draft-ietf-avt-rtp-evrc-wb-09.txt   rfc5188.txt 
Network Working Group H. Desineni Network Working Group H. Desineni
Internet-Draft Qualcomm Request for Comments: 5188 Qualcomm
Updates: 4788 (if approved) Q. Xie Updates: 4788 Q. Xie
Intended status: Standards Track Motorola Category: Standards Track Motorola
Expires: June 5, 2008 December 3, 2007 February 2008
RTP payload format for Enhanced Variable Rate Wideband Codec (EVRC-WB)
and media subtype updates for EVRC-B codec
draft-ietf-avt-rtp-evrc-wb-09.txt
Status of this Memo
By submitting this Internet-Draft, each author represents that any
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
aware will be disclosed, in accordance with Section 6 of BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet-
Drafts.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
This Internet-Draft will expire on June 5, 2008. RTP Payload Format for
the Enhanced Variable Rate Wideband Codec (EVRC-WB)
and the Media Subtype Updates for EVRC-B Codec
Copyright Notice Status of This Memo
Copyright (C) The IETF Trust (2007). This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
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 Enhanced Variable Rate Wideband Codec formats to be used for the Enhanced Variable Rate Wideband Codec
(EVRC-WB) and updates the media type registrations for EVRC-B codec. (EVRC-WB) and updates the media type registrations for EVRC-B codec.
Several media type registrations are included for EVRC-WB RTP payload Several media type registrations are included for EVRC-WB RTP payload
formats. In addition, a file format is specified for transport of formats. In addition, a file format is specified for transport of
EVRC-WB speech data in storage mode applications such as e-mail. EVRC-WB speech data in storage mode applications such as email.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Background . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3. Background . . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. EVRC-WB codec . . . . . . . . . . . . . . . . . . . . . . . . 6 4. EVRC-WB Codec . . . . . . . . . . . . . . . . . . . . . . . . 3
5. RTP header usage . . . . . . . . . . . . . . . . . . . . . . . 7 5. RTP Header Usage . . . . . . . . . . . . . . . . . . . . . . . 4
6. Payload format . . . . . . . . . . . . . . . . . . . . . . . . 8 6. Payload Format . . . . . . . . . . . . . . . . . . . . . . . . 4
7. Congestion Control Considerations . . . . . . . . . . . . . . 9 7. Congestion Control Considerations . . . . . . . . . . . . . . 5
8. Storage format for the EVRC-WB Codec . . . . . . . . . . . . . 10 8. Storage Format for the EVRC-WB Codec . . . . . . . . . . . . . 5
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
9.1. Media Type Registrations . . . . . . . . . . . . . . . . . 11 9.1. Media Type Registrations . . . . . . . . . . . . . . . . . 5
9.1.1. Registration of Media Type audio/EVRCWB . . . . . . . 11 9.1.1. Registration of Media Type audio/EVRCWB . . . . . . . 6
9.1.2. Registration of Media Type audio/EVRCWB0 . . . . . . . 13 9.1.2. Registration of Media Type audio/EVRCWB0 . . . . . . . 8
9.1.3. Registration of Media Type audio/EVRCWB1 . . . . . . . 15 9.1.3. Registration of Media Type audio/EVRCWB1 . . . . . . . 9
9.1.4. Updated Registration of Media Type audio/EVRCB . . . . 17 9.1.4. Updated Registration of Media Type audio/EVRCB . . . . 11
9.1.5. Updated Registration of Media Type audio/EVRCB0 . . . 19 9.1.5. Updated Registration of Media Type audio/EVRCB0 . . . 13
10. SDP mode attributes for EVRC-WB and EVRC-B . . . . . . . . . . 21 10. SDP Mode Attributes for EVRC-WB and EVRC-B . . . . . . . . . . 15
11. EVRC-B Interoperability with legacy implementations (RFC 11. EVRC-B Interoperability with Legacy Implementations (RFC 4788) 15
4788) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 12. Mapping EVRC-WB Media Type Parameters into SDP . . . . . . . . 16
12. Mapping EVRC-WB media type parameters into SDP . . . . . . . . 23 13. Mapping EVRC-B Media Type Parameters into SDP . . . . . . . . 16
13. Mapping EVRC-B media type parameters into SDP . . . . . . . . 24 14. Offer-Answer Model Considerations for EVRC-WB . . . . . . . . 16
14. Offer-Answer Model Considerations for EVRC-WB . . . . . . . . 25 15. Offer-Answer Model Considerations for EVRC-B . . . . . . . . . 18
15. Offer-Answer Model Considerations for EVRC-B . . . . . . . . . 27 16. Declarative SDP Considerations . . . . . . . . . . . . . . . . 18
16. Declarative SDP Considerations . . . . . . . . . . . . . . . . 28 17. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
17. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 18. Security Considerations . . . . . . . . . . . . . . . . . . . 22
18. Security Considerations . . . . . . . . . . . . . . . . . . . 33 19. Changes to RFC 4788 . . . . . . . . . . . . . . . . . . . . . 22
19. Changes to RFC 4788 . . . . . . . . . . . . . . . . . . . . . 34 20. References . . . . . . . . . . . . . . . . . . . . . . . . . . 22
20. References . . . . . . . . . . . . . . . . . . . . . . . . . . 35 20.1. Normative References . . . . . . . . . . . . . . . . . . . 22
20.1. Normative References . . . . . . . . . . . . . . . . . . . 35 20.2. Informative References . . . . . . . . . . . . . . . . . . 23
20.2. Informative References . . . . . . . . . . . . . . . . . . 35
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 36
Intellectual Property and Copyright Statements . . . . . . . . . . 37
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 (RTP). It defines support for the header-free, interleaved/bundled,
and compact bundle packet formats for the EVRC-WB codec as well as and 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. The EVRC-WB codec offers better speech quality transported via RTP. The EVRC-WB codec offers better speech quality
than the EVRC and EVRC-B codecs. EVRC-WB belongs to the EVRC family than the EVRC and EVRC-B codecs. EVRC-WB belongs to the EVRC family
of codecs. This document also updates the media type registrations of codecs. This document also updates the media type registrations
for the EVRC-B codec. for the 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 the EVRC-B [4] speech codec EVRC-WB is a wideband extension of the EVRC-B [4] speech codec
developed in 3GPP2 with support for discontinuous transmission (DTX). developed in the Third Generation Partnership Project 2 (3GPP2) with
It provides enhanced (wideband) voice quality. support for discontinuous transmission (DTX). It provides enhanced
(wideband) voice quality.
