draft-ietf-avt-rfc3016bis-00.txt   draft-ietf-avt-rfc3016bis-01.txt 
AVT M. Schmidt AVT M. Schmidt
Internet-Draft Dolby Laboratories Internet-Draft Dolby Laboratories
Obsoletes: 3016 (if approved) F. de Bont Obsoletes: 3016 (if approved) F. de Bont
Intended status: Standards Track Philips Electronics Intended status: Standards Track Philips Electronics
Expires: October 4, 2010 S. Doehla Expires: April 4, 2011 S. Doehla
Fraunhofer IIS Fraunhofer IIS
Jaehwan. Kim Jaehwan. Kim
LG Electronics Inc. LG Electronics Inc.
April 2, 2010 October 1, 2010
RTP Payload Format for MPEG-4 Audio/Visual Streams RTP Payload Format for MPEG-4 Audio/Visual Streams
draft-ietf-avt-rfc3016bis-00.txt draft-ietf-avt-rfc3016bis-01.txt
Abstract Abstract
This document describes Real-Time Transport Protocol (RTP) payload This document describes Real-Time Transport Protocol (RTP) payload
formats for carrying each of MPEG-4 Audio and MPEG-4 Visual formats for carrying each of MPEG-4 Audio and MPEG-4 Visual
bitstreams without using MPEG-4 Systems. For the purpose of directly bitstreams without using MPEG-4 Systems. For the purpose of directly
mapping MPEG-4 Audio/Visual bitstreams onto RTP packets, it provides mapping MPEG-4 Audio/Visual bitstreams onto RTP packets, it provides
specifications for the use of RTP header fields and also specifies specifications for the use of RTP header fields and also specifies
fragmentation rules. It also provides specifications for Media Type fragmentation rules. It also provides specifications for Media Type
registration and the use of Session Description Protocol (SDP). registration and the use of Session Description Protocol (SDP).
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
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Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on October 4, 2010. This Internet-Draft will expire on April 4, 2011.
Copyright Notice Copyright Notice
Copyright (c) 2010 IETF Trust and the persons identified as the Copyright (c) 2010 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Provisions Relating to IETF Documents Provisions Relating to IETF Documents
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publication of this document. Please review these documents publication of this document. Please review these documents
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include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. MPEG-4 Visual RTP payload format . . . . . . . . . . . . . 4 1.1. MPEG-4 Visual RTP payload format . . . . . . . . . . . . . 4
1.2. MPEG-4 Audio RTP payload format . . . . . . . . . . . . . 5 1.2. MPEG-4 Audio RTP payload format . . . . . . . . . . . . . 5
1.3. Differences to RFC 3016 . . . . . . . . . . . . . . . . . 6 1.3. Differences to RFC 3016 . . . . . . . . . . . . . . . . . 6
1.4. Interoperability with RFC 3016 . . . . . . . . . . . . . . 7
2. Definitions and Abbreviations . . . . . . . . . . . . . . . . 7 2. Definitions and Abbreviations . . . . . . . . . . . . . . . . 7
3. RTP Packetization of MPEG-4 Visual bitstream . . . . . . . . . 8 3. RTP Packetization of MPEG-4 Visual bitstream . . . . . . . . . 8
3.1. Use of RTP header fields for MPEG-4 Visual . . . . . . . . 9 3.1. Use of RTP header fields for MPEG-4 Visual . . . . . . . . 9
3.2. Fragmentation of MPEG-4 Visual bitstream . . . . . . . . . 10 3.2. Fragmentation of MPEG-4 Visual bitstream . . . . . . . . . 10
3.3. Examples of packetized MPEG-4 Visual bitstream . . . . . . 11 3.3. Examples of packetized MPEG-4 Visual bitstream . . . . . . 11
4. RTP Packetization of MPEG-4 Audio bitstream . . . . . . . . . 15 4. RTP Packetization of MPEG-4 Audio bitstream . . . . . . . . . 14
4.1. RTP Packet Format . . . . . . . . . . . . . . . . . . . . 15 4.1. RTP Packet Format . . . . . . . . . . . . . . . . . . . . 14
4.2. Use of RTP Header Fields for MPEG-4 Audio . . . . . . . . 16 4.2. Use of RTP Header Fields for MPEG-4 Audio . . . . . . . . 16
4.3. Fragmentation of MPEG-4 Audio bitstream . . . . . . . . . 17 4.3. Fragmentation of MPEG-4 Audio bitstream . . . . . . . . . 16
5. Media Type registration for MPEG-4 Audio/Visual streams . . . 17 5. Media Type registration for MPEG-4 Audio/Visual streams . . . 16
5.1. Media Type registration for MPEG-4 Visual . . . . . . . . 17 5.1. Media Type registration for MPEG-4 Visual . . . . . . . . 17
5.2. SDP usage of MPEG-4 Visual . . . . . . . . . . . . . . . . 19 5.2. Mapping to SDP for MPEG-4 Visual . . . . . . . . . . . . . 19
5.3. Media Type registration of MPEG-4 Audio . . . . . . . . . 20 5.2.1. Declarative SDP usage for MPEG-4 Visual . . . . . . . 19
5.4. SDP usage of MPEG-4 Audio . . . . . . . . . . . . . . . . 24 5.3. Media Type registration for MPEG-4 Audio . . . . . . . . . 20
5.4.1. Example: In-band configuration . . . . . . . . . . . . 24 5.4. Mapping to SDP for MPEG-4 Audio . . . . . . . . . . . . . 23
5.4.2. Example: 6kb/s CELP . . . . . . . . . . . . . . . . . 24 5.4.1. Declarative SDP usage for MPEG-4 Audio . . . . . . . . 24
5.4.3. Example: 64 kb/s AAC LC stereo . . . . . . . . . . . . 25 5.4.1.1. Example: In-band configuration . . . . . . . . . . 24
5.4.4. Example: Use of the SBR-enabled parameter . . . . . . 25 5.4.1.2. Example: 6kb/s CELP . . . . . . . . . . . . . . . 25
5.4.5. Example: Hierarchical Signaling of SBR . . . . . . . . 26 5.4.1.3. Example: 64 kb/s AAC LC stereo . . . . . . . . . . 25
5.4.6. Example: HE AAC v2 Signaling . . . . . . . . . . . . . 26 5.4.1.4. Example: Use of the SBR-enabled parameter . . . . 25
5.4.7. Example: Hierarchical Signaling of PS . . . . . . . . 27 5.4.1.5. Example: Hierarchical Signaling of SBR . . . . . . 26
5.4.8. Example: MPEG Surround . . . . . . . . . . . . . . . . 27 5.4.1.6. Example: HE AAC v2 Signaling . . . . . . . . . . . 26
5.4.9. Example: MPEG Surround with extended SDP parameters . 27 5.4.1.7. Example: Hierarchical Signaling of PS . . . . . . 27
5.4.10. Example: MPEG Surround with single layer 5.4.1.8. Example: MPEG Surround . . . . . . . . . . . . . . 27
configuration . . . . . . . . . . . . . . . . . . . . 28 5.4.1.9. Example: MPEG Surround with extended SDP
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 28 parameters . . . . . . . . . . . . . . . . . . . . 28
5.4.1.10. Example: MPEG Surround with single layer
