the encoded video frames in pixels.

8.2.98.  PixelHeight Element

   name: "PixelHeight"

   path: "1*1(\Segment\Tracks\TrackEntry\Video\PixelHeight)"

   id: "0xBA"

   minOccurs: "1"

   maxOccurs: "1"

   range: "not 0"

   type: "uinteger"

   minver: "1"

   documentation: Height of the encoded video frames in pixels.

8.2.99.  PixelCropBottom Element

   name: "PixelCropBottom"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\PixelCropBottom)"

   id: "0x54AA"




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   maxOccurs: "1"

   default: "0"

   type: "uinteger"

   minver: "1"

   documentation: The number of video pixels to remove at the bottom of
   the image (for HDTV content).

8.2.100.  PixelCropTop Element

   name: "PixelCropTop"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\PixelCropTop)"

   id: "0x54BB"

   maxOccurs: "1"

   default: "0"

   type: "uinteger"

   minver: "1"

   documentation: The number of video pixels to remove at the top of the
   image.

8.2.101.  PixelCropLeft Element

   name: "PixelCropLeft"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\PixelCropLeft)"

   id: "0x54CC"

   maxOccurs: "1"

   default: "0"

   type: "uinteger"

   minver: "1"

   documentation: The number of video pixels to remove on the left of
   the image.



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8.2.102.  PixelCropRight Element

   name: "PixelCropRight"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\PixelCropRight)"

   id: "0x54DD"

   maxOccurs: "1"

   default: "0"

   type: "uinteger"

   minver: "1"

   documentation: The number of video pixels to remove on the right of
   the image.

8.2.103.  DisplayWidth Element

   name: "DisplayWidth"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\DisplayWidth)"

   id: "0x54B0"

   maxOccurs: "1"

   range: "not 0"

   default: "PixelWidth - PixelCropLeft - PixelCropRight"

   type: "uinteger"

   minver: "1"

   documentation: Width of the video frames to display.  Applies to the
   video frame after cropping (PixelCrop* Elements).  The default value
   is only valid when DisplayUnit is 0.

8.2.104.  DisplayHeight Element

   name: "DisplayHeight"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\DisplayHeight)"

   id: "0x54BA"



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   maxOccurs: "1"

   range: "not 0"

   default: "PixelHeight - PixelCropTop - PixelCropBottom"

   type: "uinteger"

   minver: "1"

   documentation: Height of the video frames to display.  Applies to the
   video frame after cropping (PixelCrop* Elements).  The default value
   is only valid when DisplayUnit is 0.

8.2.105.  DisplayUnit Element

   name: "DisplayUnit"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\DisplayUnit)"

   id: "0x54B2"

   maxOccurs: "1"

   default: "0"

   type: "uinteger"

   minver: "1"

   documentation: How DisplayWidth & DisplayHeight are interpreted.

8.2.106.  AspectRatioType Element

   name: "AspectRatioType"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\AspectRatioType)"

   id: "0x54B3"

   maxOccurs: "1"

   default: "0"

   type: "uinteger"

   minver: "1"




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   documentation: Specify the possible modifications to the aspect
   ratio.

8.2.107.  ColourSpace Element

   name: "ColourSpace"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\ColourSpace)"

   id: "0x2EB524"

   maxOccurs: "1"

   size: "4"

   type: "binary"

   minver: "1"

   documentation: Specify the pixel format used for the Track's data as
   a FourCC.  This value is similar in scope to the biCompression value
   of AVI's BITMAPINFOHEADER.  This Element is MANDATORY in TrackEntry
   when the CodecID Element of the TrackEntry is set to
   "V_UNCOMPRESSED".

8.2.108.  GammaValue Element

   name: "GammaValue"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\GammaValue)"

   id: "0x2FB523"

   maxOccurs: "1"

   range: "> 0x0p+0"

   type: "float"

   minver: "0"

   maxver: "0"

   documentation: Gamma Value.







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8.2.109.  FrameRate Element

   name: "FrameRate"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\FrameRate)"

   id: "0x2383E3"

   maxOccurs: "1"

   range: "> 0x0p+0"

   type: "float"

   minver: "0"

   maxver: "0"

   documentation: Number of frames per second.  Informational only.

8.2.110.  Colour Element

   name: "Colour"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour)"

   id: "0x55B0"

   maxOccurs: "1"

   type: "master"

   minver: "4"

   documentation: Settings describing the colour format.

8.2.111.  MatrixCoefficients Element

   name: "MatrixCoefficients"

   path:
   "0*1(\Segment\Tracks\TrackEntry\Video\Colour\MatrixCoefficients)"

   id: "0x55B1"

   maxOccurs: "1"

   default: "2"



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   type: "uinteger"

   minver: "4"

   documentation: The Matrix Coefficients of the video used to derive
   luma and chroma values from red, green, and blue color primaries.
   For clarity, the value and meanings for MatrixCoefficients are
   adopted from Table 4 of ISO/IEC 23001-8:2013/DCOR1.

8.2.112.  BitsPerChannel Element

   name: "BitsPerChannel"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\BitsPerChannel)"

   id: "0x55B2"

   maxOccurs: "1"

   default: "0"

   type: "uinteger"

   minver: "4"

   documentation: Number of decoded bits per channel.  A value of 0
   indicates that the BitsPerChannel is unspecified.

8.2.113.  ChromaSubsamplingHorz Element

   name: "ChromaSubsamplingHorz"

   path:
   "0*1(\Segment\Tracks\TrackEntry\Video\Colour\ChromaSubsamplingHorz)"

   id: "0x55B3"

   maxOccurs: "1"

   type: "uinteger"

   minver: "4"

   documentation: The amount of pixels to remove in the Cr and Cb
   channels for every pixel not removed horizontally.  Example: For
   video with 4:2:0 chroma subsampling, the ChromaSubsamplingHorz SHOULD
   be set to 1.




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8.2.114.  ChromaSubsamplingVert Element

   name: "ChromaSubsamplingVert"

   path:
   "0*1(\Segment\Tracks\TrackEntry\Video\Colour\ChromaSubsamplingVert)"

   id: "0x55B4"

   maxOccurs: "1"

   type: "uinteger"

   minver: "4"

   documentation: The amount of pixels to remove in the Cr and Cb
   channels for every pixel not removed vertically.  Example: For video
   with 4:2:0 chroma subsampling, the ChromaSubsamplingVert SHOULD be
   set to 1.

8.2.115.  CbSubsamplingHorz Element

   name: "CbSubsamplingHorz"

   path:
   "0*1(\Segment\Tracks\TrackEntry\Video\Colour\CbSubsamplingHorz)"

   id: "0x55B5"

   maxOccurs: "1"

   type: "uinteger"

   minver: "4"

   documentation: The amount of pixels to remove in the Cb channel for
   every pixel not removed horizontally.  This is additive with
   ChromaSubsamplingHorz.  Example: For video with 4:2:1 chroma
   subsampling, the ChromaSubsamplingHorz SHOULD be set to 1 and
   CbSubsamplingHorz SHOULD be set to 1.

8.2.116.  CbSubsamplingVert Element

   name: "CbSubsamplingVert"

   path:
   "0*1(\Segment\Tracks\TrackEntry\Video\Colour\CbSubsamplingVert)"




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   id: "0x55B6"

   maxOccurs: "1"

   type: "uinteger"

   minver: "4"

   documentation: The amount of pixels to remove in the Cb channel for
   every pixel not removed vertically.  This is additive with
   ChromaSubsamplingVert.

8.2.117.  ChromaSitingHorz Element

   name: "ChromaSitingHorz"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\ChromaSitingHorz)"

   id: "0x55B7"

   maxOccurs: "1"

   default: "0"

   type: "uinteger"

   minver: "4"

   documentation: How chroma is subsampled horizontally.

8.2.118.  ChromaSitingVert Element

   name: "ChromaSitingVert"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\ChromaSitingVert)"

   id: "0x55B8"

   maxOccurs: "1"

   default: "0"

   type: "uinteger"

   minver: "4"

   documentation: How chroma is subsampled vertically.




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8.2.119.  Range Element

   name: "Range"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\Range)"

   id: "0x55B9"

   maxOccurs: "1"

   default: "0"

   type: "uinteger"

   minver: "4"

   documentation: Clipping of the color ranges.

8.2.120.  TransferCharacteristics Element

   name: "TransferCharacteristics"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\TransferCharacteri
   stics)"

   id: "0x55BA"

   maxOccurs: "1"

   default: "2"

   type: "uinteger"

   minver: "4"

   documentation: The transfer characteristics of the video.  For
   clarity, the value and meanings for TransferCharacteristics 1-15 are
   adopted from Table 3 of ISO/IEC 23001-8:2013/DCOR1.
   TransferCharacteristics 16-18 are proposed values.

8.2.121.  Primaries Element

   name: "Primaries"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\Primaries)"

   id: "0x55BB"




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   maxOccurs: "1"

   default: "2"

   type: "uinteger"

   minver: "4"

   documentation: The colour primaries of the video.  For clarity, the
   value and meanings for Primaries are adopted from Table 2 of ISO/IEC
   23001-8:2013/DCOR1.

8.2.122.  MaxCLL Element

   name: "MaxCLL"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\MaxCLL)"

   id: "0x55BC"

   maxOccurs: "1"

   type: "uinteger"

   minver: "4"

   documentation: Maximum brightness of a single pixel (Maximum Content
   Light Level) in candelas per square meter (cd/m^2).

8.2.123.  MaxFALL Element

   name: "MaxFALL"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\MaxFALL)"

   id: "0x55BD"

   maxOccurs: "1"

   type: "uinteger"

   minver: "4"

   documentation: Maximum brightness of a single full frame (Maximum
   Frame-Average Light Level) in candelas per square meter (cd/m^2).






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8.2.124.  MasteringMetadata Element

   name: "MasteringMetadata"

   path:
   "0*1(\Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata)"

   id: "0x55D0"

   maxOccurs: "1"

   type: "master"

   minver: "4"

   documentation: SMPTE 2086 mastering data.

8.2.125.  PrimaryRChromaticityX Element

   name: "PrimaryRChromaticityX"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\
   PrimaryRChromaticityX)"

   id: "0x55D1"

   maxOccurs: "1"

   range: "0-1"

   type: "float"

   minver: "4"

   documentation: Red X chromaticity coordinate as defined by CIE 1931.

8.2.126.  PrimaryRChromaticityY Element

   name: "PrimaryRChromaticityY"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\
   PrimaryRChromaticityY)"

   id: "0x55D2"

   maxOccurs: "1"

   range: "0-1"



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   type: "float"

   minver: "4"

   documentation: Red Y chromaticity coordinate as defined by CIE 1931.

8.2.127.  PrimaryGChromaticityX Element

   name: "PrimaryGChromaticityX"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\
   PrimaryGChromaticityX)"

   id: "0x55D3"

   maxOccurs: "1"

   range: "0-1"

   type: "float"

   minver: "4"

   documentation: Green X chromaticity coordinate as defined by CIE
   1931.

8.2.128.  PrimaryGChromaticityY Element

   name: "PrimaryGChromaticityY"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\
   PrimaryGChromaticityY)"

   id: "0x55D4"

   maxOccurs: "1"

   range: "0-1"

   type: "float"

   minver: "4"

   documentation: Green Y chromaticity coordinate as defined by CIE
   1931.






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8.2.129.  PrimaryBChromaticityX Element

   name: "PrimaryBChromaticityX"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\
   PrimaryBChromaticityX)"

   id: "0x55D5"

   maxOccurs: "1"

   range: "0-1"

   type: "float"

   minver: "4"

   documentation: Blue X chromaticity coordinate as defined by CIE 1931.

8.2.130.  PrimaryBChromaticityY Element

   name: "PrimaryBChromaticityY"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\
   PrimaryBChromaticityY)"

   id: "0x55D6"

   maxOccurs: "1"

   range: "0-1"

   type: "float"

   minver: "4"

   documentation: Blue Y chromaticity coordinate as defined by CIE 1931.

8.2.131.  WhitePointChromaticityX Element

   name: "WhitePointChromaticityX"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\
   WhitePointChromaticityX)"

   id: "0x55D7"

   maxOccurs: "1"



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   range: "0-1"

   type: "float"

   minver: "4"

   documentation: White X chromaticity coordinate as defined by CIE
   1931.

8.2.132.  WhitePointChromaticityY Element

   name: "WhitePointChromaticityY"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\
   WhitePointChromaticityY)"

   id: "0x55D8"

   maxOccurs: "1"

   range: "0-1"

   type: "float"

   minver: "4"

   documentation: White Y chromaticity coordinate as defined by CIE
   1931.

8.2.133.  LuminanceMax Element

   name: "LuminanceMax"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\
   LuminanceMax)"

   id: "0x55D9"

   maxOccurs: "1"

   range: ">= 0x0p+0"

   type: "float"

   minver: "4"

   documentation: Maximum luminance.  Represented in candelas per square
   meter (cd/m^2).



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8.2.134.  LuminanceMin Element

   name: "LuminanceMin"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\
   LuminanceMin)"

   id: "0x55DA"

   maxOccurs: "1"

   range: ">= 0x0p+0"

   type: "float"

   minver: "4"

   documentation: Mininum luminance.  Represented in candelas per square
   meter (cd/m^2).

8.2.135.  Projection Element

   name: "Projection"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\Projection)"

   id: "0x7670"

   maxOccurs: "1"

   type: "master"

   minver: "4"

   documentation: Describes the video projection details.  Used to
   render spherical and VR videos.

8.2.136.  ProjectionType Element

   name: "ProjectionType"

   path:
   "1*1(\Segment\Tracks\TrackEntry\Video\Projection\ProjectionType)"

   id: "0x7671"

   minOccurs: "1"




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   maxOccurs: "1"

   range: "0-3"

   default: "0"

   type: "uinteger"

   minver: "4"

   documentation: Describes the projection used for this video track.

8.2.137.  ProjectionPrivate Element

   name: "ProjectionPrivate"

   path:
   "0*1(\Segment\Tracks\TrackEntry\Video\Projection\ProjectionPrivate)"

   id: "0x7672"

   maxOccurs: "1"

   type: "binary"

   minver: "4"

   documentation: Private data that only applies to a specific
   projection.SemanticsIf ProjectionType equals 0 (Rectangular), then
   this element must not be present.If ProjectionType equals 1
   (Equirectangular), then this element must be present and contain the
   same binary data that would be stored inside an ISOBMFF
   Equirectangular Projection Box ('equi').If ProjectionType equals 2
   (Cubemap), then this element must be present and contain the same
   binary data that would be stored inside an ISOBMFF Cubemap Projection
   Box ('cbmp').If ProjectionType equals 3 (Mesh), then this element
   must be present and contain the same binary data that would be stored
   inside an ISOBMFF Mesh Projection Box ('mshp').Note: ISOBMFF box size
   and fourcc fields are not included in the binary data, but the
   FullBox version and flag fields are.  This is to avoid redundant
   framing information while preserving versioning and semantics between
   the two container formats.

