draft-ietf-avt-rtp-evrc-wb-01.txt   draft-ietf-avt-rtp-evrc-wb-02.txt 
Network Working Group H. Desineni Network Working Group H. Desineni
Internet-Draft Qualcomm Internet-Draft Qualcomm
Updates: 4788 (if approved) Q. Xie Updates: 4788 (if approved) Q. Xie
Intended status: Standards Track Motorola Intended status: Standards Track Motorola
Expires: October 6, 2007 April 4, 2007 Expires: November 20, 2007 May 19, 2007
RTP payload format for EVRC-WB codec and MIME updates for EVRC-B codec RTP payload format for EVRC-WB codec and media subtype updates for
draft-ietf-avt-rtp-evrc-wb-01.txt EVRC-B codec
draft-ietf-avt-rtp-evrc-wb-02.txt
Status of this Memo Status of this Memo
By submitting this Internet-Draft, each author represents that any By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79. aware will be disclosed, in accordance with Section 6 of BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
skipping to change at page 1, line 35 skipping to change at page 1, line 36
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."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt. http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
This Internet-Draft will expire on October 6, 2007. This Internet-Draft will expire on November 20, 2007.
Copyright Notice Copyright Notice
Copyright (C) The IETF Trust (2007). Copyright (C) The IETF Trust (2007).
Abstract Abstract
This document specifies real-time transport protocol (RTP) payload This document specifies real-time transport protocol (RTP) payload
formats to be used for the EVRC wideband codec (EVRC-WB) and updates formats to be used for the EVRC wideband codec (EVRC-WB) and updates
the MIME registrations for EVRC-B codec. Several media type the media type registrations for EVRC-B codec. Several media type
registrations are included for EVRC-WB RTP payload formats. In registrations are included for EVRC-WB RTP payload formats. In
addition, a file format is specified for transport of EVRC-WB speech addition, a file format is specified for transport of EVRC-WB speech
data in storage mode applications such as e-mail. data in storage mode applications such as e-mail.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Background . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3. Background . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4. EVRC-WB codec . . . . . . . . . . . . . . . . . . . . . . . . 6 4. EVRC-WB codec . . . . . . . . . . . . . . . . . . . . . . . . 6
5. RTP header usage . . . . . . . . . . . . . . . . . . . . . . . 7 5. RTP header usage . . . . . . . . . . . . . . . . . . . . . . . 7
6. Payload format . . . . . . . . . . . . . . . . . . . . . . . . 8 6. Payload format . . . . . . . . . . . . . . . . . . . . . . . . 8
7. Congestion Control Considerations . . . . . . . . . . . . . . 9 7. Congestion Control Considerations . . . . . . . . . . . . . . 9
8. Storage format for EVRC-WB Codec . . . . . . . . . . . . . . . 10 8. Storage format for EVRC-WB Codec . . . . . . . . . . . . . . . 10
9. Media type definitions . . . . . . . . . . . . . . . . . . . . 11 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
9.1. Registration of Media Type EVRCWB . . . . . . . . . . . . 11 9.1. Media Type Registration . . . . . . . . . . . . . . . . . 11
9.2. Registration of Media Type EVRCWB0 . . . . . . . . . . . . 13 9.1.1. Registration of Media Type EVRCWB . . . . . . . . . . 11
9.3. Registration of Media Type EVRCWB1 . . . . . . . . . . . . 15 9.1.2. Registration of Media Type EVRCWB0 . . . . . . . . . . 13
9.4. Updated Registration of Media Type EVRCB . . . . . . . . . 17 9.1.3. Registration of Media Type EVRCWB1 . . . . . . . . . . 15
9.5. Updated Registration of Media Type EVRCB0 . . . . . . . . 19 9.1.4. Updated Registration of Media Type EVRCB . . . . . . . 17
9.1.5. Updated Registration of Media Type EVRCB0 . . . . . . 19
10. EVRC-B RFC XXXX Interoperability with legacy EVRC-B (RFC 10. EVRC-B RFC XXXX Interoperability with legacy EVRC-B (RFC
4788) implementations . . . . . . . . . . . . . . . . . . . . 21 4788) implementations . . . . . . . . . . . . . . . . . . . . 22
11. Mapping EVRC-WB MIME Parameters into SDP . . . . . . . . . . . 22 11. Mapping EVRC-WB media type parameters into SDP . . . . . . . . 23
12. Mapping EVRC-B MIME Parameters into SDP . . . . . . . . . . . 23 12. Mapping EVRC-B media type parameters into SDP . . . . . . . . 24
13. Offer-Answer Model Considerations for EVRC-WB . . . . . . . . 24 13. Offer-Answer Model Considerations for EVRC-WB . . . . . . . . 25
14. Offer-Answer Model Considerations for EVRC-B . . . . . . . . . 26 14. Offer-Answer Model Considerations for EVRC-B . . . . . . . . . 27
15. Declarative SDP Considerations . . . . . . . . . . . . . . . . 27 15. Declarative SDP Considerations . . . . . . . . . . . . . . . . 28
16. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 16. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
17. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 32 17. Security Considerations . . . . . . . . . . . . . . . . . . . 33
18. Security Considerations . . . . . . . . . . . . . . . . . . . 33 18. Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
19. Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 19. References . . . . . . . . . . . . . . . . . . . . . . . . . . 35
20. References . . . . . . . . . . . . . . . . . . . . . . . . . . 35 19.1. Normative References . . . . . . . . . . . . . . . . . . . 35
20.1. Normative References . . . . . . . . . . . . . . . . . . . 35 19.2. Informative References . . . . . . . . . . . . . . . . . . 35
20.2. Informative References . . . . . . . . . . . . . . . . . . 35 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 36
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 37 Intellectual Property and Copyright Statements . . . . . . . . . . 37
Intellectual Property and Copyright Statements . . . . . . . . . . 38
1. Introduction 1. Introduction
This document specifies the payload formats for packetization of This document specifies the payload formats for packetization of
EVRC-WB encoded speech signals into the real-time transport protocol EVRC-WB encoded speech signals into the real-time transport protocol
(RTP).It defines support for the header-free, interleaved/bundled and (RTP).It defines support for the header-free, interleaved/bundled and
compact bundle packet formats for the EVRC-WB codec as well as compact bundle packet formats for the EVRC-WB codec as well as
discontinuous transmission (DTX) support for EVRC-WB encoded speech discontinuous transmission (DTX) support for EVRC-WB encoded speech
transported via RTP.EVRC-WB codec offers better speech quality than transported via RTP.EVRC-WB codec offers better speech quality than
EVRC and EVRC-B codecs. EVRC-WB belongs to the EVRC family of EVRC and EVRC-B codecs. EVRC-WB belongs to the EVRC family of
codecs.This document also updates the MIME registrations for EVRC-B codecs.This document also updates the media type registrations for
codec. EVRC-B codec.