configuration . . . . . . . . . . . . . . . . . . 28
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 29
6.1. Media Type Registration . . . . . . . . . . . . . . . . . 29 6.1. Media Type Registration . . . . . . . . . . . . . . . . . 29
6.2. Usage of SDP . . . . . . . . . . . . . . . . . . . . . . . 29 6.2. Usage of SDP . . . . . . . . . . . . . . . . . . . . . . . 29
7. Security Considerations . . . . . . . . . . . . . . . . . . . 29 7. Security Considerations . . . . . . . . . . . . . . . . . . . 29
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 30 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 30
8.1. Normative References . . . . . . . . . . . . . . . . . . . 30 8.1. Normative References . . . . . . . . . . . . . . . . . . . 30
8.2. Informative References . . . . . . . . . . . . . . . . . . 31 8.2. Informative References . . . . . . . . . . . . . . . . . . 31
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 31 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 32
1. Introduction 1. Introduction
The RTP payload formats described in this document specify how MPEG-4 The RTP payload formats described in this document specify how MPEG-4
Audio [14496-3] and MPEG-4 Visual streams [14496-2] are to be Audio [14496-3] and MPEG-4 Visual streams [14496-2] are to be
fragmented and mapped directly onto RTP packets. fragmented and mapped directly onto RTP packets.
These RTP payload formats enable transport of MPEG-4 Audio/Visual These RTP payload formats enable transport of MPEG-4 Audio/Visual
streams without using the synchronization and stream management streams without using the synchronization and stream management
functionality of MPEG-4 Systems [14496-1]. Such RTP payload formats functionality of MPEG-4 Systems [14496-1]. Such RTP payload formats
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SBR (Spectral Band Replication) SBR (Spectral Band Replication)
o The number of audio channel parameter specification is ambiguous o The number of audio channel parameter specification is ambiguous
in the presence of PS (Parametric Stereo) in the presence of PS (Parametric Stereo)
Furthermore some comments have been addressed and signaling support Furthermore some comments have been addressed and signaling support
for MPEG surround [23003-1] was added. It should be noted that the for MPEG surround [23003-1] was added. It should be noted that the
audio payload format described here has some known limitations. For audio payload format described here has some known limitations. For
new system designs RFC 3640 [RFC3640] is recommended. new system designs RFC 3640 [RFC3640] is recommended.
1.4. Interoperability with RFC 3016
Although strictly speaking systems that support MPEG-4 Audio as
specified in RFC 3016 [RFC3016] will be incompatible with systems
supporting this document, existing systems already comply with the
specification in 3GPP PSS service [3GPP] and therefore no
incompatibility issues are foreseen.
2. Definitions and Abbreviations 2. Definitions and Abbreviations
This memo makes use of terms, specified in [14496-2], [14496-3], and This memo makes use of terms, specified in [14496-2], [14496-3], and
[23003-1]. In addition, the following terms are used in this [23003-1]. In addition, the following terms are used in this
document and have specific meaning within the context of this document and have specific meaning within the context of this
document. document.
Core codec sampling rate: Core codec sampling rate:
Audio codec sampling rate. When SBR (Spectral Band Replication) Audio codec sampling rate. When SBR (Spectral Band Replication)
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RTP packet and the length of the RTP packet can be determined RTP packet and the length of the RTP packet can be determined
considering the packet-loss rate and the bit-rate of the underlying considering the packet-loss rate and the bit-rate of the underlying
network. network.
(f) is an example of the case when the video packet is disabled by (f) is an example of the case when the video packet is disabled by
setting resync_marker_disable in the VOL header to 1. In this case, setting resync_marker_disable in the VOL header to 1. In this case,
a VOP may be split into a plurality of RTP packets at arbitrary byte- a VOP may be split into a plurality of RTP packets at arbitrary byte-
positions. For example, it is possible to split a VOP into fixed- positions. For example, it is possible to split a VOP into fixed-
length packets. This kind of coder configuration and RTP packet length packets. This kind of coder configuration and RTP packet
fragmentation may be used when the underlying network is guaranteed fragmentation may be used when the underlying network is guaranteed
to be error-free. On the other hand, it is not recommended to use it to be error-free.
in error-prone environment since it provides only poor packet loss
resiliency.
Figure 3 shows examples of RTP packets prohibited by the criteria of Figure 3 shows examples of RTP packets prohibited by the criteria of
3.2. 3.2.
Fragmentation of a header into multiple RTP packets, as in (a), will Fragmentation of a header into multiple RTP packets, as in (a), will
not only increase the overhead of RTP/IP headers but also decrease not only increase the overhead of RTP/IP headers but also decrease
the error resiliency. Therefore, it is prohibited by the criterion the error resiliency. Therefore, it is prohibited by the criterion
(3). (3).
When concatenating more than one video packets into an RTP packet, When concatenating more than one video packets into an RTP packet,
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It is RECOMMENDED to put one audioMuxElement in each RTP packet. If It is RECOMMENDED to put one audioMuxElement in each RTP packet. If
the size of an audioMuxElement can be kept small enough that the size the size of an audioMuxElement can be kept small enough that the size
of the RTP packet containing it does not exceed the size of the path- of the RTP packet containing it does not exceed the size of the path-
MTU, this will be no problem. If it cannot, the audioMuxElement MAY MTU, this will be no problem. If it cannot, the audioMuxElement MAY
be fragmented and spread across multiple packets. be fragmented and spread across multiple packets.
