draft-ietf-avt-rtp-evrc-wb-02.txt   draft-ietf-avt-rtp-evrc-wb-03.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: November 20, 2007 May 19, 2007 Expires: January 17, 2008 July 16, 2007
RTP payload format for EVRC-WB codec and media subtype updates for RTP payload format for EVRC-WB codec and media subtype updates for
EVRC-B codec EVRC-B codec
draft-ietf-avt-rtp-evrc-wb-02.txt draft-ietf-avt-rtp-evrc-wb-03.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 36 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 November 20, 2007. This Internet-Draft will expire on January 17, 2008.
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 media type registrations for EVRC-B codec. Several media type the media type registrations for EVRC-B codec. Several media type
skipping to change at page 2, line 31 skipping to change at page 2, line 31
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. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
9.1. Media Type Registration . . . . . . . . . . . . . . . . . 11 9.1. Media Type Registration . . . . . . . . . . . . . . . . . 11
9.1.1. Registration of Media Type EVRCWB . . . . . . . . . . 11 9.1.1. Registration of Media Type EVRCWB . . . . . . . . . . 11
9.1.2. Registration of Media Type EVRCWB0 . . . . . . . . . . 13 9.1.2. Registration of Media Type EVRCWB0 . . . . . . . . . . 13
9.1.3. Registration of Media Type EVRCWB1 . . . . . . . . . . 15 9.1.3. Registration of Media Type EVRCWB1 . . . . . . . . . . 15
9.1.4. Updated Registration of Media Type EVRCB . . . . . . . 17 9.1.4. Updated Registration of Media Type EVRCB . . . . . . . 17
9.1.5. Updated Registration of Media Type EVRCB0 . . . . . . 19 9.1.5. Updated Registration of Media Type EVRCB0 . . . . . . 19
10. EVRC-B RFC XXXX Interoperability with legacy EVRC-B (RFC 10. SDP mode attributs for EVRC-WB and EVRC-B . . . . . . . . . . 21
11. EVRC-B RFC XXXX Interoperability with legacy EVRC-B (RFC
4788) implementations . . . . . . . . . . . . . . . . . . . . 22 4788) implementations . . . . . . . . . . . . . . . . . . . . 22
11. Mapping EVRC-WB media type parameters into SDP . . . . . . . . 23 12. Mapping EVRC-WB media type parameters into SDP . . . . . . . . 23
12. Mapping EVRC-B media type parameters into SDP . . . . . . . . 24 13. Mapping EVRC-B media type parameters into SDP . . . . . . . . 24
13. Offer-Answer Model Considerations for EVRC-WB . . . . . . . . 25 14. Offer-Answer Model Considerations for EVRC-WB . . . . . . . . 25
14. Offer-Answer Model Considerations for EVRC-B . . . . . . . . . 27 15. Offer-Answer Model Considerations for EVRC-B . . . . . . . . . 27
15. Declarative SDP Considerations . . . . . . . . . . . . . . . . 28 16. Declarative SDP Considerations . . . . . . . . . . . . . . . . 28
16. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 17. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
17. Security Considerations . . . . . . . . . . . . . . . . . . . 33 18. Security Considerations . . . . . . . . . . . . . . . . . . . 33
18. Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 19. Changes to RFC4788 . . . . . . . . . . . . . . . . . . . . . . 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 . . . . . . . . . . . . . . . . . . . . . . . . 36
Intellectual Property and Copyright Statements . . . . . . . . . . 37 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 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
skipping to change at page 5, line 7 skipping to change at page 5, line 7
EVRC-B 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 [3] speech codec developed EVRC-WB is a wideband extension of EVRC-B [4] 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 [4]. EVRC-WB modes 4,7 are supported. EVRC-WB codec can operate in three modes (0,4 and 7)
interoperable with EVRC-B. EVRC-WB provides a standardized solution defined in [5]. EVRC-WB modes 4,7 are interoperable with EVRC-B.