2. Conventions 2. Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [1]. document are to be interpreted as described in RFC 2119 [1].
3. Background 3. Background
EVRC-WB is a wideband extension of EVRC-B [4] speech codec developed EVRC-WB is a wideband extension of EVRC-B [3] speech codec developed
in 3GPP2 with support for discontinuous transmission (DTX). It in 3GPP2 with support for discontinuous transmission (DTX). It
provides enhanced (wideband) voice quality. provides enhanced (wideband) voice quality.
EVRC-WB codec operates on 20 ms frames, and the default sampling rate EVRC-WB codec operates on 20 ms frames, and the default sampling rate
is 16 kHz. Input and output at 8 kHz sampling rate is also is 16 kHz. Input and output at 8 kHz sampling rate is also
supported. EVRC-WB modes are defined in [5]. EVRC-WB modes 4,7 are supported. EVRC-WB modes are defined in [4]. EVRC-WB modes 4,7 are
interoperable with EVRC-B. EVRC-WB provides a standardized solution interoperable with EVRC-B. EVRC-WB provides a standardized solution
for packetized voice applications that allow transitions between for packetized voice applications that allow transitions between
narrowband and wideband telephony. The most important service narrowband and wideband telephony. The most important service
addressed is IP telephony. Target devices can be IP phones or VoIP addressed is IP telephony. Target devices can be IP phones or VoIP
handsets, media gateways, voice messaging servers, etc. handsets, media gateways, voice messaging servers, etc.
4. EVRC-WB codec 4. EVRC-WB codec
EVRC-WB codec operates on 20 ms frames. It produces output frames of EVRC-WB codec operates on 20 ms frames. It produces output frames of
one of the three different sizes: 171 bits, 80 bits or 16 bits. In one of the three different sizes: 171 bits, 80 bits or 16 bits. In
skipping to change at page 7, line 7 skipping to change at page 7, line 7
-------------------------------------------------------------------- --------------------------------------------------------------------
0 Blank 0 (0 bit) 0 Blank 0 (0 bit)
1 1/8 2 (16 bits) 1 1/8 2 (16 bits)
2 1/4 5 (40 bits; not valid for EVRC-WB) 2 1/4 5 (40 bits; not valid for EVRC-WB)
3 1/2 10 (80 bits) 3 1/2 10 (80 bits)
4 1 22 (171 bits; 5 bits padded at the end) 4 1 22 (171 bits; 5 bits padded at the end)
5 Erasure 0 (SHOULD NOT be transmitted by sender) 5 Erasure 0 (SHOULD NOT be transmitted by sender)
5. RTP header usage 5. RTP header usage
The format of the RTP header is specified in RFC 3550 [6]. The The format of the RTP header is specified in RFC 3550 [5]. The
EVRC-WB payload formats (Section 6) use the fields of the RTP header EVRC-WB payload formats (Section 6) use the fields of the RTP header
in a manner consistent with RFC 3550. in a manner consistent with RFC 3550.
EVRC-WB has also the capability to operate with 8 kHz sampled input/ EVRC-WB has also the capability to operate with 8 kHz sampled input/
output signals. The decoder does not require a priori knowledge output signals. The decoder does not require a priori knowledge
about the sampling rate of the original signal at the input of the about the sampling rate of the original signal at the input of the
encoder. The decoder output can be at 8kHz or 16kHz regardless of encoder. The decoder output can be at 8kHz or 16kHz regardless of
the sampling rate used at the encoder. Therefore, depending on the the sampling rate used at the encoder. Therefore, depending on the
implementation and the audio electro acoustic capabilities of the implementation and the audio electro acoustic capabilities of the
devices, the input of the encoder and/or the output of the decoder devices, the input of the encoder and/or the output of the decoder
skipping to change at page 8, line 12 skipping to change at page 8, line 12
for this codec or specify that the payload type is to be bound for this codec or specify that the payload type is to be bound
dynamically (see Section 11). dynamically (see Section 11).
6. Payload format 6. Payload format
Three RTP packet formats are supported for the EVRC-WB codec - the Three RTP packet formats are supported for the EVRC-WB codec - the
interleaved/bundled packet format, the header-free packet format and interleaved/bundled packet format, the header-free packet format and
the compact bundled packet format. For all these formats, the the compact bundled packet format. For all these formats, the
operational details and capabilities, such as ToC, interleaving, DTX, operational details and capabilities, such as ToC, interleaving, DTX,
and bundling, of EVRC-WB are exactly the same as those of EVRC-B, as and bundling, of EVRC-WB are exactly the same as those of EVRC-B, as
defined in [4], except that the mode change request field in the ToC defined in [3], except that the mode change request field in the ToC
MUST be interpreted according to the definition of the RATE_REDUC MUST be interpreted according to the definition of the RATE_REDUC
parameter as defined in EVRC-WB [5]. parameter as defined in EVRC-WB [4].
7. Congestion Control Considerations 7. Congestion Control Considerations
Congestion control for RTP SHALL be used in accordance with RFC 3550 Congestion control for RTP SHALL be used in accordance with RFC 3550
[6], and with any applicable RTP profile; e.g., RFC 3551 [12]. [5], and with any applicable RTP profile; e.g., RFC 3551 [9].
Due to the header overhead, the number of frames encapsulated in each Due to the header overhead, the number of frames encapsulated in each
RTP packet influences the overall bandwidth of the RTP stream. RTP packet influences the overall bandwidth of the RTP stream.
Packing more frames in each RTP packet can reduce the number of Packing more frames in each RTP packet can reduce the number of
packets sent and hence the header overhead, at the expense of packets sent and hence the header overhead, at the expense of
increased delay and reduced error robustness. increased delay and reduced error robustness.