5. Media Type registration for MPEG-4 Audio/Visual streams 5. Media Type registration for MPEG-4 Audio/Visual streams
The following sections describe the Media Type registrations for The following sections describe the Media Type registrations for
MPEG-4 Audio/Visual streams. Media Type registration and SDP usage MPEG-4 Audio/Visual streams, which are registered in accordance with
for the MPEG-4 Visual stream are described in Sections 5.1 and 5.2,
respectively, while Media Type registration and SDP usage for MPEG-4 [RFC4855] and uses the template of [RFC4288]. Media Type
Audio stream are described in Sections 5.3 and 5.4, respectively. registration and SDP usage for the MPEG-4 Visual stream are described
in Sections 5.1 and 5.2, respectively, while Media Type registration
and SDP usage for MPEG-4 Audio stream are described in Sections 5.3
and 5.4, respectively.
5.1. Media Type registration for MPEG-4 Visual 5.1. Media Type registration for MPEG-4 Visual
Media type name: video Note, any unspecified parameter MUST be ignored by the receiver to
ensure that additional parameters can be added in any future revision
of this specification.
Media subtype name: MP4V-ES Type name: video
Subtype name: MP4V-ES
Required parameters: none Required parameters: none
Optional parameters: Optional parameters:
rate: This parameter is used only for RTP transport. It indicates rate: This parameter is used only for RTP transport. It indicates
the resolution of the timestamp field in the RTP header. If this the resolution of the timestamp field in the RTP header. If this
parameter is not specified, its default value of 90000 (90kHz) is parameter is not specified, its default value of 90000 (90kHz) is
used. used.
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[14496-2]. The configuration information is mapped onto the octet [14496-2]. The configuration information is mapped onto the octet
string in an MSB-first basis. The first bit of the configuration string in an MSB-first basis. The first bit of the configuration
information SHALL be located at the MSB of the first octet. The information SHALL be located at the MSB of the first octet. The
configuration information indicated by this parameter SHALL be the configuration information indicated by this parameter SHALL be the
same as the configuration information in the corresponding MPEG-4 same as the configuration information in the corresponding MPEG-4
Visual stream, except for first_half_vbv_occupancy and Visual stream, except for first_half_vbv_occupancy and
latter_half_vbv_occupancy, if exist, which may vary in the latter_half_vbv_occupancy, if exist, which may vary in the
repeated configuration information inside an MPEG-4 Visual stream repeated configuration information inside an MPEG-4 Visual stream
(See 6.2.1 Start codes of ISO/IEC14496-2). (See 6.2.1 Start codes of ISO/IEC14496-2).
Example usages for these parameters are:
* MPEG-4 Visual Simple Profile/Level 1: Content-type: video/
mp4v-es; profile-level-id=1
* MPEG-4 Visual Core Profile/Level 2: Content-type: video/
mp4v-es; profile-level-id=34
* MPEG-4 Visual Advanced Real Time Simple Profile/Level 1:
Content-type: video/mp4v-es; profile-level-id=145
Published specification: Published specification:
The specifications for MPEG-4 Visual streams are presented in ISO/ The specifications for MPEG-4 Visual streams are presented in ISO/
IEC 14469-2 [14496-2]. The RTP payload format is described in RFC IEC 14469-2 [14496-2]. The RTP payload format is described in RFC
3016. XXXX.
Encoding considerations: Encoding considerations:
Video bitstreams MUST be generated according to MPEG-4 Visual Video bitstreams MUST be generated according to MPEG-4 Visual
specifications (ISO/IEC 14496-2). A video bitstream is binary specifications (ISO/IEC 14496-2). A video bitstream is binary
data and MUST be encoded for non-binary transport (for Email, the data and MUST be encoded for non-binary transport (for Email, the
Base64 encoding is sufficient). This type is also defined for Base64 encoding is sufficient). This type is also defined for
transfer via RTP. The RTP packets MUST be packetized according to transfer via RTP. The RTP packets MUST be packetized according to
the MPEG-4 Visual RTP payload format defined in RFC 3016. the MPEG-4 Visual RTP payload format defined in RFC XXXX.
Security considerations: Security considerations:
See section 7 of RFC 3016. See section 7 of RFC XXXX.
Interoperability considerations: Interoperability considerations:
MPEG-4 Visual provides a large and rich set of tools for the MPEG-4 Visual provides a large and rich set of tools for the
coding of visual objects. For effective implementation of the coding of visual objects. For effective implementation of the
standard, subsets of the MPEG-4 Visual tool sets have been standard, subsets of the MPEG-4 Visual tool sets have been
provided for use in specific applications. These subsets, called provided for use in specific applications. These subsets, called
'Profiles', limit the size of the tool set a decoder is required 'Profiles', limit the size of the tool set a decoder is required
to implement. In order to restrict computational complexity, one to implement. In order to restrict computational complexity, one
or more Levels are set for each Profile. A Profile@Level or more Levels are set for each Profile. A Profile@Level
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Audio and visual streaming and conferencing tools Audio and visual streaming and conferencing tools
Additional information: none Additional information: none
Person and email address to contact for further information: Person and email address to contact for further information:
See Authors' Address section at the end of this document. See Authors' Address section at the end of this document.
Intended usage: COMMON Intended usage: COMMON
Author/Change controller: Author:
See Authors' Address section at the end of this document. See Authors' Address section at the end of this document.
5.2. SDP usage of MPEG-4 Visual Change controller:
IETF Audio/Video Transport working group delegated from the IESG.
5.2. Mapping to SDP for MPEG-4 Visual
The Media Type video/MP4V-ES string is mapped to fields in the The Media Type video/MP4V-ES string is mapped to fields in the
Session Description Protocol (SDP) [RFC4566], as follows: Session Description Protocol (SDP) [RFC4566], as follows:
o The Media Type (video) goes in SDP "m=" as the media name. o The Media Type (video) goes in SDP "m=" as the media name.
o The Media subtype (MP4V-ES) goes in SDP "a=rtpmap" as the encoding o The Media subtype (MP4V-ES) goes in SDP "a=rtpmap" as the encoding
name. name.
o The optional parameter "rate" goes in "a=rtpmap" as the clock o The optional parameter "rate" goes in "a=rtpmap" as the clock
rate. rate.
o The optional parameter "profile-level-id" and "config" go in the o The optional parameter "profile-level-id" and "config" go in the
"a=fmtp" line to indicate the coder capability and configuration, "a=fmtp" line to indicate the coder capability and configuration,
respectively. These parameters are expressed as a string, in the respectively. These parameters are expressed as a string, in the
form of as a semicolon separated list of parameter=value pairs. form of as a semicolon separated list of parameter=value pairs.