The EVRC-WB codec operates on 20 ms frames, and the default sampling The 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 rate is 16 kHz. Input and output at an 8-kHz sampling rate are also
supported. The EVRC-WB codec can operate in three modes (0, 4 and 7) supported. The EVRC-WB codec can operate in three modes (0, 4, and
defined in [5]. EVRC-WB modes 4 and 7 are interoperable with EVRC-B. 7) defined in [5]. EVRC-WB modes 4 and 7 are interoperable with
EVRC-WB mode 4 uses full rate, 1/2 rate and 1/8 rate frames. EVRC-WB EVRC-B. EVRC-WB mode 4 uses full-rate, 1/2-rate, and 1/8-rate
mode 7 uses only 1/2 rate and 1/8 rate frames. Mode change results frames. EVRC-WB mode 7 uses only 1/2 rate and 1/8 rate frames. Mode
in codec output bit-rate change but does not cause any decoding change results in codec output bit-rate change but do not cause any
problems at the receiver. For successful decoding, the decoder does decoding problems at the receiver. For successful decoding, the
not need to know the encoder's current mode of operation. EVRC-WB decoder does not need to know the encoder's current mode of
provides a standardized solution for packetized voice applications operation. EVRC-WB provides a standardized solution for packetized
that allow transitions between narrowband and wideband telephony. voice applications that allow transitions between narrowband and
The most important service addressed is IP telephony. Target devices wideband telephony. The most important service addressed is IP
can be IP phones or VoIP handsets, media gateways, voice messaging telephony. Target devices can be IP phones or Voice over IP (VoIP)
servers, etc. handsets, media gateways, voice messaging servers, etc.
4. EVRC-WB codec 4. EVRC-WB Codec
The EVRC-WB codec operates on 20 ms frames. It produces output The 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 frames of one of the three different sizes: 171 bits, 80 bits, or 16
bits. In addition, there are two zero bit codec frame types: blank bits. In addition, there are two zero-bit codec frame types: blank
(null) frames and erasure frames. The default sampling rate is 16 (null) frames and erasure frames. The default sampling rate is 16
kHz. Input and output at 8 kHz sampling rate is also supported. kHz. Input and output at an 8-kHz sampling rate are also supported.
The frame type values and sizes of the associated codec data frames The frame type values and sizes of the associated codec data frames
are listed in the table below: are listed in the table below:
Value Rate Total codec data frame size in bytes (and in bits) Value Rate Total codec data frame size in bytes (and in bits)
-------------------------------------------------------------------- --------------------------------------------------------------------
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) 2 1/4 5 (40 bits)
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 [6]. 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 [6]. in a manner consistent with RFC 3550 [6].
EVRC-WB has also the capability to operate with 8 kHz sampled input/ EVRC-WB also has 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 electro acoustic audio capabilities of the implementation and the electro acoustic audio 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
can be configured at 8 kHz; however, a 16 kHz RTP clock rate MUST can be configured at 8 kHz; however, a 16-kHz RTP clock rate MUST
always be used. The RTP timestamp is increased by 320 for each 20 always be used. The RTP timestamp is increased by 320 for each 20
milliseconds. milliseconds.
The RTP header marker bit (M) SHALL be set to 1 if the first frame The RTP header marker bit (M) SHALL be set to 1 if the first frame
carried in the packet contains a speech frame which is the first in a carried in the packet contains a speech frame that is the first in a
talkspurt. For all other packets the marker bit SHALL be set to zero talkspurt. For all other packets, the marker bit SHALL be set to
(M=0). zero (M=0).
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 Table of Contents
and bundling, of EVRC-WB are exactly the same as those of EVRC-B, as (ToC), interleaving, DTX, and bundling, of EVRC-WB are exactly the
defined in [3], except that the mode change request field in the ToC same as those of EVRC-B, as defined in [3], except that the mode
MUST be interpreted according to the definition of the RATE_REDUC change request field in the ToC MUST be interpreted according to the
parameter as defined in EVRC-WB [5]. The media type audio/EVRCWB definition of the RATE_REDUC parameter as defined in EVRC-WB [5].
maps to the interleaved/bundled packet format, audio/EVRCWB0 maps to The media type audio/EVRCWB maps to the interleaved/bundled packet
the header-free packet format and audio/EVRCWB1 maps to the compact format, audio/EVRCWB0 maps to the header-free packet format, and
bundled packet format. audio/EVRCWB1 maps to the compact bundled packet format.
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 [11]. [6], and with any applicable RTP profile, e.g., RFC 3551 [11].
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 the EVRC-WB Codec 8. Storage Format for the 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,
e.g., as a file or e-mail attachment. e.g., as a file or email attachment.
The file begins with a magic number to identify the vocoder that is The file begins with a magic number to identify the vocoder that is
used. The magic number for EVRC-WB corresponds to the ASCII used. The magic number for EVRC-WB corresponds to the ASCII
character string "#!EVCWB\n", i.e., "0x23 0x21 0x45 0x56 0x43 0x57 character string "#!EVCWB\n", i.e., "0x23 0x21 0x45 0x56 0x43 0x57
0x42 0x0A". 0x42 0x0A".
The codec data frames are stored in consecutive order, with a single The codec data frames are stored in consecutive order, with a single
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
skipping to change at page 11, line 10 skipping to change at page 5, line 42
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. IANA Considerations 9. IANA Considerations
This document updates the audio/EVRCB and audio/EVRCB0 media types This document updates the audio/EVRCB and audio/EVRCB0 media types
defined in RFC 4788 [3] and adds new EVRC-WB 'audio' media subtypes. defined in RFC 4788 [3] and adds new EVRC-WB 'audio' 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.]
9.1. Media Type Registrations 9.1. Media Type Registrations
Following the guidelines in RFC 4855 [9] and RFC 4288 [10], this Following the guidelines in RFC 4855 [9] and RFC 4288 [10], this
section registers new 'audio' media subtypes for EVRC-WB and updates section registers new 'audio' media subtypes for EVRC-WB and updates
the audio/EVRCB and audio/EVRCB0 media type registrations contained the audio/EVRCB and audio/EVRCB0 media type registrations contained
in RFC 4788 [3]. in RFC 4788 [3].
9.1.1. Registration of Media Type audio/EVRCWB 9.1.1. Registration of Media Type audio/EVRCWB
Type name: audio Type name: audio
Subtype names: EVRCWB Subtype name: EVRCWB
Required parameters: none Required parameters: None
Optional parameters: Optional parameters:
These parameters apply to RTP transfer only. These parameters apply to RTP transfer only.