8. Storage format for EVRC-WB Codec 8. Storage format for EVRC-WB Codec
The storage format is used for storing EVRC-WB encoded speech frames, The storage format is used for storing EVRC-WB encoded speech frames,
skipping to change at page 11, line 5 skipping to change at page 11, line 5
TOC entry field, extended to one octet, prefixing each codec data TOC entry field, extended to one octet, prefixing each codec data
frame. The ToC field is extended to one octet by setting the four frame. The ToC field is extended to one octet by setting the four
most significant bits of the octet to zero. For example, a ToC value most significant bits of the octet to zero. For example, a ToC value
of 4 (a full-rate frame) is stored as 0x04. See Section 4 for the of 4 (a full-rate frame) is stored as 0x04. See Section 4 for the
mapping from frame type to ToC value. mapping from frame type to ToC value.
Speech frames lost in transmission and non-received frames MUST be Speech frames lost in transmission and non-received frames MUST be
stored as erasure frames (ToC value of 5) to maintain synchronization stored as erasure frames (ToC value of 5) to maintain synchronization
with the original media. with the original media.
9. Media type definitions 9. IANA Considerations
9.1. Registration of Media Type EVRCWB This document updates EVRCB, EVRCB0 media subtypes defined in RFC
4788 [2] and adds new EVRC-WB media subtypes.
[-- RFC Editor: Please replace all instances of "RFC XXXX" in this
document with the RFC number of this document prior to IANA
registration and RFC publication, and remove this note.]
[-- RFC Editor:Please add media subtypes "EVRCWB","EVRCWB0", and
"EVRCWB1" to the IANA registry for "RTP Payload Format media types"
at http://www.iana.org/assignments/rtp-parameters, and remove this
note.]
9.1. Media Type Registration
Following the guidelines in RFC 4288 [8], this section registers new
media subtypes for EVRC-WB and updates EVRCB, EVRCB0 media subtypes
defined in RFC 4788 [2].
9.1.1. Registration of Media Type EVRCWB
Type name: audio Type name: audio
Subtype names: EVRCWB Subtype names: EVRCWB
Required parameters: none Required parameters: none
Optional parameters: Optional parameters:
mode-set-recv: A subset of EVRC-WB modes. Possible values are a mode-set-recv: A subset of EVRC-WB modes. Possible values are a
comma separated list of modes from the set: 0,4,7 (see Table2.5.1.2-1 comma separated list of modes from the set: 0,4,7 (see Table
[5]). A decoder can use this to signal an encoder to limit its modes 2.5.1.2-1 [4]). A decoder can use this to signal an encoder to limit
to the specified subset. Absence of this parameter signals a set of its modes to the specified subset. Absence of this parameter signals
all EVRC-WB modes. The default value of 'mode-set-recv' is 0,4,7. the mode set {0,4,7}.
sendmode: A mode of EVRC-WB codec. Encoder can use this to signal sendmode: A mode of EVRC-WB codec. Encoder can use this to signal
its current mode of operation. Possible values are a comma separated its current mode of operation. Possible values are 0,4,7 (see Table
list of modes from the set: 0,4,7 (see Table2.5.1.2-1 [5]). The 2.5.1.2-1 [4]). Absence of this parameter signals mode 0.
default value of 'sendmode' is 0.
ptime: see RFC 4566 [9]. ptime: see RFC 4566 [7].
maxptime: The maximum amount of media which can be encapsulated in maxptime: The maximum amount of media which can be encapsulated in
each packet, expressed as time in milliseconds. The time MUST be each packet, expressed as time in milliseconds. The time MUST be
calculated as the sum of the time the media present in the packet calculated as the sum of the time the media present in the packet
represents. The time SHOULD be a multiple of the duration of a represents. The time SHOULD be a multiple of the duration of a
single codec data frame (20 msec). If not signaled, the default single codec data frame (20 msec). If not signaled, the default
maxptime value MUST be 200 milliseconds. maxptime value MUST be 200 milliseconds.
maxinterleave: Maximum number for interleaving length (field LLL in maxinterleave: Maximum number for interleaving length (field LLL in
the Interleaving Octet). The interleaving lengths used in the entire the Interleaving Octet). The interleaving lengths used in the entire
skipping to change at page 12, line 5 skipping to change at page 12, line 22
dtxmax: see Section 6.1 in [2] dtxmax: see Section 6.1 in [2]
dtxmin: see Section 6.1 in [2] dtxmin: see Section 6.1 in [2]
hangover: see Section 6.1 in [2] hangover: see Section 6.1 in [2]
Encoding considerations: Encoding considerations:
This media type is framed binary data (see RFC 4288, Section 4.8) and This media type is framed binary data (see RFC 4288, Section 4.8) and
is defined for transfer of EVRC-WB encoded data via RTP using the is defined for transfer of EVRC-WB encoded data via RTP using the
Interleaved/Bundled packet format specified in RFC 3558 [14]. Interleaved/Bundled packet format specified in RFC 3558 [10].
Security considerations: See Section 18 of RFC XXXX. Security considerations: See Section 17 of RFC XXXX.
Interoperability considerations: none Interoperability considerations: none
Published specification: Published specification:
The EVRC-WB vocoder is specified in 3GPP2 C.S0014-C [5]. Transfer The EVRC-WB vocoder is specified in 3GPP2 C.S0014-C [4]. Transfer
method with Interleaved/Bundled packet format via RTP is specified in method with Interleaved/Bundled packet format via RTP is specified in
RFC 3558 and RFC XXXX. RFC 3558 and RFC XXXX.
3GPP2 C.S0050-B, 3GPP2 File Formats for Multimedia Services. 3GPP2 C.S0050-B, 3GPP2 File Formats for Multimedia Services.
3GPP2 specifications are publicly accessible at http://www.3gpp2.org 3GPP2 specifications are publicly accessible at http://www.3gpp2.org
Applications that use this media type: Applications that use this media type:
It is expected that many VoIP applications (as well as mobile It is expected that many VoIP applications (as well as mobile
skipping to change at page 13, line 15 skipping to change at page 13, line 31
Section 8 MAY be used. Section 8 MAY be used.
Author: Author:
Harikishan Desineni Harikishan Desineni
Change controller: Change controller:
IETF Audio/Video Transport working group delegated from the IESG. IETF Audio/Video Transport working group delegated from the IESG.