Example usages for the profile-level-id parameter are:
1 : MPEG-4 Visual Simple Profile/Level 1
34 : MPEG-4 Visual Core Profile/Level 2
145: MPEG-4 Visual Advanced Real Time Simple Profile/Level 1
5.2.1. Declarative SDP usage for MPEG-4 Visual
The following are some examples of media representation in SDP: The following are some examples of media representation in SDP:
Simple Profile/Level 1, rate=90000(90kHz), "profile-level-id" and Simple Profile/Level 1, rate=90000(90kHz), "profile-level-id" and
"config" are present in "a=fmtp" line: "config" are present in "a=fmtp" line:
m=video 49170/2 RTP/AVP 98 m=video 49170/2 RTP/AVP 98
a=rtpmap:98 MP4V-ES/90000 a=rtpmap:98 MP4V-ES/90000
a=fmtp:98 profile-level-id=1;config=000001B001000001B50900000100000001 a=fmtp:98 profile-level-id=1;config=000001B001000001B50900000100000001
20008440FA282C2090A21F 20008440FA282C2090A21F
Core Profile/Level 2, rate=90000(90kHz), "profile-level-id" is present Core Profile/Level 2, rate=90000(90kHz), "profile-level-id" is present
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m=video 49170/2 RTP/AVP 98 m=video 49170/2 RTP/AVP 98
a=rtpmap:98 MP4V-ES/90000 a=rtpmap:98 MP4V-ES/90000
a=fmtp:98 profile-level-id=34 a=fmtp:98 profile-level-id=34
Advance Real Time Simple Profile/Level 1, rate=90000(90kHz), Advance Real Time Simple Profile/Level 1, rate=90000(90kHz),
"profile-level-id" is present in "a=fmtp" line: "profile-level-id" is present in "a=fmtp" line:
m=video 49170/2 RTP/AVP 98 m=video 49170/2 RTP/AVP 98
a=rtpmap:98 MP4V-ES/90000 a=rtpmap:98 MP4V-ES/90000
a=fmtp:98 profile-level-id=145 a=fmtp:98 profile-level-id=145
5.3. Media Type registration of MPEG-4 Audio 5.3. Media Type registration for MPEG-4 Audio
Media type name: audio Note, any unspecified parameter MUST be ignored by the receiver to
ensure that additional parameters can be added in any future revision
of this specification.
Media subtype name: MP4A-LATM Type name: audio
Subtype name: MP4A-LATM
Required parameters: Required parameters:
rate: the rate parameter indicates the RTP time stamp clock rate. rate: the rate parameter indicates the RTP time stamp clock rate.
The default value is 90000. Other rates MAY be specified only if The default value is 90000. Other rates MAY be specified only if
they are set to the same value as the audio sampling rate (number they are set to the same value as the audio sampling rate (number
of samples per second). of samples per second).
In the presence of SBR, the sampling rates for the core en-/ In the presence of SBR, the sampling rates for the core en-/
decoder and the SBR tool are different in most cases. This decoder and the SBR tool are different in most cases. This
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Optional parameters: Optional parameters:
profile-level-id: a decimal representation of MPEG-4 Audio Profile profile-level-id: a decimal representation of MPEG-4 Audio Profile
Level indication value defined in ISO/IEC 14496-3 [14496-3]. This Level indication value defined in ISO/IEC 14496-3 [14496-3]. This
parameter indicates which MPEG-4 Audio tool subsets the decoder is parameter indicates which MPEG-4 Audio tool subsets the decoder is
capable of using. If this parameter is not specified in the capable of using. If this parameter is not specified in the
capability exchange or session setup procedure, its default value capability exchange or session setup procedure, its default value
of 30 (Natural Audio Profile/Level 1) is used. of 30 (Natural Audio Profile/Level 1) is used.
Followings are some examples of this value:
1 : Main Audio Profile Level 1
9 : Speech Audio Profile Level 1
15: High Quality Audio Profile Level 2
30: Natural Audio Profile Level 1
44: High Efficiency AAC Profile Level 2
48: High Efficiency AAC v2 Profile Level 2
55: Baseline MPEG Surround Profile (see ISO/IEC 23003-1) Level 3
MPS-profile-level-id: a decimal representation of the MPEG MPS-profile-level-id: a decimal representation of the MPEG
Surround Profile Level indication as defined in ISO/IEC 14496-3 Surround Profile Level indication as defined in ISO/IEC 14496-3
[14496-3]. This parameter indicates the MPEG Surround profile and [14496-3]. This parameter indicates the MPEG Surround profile and
level that the decoder must be capable in order to decode the level that the decoder must be capable in order to decode the
stream. stream.
object: a decimal representation of the MPEG-4 Audio Object Type object: a decimal representation of the MPEG-4 Audio Object Type
value defined in ISO/IEC 14496-3 [14496-3]. This parameter value defined in ISO/IEC 14496-3 [14496-3]. This parameter
specifies the tool to be used by the coder. It CAN be used to specifies the tool to be used by the coder. It CAN be used to
limit the capability within the specified "profile-level-id". limit the capability within the specified "profile-level-id".
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parameter defaults to 1 for an SBR-capable decoder. If the parameter defaults to 1 for an SBR-capable decoder. If the
resulting output sampling rate or the computational complexity is resulting output sampling rate or the computational complexity is
not supported, the SBR tool may be disabled or run in downsampled not supported, the SBR tool may be disabled or run in downsampled
mode. mode.
The timestamp resolution at RTP layer is determined by the rate The timestamp resolution at RTP layer is determined by the rate
parameter. parameter.
Published specification: Published specification:
Payload format specifications are described in this document.
Encoding specifications are provided in ISO/IEC 14496-3 [14496-3]. Encoding specifications are provided in ISO/IEC 14496-3 [14496-3].
The RTP payload format specification is described in RFC XXXX.