for packetized voice applications that allow transitions between EVRC-WB mode 4 uses full rate, 1/2 rate and 1/8 rate frames. EVRC-WB
narrowband and wideband telephony. The most important service mode 7 uses only 1/2 rate and 1/8 rate frames. Mode change results
addressed is IP telephony. Target devices can be IP phones or VoIP in codec output bit-rate but does not cause any decoding problems at
handsets, media gateways, voice messaging servers, etc. the receiver. For successful decoding, the decoder does not need to
know the encoder's current mode of operation. EVRC-WB provides a
standardized solution for packetized voice applications that allow
transitions between narrowband and wideband telephony. The most
important service addressed is IP telephony. Target devices can be
IP phones or VoIP 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
addition, there are two zero bit codec frame types: null frames and addition, there are two zero bit codec frame types: blank (null)
erasure frames. The default sampling rate is 16 kHz. Input and frames and erasure frames. The default sampling rate is 16 kHz.
output at 8 kHz sampling rate is also supported. Input and output at 8 kHz sampling rate is also supported.
The frame type values and size of the associated codec data frame are The frame type values and size of the associated codec data frame are
listed in the table below: listed in the table below:
Value Rate Total codec data frame size (in octets) Value Rate Total codec data frame size (in octets)
-------------------------------------------------------------------- --------------------------------------------------------------------
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)
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 [5]. 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. 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
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 assignment of an RTP payload type for the payload formats The RTP header marker bit (M) SHALL be set to 1 if the first frame
described in Section 6 is outside the scope of the document, and will carried in the packet contains a speech frame which is the first in a
not be specified here. It is expected that the RTP profile under talkspurt. For all other packets the marker bit SHALL be set to zero
which this payload format is being used will assign a payload type (M=0).
for this codec or specify that the payload type is to be bound
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 [3], 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 [4]. parameter as defined in EVRC-WB [5].
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
[5], and with any applicable RTP profile; e.g., RFC 3551 [9]. [6], and with any applicable RTP profile; e.g., RFC 3551 [10].
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 8 skipping to change at page 11, line 8
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. IANA Considerations 9. IANA Considerations
This document updates EVRCB, EVRCB0 media subtypes defined in RFC This document updates EVRCB, EVRCB0 media subtypes defined in RFC
4788 [2] and adds new EVRC-WB media subtypes. 4788 [3] and adds new EVRC-WB media subtypes.
[-- RFC Editor: Please replace all instances of "RFC XXXX" in this [-- RFC Editor: Please replace all instances of "RFC XXXX" in this
document with the RFC number of this document prior to IANA document with the RFC number of this document prior to IANA
registration and RFC publication, and remove this note.] 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 9.1. Media Type Registration
Following the guidelines in RFC 4288 [8], this section registers new Following the guidelines in RFC 4288 [9], this section registers new
media subtypes for EVRC-WB and updates EVRCB, EVRCB0 media subtypes media subtypes for EVRC-WB and updates EVRCB, EVRCB0 media subtypes
defined in RFC 4788 [2]. defined in RFC 4788 [3].
9.1.1. Registration of Media Type EVRCWB 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 Table comma separated list of modes from the set: 0,4,7 (see Table
2.5.1.2-1 [4]). A decoder can use this to signal an encoder to limit 2.5.1.2-1 [5]). A decoder can use this attribute to inform its
its modes to the specified subset. Absence of this parameter signals preference to an encoder to operate in a specified subset of modes.
the mode set {0,4,7}. Absence of this parameter signals 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 0,4,7 (see Table its current mode of operation. Possible values are 0,4,7 (see Table
2.5.1.2-1 [4]). Absence of this parameter signals mode 0. 2.5.1.2-1 [5]). Absence of this parameter signals mode 0.
ptime: see RFC 4566 [7]. ptime: see RFC 4566 [8].
maxptime: The maximum amount of media which can be encapsulated in maxptime: see RFC 4566 [8].
each packet, expressed as time in milliseconds. The time MUST be
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
single codec data frame (20 msec). If not signaled, the default
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
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 in [2] silencesupp: see Section 6.1 in [3]
dtxmax: see Section 6.1 in [2]
dtxmin: see Section 6.1 in [2] dtxmax: see Section 6.1 in [3]
dtxmin: see Section 6.1 in [3]
hangover: see Section 6.1 in [2] hangover: see Section 6.1 in [3]
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 [10]. Interleaved/Bundled packet format specified in RFC 3558 [2].