9.2. Registration of Media Type EVRCWB0 9.1.2. Registration of Media Type EVRCWB0
Type name: audio Type name: audio
Subtype names: EVRCWB0 Subtype names: EVRCWB0
Required parameters: Required parameters:
Optional parameters: Optional parameters:
mode-set-recv: A subset of EVRC-WB modes. Possible values are a mode-set-recv: A subset of EVRC-WB modes. Possible values are a
comma separated list of modes from the set: 0,4,7 (see Table2.5.1.2-1 comma separated list of modes from the set: 0,4,7 (see Table
[5]). A decoder can use this to signal an encoder to limit its modes 2.5.1.2-1 [4]). A decoder can use this to signal an encoder to limit
to the specified subset. Absence of this parameter signals a set of its modes to the specified subset. Absence of this parameter signals
all EVRC-WB modes. The default value of 'mode-set-recv' is 0,4,7. the mode set {0,4,7}.
sendmode: A mode of EVRC-WB codec. Encoder can use this to signal sendmode: A mode of EVRC-WB codec. Encoder can use this to signal
its current mode of operation. Possible values are a comma separated its current mode of operation. Possible values are 0,4,7 (see Table
list of modes from the set: 0,4,7 (see Table2.5.1.2-1 [5]). The 2.5.1.2-1 [4]). Absence of this parameter signals mode 0.
default value of 'sendmode' is 0.
ptime: see RFC 4566 [9]. ptime: see RFC 4566 [7].
silencesupp: see Section 6.1 in [2] silencesupp: see Section 6.1 in [2]
dtxmax: see Section 6.1 in [2] dtxmax: see Section 6.1 in [2]
dtxmin: see Section 6.1 in [2] dtxmin: see Section 6.1 in [2]
hangover: see Section 6.1 in [2] hangover: see Section 6.1 in [2]
Encoding considerations: Encoding considerations:
This media type is framed binary data (see RFC 4288, Section 4.8) and This media type is framed binary data (see RFC 4288, Section 4.8) and
is defined for transfer of EVRC-WB encoded data via RTP using the is defined for transfer of EVRC-WB encoded data via RTP using the
Header-Free packet format specified in RFC 3558. Header-Free packet format specified in RFC 3558.
Security considerations: See Section 18 of RFC XXXX. Security considerations: See Section 17 of RFC XXXX.
Interoperability considerations: none Interoperability considerations: none
Published specification: Published specification:
The EVRC-WB vocoder is specified in 3GPP2 C.S0014-C [5]. Transfer The EVRC-WB vocoder is specified in 3GPP2 C.S0014-C [4]. Transfer
method with header free packet format via RTP is specified in RFC method with header free packet format via RTP is specified in RFC
3558 and RFC XXXX. 3558 and RFC XXXX.
3GPP2 C.S0050-B, 3GPP2 File Formats for Multimedia Services. 3GPP2 C.S0050-B, 3GPP2 File Formats for Multimedia Services.
3GPP2 specifications are publicly accessible at http://www.3gpp2.org 3GPP2 specifications are publicly accessible at http://www.3gpp2.org
Applications that use this media type: Applications that use this media type:
It is expected that many VoIP applications (as well as mobile It is expected that many VoIP applications (as well as mobile
skipping to change at page 15, line 13 skipping to change at page 15, line 26
Section 8 MAY be used. Section 8 MAY be used.
Author: Author:
Harikishan Desineni Harikishan Desineni
Change controller: Change controller:
IETF Audio/Video Transport working group delegated from the IESG. IETF Audio/Video Transport working group delegated from the IESG.
9.3. Registration of Media Type EVRCWB1 9.1.3. Registration of Media Type EVRCWB1
Type name: audio Type name: audio
Subtype names: EVRCWB1 Subtype names: EVRCWB1
Required parameters: Required parameters:
Optional parameters: Optional parameters:
mode-set-recv: A subset of EVRC-WB modes. Possible values are a mode-set-recv: A subset of EVRC-WB modes. Possible values are a
comma separated list of modes from the set: 0,4,7 (see Table2.5.1.2-1 comma separated list of modes from the set: 0,4,7 (see Table
[5]). A decoder can use this to signal an encoder to limit its modes 2.5.1.2-1 [4]). A decoder can use this to signal an encoder to limit
to the specified subset. Absence of this parameter signals a set of its modes to the specified subset. Value of 0 signals the support
all EVRC-WB modes. Value of 0 signals the support for wideband fixed for wideband fixed rate (full or half rate, depending on the value of
rate (full or half rate, depending on the value of 'fixedrate' 'fixedrate' parameter). Value of 4 signals narroband fixed full
parameter). Value of 4 signals narroband fixed full rate. Value of rate. Value of 7 signals narrowband fixed half rate. Absence of
7 signals narrowband fixed half rate. The default value of 'mode- this parameter signals mode 0.
set-recv' is 0.
sendmode: A mode of EVRC-WB codec. Encoder can use this to signal sendmode: A mode of EVRC-WB codec. Encoder can use this to signal
its current mode of operation. Possible values are a comma separated its current mode of operation. Possible values are a comma separated
list of modes from the set: 0,4,7 (see Table2.5.1.2-1 [5]). list of modes from the set: 0,4,7 (see Table 2.5.1.2-1 [4]).
'sendmode' with value 0 signals wideband fixed rate (full or half 'sendmode' with value 0 signals wideband fixed rate (full or half
rate, depending on the value of 'fixedrate' parameter) operation. rate, depending on the value of 'fixedrate' parameter) operation.
'sendmode' with value 4 signals narrowband fixed full rate operation. 'sendmode' with value 4 signals narrowband fixed full rate operation.
'sendmode' with value 7 signals narrowband fixed half rate operation. 'sendmode' with value 7 signals narrowband fixed half rate operation.