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 Table comma-separated list of modes from the set {0,4,7} (see Table
2.5.1.2-1 in 3GPP2 C.S0014-C). A decoder can use this attribute to 2.5.1.2-1 in 3GPP2 C.S0014-C). A decoder can use this attribute to
inform an encoder of its preference to operate in a specified subset inform an encoder of its preference to operate in a specified subset
of modes. Absence of this parameter signals the mode set {0,4,7}. of modes. Absence of this parameter signals the mode set {0,4,7}.
sendmode: A mode of the EVRC-WB codec. An encoder can use this to sendmode: A mode of the EVRC-WB codec. An encoder can use this to
signal its current mode of operation. Possible values are 0,4,7 (see signal its current mode of operation. Possible values are 0,4,7 (see
Table 2.5.1.2-1 in 3GPP2 C.S0014-C). Absence of this parameter Table 2.5.1.2-1 in 3GPP2 C.S0014-C). Absence of this parameter
signals mode 0. signals mode 0.
ptime: see RFC 4566. ptime: See RFC 4566.
maxptime: see RFC 4566. maxptime: See RFC 4566.
maxinterleave: Maximum number for interleaving length (field LLL in maxinterleave: Maximum number for interleaving length (field LLL in
the Interleaving Octet)[0..7]. The interleaving lengths used in the the Interleaving Octet)[0..7]. The interleaving lengths used in the
entire session MUST NOT exceed this maximum value. If not signaled, entire session MUST NOT exceed this maximum value. If not signaled,
the maxinterleave length MUST be 5. the maxinterleave length MUST be 5.
silencesupp: see Section 6.1 in RFC 4788. silencesupp: See Section 6.1 in RFC 4788.
dtxmax: see Section 6.1 in RFC 4788. dtxmax: See Section 6.1 in RFC 4788.
dtxmin: see Section 6.1 in RFC 4788. dtxmin: See Section 6.1 in RFC 4788.
hangover: see Section 6.1 in RFC 4788. hangover: See Section 6.1 in RFC 4788.
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. interleaved/bundled packet format specified in RFC 3558.
Security considerations: See Section 18 of RFC XXXX. Security considerations: See Section 18 of RFC 5188.
Interoperability considerations: none Interoperability considerations: None
Published specification: Published specification:
The EVRC-WB vocoder is specified in 3GPP2 C.S0014-C. The transfer The EVRC-WB vocoder is specified in 3GPP2 C.S0014-C. The transfer
method with the Interleaved/Bundled packet format via RTP is method with the interleaved/bundled packet format via RTP is
specified in RFC 3558 and RFC XXXX. specified in RFC 3558 and RFC 5188.
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
applications) will use this type. applications) will use this type.
Additional information: Additional information:
The following applies to stored-file transfer methods: The following applies to stored-file transfer methods:
Magic number: #!EVCWB\n (see Section 8 of RFC XXXX) Magic number: #!EVCWB\n (see Section 8 of RFC 5188)
File extensions: evw, EVW File extensions: evw, EVW
Macintosh file type code: none Macintosh file type code: None
Object identifier or OID: none Object identifier or OID: None
EVRC-WB speech frames may also be stored in the file format "3g2" EVRC-WB speech frames may also be stored in the file format "3g2"
defined in 3GPP2 C.S0050-B, which is identified using the media types defined in 3GPP2 C.S0050-B, which is identified using the media types
"audio/3gpp2" or "video/3gpp2" registered by RFC 4393. "audio/3gpp2" or "video/3gpp2" registered by RFC 4393.
Person & email address to contact for further information: Person & email address to contact for further information:
Harikishan Desineni <hd@qualcomm.com> Harikishan Desineni <hd@qualcomm.com>
Intended usage: COMMON Intended usage: COMMON
Restrictions on usage: Restrictions on usage:
When this media type is used in the context of transfer over RTP, the When this media type is used in the context of transfer over RTP, the
RTP payload format specified in Section 4.1 of RFC 3558 SHALL be RTP payload format specified in Section 4.1 of RFC 3558 SHALL be
used. In all other contexts, the file format defined in Section 8 of used. In all other contexts, the file format defined in Section 8 of
RFC XXXX SHALL be used. RFC 5188 SHALL 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.
9.1.2. Registration of Media Type audio/EVRCWB0 9.1.2. Registration of Media Type audio/EVRCWB0
Type name: audio Type name: audio
Subtype names: EVRCWB0 Subtype name: EVRCWB0
Required parameters: Required parameters: None
Optional parameters: Optional parameters:
These parameters apply to RTP transfer only. These parameters apply to RTP transfer only.
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 Table comma-separated list of modes from the set {0,4,7} (see Table
2.5.1.2-1 in 3GPP2 C.S0014-C). A decoder can use this attribute to 2.5.1.2-1 in 3GPP2 C.S0014-C). A decoder can use this attribute to
inform an encoder of its preference to operate in a specified subset inform an encoder of its preference to operate in a specified subset
of modes. Absence of this parameter signals the mode set {0,4,7}. of modes. Absence of this parameter signals the mode set {0,4,7}.
sendmode: A mode of the EVRC-WB codec. An encoder can use this to sendmode: A mode of the EVRC-WB codec. An encoder can use this to
signal its current mode of operation. Possible values are 0,4,7 (see signal its current mode of operation. Possible values are 0,4,7 (see
Table 2.5.1.2-1 in 3GPP2 C.S0014-C). Absence of this parameter Table 2.5.1.2-1 in 3GPP2 C.S0014-C). Absence of this parameter
signals mode 0. signals mode 0.
ptime: see RFC 4566. ptime: See RFC 4566.
silencesupp: see Section 6.1 in RFC 4788. silencesupp: See Section 6.1 in RFC 4788.
dtxmax: see Section 6.1 in RFC 4788. dtxmax: See Section 6.1 in RFC 4788.
dtxmin: see Section 6.1 in RFC 4788. dtxmin: See Section 6.1 in RFC 4788.
hangover: see Section 6.1 in RFC 4788. hangover: See Section 6.1 in RFC 4788.
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 18 of RFC 5188.
Interoperability considerations: none Interoperability considerations: None
Published specification: Published specification:
The EVRC-WB vocoder is specified in 3GPP2 C.S0014-C. The transfer The EVRC-WB vocoder is specified in 3GPP2 C.S0014-C. The transfer
method with the Header-Free packet format via RTP is specified in RFC method with the header-free packet format via RTP is specified in RFC
3558 and RFC XXXX. 3558 and RFC 5188.