8.2.138.  ProjectionPoseYaw Element

   name: "ProjectionPoseYaw"





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   path:
   "1*1(\Segment\Tracks\TrackEntry\Video\Projection\ProjectionPoseYaw)"

   id: "0x7673"

   minOccurs: "1"

   maxOccurs: "1"

   default: "0x0p+0"

   type: "float"

   minver: "4"

   documentation: Specifies a yaw rotation to the
   projection.SemanticsValue represents a clockwise rotation, in
   degrees, around the up vector.  This rotation must be applied before
   any ProjectionPosePitch or ProjectionPoseRoll rotations.  The value
   of this field should be in the -180 to 180 degree range.

8.2.139.  ProjectionPosePitch Element

   name: "ProjectionPosePitch"

   path: "1*1(\Segment\Tracks\TrackEntry\Video\Projection\ProjectionPose
   Pitch)"

   id: "0x7674"

   minOccurs: "1"

   maxOccurs: "1"

   default: "0x0p+0"

   type: "float"

   minver: "4"

   documentation: Specifies a pitch rotation to the
   projection.SemanticsValue represents a counter-clockwise rotation, in
   degrees, around the right vector.  This rotation must be applied
   after the ProjectionPoseYaw rotation and before the
   ProjectionPoseRoll rotation.  The value of this field should be in
   the -90 to 90 degree range.





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8.2.140.  ProjectionPoseRoll Element

   name: "ProjectionPoseRoll"

   path:
   "1*1(\Segment\Tracks\TrackEntry\Video\Projection\ProjectionPoseRoll)"

   id: "0x7675"

   minOccurs: "1"

   maxOccurs: "1"

   default: "0x0p+0"

   type: "float"

   minver: "4"

   documentation: Specifies a roll rotation to the
   projection.SemanticsValue represents a counter-clockwise rotation, in
   degrees, around the forward vector.  This rotation must be applied
   after the ProjectionPoseYaw and ProjectionPosePitch rotations.  The
   value of this field should be in the -180 to 180 degree range.

8.2.141.  Audio Element

   name: "Audio"

   path: "0*1(\Segment\Tracks\TrackEntry\Audio)"

   id: "0xE1"

   maxOccurs: "1"

   type: "master"

   minver: "1"

   documentation: Audio settings.

8.2.142.  SamplingFrequency Element

   name: "SamplingFrequency"

   path: "1*1(\Segment\Tracks\TrackEntry\Audio\SamplingFrequency)"

   id: "0xB5"



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   minOccurs: "1"

   maxOccurs: "1"

   range: "> 0x0p+0"

   default: "0x1.f4p+12"

   type: "float"

   minver: "1"

   documentation: Sampling frequency in Hz.

8.2.143.  OutputSamplingFrequency Element

   name: "OutputSamplingFrequency"

   path: "0*1(\Segment\Tracks\TrackEntry\Audio\OutputSamplingFrequency)"

   id: "0x78B5"

   maxOccurs: "1"

   range: "> 0x0p+0"

   default: "SamplingFrequency"

   type: "float"

   minver: "1"

   documentation: Real output sampling frequency in Hz (used for SBR
   techniques).

8.2.144.  Channels Element

   name: "Channels"

   path: "1*1(\Segment\Tracks\TrackEntry\Audio\Channels)"

   id: "0x9F"

   minOccurs: "1"

   maxOccurs: "1"

   range: "not 0"



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   default: "1"

   type: "uinteger"

   minver: "1"

   documentation: Numbers of channels in the track.

8.2.145.  ChannelPositions Element

   name: "ChannelPositions"

   path: "0*1(\Segment\Tracks\TrackEntry\Audio\ChannelPositions)"

   id: "0x7D7B"

   maxOccurs: "1"

   type: "binary"

   minver: "0"

   maxver: "0"

   documentation: Table of horizontal angles for each successive
   channel, see appendix.

8.2.146.  BitDepth Element

   name: "BitDepth"

   path: "0*1(\Segment\Tracks\TrackEntry\Audio\BitDepth)"

   id: "0x6264"

   maxOccurs: "1"

   range: "not 0"

   type: "uinteger"

   minver: "1"

   documentation: Bits per sample, mostly used for PCM.







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8.2.147.  TrackOperation Element

   name: "TrackOperation"

   path: "0*1(\Segment\Tracks\TrackEntry\TrackOperation)"

   id: "0xE2"

   maxOccurs: "1"

   type: "master"

   minver: "3"

   documentation: Operation that needs to be applied on tracks to create
   this virtual track.  For more details look at the Specification Notes
   on the subject.

8.2.148.  TrackCombinePlanes Element

   name: "TrackCombinePlanes"

   path:
   "0*1(\Segment\Tracks\TrackEntry\TrackOperation\TrackCombinePlanes)"

   id: "0xE3"

   maxOccurs: "1"

   type: "master"

   minver: "3"

   documentation: Contains the list of all video plane tracks that need
   to be combined to create this 3D track

8.2.149.  TrackPlane Element

   name: "TrackPlane"

   path: "1*(\Segment\Tracks\TrackEntry\TrackOperation\TrackCombinePlane
   s\TrackPlane)"

   id: "0xE4"

   minOccurs: "1"

   type: "master"



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   minver: "3"

   documentation: Contains a video plane track that need to be combined
   to create this 3D track

8.2.150.  TrackPlaneUID Element

   name: "TrackPlaneUID"

   path: "1*1(\Segment\Tracks\TrackEntry\TrackOperation\TrackCombinePlan
   es\TrackPlane\TrackPlaneUID)"

   id: "0xE5"

   minOccurs: "1"

   maxOccurs: "1"

   range: "not 0"

   type: "uinteger"

   minver: "3"

   documentation: The trackUID number of the track representing the
   plane.

8.2.151.  TrackPlaneType Element

   name: "TrackPlaneType"

   path: "1*1(\Segment\Tracks\TrackEntry\TrackOperation\TrackCombinePlan
   es\TrackPlane\TrackPlaneType)"

   id: "0xE6"

   minOccurs: "1"

   maxOccurs: "1"

   type: "uinteger"

   minver: "3"

   documentation: The kind of plane this track corresponds to.






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8.2.152.  TrackJoinBlocks Element

   name: "TrackJoinBlocks"

   path:
   "0*1(\Segment\Tracks\TrackEntry\TrackOperation\TrackJoinBlocks)"

   id: "0xE9"

   maxOccurs: "1"

   type: "master"

   minver: "3"

   documentation: Contains the list of all tracks whose Blocks need to
   be combined to create this virtual track

8.2.153.  TrackJoinUID Element

   name: "TrackJoinUID"

   path: "1*(\Segment\Tracks\TrackEntry\TrackOperation\TrackJoinBlocks\T
   rackJoinUID)"

   id: "0xED"

   minOccurs: "1"

   range: "not 0"

   type: "uinteger"

   minver: "3"

   documentation: The trackUID number of a track whose blocks are used
   to create this virtual track.

8.2.154.  TrickTrackUID Element

   name: "TrickTrackUID"

   path: "0*1(\Segment\Tracks\TrackEntry\TrickTrackUID)"

   id: "0xC0"

   maxOccurs: "1"




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   type: "uinteger"

   minver: "0"

   maxver: "0"

   documentation: DivX trick track extensions

8.2.155.  TrickTrackSegmentUID Element

   name: "TrickTrackSegmentUID"

   path: "0*1(\Segment\Tracks\TrackEntry\TrickTrackSegmentUID)"

   id: "0xC1"

   maxOccurs: "1"

   size: "16"

   type: "binary"

   minver: "0"

   maxver: "0"

   documentation: DivX trick track extensions

8.2.156.  TrickTrackFlag Element

   name: "TrickTrackFlag"

   path: "0*1(\Segment\Tracks\TrackEntry\TrickTrackFlag)"

   id: "0xC6"

   maxOccurs: "1"

   default: "0"

   type: "uinteger"

   minver: "0"

   maxver: "0"

   documentation: DivX trick track extensions




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8.2.157.  TrickMasterTrackUID Element

   name: "TrickMasterTrackUID"

   path: "0*1(\Segment\Tracks\TrackEntry\TrickMasterTrackUID)"

   id: "0xC7"

   maxOccurs: "1"

   type: "uinteger"

   minver: "0"

   maxver: "0"

   documentation: DivX trick track extensions

8.2.158.  TrickMasterTrackSegmentUID Element

   name: "TrickMasterTrackSegmentUID"

   path: "0*1(\Segment\Tracks\TrackEntry\TrickMasterTrackSegmentUID)"

   id: "0xC4"

   maxOccurs: "1"

   size: "16"

   type: "binary"

   minver: "0"

   maxver: "0"

   documentation: DivX trick track extensions

8.2.159.  ContentEncodings Element

   name: "ContentEncodings"

   path: "0*1(\Segment\Tracks\TrackEntry\ContentEncodings)"

   id: "0x6D80"

   maxOccurs: "1"




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   type: "master"

   minver: "1"

   documentation: Settings for several content encoding mechanisms like
   compression or encryption.

8.2.160.  ContentEncoding Element

   name: "ContentEncoding"

   path:
   "1*(\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding)"

   id: "0x6240"

   minOccurs: "1"

   type: "master"

   minver: "1"

   documentation: Settings for one content encoding like compression or
   encryption.

8.2.161.  ContentEncodingOrder Element

   name: "ContentEncodingOrder"

   path: "1*1(\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncodin
   g\ContentEncodingOrder)"

   id: "0x5031"

   minOccurs: "1"

   maxOccurs: "1"

   default: "0"

   type: "uinteger"

   minver: "1"

   documentation: Tells when this modification was used during encoding/
   muxing starting with 0 and counting upwards.  The decoder/demuxer has
   to start with the highest order number it finds and work its way




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   down.  This value has to be unique over all ContentEncodingOrder
   Elements in the Segment.

8.2.162.  ContentEncodingScope Element

   name: "ContentEncodingScope"

   path: "1*1(\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncodin
   g\ContentEncodingScope)"

   id: "0x5032"

   minOccurs: "1"

   maxOccurs: "1"

   range: "not 0"

   default: "1"

   type: "uinteger"

   minver: "1"

   documentation: A bit field that describes which Elements have been
   modified in this way.  Values (big endian) can be OR'ed.  Possible
   values: 1 - all frame contents, 2 - the track's private data, 4 - the
   next ContentEncoding (next ContentEncodingOrder.  Either the data
   inside ContentCompression and/or ContentEncryption)

8.2.163.  ContentEncodingType Element

   name: "ContentEncodingType"

   path: "1*1(\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncodin
   g\ContentEncodingType)"

   id: "0x5033"

   minOccurs: "1"

   maxOccurs: "1"

   default: "0"

   type: "uinteger"

   minver: "1"



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   documentation: A value describing what kind of transformation has
   been done.  Possible values: 0 - compression, 1 - encryption

8.2.164.  ContentCompression Element

   name: "ContentCompression"

   path: "0*1(\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncodin
   g\ContentCompression)"

   id: "0x5034"

   maxOccurs: "1"

   type: "master"

   minver: "1"

   documentation: Settings describing the compression used.  This
   Element MUST be present if the value of ContentEncodingType is 0 and
   absent otherwise.  Each block MUST be decompressable even if no
   previous block is available in order not to prevent seeking.

8.2.165.  ContentCompAlgo Element

   name: "ContentCompAlgo"

   path: "1*1(\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncodin
   g\ContentCompression\ContentCompAlgo)"

   id: "0x4254"

   minOccurs: "1"

   maxOccurs: "1"

   default: "0"

   type: "uinteger"

   minver: "1"

   documentation: The compression algorithm used.  Algorithms that have
   been specified so far are: 0 - zlib, 1 - bzlib, 2 - lzo1x 3 - Header
   Stripping






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8.2.166.  ContentCompSettings Element

   name: "ContentCompSettings"

   path: "0*1(\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncodin
   g\ContentCompression\ContentCompSettings)"

   id: "0x4255"

   maxOccurs: "1"

   type: "binary"

   minver: "1"

   documentation: Settings that might be needed by the decompressor.
   For Header Stripping (ContentCompAlgo=3), the bytes that were removed
   from the beggining of each frames of the track.

8.2.167.  ContentEncryption Element

   name: "ContentEncryption"

   path: "0*1(\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncodin
   g\ContentEncryption)"

   id: "0x5035"

   maxOccurs: "1"

   type: "master"

   minver: "1"

   documentation: Settings describing the encryption used.  This Element
   MUST be present if the value of ContentEncodingType is 1 and absent
   otherwise.

8.2.168.  ContentEncAlgo Element

   name: "ContentEncAlgo"

   path: "0*1(\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncodin
   g\ContentEncryption\ContentEncAlgo)"

   id: "0x47E1"

   maxOccurs: "1"



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   default: "0"

   type: "uinteger"

   minver: "1"

   documentation: The encryption algorithm used.  The value '0' means
   that the contents have not been encrypted but only signed.
   Predefined values: 1 - DES, 2 - 3DES, 3 - Twofish, 4 - Blowfish, 5 -
   AES

8.2.169.  ContentEncKeyID Element

   name: "ContentEncKeyID"

   path: "0*1(\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncodin
   g\ContentEncryption\ContentEncKeyID)"

   id: "0x47E2"

   maxOccurs: "1"

   type: "binary"

   minver: "1"

   documentation: For public key algorithms this is the ID of the public
   key the the data was encrypted with.

8.2.170.  ContentSignature Element

   name: "ContentSignature"

   path: "0*1(\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncodin
   g\ContentEncryption\ContentSignature)"

   id: "0x47E3"

   maxOccurs: "1"

   type: "binary"

   minver: "1"

   documentation: A cryptographic signature of the contents.






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8.2.171.  ContentSigKeyID Element

   name: "ContentSigKeyID"

   path: "0*1(\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncodin
   g\ContentEncryption\ContentSigKeyID)"

   id: "0x47E4"

   maxOccurs: "1"

   type: "binary"

   minver: "1"

   documentation: This is the ID of the private key the data was signed
   with.

8.2.172.  ContentSigAlgo Element

   name: "ContentSigAlgo"

   path: "0*1(\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncodin
   g\ContentEncryption\ContentSigAlgo)"

   id: "0x47E5"

   maxOccurs: "1"

   default: "0"

   type: "uinteger"

   minver: "1"

   documentation: The algorithm used for the signature.  A value of '0'
   means that the contents have not been signed but only encrypted.
   Predefined values: 1 - RSA

8.2.173.  ContentSigHashAlgo Element

   name: "ContentSigHashAlgo"

   path: "0*1(\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncodin
   g\ContentEncryption\ContentSigHashAlgo)"

   id: "0x47E6"




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   maxOccurs: "1"

   default: "0"

   type: "uinteger"

   minver: "1"

   documentation: The hash algorithm used for the signature.  A value of
   '0' means that the contents have not been signed but only encrypted.
   Predefined values: 1 - SHA1-160 2 - MD5

8.2.174.  Cues Element

   name: "Cues"

   path: "0*1(\Segment\Cues)"

   id: "0x1C53BB6B"

   maxOccurs: "1"

   type: "master"

   minver: "1"

   documentation: A Top-Level Element to speed seeking access.  All
   entries are local to the Segment.  This Element SHOULD be mandatory
   for non "live" streams.