Encoding considerations: Encoding considerations:
This type is only defined for transfer via RTP. This type is only defined for transfer via RTP.
Security considerations: Security considerations:
See Section 7 of RFC 3016. See Section 7 of RFC XXXX.
Interoperability considerations: Interoperability considerations:
MPEG-4 Audio provides a large and rich set of tools for the coding MPEG-4 Audio provides a large and rich set of tools for the coding
of audio objects. For effective implementation of the standard, of audio objects. For effective implementation of the standard,
subsets of the MPEG-4 Audio tool sets similar to those used in subsets of the MPEG-4 Audio tool sets similar to those used in
MPEG-4 Visual have been provided (see section 5.1). MPEG-4 Visual have been provided (see section 5.1).
The audio stream SHALL be compliant with the MPEG-4 Audio Profile@ The audio stream SHALL be compliant with the MPEG-4 Audio Profile@
Level specified by the parameters "profile-level-id" and "MPS- Level specified by the parameters "profile-level-id" and "MPS-
skipping to change at page 23, line 47 skipping to change at page 23, line 34
Audio and video streaming and conferencing tools. Audio and video streaming and conferencing tools.
Additional information: none Additional information: none
Personal and email address to contact for further information: Personal and email address to contact for further information:
See Authors' Address section at the end of this document. See Authors' Address section at the end of this document.
Intended usage: COMMON Intended usage: COMMON
Author/Change controller: Author:
See Authors' Address section at the end of this document. See Authors' Address section at the end of this document.
5.4. SDP usage of MPEG-4 Audio Change controller:
IETF Audio/Video Transport working group delegated from the IESG.
5.4. Mapping to SDP for MPEG-4 Audio
The Media Type audio/MP4A-LATM string is mapped to fields in the The Media Type audio/MP4A-LATM string is mapped to fields in the
Session Description Protocol (SDP) [RFC4566], as follows: Session Description Protocol (SDP) [RFC4566], as follows:
o The Media Type (audio) goes in SDP "m=" as the media name. o The Media Type (audio) goes in SDP "m=" as the media name.
o The Media subtype (MP4A-LATM) goes in SDP "a=rtpmap" as the o The Media subtype (MP4A-LATM) goes in SDP "a=rtpmap" as the
encoding name. encoding name.
o The required parameter "rate" goes in "a=rtpmap" as the clock o The required parameter "rate" goes in "a=rtpmap" as the clock
rate. rate.
o The optional parameter "ptime" goes in SDP "a=ptime" attribute. o The optional parameter "ptime" goes in SDP "a=ptime" attribute.
o The optional parameters "profile-level-id" and o The optional parameters "profile-level-id", "MPS-profile-level-id"
"MPS-profile-level-id" goes in the "a=fmtp" line to indicate the and "object" goes in the "a=fmtp" line to indicate the coder
coder capability. The "object" parameter goes in the "a=fmtp" capability.
attribute. The payload-format-specific parameters "bitrate",
"cpresent", "config", "MPS-asc" and "SBR-enabled" go in the Followings are some examples of the profile-level-id value:
1 : Main Audio Profile Level 1
9 : Speech Audio Profile Level 1
15: High Quality Audio Profile Level 2
30: Natural Audio Profile Level 1
44: High Efficiency AAC Profile Level 2
48: High Efficiency AAC v2 Profile Level 2
55: Baseline MPEG Surround Profile (see ISO/IEC 23003-1) Level 3
The optional payload-format-specific parameters "bitrate",
"cpresent", "config", "MPS-asc" and "SBR-enabled" go also in the
"a=fmtp" line. These parameters are expressed as a string, in the "a=fmtp" line. These parameters are expressed as a string, in the
form of as a semicolon separated list of parameter=value pairs. form of as a semicolon separated list of parameter=value pairs.
5.4.1. Declarative SDP usage for MPEG-4 Audio
The following sections contain some examples of the media The following sections contain some examples of the media
representation in SDP. representation in SDP.
Note that the a=fmtp line in some of the examples has been wrapped to Note that the a=fmtp line in some of the examples has been wrapped to
fit the page; they would comprise a single line in the SDP file. fit the page; they would comprise a single line in the SDP file.
5.4.1. Example: In-band configuration 5.4.1.1. Example: In-band configuration
In this example the audio configuration data appears in the RTP In this example the audio configuration data appears in the RTP
payload exclusively (i.e., the MPEG-4 audio configuration is known payload exclusively (i.e., the MPEG-4 audio configuration is known
when a StreamMuxConfig element appears within the RTP payload). when a StreamMuxConfig element appears within the RTP payload).
m=audio 49230 RTP/AVP 96 m=audio 49230 RTP/AVP 96
a=rtpmap:96 MP4A-LATM/90000 a=rtpmap:96 MP4A-LATM/90000
a=fmtp:96 object=2; cpresent=1 a=fmtp:96 object=2; cpresent=1
The "clock rate" is set to 90kHz. This is the default value and the The "clock rate" is set to 90kHz. This is the default value and the
real audio sampling rate is known when the audio configuration data real audio sampling rate is known when the audio configuration data
is received. is received.
5.4.2. Example: 6kb/s CELP 5.4.1.2. Example: 6kb/s CELP
6 kb/s CELP bitstreams (with an audio sampling rate of 8 kHz) 6 kb/s CELP bitstreams (with an audio sampling rate of 8 kHz)
m=audio 49230 RTP/AVP 96 m=audio 49230 RTP/AVP 96
a=rtpmap:96 MP4A-LATM/8000 a=rtpmap:96 MP4A-LATM/8000
a=fmtp:96 profile-level-id=9; object=8; cpresent=0; a=fmtp:96 profile-level-id=9; object=8; cpresent=0;
config=40008B18388380 config=40008B18388380
a=ptime:20 a=ptime:20
In this example audio configuration data is not multiplexed into the In this example audio configuration data is not multiplexed into the
RTP payload and is described only in SDP. Furthermore, the "clock RTP payload and is described only in SDP. Furthermore, the "clock
rate" is set to the audio sampling rate. rate" is set to the audio sampling rate.
skipping to change at page 25, line 14 skipping to change at page 25, line 19
m=audio 49230 RTP/AVP 96 m=audio 49230 RTP/AVP 96
a=rtpmap:96 MP4A-LATM/8000 a=rtpmap:96 MP4A-LATM/8000
a=fmtp:96 profile-level-id=9; object=8; cpresent=0; a=fmtp:96 profile-level-id=9; object=8; cpresent=0;
config=40008B18388380 config=40008B18388380
a=ptime:20 a=ptime:20
In this example audio configuration data is not multiplexed into the In this example audio configuration data is not multiplexed into the
RTP payload and is described only in SDP. Furthermore, the "clock RTP payload and is described only in SDP. Furthermore, the "clock
rate" is set to the audio sampling rate. rate" is set to the audio sampling rate.
