draft-ietf-avt-rtp-evrc-nw-03.txt   draft-ietf-avt-rtp-evrc-nw-04.txt 
Network Working Group Z. Fang Network Working Group Z. Fang
Internet-Draft Qualcomm Internet-Draft Qualcomm
Intended status: Standards Track April 23, 2011 Intended status: Standards Track October 6, 2011
Expires: October 25, 2011 Expires: April 8, 2012
RTP payload format for Enhanced Variable Rate Narrowband-Wideband Codec RTP payload format for Enhanced Variable Rate Narrowband-Wideband Codec
(EVRC-NW) (EVRC-NW)
draft-ietf-avt-rtp-evrc-nw-03 draft-ietf-avt-rtp-evrc-nw-04
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 Narrowband-Wideband formats to be used for the Enhanced Variable Rate Narrowband-Wideband
Codec (EVRC-NW). Three media type registrations are included for Codec (EVRC-NW). Three media type registrations are included for
EVRC-NW RTP payload formats. In addition, a file format is specified EVRC-NW RTP payload formats. In addition, a file format is specified
for transport of EVRC-NW speech data in storage mode applications for transport of EVRC-NW speech data in storage mode applications
such as e-mail. such as e-mail.
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on October 25, 2011. This Internet-Draft will expire on April 8, 2012.
Copyright Notice Copyright Notice
Copyright (c) 2011 IETF Trust and the persons identified as the Copyright (c) 2011 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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carried in the packet contains a speech frame which is the first in a carried in the packet contains a speech frame which 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 zero
(M=0). (M=0).
6. Payload format 6. Payload format
Three RTP packet formats are supported for the EVRC-NW codec - the Three RTP packet formats are supported for the EVRC-NW 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-NW are exactly the same as those of EVRC-B and and bundling, of EVRC-NW are exactly the same as those defined in
EVRC-WB, as defined in [2] and [3], except that EVRC [6], EVRC-B [2] and EVRC-WB [3], except that
1. the mode change request field in the interleaved/bundled packet 1. the mode change request field in the interleaved/bundled packet
format MUST be interpreted according to the definition of the format MUST be interpreted according to the definition of the
RATE_REDUC parameter as defined in EVRC-NW [4]. RATE_REDUC parameter as defined in EVRC-NW [4].
2. the mode change request field in the interleaved/bundled packet 2. the mode change request field in the interleaved/bundled packet
format SHOULD be honored by an EVRCNW encoding end point in an format SHOULD be honored by an EVRCNW encoding end point in an
one-to-one session with a dedicated EVRCNW decoding end point one-to-one session with a dedicated EVRCNW decoding end point
such as in a two-party call or in a conference leg. such as in a two-party call or in a conference leg.
The media type audio/EVRCNW maps to the interleaved/bundled packet The media type audio/EVRCNW maps to the interleaved/bundled packet
format, audio/EVRCNW0 maps to the header-free packet format and format, audio/EVRCNW0 maps to the header-free packet format and
audio/EVRCNW1 maps to the compact bundled packet format. audio/EVRCNW1 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
[5], and with any applicable RTP profile; e.g., RFC 3551 [6]. [5], and with any applicable RTP profile; e.g., RFC 3551 [7].
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-NW Codec 8. Storage format for the EVRC-NW Codec
The storage format is used for storing EVRC-NW encoded speech frames, The storage format is used for storing EVRC-NW encoded speech frames,
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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 introduces a new EVRC-NW 'audio' media subtype. This document introduces a new EVRC-NW 'audio' media subtype.
9.1. Media Type Registrations 9.1. Media Type Registrations
Following the guidelines in RFC 4855 [7] and RFC 4288 [8], this Following the guidelines in RFC 4855 [8] and RFC 4288 [9], this
section registers new 'audio' media subtypes for EVRC-NW. section registers new 'audio' media subtypes for EVRC-NW.
9.1.1. Registration of Media Type audio/EVRCNW 9.1.1. Registration of Media Type audio/EVRCNW
Type name: audio Type name: audio
Subtype names: EVRCNW Subtype names: EVRCNW
Required parameters: None Required parameters: None
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These parameters apply to RTP transfer only. These parameters apply to RTP transfer only.
mode-set-recv: A subset of EVRC-NW modes. Possible values are a mode-set-recv: A subset of EVRC-NW modes. Possible values are a
comma separated list of modes from the set {0,1,2,3,4,5,6,7} (see comma separated list of modes from the set {0,1,2,3,4,5,6,7} (see
Table 2.6.1.2-4 in 3GPP2 C.S0014-D). A decoder can use this Table 2.6.1.2-4 in 3GPP2 C.S0014-D). 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 subset of modes. Absence of this parameter signals the specified subset of modes. Absence of this parameter signals the
mode set {1,2,3,4,5,6,7}. mode set {1,2,3,4,5,6,7}.
sendmode: The "sendmode" parameter is deprecated for EVRCNW. An ptime: see RFC 4566 [10].
EVRCNW receiver MUST ignore this parameter if present.
ptime: see RFC 4566 [9].
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-NW encoded data via RTP using the is defined for transfer of EVRC-NW encoded data via RTP using the
Interleaved/Bundled packet format specified in RFC 3558. Interleaved/Bundled packet format specified in RFC 3558 [6].