8.2.175.  CuePoint Element

   name: "CuePoint"

   path: "1*(\Segment\Cues\CuePoint)"

   id: "0xBB"

   minOccurs: "1"

   type: "master"

   minver: "1"

   documentation: Contains all information relative to a seek point in
   the Segment.





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8.2.176.  CueTime Element

   name: "CueTime"

   path: "1*1(\Segment\Cues\CuePoint\CueTime)"

   id: "0xB3"

   minOccurs: "1"

   maxOccurs: "1"

   type: "uinteger"

   minver: "1"

   documentation: Absolute timestamp according to the Segment time base.

8.2.177.  CueTrackPositions Element

   name: "CueTrackPositions"

   path: "1*(\Segment\Cues\CuePoint\CueTrackPositions)"

   id: "0xB7"

   minOccurs: "1"

   type: "master"

   minver: "1"

   documentation: Contain positions for different tracks corresponding
   to the timestamp.

8.2.178.  CueTrack Element

   name: "CueTrack"

   path: "1*1(\Segment\Cues\CuePoint\CueTrackPositions\CueTrack)"

   id: "0xF7"

   minOccurs: "1"

   maxOccurs: "1"

   range: "not 0"



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   type: "uinteger"

   minver: "1"

   documentation: The track for which a position is given.

8.2.179.  CueClusterPosition Element

   name: "CueClusterPosition"

   path:
   "1*1(\Segment\Cues\CuePoint\CueTrackPositions\CueClusterPosition)"

   id: "0xF1"

   minOccurs: "1"

   maxOccurs: "1"

   type: "uinteger"

   minver: "1"

   documentation: The Segment Position of the Cluster containing the
   associated Block.

8.2.180.  CueRelativePosition Element

   name: "CueRelativePosition"

   path:
   "0*1(\Segment\Cues\CuePoint\CueTrackPositions\CueRelativePosition)"

   id: "0xF0"

   maxOccurs: "1"

   type: "uinteger"

   minver: "4"

   documentation: The relative position of the referenced block inside
   the cluster with 0 being the first possible position for an Element
   inside that cluster.







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8.2.181.  CueDuration Element

   name: "CueDuration"

   path: "0*1(\Segment\Cues\CuePoint\CueTrackPositions\CueDuration)"

   id: "0xB2"

   maxOccurs: "1"

   type: "uinteger"

   minver: "4"

   documentation: The duration of the block according to the Segment
   time base.  If missing the track's DefaultDuration does not apply and
   no duration information is available in terms of the cues.

8.2.182.  CueBlockNumber Element

   name: "CueBlockNumber"

   path: "0*1(\Segment\Cues\CuePoint\CueTrackPositions\CueBlockNumber)"

   id: "0x5378"

   maxOccurs: "1"

   range: "not 0"

   default: "1"

   type: "uinteger"

   minver: "1"

   documentation: Number of the Block in the specified Cluster.

8.2.183.  CueCodecState Element

   name: "CueCodecState"

   path: "0*1(\Segment\Cues\CuePoint\CueTrackPositions\CueCodecState)"

   id: "0xEA"

   maxOccurs: "1"




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   default: "0"

   type: "uinteger"

   minver: "2"

   documentation: The Segment Position of the Codec State corresponding
   to this Cue Element. 0 means that the data is taken from the initial
   Track Entry.

8.2.184.  CueReference Element

   name: "CueReference"

   path: "0*(\Segment\Cues\CuePoint\CueTrackPositions\CueReference)"

   id: "0xDB"

   type: "master"

   minver: "2"

   documentation: The Clusters containing the referenced Blocks.

8.2.185.  CueRefTime Element

   name: "CueRefTime"

   path: "1*1(\Segment\Cues\CuePoint\CueTrackPositions\CueReference\CueR
   efTime)"

   id: "0x96"

   minOccurs: "1"

   maxOccurs: "1"

   type: "uinteger"

   minver: "2"

   documentation: Timestamp of the referenced Block.

8.2.186.  CueRefCluster Element

   name: "CueRefCluster"





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   path: "1*1(\Segment\Cues\CuePoint\CueTrackPositions\CueReference\CueR
   efCluster)"

   id: "0x97"

   minOccurs: "1"

   maxOccurs: "1"

   type: "uinteger"

   minver: "0"

   maxver: "0"

   documentation: The Segment Position of the Cluster containing the
   referenced Block.

8.2.187.  CueRefNumber Element

   name: "CueRefNumber"

   path: "0*1(\Segment\Cues\CuePoint\CueTrackPositions\CueReference\CueR
   efNumber)"

   id: "0x535F"

   maxOccurs: "1"

   range: "not 0"

   default: "1"

   type: "uinteger"

   minver: "0"

   maxver: "0"

   documentation: Number of the referenced Block of Track X in the
   specified Cluster.

8.2.188.  CueRefCodecState Element

   name: "CueRefCodecState"

   path: "0*1(\Segment\Cues\CuePoint\CueTrackPositions\CueReference\CueR
   efCodecState)"



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   id: "0xEB"

   maxOccurs: "1"

   default: "0"

   type: "uinteger"

   minver: "0"

   maxver: "0"

   documentation: The Segment Position of the Codec State corresponding
   to this referenced Element. 0 means that the data is taken from the
   initial Track Entry.

8.2.189.  Attachments Element

   name: "Attachments"

   path: "0*1(\Segment\Attachments)"

   id: "0x1941A469"

   maxOccurs: "1"

   type: "master"

   minver: "1"

   documentation: Contain attached files.

8.2.190.  AttachedFile Element

   name: "AttachedFile"

   path: "1*(\Segment\Attachments\AttachedFile)"

   id: "0x61A7"

   minOccurs: "1"

   type: "master"

   minver: "1"

   documentation: An attached file.




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8.2.191.  FileDescription Element

   name: "FileDescription"

   path: "0*1(\Segment\Attachments\AttachedFile\FileDescription)"

   id: "0x467E"

   maxOccurs: "1"

   type: "utf-8"

   minver: "1"

   documentation: A human-friendly name for the attached file.

8.2.192.  FileName Element

   name: "FileName"

   path: "1*1(\Segment\Attachments\AttachedFile\FileName)"

   id: "0x466E"

   minOccurs: "1"

   maxOccurs: "1"

   type: "utf-8"

   minver: "1"

   documentation: Filename of the attached file.

8.2.193.  FileMimeType Element

   name: "FileMimeType"

   path: "1*1(\Segment\Attachments\AttachedFile\FileMimeType)"

   id: "0x4660"

   minOccurs: "1"

   maxOccurs: "1"

   type: "string"




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   minver: "1"

   documentation: MIME type of the file.

8.2.194.  FileData Element

   name: "FileData"

   path: "1*1(\Segment\Attachments\AttachedFile\FileData)"

   id: "0x465C"

   minOccurs: "1"

   maxOccurs: "1"

   type: "binary"

   minver: "1"

   documentation: The data of the file.

8.2.195.  FileUID Element

   name: "FileUID"

   path: "1*1(\Segment\Attachments\AttachedFile\FileUID)"

   id: "0x46AE"

   minOccurs: "1"

   maxOccurs: "1"

   range: "not 0"

   type: "uinteger"

   minver: "1"

   documentation: Unique ID representing the file, as random as
   possible.

8.2.196.  FileReferral Element

   name: "FileReferral"

   path: "0*1(\Segment\Attachments\AttachedFile\FileReferral)"



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   id: "0x4675"

   maxOccurs: "1"

   type: "binary"

   minver: "0"

   maxver: "0"

   documentation: A binary value that a track/codec can refer to when
   the attachment is needed.

8.2.197.  FileUsedStartTime Element

   name: "FileUsedStartTime"

   path: "0*1(\Segment\Attachments\AttachedFile\FileUsedStartTime)"

   id: "0x4661"

   maxOccurs: "1"

   type: "uinteger"

   minver: "0"

   maxver: "0"

   documentation: DivX font extension

8.2.198.  FileUsedEndTime Element

   name: "FileUsedEndTime"

   path: "0*1(\Segment\Attachments\AttachedFile\FileUsedEndTime)"

   id: "0x4662"

   maxOccurs: "1"

   type: "uinteger"

   minver: "0"

   maxver: "0"

   documentation: DivX font extension



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8.2.199.  Chapters Element

   name: "Chapters"

   path: "0*1(\Segment\Chapters)"

   id: "0x1043A770"

   maxOccurs: "1"

   type: "master"

   minver: "1"

   documentation: A system to define basic menus and partition data.
   For more detailed information, look at the Chapters Explanation.

8.2.200.  EditionEntry Element

   name: "EditionEntry"

   path: "1*(\Segment\Chapters\EditionEntry)"

   id: "0x45B9"

   minOccurs: "1"

   type: "master"

   minver: "1"

   documentation: Contains all information about a Segment edition.

8.2.201.  EditionUID Element

   name: "EditionUID"

   path: "0*1(\Segment\Chapters\EditionEntry\EditionUID)"

   id: "0x45BC"

   maxOccurs: "1"

   range: "not 0"

   type: "uinteger"

   minver: "1"



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   documentation: A unique ID to identify the edition.  It's useful for
   tagging an edition.

8.2.202.  EditionFlagHidden Element

   name: "EditionFlagHidden"

   path: "1*1(\Segment\Chapters\EditionEntry\EditionFlagHidden)"

   id: "0x45BD"

   minOccurs: "1"

   maxOccurs: "1"

   range: "0-1"

   default: "0"

   type: "uinteger"

   minver: "1"

   documentation: If an edition is hidden (1), it SHOULD NOT be
   available to the user interface (but still to Control Tracks; see
   flag notes). (1 bit)

8.2.203.  EditionFlagDefault Element

   name: "EditionFlagDefault"

   path: "1*1(\Segment\Chapters\EditionEntry\EditionFlagDefault)"

   id: "0x45DB"

   minOccurs: "1"

   maxOccurs: "1"

   range: "0-1"

   default: "0"

   type: "uinteger"

   minver: "1"





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   documentation: If a flag is set (1) the edition SHOULD be used as the
   default one. (1 bit)

8.2.204.  EditionFlagOrdered Element

   name: "EditionFlagOrdered"

   path: "0*1(\Segment\Chapters\EditionEntry\EditionFlagOrdered)"

   id: "0x45DD"

   maxOccurs: "1"

   range: "0-1"

   default: "0"

   type: "uinteger"

   minver: "1"

   documentation: Specify if the chapters can be defined multiple times
   and the order to play them is enforced. (1 bit)

8.2.205.  ChapterAtom Element

   name: "ChapterAtom"

   path: "1*(\Segment\Chapters\EditionEntry(1*(\ChapterAtom)))"

   id: "0xB6"

   minOccurs: "1"

   type: "master"

   recursive: "1"

   minver: "1"

   documentation: Contains the atom information to use as the chapter
   atom (apply to all tracks).

8.2.206.  ChapterUID Element

   name: "ChapterUID"

   path: "1*1(\Segment\Chapters\EditionEntry\ChapterAtom\ChapterUID)"



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   id: "0x73C4"

   minOccurs: "1"

   maxOccurs: "1"

   range: "not 0"

   type: "uinteger"

   minver: "1"

   documentation: A unique ID to identify the Chapter.

8.2.207.  ChapterStringUID Element

   name: "ChapterStringUID"

   path:
   "0*1(\Segment\Chapters\EditionEntry\ChapterAtom\ChapterStringUID)"

   id: "0x5654"

   maxOccurs: "1"

   type: "utf-8"

   minver: "3"

   documentation: A unique string ID to identify the Chapter.  Use for
   WebVTT cue identifier storage.

8.2.208.  ChapterTimeStart Element

   name: "ChapterTimeStart"

   path:
   "1*1(\Segment\Chapters\EditionEntry\ChapterAtom\ChapterTimeStart)"

   id: "0x91"

   minOccurs: "1"

   maxOccurs: "1"

   type: "uinteger"

   minver: "1"



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   documentation: Timestamp of the start of Chapter (not scaled).

8.2.209.  ChapterTimeEnd Element

   name: "ChapterTimeEnd"

   path:
   "0*1(\Segment\Chapters\EditionEntry\ChapterAtom\ChapterTimeEnd)"

   id: "0x92"

   maxOccurs: "1"

   type: "uinteger"

   minver: "1"

   documentation: Timestamp of the end of Chapter (timestamp excluded,
   not scaled).

8.2.210.  ChapterFlagHidden Element

   name: "ChapterFlagHidden"

   path:
   "1*1(\Segment\Chapters\EditionEntry\ChapterAtom\ChapterFlagHidden)"

   id: "0x98"

   minOccurs: "1"

   maxOccurs: "1"

   range: "0-1"

   default: "0"

   type: "uinteger"

   minver: "1"

   documentation: If a chapter is hidden (1), it SHOULD NOT be available
   to the user interface (but still to Control Tracks; see flag notes).
   (1 bit)







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8.2.211.  ChapterFlagEnabled Element

   name: "ChapterFlagEnabled"

   path:
   "1*1(\Segment\Chapters\EditionEntry\ChapterAtom\ChapterFlagEnabled)"

   id: "0x4598"

   minOccurs: "1"

   maxOccurs: "1"

   range: "0-1"

   default: "1"

   type: "uinteger"

   minver: "1"

   documentation: Specify whether the chapter is enabled.  It can be
   enabled/disabled by a Control Track.  When disabled, the movie SHOULD
   skip all the content between the TimeStart and TimeEnd of this
   chapter (see flag notes). (1 bit)

8.2.212.  ChapterSegmentUID Element

   name: "ChapterSegmentUID"

   path:
   "0*1(\Segment\Chapters\EditionEntry\ChapterAtom\ChapterSegmentUID)"

   id: "0x6E67"

   maxOccurs: "1"

   range: ">0"

   size: "16"

   type: "binary"

   minver: "1"

   documentation: The SegmentUID of another Segment to play during this
   chapter.




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   usage notes: ChapterSegmentUID is mandatory if
   ChapterSegmentEditionUID is used.

8.2.213.  ChapterSegmentEditionUID Element

   name: "ChapterSegmentEditionUID"

   path: "0*1(\Segment\Chapters\EditionEntry\ChapterAtom\ChapterSegmentE
   ditionUID)"

   id: "0x6EBC"

   maxOccurs: "1"

   range: "not 0"

   type: "uinteger"

   minver: "1"

   documentation: The EditionUID to play from the Segment linked in
   ChapterSegmentUID.  If ChapterSegmentEditionUID is undeclared then no
   Edition of the linked Segment is used.

8.2.214.  ChapterPhysicalEquiv Element

   name: "ChapterPhysicalEquiv"

   path: "0*1(\Segment\Chapters\EditionEntry\ChapterAtom\ChapterPhysical
   Equiv)"

   id: "0x63C3"

   maxOccurs: "1"

   type: "uinteger"

   minver: "1"

   documentation: Specify the physical equivalent of this ChapterAtom
   like "DVD" (60) or "SIDE" (50), see complete list of values.