Security considerations: See Section 17 of RFC XXXX. Security considerations: See Section 18 of RFC XXXX.
Interoperability considerations: none Interoperability considerations: none
Published specification: Published specification:
The EVRC-WB vocoder is specified in 3GPP2 C.S0014-C [4]. Transfer The EVRC-WB vocoder is specified in 3GPP2 C.S0014-C [5]. 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 4 skipping to change at page 12, line 42
Additional information: Additional information:
The following information applies for storage format only. The following information applies for storage format only.
Magic number: #!EVCWB\n (see Section 8 of RFC XXXX) Magic number: #!EVCWB\n (see Section 8 of RFC XXXX)
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 RFC4393. "audio/3gpp2" or "video/3gpp2" registered by RFC4393.
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 may be used with RTP framing (RFC 3550 [6]) and as a This media type depends on RTP framing, and hence is only defined for
storage format. When used with RTP, the procedures in Section 6 MUST transfer via RTP (RFC 3550). Transfer within other framing protocols
be followed. In all other contexts, the storage format defined in is not defined at this time.
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.
9.1.2. Registration of Media Type EVRCWB0 9.1.2. Registration of Media Type EVRCWB0
skipping to change at page 13, line 43 skipping to change at page 13, line 32
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 Table comma separated list of modes from the set: 0,4,7 (see Table
2.5.1.2-1 [4]). A decoder can use this to signal an encoder to limit 2.5.1.2-1 [5]). A decoder can use this attribute to inform its
its modes to the specified subset. Absence of this parameter signals preference to an encoder to operate in a specified subset of modes.
the mode set {0,4,7}. Absence of this parameter signals 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 0,4,7 (see Table its current mode of operation. Possible values are 0,4,7 (see Table
2.5.1.2-1 [4]). Absence of this parameter signals mode 0. 2.5.1.2-1 [5]). Absence of this parameter signals mode 0.
ptime: see RFC 4566 [7]. ptime: see RFC 4566 [8].
silencesupp: see Section 6.1 in [2] silencesupp: see Section 6.1 in [3]
dtxmax: see Section 6.1 in [2] dtxmax: see Section 6.1 in [3]
dtxmin: see Section 6.1 in [2] dtxmin: see Section 6.1 in [3]
hangover: see Section 6.1 in [2] hangover: see Section 6.1 in [3]
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 17 of RFC XXXX. Security considerations: See Section 18 of RFC XXXX.
Interoperability considerations: none Interoperability considerations: none
Published specification: Published specification:
The EVRC-WB vocoder is specified in 3GPP2 C.S0014-C [4]. Transfer The EVRC-WB vocoder is specified in 3GPP2 C.S0014-C [5]. 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 14, line 52
"audio/3gpp2" or "video/3gpp2" registered by RFC4393. "audio/3gpp2" or "video/3gpp2" registered by RFC4393.
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 may be used with RTP framing (RFC 3550) and as a This media type depends on RTP framing, and hence is only defined for
storage format. When used with RTP, the procedures in Section 6 MUST transfer via RTP (RFC 3550). Transfer within other framing protocols
be followed. In all other contexts, the storage format defined in is not defined at this time.
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.
9.1.3. Registration of Media Type EVRCWB1 9.1.3. Registration of Media Type EVRCWB1
skipping to change at page 15, line 38 skipping to change at page 15, line 27
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 Table comma separated list of modes from the set: 0,4,7 (see Table
2.5.1.2-1 [4]). A decoder can use this to signal an encoder to limit 2.5.1.2-1 [5]). A decoder can use this attribute to inform its
its modes to the specified subset. Value of 0 signals the support preference to an encoder to operate in a specified subset of modes.
for wideband fixed rate (full or half rate, depending on the value of Value of 0 signals the support for wideband fixed rate (full or half
'fixedrate' parameter). Value of 4 signals narroband fixed full rate, depending on the value of 'fixedrate' parameter). Value of 4
rate. Value of 7 signals narrowband fixed half rate. Absence of signals narroband fixed full rate. Value of 7 signals narrowband
this parameter signals mode 0. fixed half rate. Absence of this parameter signals mode 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 Table 2.5.1.2-1 [4]). list of modes from the set: 0,4,7 (see Table 2.5.1.2-1 [5]).