5.4.3. Example: 64 kb/s AAC LC stereo 5.4.1.3. Example: 64 kb/s AAC LC stereo
64 kb/s AAC LC stereo bitstream (with an audio sampling rate of 24 64 kb/s AAC LC stereo bitstream (with an audio sampling rate of 24
kHz) kHz)
m=audio 49230 RTP/AVP 96 m=audio 49230 RTP/AVP 96
a=rtpmap:96 MP4A-LATM/24000/2 a=rtpmap:96 MP4A-LATM/24000/2
a=fmtp:96 profile-level-id=1; bitrate=64000; cpresent=0; a=fmtp:96 profile-level-id=1; bitrate=64000; cpresent=0;
object=2; config=400026203fc0 object=2; config=400026203fc0
In this example audio configuration data is not multiplexed into the In this example audio configuration data is not multiplexed into the
RTP payload and is described only in SDP. Furthermore, the "clock RTP payload and is described only in SDP. Furthermore, the "clock
rate" is set to the audio sampling rate. rate" is set to the audio sampling rate.
In this example, the presence of SBR can not be determined by the SDP In this example, the presence of SBR can not be determined by the SDP
parameter set. The clock rate represents the core codec sampling parameter set. The clock rate represents the core codec sampling
rate. An SBR enabled decoder SHOULD use the SBR tool to upsample the rate. An SBR enabled decoder SHOULD use the SBR tool to upsample the
audio data if complexity and resulting output sampling rate permits. audio data if complexity and resulting output sampling rate permits.
5.4.4. Example: Use of the SBR-enabled parameter 5.4.1.4. Example: Use of the SBR-enabled parameter
These two examples are identical to the example above with the These two examples are identical to the example above with the
exception of the SBR-enabled parameter. The presence of SBR is not exception of the SBR-enabled parameter. The presence of SBR is not
signaled by the SDP parameters object, profile-level-id and config, signaled by the SDP parameters object, profile-level-id and config,
but instead the SBR-enabled parameter is present. The rate parameter but instead the SBR-enabled parameter is present. The rate parameter
and the StreamMuxConfig contain the core codec sampling rate. and the StreamMuxConfig contain the core codec sampling rate.
Example with "SBR-enabled=0", definitive and core codec sampling rate Example with "SBR-enabled=0", definitive and core codec sampling rate
24kHz: 24kHz:
skipping to change at page 26, line 17 skipping to change at page 26, line 20
a=fmtp:96 profile-level-id=1; bitrate=64000; cpresent=0; a=fmtp:96 profile-level-id=1; bitrate=64000; cpresent=0;
SBR-enabled=1; config=400026203fc0 SBR-enabled=1; config=400026203fc0
In this example, the clock rate is still 24000 and this information In this example, the clock rate is still 24000 and this information
should be used for RTP timestamp calculation. The value of 24000 is should be used for RTP timestamp calculation. The value of 24000 is
used to support old AAC decoders. This makes the decoder supporting used to support old AAC decoders. This makes the decoder supporting
only AAC understand the HE AAC coded data, although only plain AAC is only AAC understand the HE AAC coded data, although only plain AAC is
supported. A HE AAC decoder is able to generate output data with the supported. A HE AAC decoder is able to generate output data with the
SBR sampling rate. SBR sampling rate.
5.4.5. Example: Hierarchical Signaling of SBR 5.4.1.5. Example: Hierarchical Signaling of SBR
When the presence of SBR is explicitly signaled by the SDP parameters When the presence of SBR is explicitly signaled by the SDP parameters
object, profile-level-id or the config string as in the example object, profile-level-id or the config string as in the example
below, the StreamMuxConfig contains both the core codec sampling rate below, the StreamMuxConfig contains both the core codec sampling rate
and the SBR sampling rate. and the SBR sampling rate.
m=audio 49230 RTP/AVP 96 m=audio 49230 RTP/AVP 96
a=rtpmap:96 MP4A-LATM/48000/2 a=rtpmap:96 MP4A-LATM/48000/2
a=fmtp:96 profile-level-id=44; bitrate=64000; cpresent=0; a=fmtp:96 profile-level-id=44; bitrate=64000; cpresent=0;
config=40005623101fe0; SBR-enabled=1 config=40005623101fe0; SBR-enabled=1
This config string uses the explicit signaling mode 2.A (hierarchical This config string uses the explicit signaling mode 2.A (hierarchical
signaling; See ISO/IEC 14496-3 [14496-3]). This means that the signaling; See ISO/IEC 14496-3 [14496-3]). This means that the
AOT(Audio Object Type) is SBR(5) and SFI(Sampling Frequency Index) is AOT(Audio Object Type) is SBR(5) and SFI(Sampling Frequency Index) is
6(24000 Hz) which refers to the underlying core codec sampling 6(24000 Hz) which refers to the underlying core codec sampling
frequency. CC(Channel Configuration) is stereo(2), and the frequency. CC(Channel Configuration) is stereo(2), and the
ESFI(Extension Sampling Frequency Index)=3 (48000) is referring to ESFI(Extension Sampling Frequency Index)=3 (48000) is referring to
the sampling frequency of the extension tool(SBR). the sampling frequency of the extension tool(SBR).
5.4.6. Example: HE AAC v2 Signaling 5.4.1.6. Example: HE AAC v2 Signaling
HE AAC v2 decoders are required to always produce a stereo signal HE AAC v2 decoders are required to always produce a stereo signal
from a mono signal. Hence, there is no parameter necessary to signal from a mono signal. Hence, there is no parameter necessary to signal
the presence of PS. the presence of PS.