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
applications) will use this type. applications) will use this type.
Additional information: None Additional information: None
Person & email address to contact for further information: Person & email address to contact for further information:
Harikishan Desineni <hd@qualcomm.com> Harikishan Desineni <hd@qualcomm.com>
Intended usage: COMMON Intended usage: COMMON
Restrictions on usage: Restrictions on usage:
This media type depends on RTP framing, and hence is only defined for This media type depends on RTP framing and hence is only defined for
transfer via RTP [RFC3550], the RTP payload format specified in transfer via RTP [6]; the RTP payload format specified in Section 4.2
Section 4.2 of RFC 3558 SHALL be used. This media type SHALL NOT be of RFC 3558 SHALL be used. This media type SHALL NOT be used for
used for storage or file transfer using the file format defined in storage or file transfer using the file format defined in Section 8
Section 8 of RFC XXXX, instead audio/EVRCWB SHALL be used. of RFC 5188; instead, audio/EVRCWB SHALL 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.
9.1.3. Registration of Media Type audio/EVRCWB1 9.1.3. Registration of Media Type audio/EVRCWB1
Type name: audio Type name: audio
Subtype names: EVRCWB1 Subtype name: EVRCWB1
Required parameters:
Required parameters: None
Optional parameters: Optional parameters:
These parameters apply to RTP transfer only. These parameters apply to RTP transfer only.
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 Table comma-separated list of modes from the set {0,4,7} (see Table
2.5.1.2-1 in 3GPP2 C.S0014-C). A decoder can use this attribute to 2.5.1.2-1 in 3GPP2 C.S0014-C). A decoder can use this attribute to
inform an encoder of its preference to operate in a specified subset inform an encoder of its preference to operate in a specified subset
of modes. A value of 0 signals the support for wideband fixed rate of modes. A value of 0 signals the support for wideband fixed rate
(full or half rate, depending on the value of 'fixedrate' parameter). (full or half rate, depending on the value of the 'fixedrate'
A value of 4 signals narroband fixed full rate. A value of 7 signals parameter). A value of 4 signals narrowband fixed full rate. A
narrowband fixed half rate. Absence of this parameter signals mode value of 7 signals narrowband fixed half rate. Absence of this
0. parameter signals mode 0.
sendmode: A mode of the EVRC-WB codec. An encoder can use this to sendmode: A mode of the EVRC-WB codec. An encoder can use this to
signal its current mode of operation. Possible values are 0,4,7 (see signal its current mode of operation. Possible values are 0,4,7 (see
Table 2.5.1.2-1 in 3GPP2 C.S0014-C). 'sendmode' with value 0 signals Table 2.5.1.2-1 in 3GPP2 C.S0014-C). 'sendmode' with value 0 signals
wideband fixed rate operation (full or half rate, depending on the wideband fixed-rate operation (full or half rate, depending on the
value of the 'fixedrate' parameter). 'sendmode' with value 4 signals value of the 'fixedrate' parameter). 'sendmode' with value 4 signals
narrowband fixed full rate operation. 'sendmode' with value 7 signals narrowband fixed full-rate operation. 'sendmode' with value 7 signals
narrowband fixed half rate operation. The 'fixedrate' parameter MUST narrowband fixed half-rate operation. The 'fixedrate' parameter MUST
NOT be present when the 'sendmode' value is 4 or 7. Absence of this NOT be present when the 'sendmode' value is 4 or 7. Absence of this
parameter signals mode 0. parameter signals mode 0.
ptime: see RFC 4566. ptime: See RFC 4566.
maxptime: see RFC 4566. maxptime: See RFC 4566.
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 0.5
0.5 indicates the 1/2 rate while a value of 1 indicates the full indicates the 1/2 rate while a value of 1 indicates the full rate.
rate. If this parameter is not present, 1/2 rate is assumed. If this parameter is not present, 1/2 rate is assumed.
silencesupp: see Section 6.1 in RFC 4788. silencesupp: See Section 6.1 in RFC 4788.
dtxmax: see Section 6.1 in RFC 4788. dtxmax: See Section 6.1 in RFC 4788.
dtxmin: see Section 6.1 in RFC 4788. dtxmin: See Section 6.1 in RFC 4788.
hangover: see Section 6.1 in RFC 4788. hangover: See Section 6.1 in RFC 4788.
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 18 of RFC 5188.
Interoperability considerations: none Interoperability considerations: None
Published specification: Published specification:
The EVRC-WB vocoder is specified in 3GPP2 C.S0014-C. The transfer The EVRC-WB vocoder is specified in 3GPP2 C.S0014-C. The transfer
method with the compact bundled packet format via RTP is specified in method with the compact bundled packet format via RTP is specified in
RFC 4788 and RFC XXXX. RFC 4788 and RFC 5188.
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
applications) will use this type. applications) will use this type.
Additional information: None Additional information: None
Person & email address to contact for further information: Person & email address to contact for further information:
Harikishan Desineni <hd@qualcomm.com> Harikishan Desineni <hd@qualcomm.com>
Intended usage: COMMON Intended usage: COMMON
Restrictions on usage: Restrictions on usage:
This media type depends on RTP framing, and hence is only defined for This media type depends on RTP framing and hence is only defined for
transfer via RTP [RFC3550], the RTP payload format specified in transfer via RTP [6]; the RTP payload format specified in Section 4
Section 4 of RFC 4788 SHALL be used. This media type SHALL NOT be of RFC 4788 SHALL be used. This media type SHALL NOT be used for
used for storage or file transfer using the file format defined in storage or file transfer using the file format defined in Section 8
Section 8 of RFC XXXX, instead audio/EVRCWB SHALL be used. of RFC 5188; instead, audio/EVRCWB SHALL 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.