8.2.215.  ChapterTrack Element

   name: "ChapterTrack"

   path: "0*1(\Segment\Chapters\EditionEntry\ChapterAtom\ChapterTrack)"




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   id: "0x8F"

   maxOccurs: "1"

   type: "master"

   minver: "1"

   documentation: List of tracks on which the chapter applies.  If this
   Element is not present, all tracks apply

8.2.216.  ChapterTrackNumber Element

   name: "ChapterTrackNumber"

   path: "1*(\Segment\Chapters\EditionEntry\ChapterAtom\ChapterTrack\Cha
   pterTrackNumber)"

   id: "0x89"

   minOccurs: "1"

   range: "not 0"

   type: "uinteger"

   minver: "1"

   documentation: UID of the Track to apply this chapter too.  In the
   absence of a control track, choosing this chapter will select the
   listed Tracks and deselect unlisted tracks.  Absence of this Element
   indicates that the Chapter SHOULD be applied to any currently used
   Tracks.

8.2.217.  ChapterDisplay Element

   name: "ChapterDisplay"

   path: "0*(\Segment\Chapters\EditionEntry\ChapterAtom\ChapterDisplay)"

   id: "0x80"

   type: "master"

   minver: "1"

   documentation: Contains all possible strings to use for the chapter
   display.



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8.2.218.  ChapString Element

   name: "ChapString"

   path: "1*1(\Segment\Chapters\EditionEntry\ChapterAtom\ChapterDisplay\
   ChapString)"

   id: "0x85"

   minOccurs: "1"

   maxOccurs: "1"

   type: "utf-8"

   minver: "1"

   documentation: Contains the string to use as the chapter atom.

8.2.219.  ChapLanguage Element

   name: "ChapLanguage"

   path: "1*(\Segment\Chapters\EditionEntry\ChapterAtom\ChapterDisplay\C
   hapLanguage)"

   id: "0x437C"

   minOccurs: "1"

   default: "eng"

   type: "string"

   minver: "1"

   documentation: The languages corresponding to the string, in the
   bibliographic ISO-639-2 form.  This Element MUST be ignored if the
   ChapLanguageIETF Element is used within the same ChapterDisplay
   Element.

8.2.220.  ChapLanguageIETF Element

   name: "ChapLanguageIETF"

   path: "0*1(\Segment\Chapters\EditionEntry\ChapterAtom\ChapterDisplay\
   ChapLanguageIETF)"




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   id: "0x437D"

   maxOccurs: "1"

   type: "string"

   minver: "4"

   documentation: Specifies the language used in the ChapString
   according to BCP 47 and using the IANA Language Subtag Registry.  If
   this Element is used, then any ChapLanguage Elements used in the same
   ChapterDisplay MUST be ignored.

8.2.221.  ChapCountry Element

   name: "ChapCountry"

   path: "0*(\Segment\Chapters\EditionEntry\ChapterAtom\ChapterDisplay\C
   hapCountry)"

   id: "0x437E"

   type: "string"

   minver: "1"

   documentation: The countries corresponding to the string, same 2
   octets as in Internet domains.  This Element MUST be ignored if the
   ChapLanguageIETF Element is used within the same ChapterDisplay
   Element.

8.2.222.  ChapProcess Element

   name: "ChapProcess"

   path: "0*(\Segment\Chapters\EditionEntry\ChapterAtom\ChapProcess)"

   id: "0x6944"

   type: "master"

   minver: "1"

   documentation: Contains all the commands associated to the Atom.







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8.2.223.  ChapProcessCodecID Element

   name: "ChapProcessCodecID"

   path: "1*1(\Segment\Chapters\EditionEntry\ChapterAtom\ChapProcess\Cha
   pProcessCodecID)"

   id: "0x6955"

   minOccurs: "1"

   maxOccurs: "1"

   default: "0"

   type: "uinteger"

   minver: "1"

   documentation: Contains the type of the codec used for the
   processing.  A value of 0 means native Matroska processing (to be
   defined), a value of 1 means the DVD command set is used.  More codec
   IDs can be added later.

8.2.224.  ChapProcessPrivate Element

   name: "ChapProcessPrivate"

   path: "0*1(\Segment\Chapters\EditionEntry\ChapterAtom\ChapProcess\Cha
   pProcessPrivate)"

   id: "0x450D"

   maxOccurs: "1"

   type: "binary"

   minver: "1"

   documentation: Some optional data attached to the ChapProcessCodecID
   information.  For ChapProcessCodecID = 1, it is the "DVD level"
   equivalent.

8.2.225.  ChapProcessCommand Element

   name: "ChapProcessCommand"





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   path: "0*(\Segment\Chapters\EditionEntry\ChapterAtom\ChapProcess\Chap
   ProcessCommand)"

   id: "0x6911"

   type: "master"

   minver: "1"

   documentation: Contains all the commands associated to the Atom.

8.2.226.  ChapProcessTime Element

   name: "ChapProcessTime"

   path: "1*1(\Segment\Chapters\EditionEntry\ChapterAtom\ChapProcess\Cha
   pProcessCommand\ChapProcessTime)"

   id: "0x6922"

   minOccurs: "1"

   maxOccurs: "1"

   type: "uinteger"

   minver: "1"

   documentation: Defines when the process command SHOULD be handled

8.2.227.  ChapProcessData Element

   name: "ChapProcessData"

   path: "1*1(\Segment\Chapters\EditionEntry\ChapterAtom\ChapProcess\Cha
   pProcessCommand\ChapProcessData)"

   id: "0x6933"

   minOccurs: "1"

   maxOccurs: "1"

   type: "binary"

   minver: "1"





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   documentation: Contains the command information.  The data SHOULD be
   interpreted depending on the ChapProcessCodecID value.  For
   ChapProcessCodecID = 1, the data correspond to the binary DVD cell
   pre/post commands.

8.2.228.  Tags Element

   name: "Tags"

   path: "0*(\Segment\Tags)"

   id: "0x1254C367"

   type: "master"

   minver: "1"

   documentation: Element containing metadata describing Tracks,
   Editions, Chapters, Attachments, or the Segment as a whole.  A list
   of valid tags can be found here.

8.2.229.  Tag Element

   name: "Tag"

   path: "1*(\Segment\Tags\Tag)"

   id: "0x7373"

   minOccurs: "1"

   type: "master"

   minver: "1"

   documentation: A single metadata descriptor.

8.2.230.  Targets Element

   name: "Targets"

   path: "1*1(\Segment\Tags\Tag\Targets)"

   id: "0x63C0"

   minOccurs: "1"

   maxOccurs: "1"



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   type: "master"

   minver: "1"

   documentation: Specifies which other elements the metadata
   represented by the Tag applies to.  If empty or not present, then the
   Tag describes everything in the Segment.

8.2.231.  TargetTypeValue Element

   name: "TargetTypeValue"

   path: "0*1(\Segment\Tags\Tag\Targets\TargetTypeValue)"

   id: "0x68CA"

   maxOccurs: "1"

   default: "50"

   type: "uinteger"

   minver: "1"

   documentation: A number to indicate the logical level of the target.

8.2.232.  TargetType Element

   name: "TargetType"

   path: "0*1(\Segment\Tags\Tag\Targets\TargetType)"

   id: "0x63CA"

   maxOccurs: "1"

   type: "string"

   minver: "1"

   documentation: An informational string that can be used to display
   the logical level of the target like "ALBUM", "TRACK", "MOVIE",
   "CHAPTER", etc (see TargetType).








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8.2.233.  TagTrackUID Element

   name: "TagTrackUID"

   path: "0*(\Segment\Tags\Tag\Targets\TagTrackUID)"

   id: "0x63C5"

   default: "0"

   type: "uinteger"

   minver: "1"

   documentation: A unique ID to identify the Track(s) the tags belong
   to.  If the value is 0 at this level, the tags apply to all tracks in
   the Segment.

8.2.234.  TagEditionUID Element

   name: "TagEditionUID"

   path: "0*(\Segment\Tags\Tag\Targets\TagEditionUID)"

   id: "0x63C9"

   default: "0"

   type: "uinteger"

   minver: "1"

   documentation: A unique ID to identify the EditionEntry(s) the tags
   belong to.  If the value is 0 at this level, the tags apply to all
   editions in the Segment.

8.2.235.  TagChapterUID Element

   name: "TagChapterUID"

   path: "0*(\Segment\Tags\Tag\Targets\TagChapterUID)"

   id: "0x63C4"

   default: "0"

   type: "uinteger"




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   minver: "1"

   documentation: A unique ID to identify the Chapter(s) the tags belong
   to.  If the value is 0 at this level, the tags apply to all chapters
   in the Segment.

8.2.236.  TagAttachmentUID Element

   name: "TagAttachmentUID"

   path: "0*(\Segment\Tags\Tag\Targets\TagAttachmentUID)"

   id: "0x63C6"

   default: "0"

   type: "uinteger"

   minver: "1"

   documentation: A unique ID to identify the Attachment(s) the tags
   belong to.  If the value is 0 at this level, the tags apply to all
   the attachments in the Segment.

8.2.237.  SimpleTag Element

   name: "SimpleTag"

   path: "1*(\Segment\Tags\Tag(1*(\SimpleTag)))"

   id: "0x67C8"

   minOccurs: "1"

   type: "master"

   recursive: "1"

   minver: "1"

   documentation: Contains general information about the target.

8.2.238.  TagName Element

   name: "TagName"

   path: "1*1(\Segment\Tags\Tag\SimpleTag\TagName)"




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   id: "0x45A3"

   minOccurs: "1"

   maxOccurs: "1"

   type: "utf-8"

   minver: "1"

   documentation: The name of the Tag that is going to be stored.

8.2.239.  TagLanguage Element

   name: "TagLanguage"

   path: "1*1(\Segment\Tags\Tag\SimpleTag\TagLanguage)"

   id: "0x447A"

   minOccurs: "1"

   maxOccurs: "1"

   default: "und"

   type: "string"

   minver: "1"

   documentation: Specifies the language of the tag specified, in the
   Matroska languages form.  This Element MUST be ignored if the
   TagLanguageIETF Element is used within the same SimpleTag Element.

8.2.240.  TagLanguageIETF Element

   name: "TagLanguageIETF"

   path: "0*1(\Segment\Tags\Tag\SimpleTag\TagLanguageIETF)"

   id: "0x447B"

   maxOccurs: "1"

   type: "string"

   minver: "4"




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   documentation: Specifies the language used in the TagString according
   to BCP 47 and using the IANA Language Subtag Registry.  If this
   Element is used, then any TagLanguage Elements used in the same
   SimpleTag MUST be ignored.

8.2.241.  TagDefault Element

   name: "TagDefault"

   path: "1*1(\Segment\Tags\Tag\SimpleTag\TagDefault)"

   id: "0x4484"

   minOccurs: "1"

   maxOccurs: "1"

   range: "0-1"

   default: "1"

   type: "uinteger"

   minver: "1"

   documentation: A boolean value to indicate if this is the default/
   original language to use for the given tag.

8.2.242.  TagString Element

   name: "TagString"

   path: "0*1(\Segment\Tags\Tag\SimpleTag\TagString)"

   id: "0x4487"

   maxOccurs: "1"

   type: "utf-8"

   minver: "1"

   documentation: The value of the Tag.








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8.2.243.  TagBinary Element

   name: "TagBinary"

   path: "0*1(\Segment\Tags\Tag\SimpleTag\TagBinary)"

   id: "0x4485"

   maxOccurs: "1"

   type: "binary"

   minver: "1"

   documentation: The values of the Tag if it is binary.  Note that this
   cannot be used in the same SimpleTag as TagString.

9.  Matroska Element Ordering Guidelines

   Except for the "EBML Header" and the "CRC-32 Element", the EBML
   specification does not require any particular storage order for
   "Elements".  The Matroska specification however defines mandates and
   recommendations for ordering certain "Elements" in order to
   facilitate better playback, seeking, and editing efficiency.  This
   section describes and offers rationale for ordering requirements and
   recommendations for Matroska.

9.1.  Top-Level Elements

   The "Info Element" is the only REQUIRED "Top-Level Element" in a
   Matroska file.  To be playable, Matroska MUST also contain at least
   one "Tracks Element" and "Cluster Element".  The first "Info Element"
   and the first "Tracks Element" MUST either be stored before the first
   "Cluster Element" or both SHALL be referenced by a "SeekHead Element"
   occurring before the first "Cluster Element".

   It is possible to edit a Matroska file after it has been created.
   For example, chapters, tags or attachments can be added.  When new
   "Top-Level Elements" are added to a Matroska file, the "SeekHead"
   Element(s) MUST be updated so that the "SeekHead" Element(s) itemize
   the identity and position of all "Top-Level Elements".  Editing,
   removing, or adding "Elements" to a Matroska file often requires that
   some existing "Elements" be voided or extended; therefore, it is
   RECOMMENDED to use "Void Elements" as padding in between "Top-Level
   Elements".






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9.2.  CRC-32

   As noted by the EBML specification, if a "CRC-32 Element" is used
   then the "CRC-32 Element" MUST be the first ordered "Element" within
   its "Parent Element".  The Matroska specification recommends that
   "CRC-32 Elements" SHOULD NOT be used as an immediate "Child Element"
   of the "Segment Element"; however all "Top-Level Elements" of an
   "EBML Document" SHOULD include a "CRC-32 Element" as a "Child
   Element".

9.3.  SeekHead

   If used, the first "SeekHead Element" SHOULD be the first non-"CRC-32
   Child Element" of the "Segment Element".  If a second "SeekHead
   Element" is used, then the first "SeekHead Element" MUST reference
   the identity and position of the second "SeekHead".  Additionally,
   the second "SeekHead Element" MUST only reference "Cluster" Elements
   and not any other "Top-Level Element" already contained within the
   first "SeekHead Element".  The second "SeekHead Element" MAY be
   stored in any order relative to the other "Top-Level Elements."
   Whether one or two "SeekHead Element(s)" are used, the "SeekHead
   Element(s)" MUST collectively reference the identity and position of
   all "Top-Level Elements" except for the first "SeekHead Element".

   It is RECOMMENDED that the first "SeekHead Element" be followed by a
   "Void Element" to allow for the "SeekHead Element" to be expanded to
   cover new "Top-Level Elements" that could be added to the Matroska
   file, such as "Tags", "Chapters" and "Attachments Elements".

9.4.  Cues (index)

   The "Cues Element" is RECOMMENDED to optimize seeking access in
   Matroska.  It is programmatically simpler to add the "Cues Element"
   after all "Cluster Elements" have been written because this does not
   require a prediction of how much space to reserve before writing the
   "Cluster Elements".  However, storing the "Cues Element" before the
   "Cluster Elements" can provide some seeking advantages.  If the "Cues
   Element" is present, then it SHOULD either be stored before the first
   "Cluster Element" or be referenced by a "SeekHead Element".

9.5.  Info

   The first "Info Element" SHOULD occur before the first "Tracks
   Element" and first "Cluster Element" except when referenced by a
   "SeekHead Element".






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9.6.  Chapters

   The "Chapters Element" SHOULD be placed before the "Cluster
   Element(s)".  The "Chapters Element" can be used during playback even
   if the user does not need to seek.  It immediately gives the user
   information about what section is being read and what other sections
   are available.  In the case of Ordered Chapters it RECOMMENDED to
   evaluate the logical linking even before playing.  The "Chapters
   Element" SHOULD be placed before the first "Tracks Element" and after
   the first "Info Element".