Example with "SBR-enabled=1" and 1 channel signaled in the a=rtpmap Example with "SBR-enabled=1" and 1 channel signaled in the a=rtpmap
line and within the config parameter. Core codec sampling rate is line and within the config parameter. Core codec sampling rate is
24kHz, definitive and SBR sampling rate is 48kHz. Core codec channel 24kHz, definitive and SBR sampling rate is 48kHz. Core codec channel
configuration is mono, PS channel configuration is stereo. configuration is mono, PS channel configuration is stereo.
m=audio 49230 RTP/AVP 110 m=audio 49230 RTP/AVP 110
a=rtpmap:110 MP4A-LATM/24000/1 a=rtpmap:110 MP4A-LATM/24000/1
a=fmtp:110 profile-level-id=15; object=2; cpresent=0; a=fmtp:110 profile-level-id=15; object=2; cpresent=0;
config=400026103fc0; SBR-enabled=1 config=400026103fc0; SBR-enabled=1
5.4.7. Example: Hierarchical Signaling of PS 5.4.1.7. Example: Hierarchical Signaling of PS
Example: 48khz stereo audio input: Example: 48khz stereo audio input:
m=audio 49230 RTP/AVP 110 m=audio 49230 RTP/AVP 110
a=rtpmap:110 MP4A-LATM/48000/2 a=rtpmap:110 MP4A-LATM/48000/2
a=fmtp:110 profile-level-id=48; cpresent=0; config=4001d613101fe0 a=fmtp:110 profile-level-id=48; cpresent=0; config=4001d613101fe0
The config parameter indicates explicit hierarchical signaling of PS The config parameter indicates explicit hierarchical signaling of PS
and SBR. This configuration method is not supported by legacy AAC an and SBR. This configuration method is not supported by legacy AAC an
HE AAC decoders and these are therefore unable to decode the the HE AAC decoders and these are therefore unable to decode the the
coded data. coded data.
5.4.8. Example: MPEG Surround 5.4.1.8. Example: MPEG Surround
The following examples show how MPEG Surround configuration data can The following examples show how MPEG Surround configuration data can
be signaled using SDP. The configuration is carried within the be signaled using SDP. The configuration is carried within the
config string in the first example by using two different layers. config string in the first example by using two different layers.
The general parameters in this example are: AudioMuxVersion=1; The general parameters in this example are: AudioMuxVersion=1;
allStreamsSameTimeFraming=1; numSubFrames=0; numProgram=0; allStreamsSameTimeFraming=1; numSubFrames=0; numProgram=0;
numLayer=1. The first layer describes the HE AAC payload and signals numLayer=1. The first layer describes the HE AAC payload and signals
the following parameters: ascLen=25; audioObjectType=2 (AAC LC); the following parameters: ascLen=25; audioObjectType=2 (AAC LC);
extensionAudioObjectType=5 (SBR); samplingFrequencyIndex=6 (24kHz); extensionAudioObjectType=5 (SBR); samplingFrequencyIndex=6 (24kHz);
extensionSamplingFrequencyIndex=3 (48kHz); channelConfiguration=2 extensionSamplingFrequencyIndex=3 (48kHz); channelConfiguration=2
skipping to change at page 27, line 47 skipping to change at page 28, line 5
layers. The MPEG surround payload is carried together with the AAC layers. The MPEG surround payload is carried together with the AAC
payload in a single layer as indicated by the sacPayloadEmbedding payload in a single layer as indicated by the sacPayloadEmbedding
Flag. Flag.
m=audio 49230 RTP/AVP 96 m=audio 49230 RTP/AVP 96
a=rtpmap:96 MP4A-LATM/48000 a=rtpmap:96 MP4A-LATM/48000
a=fmtp:96 profile-level-id=1; bitrate=64000; cpresent=0; a=fmtp:96 profile-level-id=1; bitrate=64000; cpresent=0;
SBR-enabled=1; SBR-enabled=1;
config=8FF8004192B11880FF0DDE3699F2408C00536C02313CF3CE0FF0 config=8FF8004192B11880FF0DDE3699F2408C00536C02313CF3CE0FF0
5.4.9. Example: MPEG Surround with extended SDP parameters 5.4.1.9. Example: MPEG Surround with extended SDP parameters
The following example is an extension of the configuration given The following example is an extension of the configuration given
above by the MPEG Surround specific parameters. The MPS-asc above by the MPEG Surround specific parameters. The MPS-asc
parameter specifies the MPEG Surround Baseline Profile at Level 3 parameter specifies the MPEG Surround Baseline Profile at Level 3
(PLI55) and the MPS-asc string contains the hexadecimal (PLI55) and the MPS-asc string contains the hexadecimal
representation of the MPEG Surround ASC [audioObjectType=30 (MPEG representation of the MPEG Surround ASC [audioObjectType=30 (MPEG
Surround); samplingFrequencyIndex=0x3 (48kHz); channelConfiguration=6 Surround); samplingFrequencyIndex=0x3 (48kHz); channelConfiguration=6
(5.1 channels); sacPayloadEmbedding=1; SpatialSpecificConfig=(48 kHz; (5.1 channels); sacPayloadEmbedding=1; SpatialSpecificConfig=(48 kHz;
32 slots; 525 tree; ResCoding=1; ResBands=[0,13,13,13])]. 32 slots; 525 tree; ResCoding=1; ResBands=[0,13,13,13])].