9.1.4. Updated Registration of Media Type audio/EVRCB 9.1.4. Updated Registration of Media Type audio/EVRCB
Type name: audio Type name: audio
Subtype names: EVRCB Subtype name: EVRCB
Required parameters: none
Required parameters: None
Optional parameters: Optional parameters:
These parameters apply to RTP transfer only. These parameters apply to RTP transfer only.
recvmode: A mode of the EVRC-B codec. A decoder can use this recvmode: A mode of the EVRC-B codec. A decoder can use this
attribute to inform an encoder of its preference to operate in a attribute to inform an encoder of its preference to operate in a
specified mode. Possible values are 0..7 (see the encoder operating specified mode. Possible values are 0..7 (see the encoder operating
point column in Table 2-6 of 3GPP2 C.S0014-B). point column in Table 2-6 of 3GPP2 C.S0014-B).
sendmode: A mode of the EVRC-B codec. An encoder can use this to sendmode: A mode of the EVRC-B codec. An encoder can use this to
signal its current mode of operation. Possible values are 0..7 (see signal its current mode of operation. Possible values are 0..7 (see
encoder operating point column in Table 2-6 of 3GPP2 C.S0014-B). encoder operating point column in Table 2-6 of 3GPP2 C.S0014-B).
ptime: see RFC 4566. ptime: See RFC 4566.
maxptime: see RFC 4566. maxptime: See RFC 4566.
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
session MUST NOT exceed this maximum value. If not signaled, the session MUST NOT exceed this maximum value. If not signaled, the
maxinterleave length MUST be 5. maxinterleave length MUST be 5.
silencesupp: see Section 6.1 of RFC 4788 for a definition. If this silencesupp: See Section 6.1 of RFC 4788 for a definition. If this
parameter is not present, the default value 1 MUST be assumed. parameter is not present, the default value 1 MUST be assumed.
dtxmax: see Section 6.1 of RFC 4788. dtxmax: See Section 6.1 of RFC 4788.
dtxmin: see Section 6.1 of RFC 4788. dtxmin: See Section 6.1 of RFC 4788.
hangover: see Section 6.1 of RFC 4788. hangover: See Section 6.1 of RFC 4788.
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-B encoded data via RTP using the is defined for transfer of EVRC-B encoded data via RTP using the
Interleaved/Bundled packet format specified in RFC 3558. interleaved/bundled packet format specified in RFC 3558.
Security considerations: See Section 9 of RFC 4788. Security considerations: See Section 9 of RFC 4788.
Interoperability considerations: none Interoperability considerations: None
Published specification: Published specification:
The EVRC-B vocoder is specified in 3GPP2 C.S0014-B. The transfer The EVRC-B vocoder is specified in 3GPP2 C.S0014-B. The transfer
method with the Interleaved/Bundled packet format via RTP is method with the interleaved/bundled packet format via RTP is
specified in RFC 3558, RFC 4788 and RFC XXXX. specified in RFC 3558, RFC 4788, and RFC 5188.
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
applications) will use this type. applications) will use this type.
Additional information: The following information applies for the Additional information: The following information applies for the
storage format only. storage format only.
Magic number: #!EVRC-B\n (see Section 5 of RFC 4788) Magic number: #!EVRC-B\n (see Section 5 of RFC 4788)
File extensions: evb, EVB File extensions: evb, EVB
Macintosh file type code: none Macintosh file type code: None
Object identifier or OID: none Object identifier or OID: None
Person & email address to contact for further information: Person & email address to contact for further information:
Harikishan Desineni <hd@qualcomm.com> Harikishan Desineni <hd@qualcomm.com>
Intended usage: COMMON Intended usage: COMMON
Restrictions on usage: Restrictions on usage:
When this media type is used in the context of transfer over RTP, the When this media type is used in the context of transfer over RTP, the
skipping to change at page 19, line 11 skipping to change at page 13, line 46
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.
9.1.5. Updated Registration of Media Type audio/EVRCB0 9.1.5. Updated Registration of Media Type audio/EVRCB0
Type name: audio Type name: audio
Subtype names: EVRCB0 Subtype name: EVRCB0
Required parameters: none Required parameters: None
Optional parameters: Optional parameters:
These parameters apply to RTP transfer only. These parameters apply to RTP transfer only.
recvmode: A mode of the EVRC-B codec. A decoder can use this recvmode: A mode of the EVRC-B codec. A decoder can use this
attribute to inform an encoder of its preference to operate in a attribute to inform an encoder of its preference to operate in a
specified mode. Possible values are 0..7 (see the encoder operating specified mode. Possible values are 0..7 (see the encoder operating
point column in Table 2-6 of 3GPP2 C.S0014-B). point column in Table 2-6 of 3GPP2 C.S0014-B).
sendmode: A mode of the EVRC-B codec. An encoder can use this to sendmode: A mode of the EVRC-B codec. An encoder can use this to
signal its current mode of operation. Possible values are 0..7 (see signal its current mode of operation. Possible values are 0..7 (see
the encoder operating point column in Table 2-6 of 3GPP2 C.S0014-B). the encoder operating point column in Table 2-6 of 3GPP2 C.S0014-B).
silencesupp: see Section 6.1 of RFC 4788 for a definition. If this silencesupp: See Section 6.1 of RFC 4788 for a definition. If this
parameter is not present, the default value 1 MUST be assumed. parameter is not present, the default value 1 MUST be assumed.
dtxmax: see Section 6.1 of RFC 4788. dtxmax: see Section 6.1 of RFC 4788.
dtxmin: see Section 6.1 of RFC 4788. dtxmin: see Section 6.1 of RFC 4788.
hangover: see Section 6.1 of RFC 4788. hangover: see Section 6.1 of RFC 4788.
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-B encoded data via RTP using the is defined for transfer of EVRC-B 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 9 of RFC 4788. Security considerations: See Section 9 of RFC 4788.
Interoperability considerations: none Interoperability considerations: None
Published specification: Published specification:
The EVRC-B vocoder is specified in 3GPP2 C.S0014-B. The transfer The EVRC-B vocoder is specified in 3GPP2 C.S0014-B. The transfer
method with the Header-Free packet format via RTP is specified in RFC method with the header-free packet format via RTP is specified in RFC
3558, RFC 4788 and RFC XXXX. 3558, RFC 4788, and RFC 5188.
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
applications) will use this type. applications) will use this type.
Additional information: None Additional information: None
Person & email address to contact for further information: Person & email address to contact for further information:
skipping to change at page 20, line 17 skipping to change at page 15, line 4
It is expected that many VoIP applications (as well as mobile It is expected that many VoIP applications (as well as mobile
applications) will use this type. applications) will use this type.
Additional information: None Additional information: None
Person & email address to contact for further information: Person & email address to contact for further information:
Harikishan Desineni <hd@qualcomm.com> Harikishan Desineni <hd@qualcomm.com>
Intended usage: COMMON Intended usage: COMMON
Restrictions on usage: Restrictions on usage:
When this media type is used in the context of transfer over RTP, the When this media type is used in the context of transfer over RTP, the
RTP payload format specified in Section 4.2 of RFC 3558 SHALL be RTP payload format specified in Section 4.2 of RFC 3558 SHALL be
used. used.