'fixedrate' parameter MUST not be present when 'sendmode' value is 4 'fixedrate' parameter MUST not be present when 'sendmode' value is 4
or 7. The default value of 'sendmode' is 0. or 7. Absence of this parameter signals mode 0.
ptime: see RFC 4566 [9]. ptime: see RFC 4566 [7].
maxptime: The maximum amount of media which can be encapsulated in maxptime: The maximum amount of media which can be encapsulated in
each packet, expressed as time in milliseconds. The time MUST be each packet, expressed as time in milliseconds. The time MUST be
calculated as the sum of the time the media present in the packet calculated as the sum of the time the media present in the packet
represents. The time SHOULD be an integer multiple of the duration represents. The time SHOULD be an integer multiple of the duration
of a single codec data frame (20 msec). If not signaled, the default of a single codec data frame (20 msec). If not signaled, the default
maxptime value MUST be 200 milliseconds. maxptime value MUST be 200 milliseconds.
fixedrate: Indicates the EVRC-WB rate of the session while in single fixedrate: Indicates the EVRC-WB rate of the session while in single
rate operation. Valid values include: 0.5 and 1, where a value of rate operation. Valid values include: 0.5 and 1, where a value of
skipping to change at page 16, line 22 skipping to change at page 16, line 34
dtxmin: see Section 6.1 in [2] dtxmin: see Section 6.1 in [2]
hangover: see Section 6.1 in [2] hangover: see Section 6.1 in [2]
Encoding considerations: Encoding considerations:
This media type is framed binary data (see RFC 4288, Section 4.8) and This media type is framed binary data (see RFC 4288, Section 4.8) and
is defined for transfer of EVRC-WB encoded data via RTP using the is defined for transfer of EVRC-WB encoded data via RTP using the
compact bundle packet format specified in RFC 4788. compact bundle packet format specified in RFC 4788.
Security considerations: See Section 18 of RFC XXXX. Security considerations: See Section 17 of RFC XXXX.
Interoperability considerations: none Interoperability considerations: none
Published specification: Published specification:
The EVRC-WB vocoder is specified in 3GPP2 C.S0014-C. Transfer method The EVRC-WB vocoder is specified in 3GPP2 C.S0014-C. Transfer method
with compact bundled packet format via RTP is specified in RFC 4788 with compact bundled packet format via RTP is specified in RFC 4788
and RFC XXXX. and RFC XXXX.
3GPP2 C.S0050-B, 3GPP2 File Formats for Multimedia Services. 3GPP2 C.S0050-B, 3GPP2 File Formats for Multimedia Services.
skipping to change at page 17, line 29 skipping to change at page 17, line 42
Section 8 MAY be used. Section 8 MAY be used.
Author: Author:
Harikishan Desineni Harikishan Desineni
Change controller: Change controller:
IETF Audio/Video Transport working group delegated from the IESG. IETF Audio/Video Transport working group delegated from the IESG.
9.4. Updated Registration of Media Type EVRCB 9.1.4. Updated Registration of Media Type EVRCB
Type name: audio Type name: audio
Subtype names: EVRCB Subtype names: EVRCB
Required parameters: none Required parameters: none
Optional parameters: Optional parameters:
recvmode: A mode of EVRC-B codec. A decoder can use this to signal recvmode: A mode of EVRC-B codec. A decoder can use this to signal
an encoder to operate in the specified mode. Possible values are a an encoder to operate in the specified mode. Possible values are a
comma separated list of modes from the set: 0..7 (see encoder comma separated list of modes from the set: 0..7 (see encoder
operating point column in Table 2-6 [4]). operating point column in Table 2-6 [3]).
sendmode: A mode of EVRC-B codec. An encoder can use this to signal sendmode: A mode of EVRC-B codec. An encoder can use this to signal
its current mode of operation. Possible values are a comma separated its current mode of operation. Possible values are a comma separated
list of modes from the set: 0..7 (see encoder operating point column list of modes from the set: 0..7 (see encoder operating point column
in Table 2-6 [4]). in Table 2-6 [3]).
ptime: see RFC 4566 ptime: see RFC 4566
maxptime: The maximum amount of media which can be encapsulated in maxptime: The maximum amount of media which can be encapsulated in
each packet, expressed as time in milliseconds. The time MUST be each packet, expressed as time in milliseconds. The time MUST be
calculated as the sum of the time the media present in the packet calculated as the sum of the time the media present in the packet
represents. The time SHOULD be a multiple of the duration of a represents. The time SHOULD be a multiple of the duration of a
single codec data frame (20 msec). If not signaled, the default single codec data frame (20 msec). If not signaled, the default
maxptime value MUST be 200 milliseconds. maxptime value MUST be 200 milliseconds.
skipping to change at page 19, line 23 skipping to change at page 19, line 35
is not defined at this time. is not defined at this time.
Author: Author:
Qiaobing Xie / Harikishan Desineni Qiaobing Xie / Harikishan Desineni
Change controller: Change controller:
IETF Audio/Video Transport working group delegated from the IESG. IETF Audio/Video Transport working group delegated from the IESG.
9.5. Updated Registration of Media Type EVRCB0 9.1.5. Updated Registration of Media Type EVRCB0
Type name: audio Type name: audio
Subtype names: EVRCB0 Subtype names: EVRCB0
Required parameters: none Required parameters: none
Optional parameters: Optional parameters:
recvmode: A mode of EVRC-B codec. A decoder can use this to signal recvmode: A mode of EVRC-B codec. A decoder can use this to signal
an encoder to operate in the specified mode. Possible values are a an encoder to operate in the specified mode. Possible values are a
comma separated list of modes from the set: 0..7 (see encoder comma separated list of modes from the set: 0..7 (see encoder
operating point column in Table 2-6 [4]). operating point column in Table 2-6 [3]).
sendmode: A mode of EVRC-B codec. An encoder can use this to signal sendmode: A mode of EVRC-B codec. An encoder can use this to signal
its current mode of operation. Possible values are a comma separated its current mode of operation. Possible values are a comma separated
list of modes from the set: 0..7 (see encoder operating point column list of modes from the set: 0..7 (see encoder operating point column
in Table 2-6 [4]). in Table 2-6 [3]).
silencesupp: see Section 6.1 for definition. If this parameter is silencesupp: see Section 6.1 for definition. If this parameter is
not present, the default value 1 MUST be assumed. not present, the default value 1 MUST be assumed.
dtxmax: see Section 6.1 of [2] dtxmax: see Section 6.1 of [2]
dtxmin: see Section 6.1 of [2] dtxmin: see Section 6.1 of [2]
hangover: see Section 6.1 of [2] hangover: see Section 6.1 of [2]
skipping to change at page 21, line 10 skipping to change at page 22, line 10
Change controller: Change controller:
IETF Audio/Video Transport working group delegated from the IESG. IETF Audio/Video Transport working group delegated from the IESG.