m=audio 49230 RTP/AVP 96 m=audio 49230 RTP/AVP 96
a=rtpmap:96 MP4A-LATM/48000 a=rtpmap:96 MP4A-LATM/48000
a=fmtp:96 profile-level-id=44; bitrate=64000; cpresent=0; a=fmtp:96 profile-level-id=44; bitrate=64000; cpresent=0;
config=40005623101fe0; MPS-profile-level-id=55; config=40005623101fe0; MPS-profile-level-id=55;
MPS-asc=F1B4CF920442029B501185B6DA00; MPS-asc=F1B4CF920442029B501185B6DA00;
5.4.10. Example: MPEG Surround with single layer configuration 5.4.1.10. Example: MPEG Surround with single layer configuration
The following example shows how MPEG Surround configuration data can The following example shows how MPEG Surround configuration data can
be signaled using the SDP config parameter. The configuration is be signaled using the SDP config parameter. The configuration is
carried within the config string using a single layer. The general carried within the config string using a single layer. The general
parameters in this example are: AudioMuxVersion=1; parameters in this example are: AudioMuxVersion=1;
allStreamsSameTimeFraming=1; numSubFrames=0; numProgram=0; allStreamsSameTimeFraming=1; numSubFrames=0; numProgram=0;
numLayer=0. The single layer describes the combination of HE AAC and numLayer=0. The single layer describes the combination of HE AAC and
MPEG Surround payload and signals the following parameters: MPEG Surround payload and signals the following parameters:
ascLen=101; audioObjectType=2 (AAC LC); extensionAudioObjectType=5 ascLen=101; audioObjectType=2 (AAC LC); extensionAudioObjectType=5
(SBR); samplingFrequencyIndex=7 (22.05kHz); (SBR); samplingFrequencyIndex=7 (22.05kHz);
skipping to change at page 28, line 45 skipping to change at page 29, line 8
m=audio 49230 RTP/AVP 96 m=audio 49230 RTP/AVP 96
a=rtpmap:96 MP4A-LATM/44100 a=rtpmap:96 MP4A-LATM/44100
a=fmtp:96 profile-level-id=44; bitrate=64000; cpresent=0; a=fmtp:96 profile-level-id=44; bitrate=64000; cpresent=0;
SBR-enabled=1; config=8FF8000652B920876A83A1F440884053620FF0; SBR-enabled=1; config=8FF8000652B920876A83A1F440884053620FF0;
MPS-profile-level-id=55 MPS-profile-level-id=55
6. IANA Considerations 6. IANA Considerations
This memo defines additional optional format parameters to the Media This memo defines additional optional format parameters to the Media
Type "audio" and its subtype "MP4A-LATM", as defined in RFC 3016 Type "audio" and its subtype "MP4A-LATM", as defined in RFC XXXX.
[RFC3016]. The Media Type parameters are defined in sections 5.1 and The Media Type parameters are defined in sections 5.1 and 5.3 of RFC
5.3. XXXX.
6.1. Media Type Registration 6.1. Media Type Registration
This memo defines the following additional optional parameters which This memo defines the following additional optional parameters which
SHOULD be used if SBR or MPEG Surround data is present inside the SHOULD be used if SBR or MPEG Surround data is present inside the
payload of an AAC elementary stream. payload of an AAC elementary stream.
MPS-profile-level-id: a decimal representation of the MPEG MPS-profile-level-id: a decimal representation of the MPEG
Surround Profile Level indication as defined in ISO/IEC 14496-3 Surround Profile Level indication as defined in ISO/IEC 14496-3
[14496-3]. This parameter indicates the MPEG Surround profile and [14496-3]. This parameter indicates the MPEG Surround profile and
skipping to change at page 29, line 32 skipping to change at page 29, line 39
SBR-enabled: a boolean parameter which indicates whether SBR-data SBR-enabled: a boolean parameter which indicates whether SBR-data
can be expected in the RTP-payload of a stream. This parameter is can be expected in the RTP-payload of a stream. This parameter is
relevant for an SBR-capable decoder if the presence of SBR can not relevant for an SBR-capable decoder if the presence of SBR can not
be detected from an out-of-band decoder configuration (e.g. be detected from an out-of-band decoder configuration (e.g.
contained in the config string). contained in the config string).
6.2. Usage of SDP 6.2. Usage of SDP
It is assumed that the Media Type parameters are conveyed via an SDP It is assumed that the Media Type parameters are conveyed via an SDP
message as specified in RFC 3016 [RFC3016], sections 5.2 and 5.4. message as specified in sections 5.2 and 5.4.
7. Security Considerations 7. Security Considerations
RTP packets using the payload format defined in this specification RTP packets using the payload format defined in this specification
are subject to the security considerations discussed in the RTP are subject to the security considerations discussed in the RTP
specification [RFC3550]. This implies that confidentiality of the specification [RFC3550]. This implies that confidentiality of the
media streams is achieved by encryption. Because the data media streams is achieved by encryption. Because the data
compression used with this payload format is applied end-to-end, compression used with this payload format is applied end-to-end,
encryption may be performed on the compressed data so there is no encryption may be performed on the compressed data so there is no
conflict between the two operations. conflict between the two operations.
skipping to change at page 30, line 37 skipping to change at page 30, line 44
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3016] Kikuchi, Y., Nomura, T., Fukunaga, S., Matsui, Y., and H. [RFC3016] Kikuchi, Y., Nomura, T., Fukunaga, S., Matsui, Y., and H.
Kimata, "RTP Payload Format for MPEG-4 Audio/Visual Kimata, "RTP Payload Format for MPEG-4 Audio/Visual
Streams", RFC 3016, November 2000. Streams", RFC 3016, November 2000.
[RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V. [RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V.
Jacobson, "RTP: A Transport Protocol for Real-Time Jacobson, "RTP: A Transport Protocol for Real-Time
Applications", STD 64, RFC 3550, July 2003. Applications", STD 64, RFC 3550, July 2003.
[RFC4288] Freed, N. and J. Klensin, "Media Type Specifications and
Registration Procedures", BCP 13, RFC 4288, December 2005.
[RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session [RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
Description Protocol", RFC 4566, July 2006. Description Protocol", RFC 4566, July 2006.
[RFC4629] Ott, H., Bormann, C., Sullivan, G., Wenger, S., and R. [RFC4629] Ott, H., Bormann, C., Sullivan, G., Wenger, S., and R.
Even, "RTP Payload Format for ITU-T Rec", RFC 4629, Even, "RTP Payload Format for ITU-T Rec", RFC 4629,
January 2007. January 2007.
[RFC4855] Casner, S., "Media Type Registration of RTP Payload
Formats", RFC 4855, February 2007.
[RFC5583] Schierl, T. and S. Wenger, "Signaling Media Decoding [RFC5583] Schierl, T. and S. Wenger, "Signaling Media Decoding
Dependency in the Session Description Protocol (SDP)", Dependency in the Session Description Protocol (SDP)",
RFC 5583, July 2009. RFC 5583, July 2009.
8.2. Informative References 8.2. Informative References
[14496-1] MPEG, "ISO/IEC International Standard 14496-1 - Coding of [14496-1] MPEG, "ISO/IEC International Standard 14496-1 - Coding of
audio-visual objects, Part 1 Systems", 2004. audio-visual objects, Part 1 Systems", 2004.
[14496-12] [14496-12]
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