This media type depends on RTP framing, and hence is only defined for This media type depends on RTP framing and hence is only defined for
transfer via RTP [RFC3550], the RTP payload format specified in transfer via RTP [6]; the RTP payload format specified in Section 4.2
Section 4.2 of RFC 3558 SHALL be used. This media type SHALL NOT be of RFC 3558 SHALL be used. This media type SHALL NOT be used for
used for storage or file transfer using the file format defined in storage or file transfer using the file format defined in Section 5
Section 5 of RFC 4788, instead audio/EVRCB SHALL be used. of RFC 4788; instead, audio/EVRCB SHALL be used.
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.
10. SDP mode attributes for EVRC-WB and EVRC-B 10. SDP Mode Attributes for EVRC-WB and EVRC-B
'sendmode' can be used by a sender (EVRC-WB or EVRC-B) to announce 'sendmode' can be used by a sender (EVRC-WB or EVRC-B) to announce
its encoder's current mode of operation. A sender can change its its encoder's current mode of operation. A sender can change its
mode anytime and this does not cause any decoding problems at the mode anytime, and this does not cause any decoding problems at the
receiver. receiver.
'recvmode' is defined for use with EVRC-B. A decoder can use this 'recvmode' is defined for use with EVRC-B. A decoder can use this
attribute to inform an encoder of its preference to operate in a attribute to inform an encoder of its preference to operate in a
specified mode. The receiver will continue to decode properly even specified mode. The receiver will continue to decode properly even
if the sender does not operate in the preferred mode. if the sender does not operate in the preferred mode.
'mode-set-recv' is defined for use with EVRC-WB. A decoder can use 'mode-set-recv' is defined for use with EVRC-WB. A decoder can use
this attribute to inform an encoder of its preference to operate in a this attribute to inform an encoder of its preference to operate in a
specified subset of modes. The receiver will continue to decode specified subset of modes. The receiver will continue to decode
properly even if the sender does not operate in one of the preferred properly even if the sender does not operate in one of the preferred
modes. A set has been defined so that several modes can be expressed modes. A set has been defined so that several modes can be expressed
as a preference in one attempt. For instance, the set {4,7} signals as a preference in one attempt. For instance, the set {4,7} signals
that the receiver prefers the sender to operate in narrowband modes that the receiver prefers the sender to operate in narrowband modes
of EVRC-WB. of EVRC-WB.
11. EVRC-B Interoperability with legacy implementations (RFC 4788) 11. EVRC-B Interoperability with Legacy Implementations (RFC 4788)
This document adds new optional parameters "recvmode" and "sendmode" This document adds new optional parameters "recvmode" and "sendmode"
to the original EVRC-B Media types "audio/EVRCB" and "audio/EVRCB0" to the original EVRC-B media types "audio/EVRCB" and "audio/EVRCB0"
defined in RFC 4788 [3]. Existing RFC 4788 [3] implementations will defined in RFC 4788 [3]. Existing RFC 4788 [3] implementations will
not send these parameters in SDP and will ignore them if they are not send these parameters in the Session Description Protocol (SDP)
received. This will allow interoperability between RFC 4788 [3] and and will ignore them if they are received. This will allow
RFC XXXX implementations of EVRC-B. For an example offer and answer interoperability between RFC 4788 [3] and RFC 5188 implementations of
exchange, see Section 17. EVRC-B. For an example offer-and-answer exchange, see Section 17.
12. Mapping EVRC-WB media type parameters into SDP 12. Mapping EVRC-WB Media Type Parameters into SDP
Information carried in the media type specification has a specific Information carried in the media type specification has a specific
mapping to fields in the Session Description Protocol (SDP) [8], mapping to fields in the Session Description Protocol (SDP) [8],
which is commonly used to describe RTP sessions. When SDP is used to which is commonly used to describe RTP sessions. When SDP is used to
specify sessions employing EVRC-WB encoded speech, the mapping is as specify sessions employing EVRC-WB encoded speech, the mapping is as
follows. 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 ("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
media type string as a semicolon separated list of parameter=value media type string as a semicolon-separated list of parameter=value
pairs. pairs.
13. Mapping EVRC-B media type parameters into SDP 13. Mapping EVRC-B Media Type Parameters into SDP
The new optional parameters 'recvmode' and 'sendmode' (for 'audio' The new optional parameters 'recvmode' and 'sendmode' (for 'audio'
subtypes EVRCB and EVRCB0) go in the SDP "a=fmtp" attribute by subtypes EVRCB and EVRCB0) go in the SDP "a=fmtp" attribute by
copying them directly from the media type string. copying them directly from the media type string.
For all other Media Type parameteres, the specification in Section For all other media type parameters, the specification in Section 6.7
6.7 of RFC 4788 [3] still applies. of RFC 4788 [3] still applies.
14. Offer-Answer Model Considerations for EVRC-WB 14. Offer-Answer Model Considerations for EVRC-WB
The following considerations apply when using the SDP offer-answer The following considerations apply when using the SDP offer-answer
procedures of RFC 3264 [7] to negotiate the use of EVRC-WB payload in procedures of RFC 3264 [7] to negotiate the use of EVRC-WB payload in
RTP: 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 that 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
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=4 a=fmtp:99 recvmode=0 sendmode=4
If the answerer supports EVRC-WB then the answerer can keep the If the answerer supports EVRC-WB, then the answerer can keep the
payload type 98 in its answer and the conversation can be done payload type 98 in its answer and the conversation can be done using
using EVRC-WB. Else, if the answerer supports only EVRC-B then EVRC-WB. Else, if the answerer supports only EVRC-B, then the
the answerer will leave only the payload type 99 in its answer and answerer will leave only the payload type 99 in its answer and the
the conversation will be done using EVRC-B. conversation will be done using EVRC-B.