9.7.  Attachments

   The "Attachments Element" is not intended to be used by default when
   playing the file, but could contain information relevant to the
   content, such as cover art or fonts.  Cover art is useful even before
   the file is played and fonts could be needed before playback starts
   for initialization of subtitles.  The "Attachments Element" MAY be
   placed before the first "Cluster Element"; however if the
   "Attachments Element" is likely to be edited, then it SHOULD be
   placed after the last "Cluster Element".

9.8.  Tags

   The "Tags Element" is most subject to changes after the file was
   originally created.  For easier editing, the "Tags Element" SHOULD be
   placed at the end of the "Segment Element", even after the
   "Attachments Element".  On the other hand, it is inconvenient to have
   to seek in the "Segment" for tags, especially for network streams.
   So it's better if the "Tags Element" is found early in the stream.
   When editing the "Tags Element", the original "Tags Element" at the
   beginning can be overwritten with a "Void Element" and a new "Tags
   Element" written at the end of the "Segment Element".  The file size
   will only marginally change.

9.9.  Optimum layout from a muxer

   o  SeekHead

   o  Info

   o  Tracks

   o  Chapters

   o  Attachments

   o  Tags



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   o  Clusters

   o  Cues

9.10.  Optimum layout after editing tags

   o  SeekHead

   o  Info

   o  Tracks

   o  Chapters

   o  Attachments

   o  Void

   o  Clusters

   o  Cues

   o  Tags

9.11.  Optimum layout with Cues at the front

   o  SeekHead

   o  Info

   o  Tracks

   o  Chapters

   o  Attachments

   o  Tags

   o  Cues

   o  Clusters

9.12.  Cluster Timecode

   The "Timecode Element" MUST occur as in storage order before any
   "SimpleBlock", "BlockGroup", or "EncryptedBlock" within the "Cluster
   Element".




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10.  Chapters

10.1.  Edition and Chapter Flags

10.1.1.  Chapter Flags

   Two "Chapter Flags" are defined to describe the behavior of the
   "ChapterAtom Element": "ChapterFlagHidden" and "ChapterFlagEnabled".

   If a "ChapterAtom Element" is the "Child Element" of another
   "ChapterAtom Element" with a "Chapter Flag" set to "true", then the
   "Child ChapterAtom Element" MUST be interpreted as having its same
   "Chapter Flag" set to "true".  If a "ChapterAtom Element" is the
   "Child Element" of another "ChapterAtom Element" with a "Chapter
   Flag" set to "false" or if the "ChapterAtom Element" does not have a
   "ChapterAtom Element" as its "Parent Element", then it MUST be
   interpreted according to its own "Chapter Flag".

   As an example, consider a "Parent ChapterAtom Element" that has its
   "ChapterFlagHidden" set to "true" and also contains two child
   "ChapterAtoms", the first with "ChapterFlagHidden" set to "true" and
   the second with "ChapterFlagHidden" either set to "false" or not
   present at all (in which case the default value of the Element
   applies, which is "false").  Since the parent "ChapterAtom" has its
   "ChapterFlagHidden" set to "true" then all of its children
   "ChapterAtoms" MUST also be interpreted as if their
   "ChapterFlagHidden" is also set to "true".  However, if a "Control
   Track" toggles the parent's "ChapterFlagHidden" flag to "false", then
   only the parent "ChapterAtom" and its second child "ChapterAtom" MUST
   be interpreted as if "ChapterFlagHidden" is set to "false".  The
   first child "ChapterAtom" which has the "ChapterFlagHidden" flag set
   to "true" retains its value until its value is toggled to "false" by
   a "Control Track".

10.1.2.  Edition Flags

   Three "Edition Flags" are defined to describe the behavior of the
   "EditionEntry Element": "EditionFlagHidden", "EditionFlagDefault" and
   "EditionFlagOrdered".

10.1.2.1.  EditionFlagHidden

   The "EditionFlagHidden Flag" behaves similarly to the
   "ChapterFlagHidden Flag": if "EditionFlagHidden" is set to "true",
   its "Child ChapterAtoms Elements" MUST also be interpreted as if
   their "ChapterFlagHidden" is also set to "true", regardless of their
   own "ChapterFlagHidden Flags".  If "EditionFlagHidden" is toggled by
   a "Control Track" to "false", the "ChapterFlagHidden Flags" of the



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   "Child ChapterAtoms Elements" SHALL determine whether the
   "ChapterAtom" is hidden or not.

10.1.2.2.  EditionFlagDefault

   It is RECOMMENDED that no more than one "Edition" have an
   "EditionFlagDefault Flag" set to "true".  The first "Edition" with
   both the "EditionFlagDefault Flag" set to "true" and the
   "EditionFlagHidden Flag" set to "false" is the "Default Edition".
   When all "EditionFlagDefault Flags" are set to "false", then the
   first "Edition" is the "Default Edition".

10.1.2.3.  EditionFlagOrdered

   The "EditionFlagOrdered Flag" is a significant feature as it enables
   an "Edition" of "Ordered Chapters" which defines and arranges a
   virtual timeline rather than simply labeling points within the
   timeline.  For example, with "Editions" of "Ordered Chapters" a
   single "Matroska file" can present multiple edits of a film without
   duplicating content.  Alternatively if a videotape is digitized in
   full, one "Ordered Edition" could present the full content (including
   colorbars, countdown, slate, a feature presentation, and black
   frames), while another "Edition" of "Ordered Chapters" can use
   "Chapters" that only mark the intended presentation with the
   colorbars and other ancillary visual information excluded.  If an
   "Edition" of "Ordered Chapters" is enabled then the "Matroska Player"
   MUST play those Chapters in their stored order from the timecode
   marked in the "ChapterTimeStart Element" to the timecode marked in to
   "ChapterTimeEnd Element".

   If the "EditionFlagOrdered Flag" is set to "false", "Simple Chapters"
   are used and only the "ChapterTimeStart" of a "Chapter" is used as
   chapter mark to jump to the predefined point in the timeline.  With
   "Simple Chapters", a "Matroska Player" MUST ignore certain "Chapter
   Elements".  All these elements are now informational only.

   The following list shows the different usage of "Chapter Elements"
   between an ordered and non-ordered "Edition".

   Chapter elements / ordered Edition | False | True ChapterUID | X | X
   ChapterStringUID | X | X ChapterTimeStart | X | X ChapterTimeEnd |
   - | X ChapterFlagHidden | X | X ChapterFlagEnabled | X | X
   ChapterSegmentUID | - | X ChapterSegmentEditionUID | - | X
   ChapterPhysicalEquiv | X | X ChapterTrack | - | X ChapterDisplay |
   X | X ChapProcess | - | X

   Furthermore there are other EBML "Elements" which could be used if
   the "EditionFlagOrdered Flag" is set to "true".



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   Other elements / ordered Edition | False | True Info/SegmentFamily |
   - | X Info/ChapterTranslate | - | X Track/TrackTranslate | - | X

   These other "Elements" belong to the Matroska DVD menu system and are
   only used when the "ChapProcessCodecID Element" is set to 1.

10.1.2.3.1.  Ordered-Edition and Matroska Segment-Linking

   o  Hard Linking: "Ordered-Chapters" supersedes the "Hard Linking".

   o  Soft Linking: In this complex system "Ordered Chapters" are
      REQUIRED and a "Chapter CODEC" MUST interpret the "ChapProcess" of
      all chapters.

   o  Medium Linking: "Ordered Chapters" are used in a normal way and
      can be combined with the "ChapterSegmentUID" element which
      establishes a link to another Matroska file/Segment.

   See Section 23) for more information about "Hard Linking", "Soft
   Linking" and "Medium Linking".

10.2.  Menu features

   The menu features are handled like a _chapter codec_. That means each
   codec has a type, some private data and some data in the chapters.

   The type of the menu system is defined by the "ChapProcessCodecID"
   parameter.  For now only 2 values are supported : 0 matroska script,
   1 menu borrowed from the DVD.  The private data depend on the type of
   menu system (stored in ChapProcessPrivate), idem for the data in the
   chapters (stored in ChapProcessData).

10.2.1.  Matroska Script (0)

   This is the case when "ChapProcessCodecID" = 0.  This is a script
   language build for Matroska purposes.  The inspiration comes from
   ActionScript, javascript and other similar scripting languages.  The
   commands are stored as text commands, in UTF-8.  The syntax is C
   like, with commands spanned on many lines, each terminating with a
   ";".  You can also include comments at the end of lines with "//" or
   comment many lines using "/* */".  The scripts are stored in
   ChapProcessData.  For the moment ChapProcessPrivate is not used.

   The one and only command existing for the moment is "GotoAndPlay(
   ChapterUID );".  As the same suggests, it means that when this
   command is encountered, the "Matroska Player" SHOULD jump to the
   "Chapter" specified by the UID and play it.




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10.2.2.  DVD menu (1)

   This is the case when "ChapProcessCodecID" = 1.  Each level of a
   chapter corresponds to a logical level in the DVD system that is
   stored in the first octet of the ChapProcessPrivate.  This DVD
   hierarchy is as follows:

   ChapProcessPrivate | DVD Name | Hierarchy | Commands Possible |
   Comment 0x30 | SS | DVD domain | - | First Play, Video Manager, Video
   Title 0x2A | LU | Language Unit | - | Contains only PGCs 0x28 | TT |
   Title | - | Contains only PGCs 0x20 | PGC | Program Group Chain
   (PGC) | * | 0x18 | PG | Program 1 / Program 2 / Program 3 | - |
   0x10 | PTT | Part Of Title 1 / Part Of Title 2 | - | Equivalent to
   the chapters on the sleeve.  0x08 | CN | Cell 1 / Cell 2 / Cell 3 /
   Cell 4 / Cell 5 / Cell 6 | - |

   You can also recover wether a Segment is a Video Manager (VMG), Video
   Title Set (VTS) or Video Title Set Menu (VTSM) from the
   ChapterTranslateID element found in the Segment Info.  This field
   uses 2 octets as follows:

   1.  Domain Type: 0 for VMG, the domain number for VTS and VTSM

   2.  Domain Value: 0 for VMG and VTSM, 1 for the VTS source.

   For instance, the menu part from VTS_01_0.VOB would be coded [1,0]
   and the content part from VTS_02_3.VOB would be [2,1].  The VMG is
   always [0,0]

   The following octets of ChapProcessPrivate are as follows:

   Octet 1 | DVD Name | Following Octets 0x30 | SS | Domain name code
   (1: 0x00= First play, 0xC0= VMG, 0x40= VTSM, 0x80= VTS) + VTS(M)
   number (2) 0x2A | LU | Language code (2) + Language extension (1)
   0x28 | TT | global Title number (2) + corresponding TTN of the VTS
   (1) 0x20 | PGC | PGC number (2) + Playback Type (1) + Disabled User
   Operations (4) 0x18 | PG | Program number (2) 0x10 | PTT | PTT-
   chapter number (1) 0x08 | CN | Cell number [VOB ID(2)][Cell
   ID(1)][Angle Num(1)]

   If the level specified in ChapProcessPrivate is a PGC (0x20), there
   is an octet called the Playback Type, specifying the kind of PGC
   defined:

   o  0x00: entry only/basic PGC

   o  0x82: Title+Entry Menu (only found in the Video Manager domain)




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   o  0x83: Root Menu (only found in the VTSM domain)

   o  0x84: Subpicture Menu (only found in the VTSM domain)

   o  0x85: Audio Menu (only found in the VTSM domain)

   o  0x86: Angle Menu (only found in the VTSM domain)

   o  0x87: Chapter Menu (only found in the VTSM domain)

   The next 4 following octets correspond to the User Operation flags
   [17] in the standard PGC.  When a bit is set, the command SHOULD be
   disabled.

   ChapProcessData contains the pre/post/cell commands in binary format
   as there are stored on a DVD.  There is just an octet preceding these
   data to specify the number of commands in the element.  As follows:
   [# of commands(1)][command 1 (8)][command 2 (8)][command 3 (8)].

   More information on the DVD commands and format on DVD-replica [18],
   where we got most of the info about it.  You can also get information
   on DVD from the DVDinfo project [19].

10.3.  Example 1 : basic chaptering

   In this example a movie is split in different chapters.  It could
   also just be an audio file (album) on which each track corresponds to
   a chapter.

   o  00000ms - 05000ms : Intro

   o  05000ms - 25000ms : Before the crime

   o  25000ms - 27500ms : The crime

   o  27500ms - 38000ms : The killer arrested

   o  38000ms - 43000ms : Credits

   This would translate in the following matroska form :

          <Chapters>
            <EditionEntry>
              <EditionUID>16603393396715046047</EditionUID>
              <ChapterAtom>
                <ChapterUID>1193046</ChapterUID>
                <ChapterTimeStart>0</ChapterTimeStart>
                <ChapterTimeEnd>5000000000</ChapterTimeEnd>



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                <ChapterDisplay>
                  <ChapString>Intro</ChapString>
                  <ChapLanguage>eng</ChapLanguage>
                </ChapterDisplay>
                <ChapterFlagHidden>0</ChapterFlagHidden>
                <ChapterFlagEnabled>1</ChapterFlagEnabled>
              </ChapterAtom>
              <ChapterAtom>
                <ChapterUID>2311527</ChapterUID>
                <ChapterTimeStart>5000000000</ChapterTimeStart>
                <ChapterTimeEnd>25000000000</ChapterTimeEnd>
                <ChapterDisplay>
                  <ChapString>Before the crime</ChapString>
                  <ChapLanguage>eng</ChapLanguage>
                </ChapterDisplay>
                <ChapterDisplay>
                  <ChapString>Avant le crime</ChapString>
                  <ChapLanguage>fra</ChapLanguage>
                </ChapterDisplay>
                <ChapterFlagHidden>0</ChapterFlagHidden>
                <ChapterFlagEnabled>1</ChapterFlagEnabled>
              </ChapterAtom>
              <ChapterAtom>
                <ChapterUID>3430008</ChapterUID>
                <ChapterTimeStart>25000000000</ChapterTimeStart>
                <ChapterTimeEnd>27500000000</ChapterTimeEnd>
                <ChapterDisplay>
                  <ChapString>The crime</ChapString>
                  <ChapLanguage>eng</ChapLanguage>
                </ChapterDisplay>
                <ChapterDisplay>
                  <ChapString>Le crime</ChapString>
                  <ChapLanguage>fra</ChapLanguage>
                </ChapterDisplay>
                <ChapterFlagHidden>0</ChapterFlagHidden>
                <ChapterFlagEnabled>1</ChapterFlagEnabled>
              </ChapterAtom>
              <ChapterAtom>
                <ChapterUID>4548489</ChapterUID>
                <ChapterTimeStart>27500000000</ChapterTimeStart>
                <ChapterTimeEnd>38000000000</ChapterTimeEnd>
                <ChapterDisplay>
                  <ChapString>After the crime</ChapString>
                  <ChapLanguage>eng</ChapLanguage>
                </ChapterDisplay>
                <ChapterDisplay>
                  <ChapString>Apres le crime</ChapString>
                  <ChapLanguage>fra</ChapLanguage>



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                </ChapterDisplay>
                <ChapterFlagHidden>0</ChapterFlagHidden>
                <ChapterFlagEnabled>1</ChapterFlagEnabled>
              </ChapterAtom>
              <ChapterAtom>
                <ChapterUID>5666960</ChapterUID>
                <ChapterTimeStart>38000000000</ChapterTimeStart>
                <ChapterTimeEnd>43000000000</ChapterTimeEnd>
                <ChapterDisplay>
                  <ChapString>Credits</ChapString>
                  <ChapLanguage>eng</ChapLanguage>
                </ChapterDisplay>
                <ChapterDisplay>
                  <ChapString>Generique</ChapString>
                  <ChapLanguage>fra</ChapLanguage>
                </ChapterDisplay>
                <ChapterFlagHidden>0</ChapterFlagHidden>
                <ChapterFlagEnabled>1</ChapterFlagEnabled>
              </ChapterAtom>
              <EditionFlagDefault>0</EditionFlagDefault>
              <EditionFlagHidden>0</EditionFlagHidden>
            </EditionEntry>
          </Chapters>

10.4.  Example 2 : nested chapters

   In this example an (existing) album is split into different chapters,
   and one of them contain another splitting.