'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. Absence of this parameter signals mode 0. or 7. Absence of this parameter signals mode 0.
ptime: see RFC 4566 [7]. ptime: see RFC 4566 [8].
maxptime: The maximum amount of media which can be encapsulated in maxptime: see RFC 4566 [8].
each packet, expressed as time in milliseconds. The time MUST be
calculated as the sum of the time the media present in the packet
represents. The time SHOULD be an integer multiple of the duration
of a single codec data frame (20 msec). If not signaled, the default
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
0.5 indicates the 1/2 rate while a value of 1 indicates the full 0.5 indicates the 1/2 rate while a value of 1 indicates the full
rate. If this parameter is not present, 1/2 rate is assumed. rate. If this parameter is not present, 1/2 rate is assumed.
silencesupp: see Section 6.1 in [2] silencesupp: see Section 6.1 in [3]
dtxmax: see Section 6.1 in [2] dtxmax: see Section 6.1 in [3]
dtxmin: see Section 6.1 in [2] dtxmin: see Section 6.1 in [3]
hangover: see Section 6.1 in [2] hangover: see Section 6.1 in [3]
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 17 of RFC XXXX. Security considerations: See Section 18 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 13
"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:
This media type may be used with RTP framing (RFC 3550 [6]) and as a This media type depends on RTP framing, and hence is only defined for
storage format. When used with RTP, the procedures in Section 6 MUST transfer via RTP (RFC 3550). Transfer within other framing protocols
be followed. In all other contexts, the storage format defined in is not defined at this time.
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.
9.1.4. 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 attribute
an encoder to operate in the specified mode. Possible values are a to inform its preference to an encoder to operate in a specified
comma separated list of modes from the set: 0..7 (see encoder mode. Possible values are a comma separated list of modes from the
operating point column in Table 2-6 [3]). set: 0..7 (see encoder operating point column in Table 2-6 [4]).
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 [3]). in Table 2-6 [4]).
ptime: see RFC 4566 ptime: see RFC 4566
maxptime: The maximum amount of media which can be encapsulated in maxptime: see RFC 4566 [8].
each packet, expressed as time in milliseconds. The time MUST be
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
single codec data frame (20 msec). If not signaled, the default
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
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 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 [3]
dtxmin: see Section 6.1 of [2] dtxmin: see Section 6.1 of [3]
hangover: see Section 6.1 of [2] hangover: see Section 6.1 of [3]
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
skipping to change at page 19, line 45 skipping to change at page 19, line 21
9.1.5. 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 attribute
an encoder to operate in the specified mode. Possible values are a to inform its preference to an encoder to operate in a specified
comma separated list of modes from the set: 0..7 (see encoder mode. Possible values are a comma separated list of modes from the
operating point column in Table 2-6 [3]). set: 0..7 (see encoder operating point column in Table 2-6 [4]).
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 [3]). in Table 2-6 [4]).
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 [3]
dtxmin: see Section 6.1 of [2] dtxmin: see Section 6.1 of [3]
hangover: see Section 6.1 of [2] hangover: see Section 6.1 of [3]
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
skipping to change at page 22, line 5 skipping to change at page 21, line 5
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.
10. EVRC-B RFC XXXX Interoperability with legacy EVRC-B (RFC 4788) 10. SDP mode attributs for EVRC-WB and EVRC-B
'sendmode' can be used by a sender (EVRC-WB or EVRC-B) to announce
its encoder's current mode of operation. Sender can change its mode
anytime and it does not cause any decoding problems at the receiver.
'recvmode' is defined for use with EVRC-B. A decoder can use this
attribute to inform its preference to an encoder to operate in a
specified mode. Receiver will continue to decode properly even if
the sender does not operate in the preferred mode.
'mode-set-recv' is defined for use with EVRC-WB. A decoder can use
this attribute to inform its preference to an encoder to operate in a
specified subset of modes. Receiver will continue to decode properly
even if the sender does not operate in one of the preferred modes. A
set has been defiend so that several modes can be expressed as a
preference in one attempt. For ex., the set {4,7} signals that the
receiver prefers the sender to operate in narrowband modes of
EVRC-WB.