An example answer for the above offer: An example answer for the above offer is the following:
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 unidirectional receive-only parameter.
o 'sendmode' is a uni-directional send only parameter. o 'sendmode' is a unidirectional 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. Note that a receiver may receive RTP media well before operation. Note that a receiver may receive RTP media well before
the arrival of SDP with a (first time, or updated) 'sendmode' the arrival of SDP with a (first-time, or updated) 'sendmode'
parameter. 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
affect the performance of the application. The SDP offer-answer can affect the performance of the application. The SDP offer-
handling of the 'ptime' parameter is described in RFC 3264 [7]. answer handling of the 'ptime' parameter is described in RFC 3264
The 'maxptime' parameter MUST be handled in the same way. [7]. The 'maxptime' parameter MUST be handled in the same way.
o For a sendonly stream, the 'mode-set-recv' parameter is not useful o For a sendonly stream, the 'mode-set-recv' parameter is not useful
and SHOULD NOT be used. and SHOULD NOT be used.
o For a recvonly stream, the 'sendmode' parameter is not useful and o For a recvonly stream, the '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).
o For additional rules which MUST be followed while negotiating DTX o For additional rules that MUST be followed while negotiating DTX
parameters, see Section 6.8 in [3]. parameters, see Section 6.8 in [3].
o Any unknown parameter in an SDP offer MUST be ignored by the o Any unknown parameter in an SDP offer MUST be ignored by the
receiver and MUST NOT be included in the SDP answer. receiver and MUST NOT be included in the SDP answer.
15. Offer-Answer Model Considerations for EVRC-B 15. Offer-Answer Model Considerations for EVRC-B
See Section 6.8 of [3] for offer-answer usage of EVRC-B. The See Section 6.8 of [3] for offer-answer usage of EVRC-B. The
following are several additional considerations for EVRC-B. following are several additional considerations for EVRC-B.
o 'recvmode' is a uni-directional receive only parameter. o 'recvmode' is a unidirectional receive-only parameter.
o 'sendmode' is a uni-directional send only parameter. o 'sendmode' is a unidirectional 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. Note that a receiver may receive RTP media well before operation. Note that a receiver may receive RTP media well before
the arrival of SDP with a (first time, or updated)'sendmode' the arrival of SDP with a (first-time, or updated) 'sendmode'
parameter. parameter.
o For a sendonly stream, the 'recvmode' parameter is not useful and o For a sendonly stream, the 'recvmode' parameter is not useful and
SHOULD NOT be used. SHOULD NOT be used.
o For a recvonly stream, the 'sendmode' parameter is not useful and o For a recvonly stream, the 'sendmode' parameter is not useful and
SHOULD NOT be used. SHOULD NOT be used.
16. Declarative SDP Considerations 16. Declarative SDP Considerations
For declarative use of SDP in SAP [12] and RTSP [13] , the following For declarative use of SDP in the Session Announcement Protocol (SAP)
[12] and the Real Time Streaming Protocol (RTSP) [13], 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. For declarative examples, number of types should be kept small. For declarative examples,
see Section 17 see Section 17.
17. Examples 17. 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 media subtype names are case- should be ignored. Note that media subtype names are case-
insensitive. Parameter names are case-insensitive both in media insensitive. Parameter names are case-insensitive both in media
types and in the mapping to the SDP a=fmtp attribute. types and in the mapping to the SDP a=fmtp attribute.
skipping to change at page 29, line 33 skipping to change at page 19, line 33
Example usage of EVRCWB0: Example usage of EVRCWB0:
m=audio 49120 RTP/AVP 97 98 m=audio 49120 RTP/AVP 97 98
a=rtpmap:97 EVRCWB0/16000 a=rtpmap:97 EVRCWB0/16000
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
Example SDP answer from a media gateway requesting a terminal to Example SDP answer from a media gateway requesting a terminal to
limit its encoder operation to EVRC-WB mode 4. limit its encoder operation to EVRC-WB mode 4:
m=audio 49120 RTP/AVP 97 m=audio 49120 RTP/AVP 97
a=rtpmap:97 EVRCWB0/16000 a=rtpmap:97 EVRCWB0/16000
a=fmtp:97 mode-set-recv=4;sendmode=4 a=fmtp:97 mode-set-recv=4;sendmode=4
Example usage of EVRCWB1: Example usage of EVRCWB1:
m=audio 49120 RTP/AVP 97 98 m=audio 49120 RTP/AVP 97 98
a=rtpmap:97 EVRCWB1/16000 a=rtpmap:97 EVRCWB1/16000
a=fmtp:97 mode-set-recv=4;sendmode=4 a=fmtp:97 mode-set-recv=4;sendmode=4
skipping to change at page 30, line 14 skipping to change at page 20, line 14
Example usage of EVRCWB with DTX with silencesupp=1: Example usage of EVRCWB with DTX with silencesupp=1:
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 silencesupp=1;dtxmax=32;dtxmin=12;hangover=1 \ a=fmtp:97 silencesupp=1;dtxmax=32;dtxmin=12;hangover=1 \
mode-set-recv=0,4; sendmode=0 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
Examples usage of EVRCWB with DTX with silencesupp=0: Example usage of EVRCWB with DTX with silencesupp=0:
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 silencesupp=0;dtxmax=32;dtxmin=12;hangover=1 \ a=fmtp:97 silencesupp=0;dtxmax=32;dtxmin=12;hangover=1 \
mode-set-recv=0,4;sendmode=0 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
Example usage of EVRCB: Example usage of EVRCB:
skipping to change at page 31, line 4 skipping to change at page 20, line 36
m=audio 49120 RTP/AVP 97 m=audio 49120 RTP/AVP 97
a=rtpmap:97 EVRCB/8000 a=rtpmap:97 EVRCB/8000
a=fmtp:97 recvmode=0 sendmode=4 a=fmtp:97 recvmode=0 sendmode=4
a=maxptime:120 a=maxptime:120
Example usage of EVRCB0: Example usage of EVRCB0:
m=audio 49120 RTP/AVP 97 m=audio 49120 RTP/AVP 97
a=rtpmap:97 EVRCB0/8000 a=rtpmap:97 EVRCB0/8000
a=fmtp:97 recvmode=0 sendmode=4 a=fmtp:97 recvmode=0 sendmode=4
Example offer answer exchange between EVRC-WB and
Example offer-answer exchange between EVRC-WB and
legacy EVRC-B (RFC 4788): legacy EVRC-B (RFC 4788):
Offer: 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
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
Example offer-answer exchange between EVRC-WB and
Example offer answer exchange between EVRC-WB and updated EVRC-B (RFC 5188):
updated EVRC-B (RFC XXXX):
Offer: 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
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 In the above example, note that the answerer has chosen
to send in mode 4 even though the offerer was willing to to send in mode 4 even though the offerer was willing to
receive in mode 0. 'recvmode' is a receiver's preference receive in mode 0. 'recvmode' is a receiver's preference,
but the sender can send in a different mode. 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 4788) and updated EVRC-B(RFC XXXX) implementations: legacy (RFC 4788) and updated EVRC-B (RFC 5188) implementations:
Offer from an offer which supports updated EVRC-B (RFC XXXX) Offer from an offerer that supports updated EVRC-B (RFC 5188)
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
Answer from an answerer which supports only Answer from an answerer that supports only
legacy EVRC-B (RFC 4788) implementation: legacy EVRC-B (RFC 4788) implementation:
m=audio 55954 RTP/AVP 99 m=audio 55954 RTP/AVP 99
a=rtpmap:99 EVRCB0/8000 a=rtpmap:99 EVRCB0/8000
Offer from an offer which supports only Offer from an offerer that supports only
legacy EVRC-B (RFC 4788) implementation: legacy EVRC-B (RFC 4788) implementation:
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 that supports updated
Answer from an answerer which supports updated EVRC-B (RFC 5188) 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
18. Security Considerations 18. Security Considerations
Since compression is applied to the payload formats end-to-end, and Since compression is applied to the payload formats end-to-end, and
the encodings do not exhibit significant non-uniformity, the encodings do not exhibit significant non-uniformity,
implementations of this specification are subject to all the security implementations of this specification are subject to all the security
considerations specified in RFC 3558 [2]. Implementations using the considerations specified in RFC 3558 [2]. Implementations using the
payload defined in this specification are subject to the security payload defined in this specification are subject to the security
considerations discussed in RFC 3558 [2], RFC 3550 [6] and any considerations discussed in RFC 3558 [2], RFC 3550 [6], and any
appropriate profile (for example RFC 3551 [11]). appropriate profile (for example, RFC 3551 [11]).