10.4.1.  The Micronauts "Bleep To Bleep"

   o  00:00 - 12:28 : Baby Wants To Bleep/Rock

      *  00:00 - 04:38 : Baby wants to bleep (pt.1)

      *  04:38 - 07:12 : Baby wants to rock

      *  07:12 - 10:33 : Baby wants to bleep (pt.2)

      *  10:33 - 12:28 : Baby wants to bleep (pt.3)

   o  12:30 - 19:38 : Bleeper_O+2

   o  19:40 - 22:20 : Baby wants to bleep (pt.4)

   o  22:22 - 25:18 : Bleep to bleep

   o  25:20 - 33:35 : Baby wants to bleep (k)



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   o  33:37 - 44:28 : Bleeper

       <Chapters>
         <EditionEntry>
           <EditionUID>1281690858003401414</EditionUID>
           <ChapterAtom>
             <ChapterUID>1</ChapterUID>
             <ChapterTimeStart>0</ChapterTimeStart>
             <ChapterTimeEnd>748000000</ChapterTimeEnd>
             <ChapterDisplay>
               <ChapString>Baby wants to Bleep/Rock</ChapString>
               <ChapLanguage>eng</ChapLanguage>
             </ChapterDisplay>
             <ChapterAtom>
               <ChapterUID>2</ChapterUID>
               <ChapterTimeStart>0</ChapterTimeStart>
               <ChapterTimeEnd>278000000</ChapterTimeEnd>
               <ChapterDisplay>
                 <ChapString>Baby wants to bleep (pt.1)</ChapString>
                 <ChapLanguage>eng</ChapLanguage>
               </ChapterDisplay>
               <ChapterFlagHidden>0</ChapterFlagHidden>
               <ChapterFlagEnabled>1</ChapterFlagEnabled>
             </ChapterAtom>
             <ChapterAtom>
               <ChapterUID>3</ChapterUID>
               <ChapterTimeStart>278000000</ChapterTimeStart>
               <ChapterTimeEnd>432000000</ChapterTimeEnd>
               <ChapterDisplay>
                 <ChapString>Baby wants to rock</ChapString>
                 <ChapLanguage>eng</ChapLanguage>
               </ChapterDisplay>
               <ChapterFlagHidden>0</ChapterFlagHidden>
               <ChapterFlagEnabled>1</ChapterFlagEnabled>
             </ChapterAtom>
             <ChapterAtom>
               <ChapterUID>4</ChapterUID>
               <ChapterTimeStart>432000000</ChapterTimeStart>
               <ChapterTimeEnd>633000000</ChapterTimeEnd>
               <ChapterDisplay>
                 <ChapString>Baby wants to bleep (pt.2)</ChapString>
                 <ChapLanguage>eng</ChapLanguage>
               </ChapterDisplay>
               <ChapterFlagHidden>0</ChapterFlagHidden>
               <ChapterFlagEnabled>1</ChapterFlagEnabled>
             </ChapterAtom>
             <ChapterAtom>
               <ChapterUID>5</ChapterUID>



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               <ChapterTimeStart>633000000</ChapterTimeStart>
               <ChapterTimeEnd>748000000</ChapterTimeEnd>
               <ChapterDisplay>
                 <ChapString>Baby wants to bleep (pt.3)</ChapString>
                 <ChapLanguage>eng</ChapLanguage>
               </ChapterDisplay>
               <ChapterFlagHidden>0</ChapterFlagHidden>
               <ChapterFlagEnabled>1</ChapterFlagEnabled>
             </ChapterAtom>
             <ChapterFlagHidden>0</ChapterFlagHidden>
             <ChapterFlagEnabled>1</ChapterFlagEnabled>
           </ChapterAtom>
           <ChapterAtom>
             <ChapterUID>6</ChapterUID>
             <ChapterTimeStart>750000000</ChapterTimeStart>
             <ChapterTimeEnd>1178500000</ChapterTimeEnd>
             <ChapterDisplay>
               <ChapString>Bleeper_O+2</ChapString>
               <ChapLanguage>eng</ChapLanguage>
             </ChapterDisplay>
             <ChapterFlagHidden>0</ChapterFlagHidden>
             <ChapterFlagEnabled>1</ChapterFlagEnabled>
           </ChapterAtom>
           <ChapterAtom>
             <ChapterUID>7</ChapterUID>
             <ChapterTimeStart>1180500000</ChapterTimeStart>
             <ChapterTimeEnd>1340000000</ChapterTimeEnd>
             <ChapterDisplay>
               <ChapString>Baby wants to bleep (pt.4)</ChapString>
               <ChapLanguage>eng</ChapLanguage>
             </ChapterDisplay>
             <ChapterFlagHidden>0</ChapterFlagHidden>
             <ChapterFlagEnabled>1</ChapterFlagEnabled>
           </ChapterAtom>
           <ChapterAtom>
             <ChapterUID>8</ChapterUID>
             <ChapterTimeStart>1342000000</ChapterTimeStart>
             <ChapterTimeEnd>1518000000</ChapterTimeEnd>
             <ChapterDisplay>
               <ChapString>Bleep to bleep</ChapString>
               <ChapLanguage>eng</ChapLanguage>
             </ChapterDisplay>
             <ChapterFlagHidden>0</ChapterFlagHidden>
             <ChapterFlagEnabled>1</ChapterFlagEnabled>
           </ChapterAtom>
           <ChapterAtom>
             <ChapterUID>9</ChapterUID>
             <ChapterTimeStart>1520000000</ChapterTimeStart>



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             <ChapterTimeEnd>2015000000</ChapterTimeEnd>
             <ChapterDisplay>
               <ChapString>Baby wants to bleep (k)</ChapString>
               <ChapLanguage>eng</ChapLanguage>
             </ChapterDisplay>
             <ChapterFlagHidden>0</ChapterFlagHidden>
             <ChapterFlagEnabled>1</ChapterFlagEnabled>
           </ChapterAtom>
           <ChapterAtom>
             <ChapterUID>10</ChapterUID>
             <ChapterTimeStart>2017000000</ChapterTimeStart>
             <ChapterTimeEnd>2668000000</ChapterTimeEnd>
             <ChapterDisplay>
               <ChapString>Bleeper</ChapString>
               <ChapLanguage>eng</ChapLanguage>
             </ChapterDisplay>
             <ChapterFlagHidden>0</ChapterFlagHidden>
             <ChapterFlagEnabled>1</ChapterFlagEnabled>
           </ChapterAtom>
           <EditionFlagDefault>0</EditionFlagDefault>
           <EditionFlagHidden>0</EditionFlagHidden>
         </EditionEntry>
       </Chapters>

11.  Attachments

11.1.  Introduction

   Matroska supports storage of related files and data in the
   "Attachments Element" (a "Top-Level Element").  "Attachment Elements"
   can be used to store related cover art, font files, transcripts,
   reports, error recovery files, picture or text-based annotations,
   copies of specifications, or other ancillary files related to the
   "Segment".

   "Matroska Readers" MUST NOT execute files stored as "Attachment
   Elements".

11.2.  Cover Art

   This section defines a set of guidelines for the storage of cover art
   in Matroska files.  A "Matroska Reader" MAY use embedded cover art to
   display a representational still-image depiction of the multimedia
   contents of the Matroska file.

   Only JPEG and PNG image formats SHOULD be used for cover art
   pictures.




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   There can be two different covers for a movie/album: a portrait style
   (e.g., a DVD case) and a landscape style (e.g., a wide banner ad).

   There can be two versions of the same cover, the "normal cover" and
   the "small cover".  The dimension of the "normal cover" SHOULD be 600
   pixels on the smallest side (for example, 960x600 for landscape,
   600x800 for portrait, or 600x600 for square).  The dimension of the
   "small cover" SHOULD be 120 pixels on the smallest side (for example,
   192x120 or 120x160).

   Versions of cover art can be differentiated by the filename, which is
   stored in the "FileName Element".  The default filename of the
   "normal cover" in square or portrait mode is "cover.(jpg|png)".  When
   stored, the "normal cover" SHOULD be the first Attachment in storage
   order.  The "small cover" SHOULD be prefixed with "small_", such as
   "small_cover.(jpg|png)".  The landscape variant SHOULD be suffixed
   with "_land", such as "cover_land.(jpg|png)".  The filenames are case
   sensitive.

   The following table provides examples of file names for cover art in
   Attachments.

   FileName | Image Orientation | Pixel Length of Smallest Side
   cover.jpg | Portrait or square | 600 small_cover.png | Portrait or
   square | 120 cover_land.png | Landscape | 600 small_cover_land.jpg |
   Landscape | 120

12.  Cues

12.1.  Introduction

   The "Cues Element" provides an index of certain "Cluster Elements" to
   allow for optimized seeking to absolute timestamps within the
   "Segment".  The "Cues Element" contains one or many "CuePoint
   Elements" which each MUST reference an absolute timestamp (via the
   "CueTime Element"), a "Track" (via the "CueTrack Element"), and a
   "Segment Position" (via the "CueClusterPosition Element").
   Additional non-mandated Elements are part of the "CuePoint Element"
   such as "CueDuration", "CueRelativePosition", "CueCodecState" and
   others which provide any "Matroska Reader" with additional
   information to use in the optimization of seeking performance.

12.2.  Recommendations

   The following recommendations are provided to optimize Matroska
   performance.





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   o  Unless Matroska is used as a live stream, it SHOULD contain a
      "Cues Element".

   o  For each video track, each keyframe SHOULD be referenced by a
      "CuePoint Element".

   o  It is RECOMMENDED to not reference non-keyframes of video tracks
      in "Cues" unless it references a "Cluster Element" which contains
      a "CodecState Element" but no keyframes.

   o  For each subtitle track present, each subtitle frame SHOULD be
      referenced by a "CuePoint Element" with a "CueDuration Element".

   o  References to audio tracks MAY be skipped in "CuePoint Elements"
      if a video track is present.  When included the "CuePoint
      Elements" SHOULD reference audio keyframes at most once every 500
      milliseconds.

   o  If the referenced frame is not stored within the first
      "SimpleBlock" or first "BlockGroup" within its "Cluster Element",
      then the "CueRelativePosition Element" SHOULD be written to
      reference where in the "Cluster" the reference frame is stored.

   o  If a "CuePoint Element" references "Cluster Element" that includes
      a "CodecState Element", then that "CuePoint Element" MUST use a
      "CueCodecState Element".

   o  "CuePoint Elements" SHOULD be numerically sorted in storage order
      by the value of the "CueTime Element".

13.  Matroska Streaming

   In Matroska, there are two kinds of streaming: file access and
   livestreaming.

13.1.  File Access

   File access can simply be reading a file located on your computer,
   but also includes accessing a file from an HTTP (web) server or CIFS
   (Windows share) server.  These protocols are usually safe from
   reading errors and seeking in the stream is possible.  However, when
   a file is stored far away or on a slow server, seeking can be an
   expensive operation and SHOULD be avoided.  The following guidelines,
   when followed, help reduce the number of seeking operations for
   regular playback and also have the playback start quickly without a
   lot of data needed to read first (like a "Cues Element", "Attachment
   Element" or "SeekHead Element").




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   Matroska, having a small overhead, is well suited for storing music/
   videos on file servers without a big impact on the bandwidth used.
   Matroska does not require the index to be loaded before playing,
   which allows playback to start very quickly.  The index can be loaded
   only when seeking is requested the first time.

13.2.  Livestreaming

   Livestreaming is the equivalent of television broadcasting on the
   internet.  There are 2 families of servers for livestreaming: RTP/
   RTSP and HTTP.  Matroska is not meant to be used over RTP.  RTP
   already has timing and channel mechanisms that would be wasted if
   doubled in Matroska.  Additionally, having the same information at
   the RTP and Matroska level would be a source of confusion if they do
   not match.  Livestreaming of Matroska over HTTP (or any other plain
   protocol based on TCP) is possible.

   A live Matroska stream is different from a file because it usually
   has no known end (only ending when the client disconnects).  For
   this, all bits of the "size" portion of the "Segment Element" MUST be
   set to 1.  Another option is to concatenate "Segment Elements" with
   known sizes, one after the other.  This solution allows a change of
   codec/resolution between each segment.  For example, this allows for
   a switch between 4:3 and 16:9 in a television program.

   When "Segment Elements" are continuous, certain "Elements", like
   "MetaSeek", "Cues", "Chapters", and "Attachments", MUST NOT be used.

   It is possible for a "Matroska Player" to detect that a stream is not
   seekable.  If the stream has neither a "MetaSeek" list or a "Cues"
   list at the beginning of the stream, it SHOULD be considered non-
   seekable.  Even though it is possible to seek blindly forward in the
   stream, it is NOT RECOMMENDED.

   In the context of live radio or web TV, it is possible to "tag" the
   content while it is playing.  The "Tags Element" can be placed
   between "Clusters" each time it is necessary.  In that case, the new
   "Tags Element" MUST reset the previously encountered "Tags Elements"
   and use the new values instead.

14.  Menu Specifications

14.1.  Introduction

   This document is a _draft of the Menu system_ that will be the
   default one in "Matroska".  As it will just be composed of a Control
   Track, it will be seen as a "codec" and could be replaced later by
   something else if needed.



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   A menu is like what you see on DVDs, when you have some screens to
   select the audio format, subtitles or scene selection.

14.2.  Requirements

   What we'll try to have is a system that can do almost everything done
   on a DVD, or more, or better, or drop the unused features if
   necessary.

   As the name suggests, a Control Track is a track that can control the
   playback of the file and/or all the playback features.  To make it as
   simple as possible for "Matroska Players", the Control Track will
   just give orders to the "Matroska Player" and get the actions
   associated with the highlights/hotspots.

14.2.1.  Highlights/Hotspots

   A highlight is basically a rectangle/key associated with an action
   UID.  When that rectangle/key is activated, the "Matroska Player"
   send the UID of the action to the Control Track handler (codec).  The
   fact that it can also be a key means that even for audio only files,
   a keyboard shortcut or button panel could be used for menus.  But in
   that case, the hotspot will have to be associated with a name to
   display.