10. EVRC-B RFC XXXX Interoperability with legacy EVRC-B (RFC 4788) 10. EVRC-B RFC XXXX Interoperability with legacy EVRC-B (RFC 4788)
implementations implementations
This document adds new optional parameters "recvmode" and "sendmode" This document adds new optional parameters "recvmode" and "sendmode"
to the original EVRC-B payload subtypes "EVRCB" and "EVRCB0" defined to the original EVRC-B payload subtypes "EVRCB" and "EVRCB0" defined
in RFC 4788. Since the new parameters are receiver options, the in RFC 4788. The existing RFC 4788 implementations will not send
existing RFC 4788 implementations will not send these parameters in these parameters in SDP and will ignore if they are received. This
SDP and will ignore if they are received. This will allow will allow interoperability between RFC 4788 and RFC XXXX
interoperability between RFC 4788 and RFC XXXX implementations of implementations of EVRC-B. For an example offer and answer exchange,
EVRC-B. For an example offer and answer exchange, see Section 16. see Section 16.
11. Mapping EVRC-WB MIME Parameters into SDP 11. Mapping EVRC-WB media type parameters into SDP
Information carried in the MIME media type specification has a Information carried in the media type specification has a specific
specific mapping to fields in the Session Description Protocol (SDP) mapping to fields in the Session Description Protocol (SDP) [7],
[9], which is commonly used to describe RTP sessions. When SDP is which is commonly used to describe RTP sessions. When SDP is used to
used to specify sessions employing EVRC-WB encoded speech, the specify sessions employing EVRC-WB encoded speech, the mapping is as
mapping is as follows. follows.
The MIME type ("audio") goes in SDP "m=" as the media name. The media type ("audio") goes in SDP "m=" as the media name.
o The MIME subtype ("EVRCWB", "EVRCWB0" or "EVRCWB1") goes in SDP o The media subtype ("EVRCWB", "EVRCWB0" or "EVRCWB1") goes in SDP
"a=rtpmap" as the encoding name. "a=rtpmap" as the encoding name.
o The optional parameters "ptime" and "maxptime" (for subtypes o The optional parameters "ptime" and "maxptime" (for subtypes
EVRCWB, EVRCWB1) go in the SDP "a=ptime" and "a=maxptime" EVRCWB, EVRCWB1) go in the SDP "a=ptime" and "a=maxptime"
attributes, respectively. attributes, respectively.
o Any remaining parameters (for subtypes EVRCWB, EVRCWB0 and o Any remaining parameters (for subtypes EVRCWB, EVRCWB0 and
EVRCWB1) go in the SDP "a=fmtp" attribute by copying them from the EVRCWB1) go in the SDP "a=fmtp" attribute by copying them from the
MIME media type string as a semicolon separated list of media type string as a semicolon separated list of parameter=value
parameter=value pairs. pairs.
12. Mapping EVRC-B MIME Parameters into SDP 12. Mapping EVRC-B media type parameters into SDP
The optional parameters "recvmode" and "sendmode" (for subtypes EVRCB The optional parameters "recvmode" and "sendmode" (for subtypes EVRCB
and EVRCB0) go in the SDP "a=fmtp" attribute by copying them directly and EVRCB0) go in the SDP "a=fmtp" attribute by copying them directly
from the MIME media type string. from the media type string.
13. Offer-Answer Model Considerations for EVRC-WB 13. Offer-Answer Model Considerations for EVRC-WB
The following considerations apply when using SDP offer-answer The following considerations apply when using SDP offer-answer
procedures [7] to negotiate the use of EVRC-WB payload in RTP: procedures [6] to negotiate the use of EVRC-WB payload in RTP:
o Since EVRC-WB is an extension of EVRC-B, the offerer SHOULD o Since EVRC-WB is an extension of EVRC-B, the offerer SHOULD
announce EVRC-B support in its "m=audio" line, with EVRC-WB as the announce EVRC-B support in its "m=audio" line, with EVRC-WB as the
preferred codec. This will allow interoperability with an preferred codec. This will allow interoperability with an
answerer which supports only EVRC-B. answerer which supports only EVRC-B.
Below is an example of such an offer: Below is an example of such an offer:
m=audio 55954 RTP/AVP 98 99 m=audio 55954 RTP/AVP 98 99
a=rtpmap:98 EVRCWB0/16000 a=rtpmap:98 EVRCWB0/16000
skipping to change at page 24, line 40 skipping to change at page 25, line 40
m=audio 55954 RTP/AVP 98 m=audio 55954 RTP/AVP 98
a=rtpmap:98 EVRCWB0/16000 a=rtpmap:98 EVRCWB0/16000
a=fmtp:98 mode-set-recv=4;sendmode=4 a=fmtp:98 mode-set-recv=4;sendmode=4
o "mode-set-recv" is a uni-directional receive only parameter. o "mode-set-recv" is a uni-directional receive only parameter.
o "sendmode" is a uni-directional send only parameter. o "sendmode" is a uni-directional send only parameter.
o Using "sendmode", a sender can signal its current mode of o Using "sendmode", a sender can signal its current mode of
operation. operation. Note that a receiver may receive RTP media well before
the arrival of SDP with 'sendmode' parameter.
o An offerer can use "mode-set-recv" to request that the remote o An offerer can use "mode-set-recv" to request that the remote
sender's encoder be limited to the list of modes signaled in sender's encoder be limited to the list of modes signaled in
"mode-set-recv". A remote sender MAY ignore "mode-set-recv" "mode-set-recv". A remote sender MAY ignore "mode-set-recv"
requests. requests.
o The parameters "maxptime" and "ptime" will in most cases not o The parameters "maxptime" and "ptime" will in most cases not
affect interoperability, however the setting of the parameters can affect interoperability, however the setting of the parameters can
affect the performance of the application. The SDP offer-answer affect the performance of the application. The SDP offer-answer
handling of the "ptime" parameter is described in RFC3264 [7]. handling of the "ptime" parameter is described in RFC3264 [6].