11. 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. The existing RFC 4788 implementations will not send in RFC 4788. The existing RFC 4788 implementations will not send
these parameters in SDP and will ignore if they are received. This these parameters in SDP and will ignore if they are received. This
will allow interoperability between RFC 4788 and RFC XXXX will allow interoperability between RFC 4788 and RFC XXXX
implementations of EVRC-B. For an example offer and answer exchange, implementations of EVRC-B. For an example offer and answer exchange,
see Section 16. see Section 17.
11. 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) [7], 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.
The media type ("audio") goes in SDP "m=" as the media name. 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.
12. Mapping EVRC-B media type parameters into SDP 13. 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 media type string. from the media type string.
13. Offer-Answer Model Considerations for EVRC-WB 14. 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 [6] to negotiate the use of EVRC-WB payload in RTP: procedures [7] 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 25, line 51 skipping to change at page 25, line 51
the arrival of SDP with 'sendmode' parameter. 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 [6]. handling of the "ptime" parameter is described in RFC3264 [7].
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).
o For additional rules which MUST be followed while negotiating DTX o For additional rules which MUST be followed while negotiating DTX
parameters, see Section 6.8 in [2]. 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.
14. Offer-Answer Model Considerations for EVRC-B 15. Offer-Answer Model Considerations for EVRC-B
See Section 6.8 of [2] 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 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. 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 'sendmode' parameter. 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 16. Declarative SDP Considerations
For declarative use of SDP in SAP [11] and RTSP [12] , 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. For declarative examples, number of types should be kept small. For declarative examples,
see Section 16 see Section 17
16. 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.
Example usage of EVRCWB: Example usage of EVRCWB:
skipping to change at page 33, 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. Security Considerations 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 [10], subject to the security considerations discussed in RFC3558 [2],
RFC3550 [5], and any appropriate profile (for example RFC3551 [9]). RFC3550 [6], and any appropriate profile (for example RFC3551 [10]).
This payload does not specify any different security services. This payload does not specify any different security services.
18. Changes 19. Changes to RFC4788
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 media 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 media 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.
19. References 20. References
19.1. 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] Xie, Q., "Enhancements to RTP Payload Formats for EVRC Family [2] Li, A., "RTP Payload Format for Enhanced Variable Rate Codecs
(EVRC) and Selectable Mode Vocoders (SMV)", RFC 3558,
July 2003.
[3] 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 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.
[4] "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.
[5] Schulzrinne, H., "RTP: A Transport Protocol for Real-Time [6] Schulzrinne, H., "RTP: A Transport Protocol for Real-Time
Applications", STD 64, RFC 3550, March 1997. Applications", STD 64, RFC 3550, March 1997.
[6] Rosenberg, J., "An Offer/Answer Model with Session Description [7] Rosenberg, J., "An Offer/Answer Model with Session Description
Protocol (SDP)", RFC 3264, June 2002. Protocol (SDP)", RFC 3264, June 2002.
[7] Handley, M., "SDP: Session Description Protocol", RFC 4566, [8] Handley, M., "SDP: Session Description Protocol", RFC 4566,
July 2006. July 2006.
[8] Freed, N., "Media Type Specifications and Registration [9] Freed, N., "Media Type Specifications and Registration
Procedures", BCP 13, RFC 4288, December 2005. Procedures", BCP 13, RFC 4288, December 2005.
19.2. Informative References 20.2. Informative References
[9] Schulzrinne, H., "RTP Profile for Audio and Video Conferences [10] 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.
[10] Li, A., "RTP Payload Format for Enhanced Variable Rate Codecs
(EVRC) and Selectable Mode Vocoders (SMV)", RFC 3558,
July 2003.
[11] Handley, M., "Session Announcement Protocol", RFC 2974, [11] Handley, M., "Session Announcement Protocol", RFC 2974,
October 2000. October 2000.
[12] Schulzrinne, H., "Real Time Streaming Protocol (RTSP)", [12] Schulzrinne, H., "Real Time Streaming Protocol (RTSP)",
RFC 2326, April 1998. RFC 2326, April 1998.
Authors' Addresses Authors' Addresses
Harikishan Desineni Harikishan Desineni
Qualcomm Qualcomm
 End of changes. 90 change blocks. 
160 lines changed or deleted 161 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/