19. Changes to RFC 4788 19. Changes to RFC 4788
This document updates RFC 4788 [3] and the updates are summarized This document updates RFC 4788 [3], and the updates are summarized
below: below:
o Added new media type attribute "sendmode" to media sub-types EVRCB o Added new media type attribute "sendmode" to media subtypes EVRCB
and EVRCB0. This attribute can be used to signal the EVRC-B and EVRCB0. This attribute can be used to signal the EVRC-B
encoder's current mode of operation. encoder's current mode of operation.
o Added new media type attribute "recvmode" to media sub-types EVRCB o Added new media type attribute "recvmode" to media subtypes EVRCB
and EVRCB0. This attribute can be used to signal the EVRC-B and EVRCB0. This attribute can be used to signal the EVRC-B
decoder's preferred operating mode to a remote sender. decoder's preferred operating mode to a remote sender.
20. References 20. References
20.1. Normative References 20.1. 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] Li, A., "RTP Payload Format for Enhanced Variable Rate Codecs [2] 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.
[3] Xie, Q., "Enhancements to RTP Payload Formats for EVRC Family [3] Xie, Q. and R. Kapoor, "Enhancements to RTP Payload Formats for
Codecs", RFC 4788, January 2007. EVRC Family Codecs", RFC 4788, January 2007.
[4] "Enhanced Variable Rate Codec, Speech Service Option 3 and 68 [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 [5] "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 [6] Schulzrinne, H., Casner, S., Frederick, R., and V. Jacobson,
Applications", STD 64, RFC 3550, March 1997. "RTP: A Transport Protocol for Real-Time Applications", STD 64,
RFC 3550, March 1997.
[7] Rosenberg, J., "An Offer/Answer Model with Session Description [7] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model with
Protocol (SDP)", RFC 3264, June 2002. Session Description Protocol (SDP)", RFC 3264, June 2002.
[8] Handley, M., "SDP: Session Description Protocol", RFC 4566, [8] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
July 2006. Description Protocol", RFC 4566, July 2006.
[9] Casner, S., "Media Type Specifications and Registration [9] Casner, S., "Media Type Specifications and Registration
Procedures", RFC 4855, February 2007. Procedures", RFC 4855, February 2007.
[10] Freed, N., "Media Type Specifications and Registration [10] Freed, N. and J. Klensin, "Media Type Specifications and
Procedures", BCP 13, RFC 4288, December 2005. Registration Procedures", BCP 13, RFC 4288, December 2005.
20.2. Informative References 20.2. Informative References
[11] Schulzrinne, H., "RTP Profile for Audio and Video Conferences [11] Schulzrinne, H. and S. Casner, "RTP Profile for Audio and Video
with Minimal Control", STD 65, RFC 3551, July 2003. Conferences with Minimal Control", STD 65, RFC 3551, July 2003.
[12] Handley, M., "Session Announcement Protocol", RFC 2974, [12] Handley, M., Perkins, C., and E. Whelan, "Session Announcement
October 2000. Protocol", RFC 2974, October 2000.
[13] Schulzrinne, H., "Real Time Streaming Protocol (RTSP)", [13] Schulzrinne, H., Rao, A., and R. Lanphier, "Real Time Streaming
RFC 2326, April 1998. Protocol (RTSP)", RFC 2326, April 1998.
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
URI: http://www.qualcomm.com URI: http://www.qualcomm.com
Qiaobing Xie Qiaobing Xie
Motorola Motorola
1501 W. Shure Drive, 2-F9 1501 W. Shure Drive, 2-F9
Arlington Heights, IL 60004 Arlington Heights, IL 60004
USA USA
Phone: +1-847-632-3028 Phone: +1-847-372-8481
Email: Qiaobing.Xie@Motorola.com EMail: Qiaobing.Xie@Gmail.com
URI: http://www.motorola.com URI: http://www.motorola.com
Full Copyright Statement Full Copyright Statement
Copyright (C) The IETF Trust (2007). Copyright (C) The IETF Trust (2008).
This document is subject to the rights, licenses and restrictions This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors contained in BCP 78, and except as set forth therein, the authors
retain all their rights. retain all their rights.
This document and the information contained herein are provided on an This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS
OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
skipping to change at page 37, line 44 skipping to change at line 1090
attempt made to obtain a general license or permission for the use of attempt made to obtain a general license or permission for the use of
such proprietary rights by implementers or users of this such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr. http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at this standard. Please address the information to the IETF at
ietf-ipr@ietf.org. ietf-ipr@ietf.org.
Acknowledgment
Funding for the RFC Editor function is provided by the IETF
Administrative Support Activity (IASA).
 End of changes. 146 change blocks. 
283 lines changed or deleted 254 lines changed or added

This html diff was produced by rfcdiff 1.34. The latest version is available from http://tools.ietf.org/tools/rfcdiff/