   This highlight is sent from the Control Track to the "Matroska
   Player".  Then the "Matroska Player" has to handle that highlight
   until it's deactivated (see Section 14.2.2).

   The highlight contains a UID of the action, a displayable name (UTF-
   8), an associated key (list of keys to be defined, probably
   up/down/left/right/select), a screen position/range and an image to
   display.  The image will be displayed either when the user place the
   mouse over the rectangle (or any other shape), or when an option of
   the screen is selected (not activated).  There could be a second
   image used when the option is activated.  And there could be a third
   image that can serve as background.  This way you could have a still
   image (like in some DVDs) for the menu and behind that image blank
   video (small bitrate).

   When a highlight is activated by the user, the "Matroska Player" has
   to send the UID of the action to the Control Track.  Then the Control
   Track codec will handle the action and possibly give new orders to
   the "Matroska Player".

   The format used for storing images SHOULD be extensible.  For the
   moment we'll use PNG and BMP, both with alpha channel.




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14.2.2.  Playback features

   All the following features will be sent from the Control Track to the
   "Matroska Player" :

   o  Jump to chapter (UID, prev, next, number)

   o  Disable all tracks of a kind (audio, video, subtitle)

   o  Enable track UID (the kind doesn't matter)

   o  Define/Disable a highlight

   o  Enable/Disable jumping

   o  Enable/Disable track selection of a kind

   o  Select Edition ID (see chapters)

   o  Pause playback

   o  Stop playback

   o  Enable/Disable a Chapter UID

   o  Hide/Unhide a Chapter UID

   All the actions will be written in a normal Matroska track, with a
   timecode.  A "Menu Frame" SHOULD be able to contain more that one
   action/highlight for a given timecode. (to be determined, EBML format
   structure)

14.2.3.  Player requirements

   Some "Matroska Players" might not support the control track.  That
   mean they will play the active/looped parts as part of the data.  So
   I suggest putting the active/looped parts of a movie at the end of a
   movie.  When a Menu-aware "Matroska Player" encounter the default
   Control Track of a "Matroska" file, the first order SHOULD be to jump
   at the start of the active/looped part of the movie.

14.3.  Working Graph

            Matroska Source file -> Control Track <-> Player.
                                 -> other tracks   -> rendered






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14.4.  Ideas

!!!! KNOW Where the main/audio/subs menu starts wherever we are (use chapters) !!!!

!!!! Keep in mind the state of the selected tracks of each kind (more than 1 for each possible) !!!!
!!!! Order of blending !!!!
!!!! What if a command is not supported by the player ? !!!!
!!!! Track selection issue, only applies when 'quitting' the menu (but still possible to change live too) !!!!
!!!! Allow to hide (not render) some parts of a movie for certain editions !!!!
!!!! Get the parental level of the player (can be changed live) !!!!

14.5.  Data Structure

   As a Matroska side project, the obvious choice for storing binary
   data is EBML.

15.  Unknown elements

   Matroska is based upon the principle that a reading application does
   not have to support 100% of the specifications in order to be able to
   play the file.  A Matroska file therefore contains version indicators
   that tell a reading application what to expect.

   It is possible and valid to have the version fields indicate that the
   file contains Matroska "Elements" from a higher specification version
   number while signaling that a reading application MUST only support a
   lower version number properly in order to play it back (possibly with
   a reduced feature set).  For example, a reading application
   supporting at least Matroska version "V" reading a file whose
   "DocTypeReadVersion" field is equal to or lower than "V" MUST skip
   Matroska/EBML "Elements" it encounters but does not know about if
   that unknown element fits into the size constraints set by the
   current "Parent Element".

16.  Default Values

   The default value of an "Element" is assumed when not present in the
   data stream.  It is assumed only in the scope of its "Parent
   Element".  For example, the "Language Element" is in the scope of the
   "Track Element".  If the "Parent Element" is not present or assumed,
   then the "Child Element" cannot be assumed.

17.  DefaultDecodedFieldDuration

   The "DefaultDecodedFieldDuration Element" can signal to the
   displaying application how often fields of a video sequence will be
   available for displaying.  It can be used for both interlaced and
   progressive content.  If the video sequence is signaled as



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   interlaced, then the period between two successive fields at the
   output of the decoding process equals "DefaultDecodedFieldDuration".

   For video sequences signaled as progressive, it is twice the value of
   "DefaultDecodedFieldDuration".

   These values are valid at the end of the decoding process before
   post-processing (such as deinterlacing or inverse telecine) is
   applied.

   Examples:

   o  Blu-ray movie: 1000000000ns/(48/1.001) = 20854167ns

   o  PAL broadcast/DVD: 1000000000ns/(50/1.000) = 20000000ns

   o  N/ATSC broadcast: 1000000000ns/(60/1.001) = 16683333ns

   o  hard-telecined DVD: 1000000000ns/(60/1.001) = 16683333ns (60
      encoded interlaced fields per second)

   o  soft-telecined DVD: 1000000000ns/(60/1.001) = 16683333ns (48
      encoded interlaced fields per second, with "repeat_first_field =
      1")

18.  Encryption

   Encryption in Matroska is designed in a very generic style to allow
   people to implement whatever form of encryption is best for them.  It
   is possible to use the encryption framework in Matroska as a type of
   DRM (Digital Rights Management).

   Because encryption occurs within the "Block Element", it is possible
   to manipulate encrypted streams without decrypting them.  The streams
   could potentially be copied, deleted, cut, appended, or any number of
   other possible editing techniques without decryption.  The data can
   be used without having to expose it or go through the decrypting
   process.

   Encryption can also be layered within Matroska.  This means that two
   completely different types of encryption can be used, requiring two
   separate keys to be able to decrypt a stream.

   Encryption information is stored in the "ContentEncodings Element"
   under the "ContentEncryption Element".






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19.  Image cropping

   The "PixelCrop Elements" ("PixelCropTop", "PixelCropBottom",
   "PixelCropRight" and "PixelCropLeft") indicate when and by how much
   encoded videos frames SHOULD be cropped for display.  These Elements
   allow edges of the frame that are not intended for display, such as
   the sprockets of a full-frame film scan or the VANC area of a
   digitized analog videotape, to be stored but hidden.  "PixelCropTop"
   and "PixelCropBottom" store an integer of how many rows of pixels
   SHOULD be cropped from the top and bottom of the image
   (respectively).  "PixelCropLeft" and "PixelCropRight" store an
   integer of how many columns of pixels SHOULD be cropped from the left
   and right of the image (respectively).  For example, a pillar-boxed
   video that stores a 1440x1080 visual image within the center of a
   padded 1920x1080 encoded image MAY set both "PixelCropLeft" and
   "PixelCropRight" to "240", so that a "Matroska Player" SHOULD crop
   off 240 columns of pixels from the left and right of the encoded
   image to present the image with the pillar-boxes hidden.

20.  Matroska versioning

   The "EBML Header" of each Matroska document informs the reading
   application on what version of Matroska to expect.  The "Elements"
   within "EBML Header" with jurisdiction over this information are
   "DocTypeVersion" and "DocTypeReadVersion".

   "DocTypeVersion" MUST be equal to or greater than the highest
   Matroska version number of any "Element" present in the Matroska
   file.  For example, a file using the "SimpleBlock Element" MUST have
   a "DocTypeVersion" equal to or greater than 2.  A file containing
   "CueRelativePosition" Elements MUST have a "DocTypeVersion" equal to
   or greater than 4.

   The "DocTypeReadVersion" MUST contain the minimum version number that
   a reading application can minimally support in order to play the file
   back -- optionally with a reduced feature set.  For example, if a
   file contains only "Elements" of version 2 or lower except for
   "CueRelativePosition" (which is a version 4 Matroska "Element"), then
   "DocTypeReadVersion" SHOULD still be set to 2 and not 4 because
   evaluating "CueRelativePosition" is not necessary for standard
   playback -- it makes seeking more precise if used.

   "DocTypeVersion" MUST always be equal to or greater than
   "DocTypeReadVersion".

   A reading application supporting Matroska version "V" MUST NOT refuse
   to read an application with "DocReadTypeVersion" equal to or lower




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   than "V" even if "DocTypeVersion" is greater than "V".  See also the
   note about Section 15.

21.  MIME Types

   There is no IETF endorsed MIME type for Matroska files.  These
   definitions can be used:

   o  .mka : Matroska audio "audio/x-matroska"

   o  .mkv : Matroska video "video/x-matroska"

   o  .mk3d : Matroska 3D video "video/x-matroska-3d"

22.  Segment Position

   The "Segment Position" of an "Element" refers to the position of the
   first octet of the "Element ID" of that "Element", measured in
   octets, from the beginning of the "Element Data" section of the
   containing "Segment Element".  In other words, the "Segment Position"
   of an "Element" is the distance in octets from the beginning of its
   containing "Segment Element" minus the size of the "Element ID" and
   "Element Data Size" of that "Segment Element".  The "Segment
   Position" of the first "Child Element" of the "Segment Element" is 0.
   An "Element" which is not stored within a "Segment Element", such as
   the "Elements" of the "EBML Header", do not have a "Segment
   Position".

22.1.  Segment Position Exception

   "Elements" that are defined to store a "Segment Position" MAY define
   reserved values to indicate a special meaning.

22.2.  Example of Segment Position

   This table presents an example of "Segment Position" by showing a
   hexadecimal representation of a very small Matroska file with labels
   to show the offsets in octets.  The file contains a "Segment Element"
   with an "Element ID" of "0x18538067" and a "MuxingApp Element" with
   an "Element ID" of "0x4D80".

         0                             1                             2
         0  1  2  3  4  5  6  7  8  9  0  1  2  3  4  5  6  7  8  9  0
         +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
       0 |1A|45|DF|A3|8B|42|82|88|6D|61|74|72|6F|73|6B|61|18|53|80|67|
      20 |93|15|49|A9|66|8E|4D|80|84|69|65|74|66|57|41|84|69|65|74|66|





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   In the above example, the "Element ID" of the "Segment Element" is
   stored at offset 16, the "Element Data Size" of the "Segment Element"
   is stored at offset 20, and the "Element Data" of the "Segment
   Element" is stored at offset 21.

   The "MuxingApp Element" is stored at offset 26.  Since the "Segment
   Position" of an "Element" is calculated by subtracting the position
   of the "Element Data" of the containing "Segment Element" from the
   position of that "Element", the "Segment Position" of "MuxingApp
   Element" in the above example is "26 - 21" or "5".

23.  Linked Segments

   Matroska provides several methods to link two or many "Segment
   Elements" together to create a "Linked Segment".  A "Linked Segment"
   is a set of multiple "Segments" related together into a single
   presentation by using Hard Linking, Medium Linking, or Soft Linking.
   All "Segments" within a "Linked Segment" MUST utilize the same track
   numbers and timescale.  All "Segments" within a "Linked Segment" MUST
   be stored within the same directory.  All "Segments" within a "Linked
   Segment" MUST store a "SegmentUID".

23.1.  Hard Linking

   Hard Linking (also called splitting) is the process of creating a
   "Linked Segment" by relating multiple "Segment Elements" using the
   "PrevUID" and "NextUID Elements".  Within a "Linked Segment", the
   timestamps of each "Segment" MUST follow consecutively in linking
   order.  With Hard Linking, the chapters of any "Segment" within the
   "Linked Segment" MUST only reference the current "Segment".  With
   Hard Linking, the "NextUID" and "PrevUID" MUST reference the
   respective "SegmentUID" values of the next and previous "Segments".
   The first "Segment" of a "Linked Segment" MUST have a "NextUID
   Element" and MUST NOT have a "PrevUID Element".  The last "Segment"
   of a "Linked Segment" MUST have a "PrevUID Element" and MUST NOT have
   a "NextUID Element".  The middle "Segments" of a "Linked Segment"
   MUST have both a "NextUID Element" and a "PrevUID Element".

   As an example, four "Segments" can be Hard Linked as a "Linked
   Segment" through cross-referencing each other with "SegmentUID",
   "PrevUID", and "NextUID", as in this table.










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   +--------+------------------+-------------------+-------------------+
   | file   | SegmentUID       | PrevUID           | NextUID           |
   | name   |                  |                   |                   |
   +--------+------------------+-------------------+-------------------+
   | "start | "71000c23cd31099 | n/a               | "a77b3598941cb803 |
   | .mkv"  | 853fbc94dd984a5d |                   | eac0fcdafe44fac9" |
   |        | d"               |                   |                   |
   | "middl | "a77b3598941cb80 | "71000c23cd310998 | "6c92285fa6d3e827 |
   | e.mkv" | 3eac0fcdafe44fac | 53fbc94dd984a5dd" | b198d120ea3ac674" |
   |        | 9"               |                   |                   |
   | "end.m | "6c92285fa6d3e82 | "a77b3598941cb803 | n/a               |
   | kv"    | 7b198d120ea3ac67 | eac0fcdafe44fac9" |                   |
   |        | 4"               |                   |                   |
   +--------+------------------+-------------------+-------------------+

23.2.  Medium Linking

   Medium Linking creates relationships between "Segments" using Ordered
   Chapters and the "ChapterSegmentUID Element".  A "Segment Edition"
   with Ordered Chapters MAY contain "Chapter Elements" that reference
   timestamp ranges from other "Segments".  The "Segment" referenced by
   the Ordered Chapter via the "ChapterSegmentUID Element" SHOULD be
   played as part of a Linked Segment.  The timestamps of Segment
   content referenced by Ordered Chapters MUST be adjusted according to
   the cumulative duration of the the previous Ordered Chapters.

   As an example a file named "intro.mkv" could have a "SegmentUID" of
   "0xb16a58609fc7e60653a60c984fc11ead".  Another file called
   "program.mkv" could use a Chapter Edition that contains two Ordered
   Chapters.  The first chapter references the "Segment" of "intro.mkv"
   with the use of a "ChapterSegmentUID", "ChapterSegmentEditionUID",
   "ChapterTimeStart" and optionally a "ChapterTimeEnd" element.  The
   second chapter references content within the "Segment" of
   "program.mkv".  A "Matroska Player" SHOULD recognize the "Linked
   Segment" created by the use of "ChapterSegmentUID" in an enabled
   "Edition" and present the reference content of the two "Segments"
   together.

23.3.  Soft Linking

   Soft Linking is used by codec chapters.  They can reference another
   "Segment" and jump to that "Segment".  The way the "Segments" are
   described are internal to the chapter codec and unknown to the
   Matroska level.  But there are "Elements" within the "Info Element"
   (such as "ChapterTranslate") that can translate a value representing
   a "Segment" in the chapter codec and to the current "SegmentUID".
   All "Segments" that could be used in a "Linked Segment" in this way
   SHOULD be marked as members of the same family via the "SegmentFamily



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   Element", so that the "Matroska Player" can quickly switch from one
   to the other.

24.  Track Flags

24.1.  Default flag

   The "default track" flag is a hint for a "Matroska Player" and SHOULD
   always be changeable by the user.  If the user wants to see or hear a
   track of a certain kind (audio, video, subtitles) and hasn't chosen a
   specific track, the "Matroska Player" SHOULD use the first track of
   that kind whose "default track" flag is set to "1".  If no such track
   is found then the first track of this kind SHOULD be chosen.