The "maxptime" parameter MUST be handled in the same way. The "maxptime" parameter MUST be handled in the same way.
o For a sendonly stream, "mode-set-recv" parameter is not useful and o For a sendonly stream, "mode-set-recv" parameter is not useful and
SHOULD NOT be used. SHOULD NOT be used.
o For a recvonly stream, "sendmode" parameter is not useful and o For a recvonly stream, "sendmode" parameter is not useful and
SHOULD NOT be used. SHOULD NOT be used.
o When using EVRCWB1, the entire session MUST use the same fixed o When using EVRCWB1, the entire session MUST use the same fixed
rate and mode (0-Wideband or 4,7-Narrowband). rate and mode (0-Wideband or 4,7-Narrowband).
skipping to change at page 26, line 19 skipping to change at page 27, line 19
o "recvmode" is a uni-directional receive only parameter. o "recvmode" is a uni-directional receive only parameter.
o "sendmode" is a uni-directional send only parameter. o "sendmode" is a uni-directional send only parameter.
o Using "recvmode", a receiver can signal the remote sender to o Using "recvmode", a receiver can signal the remote sender to
operate its encoder in the specified mode. A remote sender MAY operate its encoder in the specified mode. A remote sender MAY
ignore "recvmode" requests. ignore "recvmode" requests.
o Using "sendmode", a sender can signal its current mode of o Using "sendmode", a sender can signal its current mode of
operation. operation. Note that a receiver may receive RTP media well before
the arrival of SDP with 'sendmode' parameter.
o For a sendonly stream, "recvmode" parameter is not useful and o For a sendonly stream, "recvmode" parameter is not useful and
SHOULD NOT be used. SHOULD NOT be used.
o For a recvonly stream, "sendmode" parameter is not useful and o For a recvonly stream, "sendmode" parameter is not useful and
SHOULD NOT be used. SHOULD NOT be used.
15. Declarative SDP Considerations 15. Declarative SDP Considerations
For declarative use of SDP in SAP [15] and RTSP [16] , the following For declarative use of SDP in SAP [11] and RTSP [12] , the following
considerations apply: considerations apply:
o Any "maxptime" and "ptime" values should be selected with care to o Any "maxptime" and "ptime" values should be selected with care to
ensure that the session's participants can achieve reasonable ensure that the session's participants can achieve reasonable
performance. performance.
o The payload format configuration parameters are all declarative o The payload format configuration parameters are all declarative
and a participant MUST use the configuration(s) that is provided and a participant MUST use the configuration(s) that is provided
for the session. More than one configuration may be provided if for the session. More than one configuration may be provided if
necessary by declaring multiple RTP payload types, however the necessary by declaring multiple RTP payload types, however the
number of types should be kept small. number of types should be kept small. For declarative examples,
see Section 16
16. Examples 16. Examples
Some example SDP session descriptions utilizing EVRC-WB and EVRC-B Some example SDP session descriptions utilizing EVRC-WB and EVRC-B
encodings follow. In these examples, long a=fmtp lines are folded to encodings follow. In these examples, long a=fmtp lines are folded to
meet the column width constraints of this document. The backslash meet the column width constraints of this document. The backslash
("\") at the end of a line and the carriage return that follows it ("\") at the end of a line and the carriage return that follows it
should be ignored. Note that MIME subtype names are case- should be ignored. Note that media subtype names are case-
insensitive. Parameter names are case-insensitive both in MIME types insensitive. Parameter names are case-insensitive both in media
and in the mapping to the SDP a=fmtp attribute. types and in the mapping to the SDP a=fmtp attribute.
Example usage of EVRCWB: Example usage of EVRCWB:
m=audio 49120 RTP/AVP 97 98 m=audio 49120 RTP/AVP 97 98
a=rtpmap:97 EVRCWB/16000 a=rtpmap:97 EVRCWB/16000
a=rtpmap:98 EVRCB0/8000 a=rtpmap:98 EVRCB0/8000
a=fmtp:97 mode-set-recv=0,4;sendmode=0 a=fmtp:97 mode-set-recv=0,4;sendmode=0
a=fmtp:98 recvmode=0 sendmode=0 a=fmtp:98 recvmode=0 sendmode=0
a=maxptime:120 a=maxptime:120
skipping to change at page 31, line 4 skipping to change at page 31, line 36
a=rtpmap:98 EVRCWB0/16000 a=rtpmap:98 EVRCWB0/16000
a=rtpmap:99 EVRCB0/8000 a=rtpmap:99 EVRCB0/8000
a=fmtp:98 mode-set-recv=0,4; sendmode=0 a=fmtp:98 mode-set-recv=0,4; sendmode=0
a=fmtp:99 recvmode=0 sendmode=0 a=fmtp:99 recvmode=0 sendmode=0
Answer: Answer:
m=audio 55954 RTP/AVP 99 m=audio 55954 RTP/AVP 99
a=rtpmap:99 EVRCB0/8000 a=rtpmap:99 EVRCB0/8000
a=fmtp:99 recvmode=0 sendmode=4 a=fmtp:99 recvmode=0 sendmode=4
In the above example, note that the answerer has chosen
to send in mode 4 even though the offerer was willing to
receive in mode 0. 'recvmode' is a receiver's preference
but the sender can send in a different mode.
Example offer answer exchanges for interoperability between Example offer answer exchanges for interoperability between
legacy (RFC XXXX) and updated EVRC-B(RFC 4788) implementations: legacy (RFC XXXX) and updated EVRC-B(RFC 4788) implementations:
Offer from an offer which supports updated EVRC-B (RFC XXXX) Offer from an offer which supports updated EVRC-B (RFC XXXX)
implementation: implementation:
m=audio 55954 RTP/AVP 99 m=audio 55954 RTP/AVP 99
a=rtpmap:99 EVRCB0/8000 a=rtpmap:99 EVRCB0/8000
a=fmtp:99 recvmode=0 sendmode=4 a=fmtp:99 recvmode=0 sendmode=4
skipping to change at page 32, line 5 skipping to change at page 33, line 5
m=audio 55954 RTP/AVP 99 m=audio 55954 RTP/AVP 99
a=rtpmap:99 EVRCB0/8000 a=rtpmap:99 EVRCB0/8000
Answer from an answerer which supports updated Answer from an answerer which supports updated
EVRC-B (RFC XXXX) implementation: EVRC-B (RFC XXXX) implementation:
m=audio 55954 RTP/AVP 99 m=audio 55954 RTP/AVP 99
a=rtpmap:99 EVRCB0/8000 a=rtpmap:99 EVRCB0/8000
a=fmtp:99 recvmode=0 sendmode=4 a=fmtp:99 recvmode=0 sendmode=4
17. IANA Considerations 17. Security Considerations
Three new MIME subtype registrations ("EVRCWB", "EVRCWB0" and
"EVRCWB1") are defined in this document.
The MIME subtype registrations "EVRCB" and "EVRCB0" originally
defined in [2] are updated with optional "recvmode" and "sendmode"
parameters (See Section 9.4 and Section 9.5).
[-- RFC Editor: Please replace all instances of "RFC XXXX" in this
document with the RFC number of this document prior to IANA
registration and RFC publication, and remove this note.]
[-- RFC Editor:Please add MIME subtypes "EVRCWB","EVRCWB0", and
"EVRCWB1" to the IANA registry for "RTP Payload Format MIME types" at
http://www.iana.org/assignments/rtp-parameters, and remove this
note.]
18. Security Considerations
Implementations using the payload defined in this specification are Implementations using the payload defined in this specification are
subject to the security considerations discussed in RFC3558 [14], subject to the security considerations discussed in RFC3558 [10],
RFC3550 [6], and any appropriate profile (for example RFC3551 [12]). RFC3550 [5], and any appropriate profile (for example RFC3551 [9]).
This payload does not specify any different security services. This payload does not specify any different security services.
19. Changes 18. Changes
This document updates RFC 4788 and the updates are summarized below: This document updates RFC 4788 and the updates are summarized below:
o Added new media type attribute "sendmode" to MIME sub-types EVRCB o Added new media type attribute "sendmode" to media sub-types EVRCB
and EVRCB0. This attribute can be used to signal EVRC-B encoder's and EVRCB0. This attribute can be used to signal EVRC-B encoder's
current mode of operation. current mode of operation.
o Added new media type attribute "recvmode" to MIME sub-types EVRCB o Added new media type attribute "recvmode" to media sub-types EVRCB
and EVRCB0. This attribute can be used to signal EVRC-B decoder's and EVRCB0. This attribute can be used to signal EVRC-B decoder's
preferred operating mode to a remote sender. preferred operating mode to a remote sender.
20. References 19. References
20.1. Normative References 19.1. Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997. Levels", BCP 14, RFC 2119, March 1997.
[2] Xie, Q., "Enhancements to RTP Payload Formats for EVRC Family [2] Xie, Q., "Enhancements to RTP Payload Formats for EVRC Family
Codecs", RFC 4788, January 2007. Codecs", RFC 4788, January 2007.
[3] "Enhanced Variable Rate Codec, Speech Service Option 3 for [3] "Enhanced Variable Rate Codec, Speech Service Option 3 and 68
Wideband Spread Spectrum Digital Systems", 3GPP2 C.S0014 ,
January 1997.
[4] "Enhanced Variable Rate Codec, Speech Service Option 3 and 68
for Wideband Spread Spectrum Digital Systems", 3GPP2 C.S0014-B for Wideband Spread Spectrum Digital Systems", 3GPP2 C.S0014-B
v1.0 , May 2006. v1.0 , May 2006.
[5] "Enhanced Variable Rate Codec, Speech Service Option 3,68 and [4] "Enhanced Variable Rate Codec, Speech Service Option 3,68 and
70 for Wideband Spread Spectrum Digital Systems", 3GPP2 70 for Wideband Spread Spectrum Digital Systems", 3GPP2
C.S0014-C v1.0 , October 2006. C.S0014-C v1.0 , October 2006.
[6] Schulzrinne, H., "RTP: A Transport Protocol for Real-Time [5] Schulzrinne, H., "RTP: A Transport Protocol for Real-Time
Applications", STD 64, RFC 3550, March 1997. Applications", STD 64, RFC 3550, March 1997.
[7] Rosenberg, J., "An Offer/Answer Model with Session Description [6] Rosenberg, J., "An Offer/Answer Model with Session Description
Protocol (SDP)", RFC 3264, June 2002. Protocol (SDP)", RFC 3264, June 2002.
[8] Narten, T., "Guidelines for Writing an IANA Considerations [7] Handley, M., "SDP: Session Description Protocol", RFC 4566,
Section in RFCs", RFC 2434, October 1998.
[9] Handley, M., "SDP: Session Description Protocol", RFC 4566,
July 2006. July 2006.
[10] Garudadri, H., "3GPP2 Multimedia Registrations", RFC 4393, [8] Freed, N., "Media Type Specifications and Registration
March 2006. Procedures", BCP 13, RFC 4288, December 2005.
[11] "3GPP2 File Formats for Multimedia Services", 3GPP2 C.S0050-B ,
April 2007.
20.2. Informative References 19.2. Informative References
[12] Schulzrinne, H., "RTP Profile for Audio and Video Conferences [9] Schulzrinne, H., "RTP Profile for Audio and Video Conferences
with Minimal Control", STD 65, RFC 3551, July 2003. with Minimal Control", STD 65, RFC 3551, July 2003.
[13] Johnston, A., "SDP Offer/Answer Examples", RFC 4317, [10] Li, A., "RTP Payload Format for Enhanced Variable Rate Codecs
December 2005.
[14] Li, A., "RTP Payload Format for Enhanced Variable Rate Codecs
(EVRC) and Selectable Mode Vocoders (SMV)", RFC 3558, (EVRC) and Selectable Mode Vocoders (SMV)", RFC 3558,
July 2003. July 2003.
[15] Handley, M., "Session Announcement Protocol", RFC 2974, [11] Handley, M., "Session Announcement Protocol", RFC 2974,
October 2000. October 2000.
[16] Schulzrinne, H., "Real Time Streaming Protocol (RTSP)", [12] Schulzrinne, H., "Real Time Streaming Protocol (RTSP)",
RFC 2326, April 1998. RFC 2326, April 1998.
[17] Westerlund, M., "How to Write an RTP Payload Format",
draft-ietf-avt-rtp-howto-01.txt(Work in Progress) , Dec 2006.
Authors' Addresses Authors' Addresses
Harikishan Desineni Harikishan Desineni
Qualcomm Qualcomm
5775 Morehouse Drive 5775 Morehouse Drive
San Diego, CA 92126 San Diego, CA 92126
USA USA
Phone: +1 858 845 8996 Phone: +1 858 845 8996
Email: hd@qualcomm.com Email: hd@qualcomm.com
 End of changes. 74 change blocks. 
157 lines changed or deleted 148 lines changed or added

This html diff was produced by rfcdiff 1.33. The latest version is available from http://tools.ietf.org/tools/rfcdiff/