   Only one track of a kind MAY have its "default track" flag set in a
   segment.  If a track entry does not contain the "default track" flag
   element then its default value "1" is to be used.

24.2.  Forced flag

   The "forced" flag tells the "Matroska Player" that it MUST display/
   play this track or another track of the same kind that also has its
   "forced" flag set.  When there are multiple "forced" tracks, the
   "Matroska Player" SHOULD determine the track based upon the language
   of the forced flag or use the default flag if no track matches the
   use languages.  Another track of the same kind without the "forced"
   flag may be use simultaneously with the "forced" track (like DVD
   subtitles for example).

24.3.  Track Operation

   "TrackOperation" allows combining multiple tracks to make a virtual
   one.  It uses two separate system to combine tracks.  One to create a
   3D "composition" (left/right/background planes) and one to simplify
   join two tracks together to make a single track.

   A track created with "TrackOperation" is a proper track with a UID
   and all its flags.  However the codec ID is meaningless because each
   "sub" track needs to be decoded by its own decoder before the
   "operation" is applied.  The "Cues Elements" corresponding to such a
   virtual track SHOULD be the sum of the "Cues Elements" for each of
   the tracks it's composed of (when the "Cues" are defined per track).

   In the case of "TrackJoinBlocks", the "Block Elements" (from
   "BlockGroup" and "SimpleBlock") of all the tracks SHOULD be used as
   if they were defined for this new virtual "Track".  When two "Block
   Elements" have overlapping start or end timecodes, it's up to the
   underlying system to either drop some of these frames or render them



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   the way they overlap.  This situation SHOULD be avoided when creating
   such tracks as you can never be sure of the end result on different
   platforms.

24.4.  Overlay Track

   Overlay tracks SHOULD be rendered in the same 'channel' as the track
   its linked to.  When content is found in such a track, it SHOULD be
   played on the rendering channel instead of the original track.

24.5.  Multi-planar and 3D videos

   There are two different ways to compress 3D videos: have each 'eye'
   track in a separate track and have one track have both 'eyes'
   combined inside (which is more efficient, compression-wise).
   Matroska supports both ways.

   For the single track variant, there is the "StereoMode Element" which
   defines how planes are assembled in the track (mono or left-right
   combined).  Odd values of StereoMode means the left plane comes first
   for more convenient reading.  The pixel count of the track
   ("PixelWidth"/"PixelHeight") is the raw amount of pixels (for example
   3840x1080 for full HD side by side) and the
   "DisplayWidth"/"DisplayHeight" in pixels is the amount of pixels for
   one plane (1920x1080 for that full HD stream).  Old stereo 3D were
   displayed using anaglyph (cyan and red colours separated).  For
   compatibility with such movies, there is a value of the StereoMode
   that corresponds to AnaGlyph.

   There is also a "packed" mode (values 13 and 14) which consists of
   packing two frames together in a "Block" using lacing.  The first
   frame is the left eye and the other frame is the right eye (or vice
   versa).  The frames SHOULD be decoded in that order and are possibly
   dependent on each other (P and B frames).

   For separate tracks, Matroska needs to define exactly which track
   does what.  "TrackOperation" with "TrackCombinePlanes" do that.  For
   more details look at Section 24.3.

   The 3D support is still in infancy and may evolve to support more
   features.

   The StereoMode used to be part of Matroska v2 but it didn't meet the
   requirement for multiple tracks.  There was also a bug in libmatroska
   prior to 0.9.0 that would save/read it as 0x53B9 instead of 0x53B8.
   "Matroska Readers" may support these legacy files by checking
   Matroska v2 or 0x53B9.  The older values [20] were 0: mono, 1: right
   eye, 2: left eye, 3: both eyes.



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25.  Timecodes

25.1.  Timecode Types

   o  Absolute Timecode = Block+Cluster

   o  Relative Timecode = Block

   o  Scaled Timecode = Block+Cluster

   o  Raw Timecode = (Block+Cluster)*TimecodeScale*TrackTimecodeScale

25.2.  Block Timecodes

   The "Block Element"'s timecode MUST be a signed integer that
   represents the "Raw Timecode" relative to the "Cluster"'s "Timecode
   Element", multiplied by the "TimecodeScale Element".  See
   Section 25.4 for more information.

   The "Block Element"'s timecode MUST be represented by a 16bit signed
   integer (sint16).  The "Block"'s timecode has a range of -32768 to
   +32767 units.  When using the default value of the "TimecodeScale
   Element", each integer represents 1ms.  The maximum time span of
   "Block Elements" in a "Cluster" using the default "TimecodeScale
   Element" of 1ms is 65536ms.

   If a "Cluster"'s "Timecode Element" is set to zero, it is possible to
   have "Block Elements" with a negative "Raw Timecode".  "Block
   Elements" with a negative "Raw Timecode" are not valid.

25.3.  Raw Timecode

   The exact time of an object SHOULD be represented in nanoseconds.  To
   find out a "Block"'s "Raw Timecode", you need the "Block"'s "Timecode
   Element", the "Cluster"'s "Timecode Element", and the "TimecodeScale
   Element".

25.4.  TimecodeScale

   The "TimecodeScale Element" is used to calculate the "Raw Timecode"
   of a "Block".  The timecode is obtained by adding the "Block"'s
   timecode to the "Cluster"'s "Timecode Element", and then multiplying
   that result by the "TimecodeScale".  The result will be the "Block"'s
   "Raw Timecode" in nanoseconds.  The formula for this would look like:







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                         (a + b) * c

                         a = `Block`'s Timecode
                         b = `Cluster`'s Timecode
                         c = `TimeCodeScale`

   For example, assume a "Cluster"'s "Timecode" has a value of 564264,
   the "Block" has a "Timecode" of 1233, and the "TimecodeScale Element"
   is the default of 1000000.

                 (1233 + 564264) * 1000000 = 565497000000

   So, the "Block" in this example has a specific time of 565497000000
   in nanoseconds.  In milliseconds this would be 565497ms.

25.5.  TimecodeScale Rounding

   Because the default value of "TimecodeScale" is 1000000, which makes
   each integer in the "Cluster" and "Block" "Timecode Elements" equal
   1ms, this is the most commonly used.  When dealing with audio, this
   causes inaccuracy when seeking.  When the audio is combined with
   video, this is not an issue.  For most cases, the the synch of audio
   to video does not need to be more than 1ms accurate.  This becomes
   obvious when one considers that sound will take 2-3ms to travel a
   single meter, so distance from your speakers will have a greater
   effect on audio/visual synch than this.

   However, when dealing with audio-only files, seeking accuracy can
   become critical.  For instance, when storing a whole CD in a single
   track, a user will want to be able to seek to the exact sample that a
   song begins at.  If seeking a few sample ahead or behind, a 'crack'
   or 'pop' may result as a few odd samples are rendered.  Also, when
   performing precise editing, it may be very useful to have the audio
   accuracy down to a single sample.

   When storing timecodes for an audio stream, the "TimecodeScale
   Element" SHOULD have an accuracy of at least that of the audio sample
   rate, otherwise there are rounding errors that prevent users from
   knowing the precise location of a sample.  Here's how a program has
   to round each timecode in order to be able to recreate the sample
   number accurately.

   Let's assume that the application has an audio track with a sample
   rate of 44100.  As written above the "TimecodeScale" MUST have at
   least the accuracy of the sample rate itself: 1000000000 / 44100 =
   22675.7369614512.  This value MUST always be truncated.  Otherwise
   the accuracy will not suffice.  So in this example the application
   will use 22675 for the "TimecodeScale".  The application could even



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   use some lower value like 22674 which would allow it to be a little
   bit imprecise about the original timecodes.  But more about that in a
   minute.

   Next the application wants to write sample number 52340 and
   calculates the timecode.  This is easy.  In order to calculate the
   "Raw Timecode" in ns all it has to do is calculate "Raw Timecode =
   round(1000000000 * sample_number / sample_rate)".  Rounding at this
   stage is very important!  The application might skip it if it choses
   a slightly smaller value for the "TimecodeScale" factor instead of
   the truncated one like shown above.  Otherwise it has to round or the
   results won't be reversible.  For our example we get "Raw Timecode =
   round(1000000000 * 52340 / 44100) = round(1186848072.56236) =
   1186848073".

   The next step is to calculate the "Absolute Timecode" - that is the
   timecode that will be stored in the Matroska file.  Here the
   application has to divide the "Raw Timecode" from the previous
   paragraph by the "TimecodeScale" factor and round the result:
   "Absolute Timecode = round(Raw Timecode / TimecodeScale_factor)"
   which will result in the following for our example: "Absolute
   Timecode = round(1186848073 / 22675) = round(52341.7011245866) =
   52342".  This number is the one the application has to write to the
   file.

   Now our file is complete, and we want to play it back with another
   application.  Its task is to find out which sample the first
   application wrote into the file.  So it starts reading the Matroska
   file and finds the "TimecodeScale" factor 22675 and the audio sample
   rate 44100.  Later it finds a data block with the "Absolute Timecode"
   of 52342.  But how does it get the sample number from these numbers?

   First it has to calculate the "Raw Timecode" of the block it has just
   read.  Here's no rounding involved, just an integer multiplication:
   "Raw Timecode = Absolute Timecode * TimecodeScale_factor".  In our
   example: "Raw Timecode = 52342 * 22675 = 1186854850".

   The conversion from the "Raw Timecode" to the sample number again
   requires rounding: "sample_number = round(Raw Timecode * sample_rate
   / 1000000000)".  In our example: "sample_number = round(1186854850 *
   44100 / 1000000000) = round(52340.298885) = 52340".  This is exactly
   the sample number that the previous program started with.

   Some general notes for a program:

   1.  Always calculate the timestamps / sample numbers with floating
       point numbers of at least 64bit precision (called 'double' in




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       most modern programming languages).  If you're calculating with
       integers then make sure they're 64bit long, too.

   2.  Always round if you divide.  Always!  If you don't you'll end up
       with situations in which you have a timecode in the Matroska file
       that does not correspond to the sample number that it started
       with.  Using a slightly lower timecode scale factor can help here
       in that it removes the need for proper rounding in the conversion
       from sample number to "Raw Timecode".

25.6.  TrackTimecodeScale

   The "TrackTimecodeScale Element" is used align tracks that would
   otherwise be played at different speeds.  An example of this would be
   if you have a film that was originally recorded at 24fps video.  When
   playing this back through a PAL broadcasting system, it is standard
   to speed up the film to 25fps to match the 25fps display speed of the
   PAL broadcasting standard.  However, when broadcasting the video
   through NTSC, it is typical to leave the film at its original speed.
   If you wanted to make a single file where there was one video stream,
   and an audio stream used from the PAL broadcast, as well as an audio
   stream used from the NTSC broadcast, you would have the problem that
   the PAL audio stream would be 1/24th faster than the NTSC audio
   stream, quickly leading to problems.  It is possible to stretch out
   the PAL audio track and re-encode it at a slower speed, however when
   dealing with lossy audio codecs, this often results in a loss of
   audio quality and/or larger file sizes.

   This is the type of problem that "TrackTimecodeScale" was designed to
   fix.  Using it, the video can be played back at a speed that will
   synch with either the NTSC or the PAL audio stream, depending on
   which is being used for playback.  To continue the above example:

                            Track 1: Video
                            Track 2: NTSC Audio
                            Track 3: PAL Audio

   Because the NTSC track is at the original speed, it will used as the
   default value of 1.0 for its "TrackTimecodeScale".  The video will
   also be aligned to the NTSC track with the default value of 1.0.

   The "TrackTimecodeScale" value to use for the PAL track would be
   calculated by determining how much faster the PAL track is than the
   NTSC track.  In this case, because we know the video for the NTSC
   audio is being played back at 24fps and the video for the PAL audio
   is being played back at 25fps, the calculation would be:

   25/24 &#8776; 1.04166666666666666667



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   When writing a file that uses a non-default "TrackTimecodeScale", the
   values of the "Block"'s timecode are whatever they would be when
   normally storing the track with a default value for the
   "TrackTimecodeScale".  However, the data is interleaved a little
   differently.  Data SHOULD be interleaved by its Section 25.3 in the
   order handed back from the encoder.  The "Raw Timecode" of a "Block"
   from a track using "TrackTimecodeScale" is calculated using:

   "(Block's Timecode + Cluster's Timecode) * TimecodeScale *
   TrackTimecodeScale"

   So, a Block from the PAL track above that had a Section 25.1 of 100
   seconds would have a "Raw Timecode" of 104.66666667 seconds, and so
   would be stored in that part of the file.

   When playing back a track using the "TrackTimecodeScale", if the
   track is being played by itself, there is no need to scale it.  From
   the above example, when playing the Video with the NTSC Audio,
   neither are scaled.  However, when playing back the Video with the
   PAL Audio, the timecodes from the PAL Audio track are scaled using
   the "TrackTimecodeScale", resulting in the video playing back in
   synch with the audio.

   It would be possible for a "Matroska Player" to also adjust the
   audio's samplerate at the same time as adjusting the timecodes if you
   wanted to play the two audio streams synchronously.  It would also be
   possible to adjust the video to match the audio's speed.  However,
   for playback, the selected track(s) timecodes SHOULD be adjusted if
   they need to be scaled.

   While the above example deals specifically with audio tracks, this
   element can be used to align video, audio, subtitles, or any other
   type of track contained in a Matroska file.

26.  References

26.1.  URIs

   [1] http://mukoli.free.fr/mcf/mcf.html

   [2] https://github.com/Matroska-Org/ebml-specification/blob/master/
       specification.markdown

   [3] https://datatracker.ietf.org/wg/cellar/charter/

   [4] https://matroska.org/files/matroska.pdf

   [5] diagram.md



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   [6] https://github.com/Matroska-Org/ebml-specification/blob/master/
       specification.markdown

   [7] https://github.com/Matroska-Org/foundation-
       source/blob/master/spectool/specdata.xml

   [8] https://tools.ietf.org/html/rfc2119

   [9] https://github.com/Matroska-Org/ebml-specification/blob/master/
       specification.markdown

   [10] https://github.com/Matroska-Org/ebml-specification/blob/master/
        specification.markdown#ebml-element-types

   [11] https://github.com/Matroska-Org/ebml-specification/blob/master/
        specification.markdown#ebml-schema

   [12] https://github.com/Matroska-Org/ebml-specification/blob/master/
        specification.markdown#structure

   [13] https://www.loc.gov/standards/iso639-2/php/English_list.php

   [14] https://tools.ietf.org/html/bcp47

   [15] https://www.iana.org/domains/root/db

   [16] http://www.webmproject.org/docs/container/

   [17] http://dvd.sourceforge.net/dvdinfo/uops.html

   [18] http://www.dvd-replica.com/DVD/

   [19] http://dvd.sourceforge.net/dvdinfo/

   [20] http://www.matroska.org/node/1/revisions/74/view#StereoMode

Authors' Addresses

   Steve Lhomme

   Email: slhomme@matroska.org


   Moritz Bunkus

   Email: moritz@bunkus.org





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   Dave Rice

   Email: dave@dericed.com
















































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