Security considerations: See Section 15. Security considerations: See Section 15.
Interoperability considerations: None Interoperability considerations: None
Published specification: Published specification:
The EVRC-NW vocoder is specified in 3GPP2 C.S0014-D. The transfer The EVRC-NW vocoder is specified in 3GPP2 C.S0014-D. 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. specified in RFC 3558 [6].
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: #!EVRCNW\n (see Section 8) Magic number: #!EVRCNW\n (see Section 8)
File extensions: enw, ENW File extensions: enw, ENW
Macintosh file type code: None Macintosh file type code: None
Object identifier or OID: None Object identifier or OID: None
EVRC-NW speech frames may also be stored in the file format "3g2" EVRC-NW 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 [10]. "audio/3gpp2" or "video/3gpp2" registered by RFC 4393 [11].
Person & email address to contact for further information: Person & email address to contact for further information:
Zheng Fang <zfang@qualcomm.com> Zheng Fang <zfang@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 [6] SHALL be
used. In all other contexts, the file format defined in Section 8 used. In all other contexts, the file format defined in Section 8
SHALL be used. SHALL be used.
Author: Author:
Zheng Fang Zheng Fang <zfang@qualcomm.com>
Change controller: Change controller:
IETF Audio/Video Transport working group delegated from the IESG. IETF Payload working group delegated from the IESG.
9.1.2. Registration of Media Type audio/EVRCNW0 9.1.2. Registration of Media Type audio/EVRCNW0
Type name: audio Type name: audio
Subtype names: EVRCNW0 Subtype names: EVRCNW0
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-NW modes. Possible values are a mode-set-recv: A subset of EVRC-NW modes. Possible values are a
comma separated list of modes from the set {0,1,2,3,4,5,6,7} (see comma separated list of modes from the set {0,1,2,3,4,5,6,7} (see
Table 2.6.1.2-4 in 3GPP2 C.S0014-D). A decoder can use this Table 2.6.1.2-4 in 3GPP2 C.S0014-D). 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 subset of modes. Absence of this parameter signals the specified subset of modes. Absence of this parameter signals the
mode set {1,2,3,4,5,6,7}. mode set {1,2,3,4,5,6,7}.
sendmode: The "sendmode" parameter is deprecated for EVRCNW. An
EVRCNW receiver MUST ignore this parameter if present.
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-NW encoded data via RTP using the is defined for transfer of EVRC-NW encoded data via RTP using the
Header-Free packet format specified in RFC 3558. Header-Free packet format specified in RFC 3558 [6].
Security considerations: See Section 15. Security considerations: See Section 15.
Interoperability considertaions: None Interoperability considertaions: None
Published specification: Published specification:
The EVRC-NW vocoder is specified in 3GPP2 C.S0014-D. The transfer The EVRC-NW vocoder is specified in 3GPP2 C.S0014-D. 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. 3558 [6].
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:
Zheng Fang <zfang@qualcomm.com> Zheng Fang <zfang@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 [5], the RTP payload format specified in Section 4.2 transfer via RTP [5], the RTP payload format specified in Section 4.2
of RFC 3558 SHALL be used. This media type SHALL NOT be used for of RFC 3558 [6] SHALL be used. This media type SHALL NOT be used for
storage or file transfer, instead audio/EVRCNW SHALL be used. storage or file transfer, instead audio/EVRCNW SHALL be used.
Author: Author:
Zheng Fang Zheng Fang <zfang@qualcomm.com>
Change controller: Change controller:
IETF Audio/Video Transport working group delegated from the IESG. IETF Payload working group delegated from the IESG.
9.1.3. Registration of Media Type audio/EVRCNW1 9.1.3. Registration of Media Type audio/EVRCNW1
Type name: audio Type name: audio
Subtype names: EVRCNW1 Subtype names: EVRCNW1
Required parameters: None Required parameters: None
Optional parameters: Optional parameters:
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mode-set-recv: A subset of EVRC-NW modes. Possible values are a mode-set-recv: A subset of EVRC-NW modes. Possible values are a
comma separated list of modes from the set {0,1} (see Table 2.6.1.2-4 comma separated list of modes from the set {0,1} (see Table 2.6.1.2-4
in 3GPP2 C.S0014-D). A decoder can use this attribute to inform an in 3GPP2 C.S0014-D). A decoder can use this attribute to inform an
encoder of its preference to operate in a specified subset of modes. encoder of its preference to operate in a specified subset of modes.
A value of 0 signals the support for wideband fixed rate (full or A value of 0 signals the support for wideband fixed rate (full or
half rate, depending on the value of 'fixedrate' parameter). A value half rate, depending on the value of 'fixedrate' parameter). A value
of 1 signals narroband fixed rate (full or half rate, depending on of 1 signals narroband fixed rate (full or half rate, depending on
the value of 'fixedrate' parameter). Absence of this parameter the value of 'fixedrate' parameter). Absence of this parameter
signals the mode 1. signals the mode 1.
sendmode: The "sendmode" parameter is deprecated for EVRCNW. An
EVRCNW receiver MUST ignore this parameter if present.
ptime: see RFC 4566. ptime: see RFC 4566.
maxptime: see RFC 4566. maxptime: see RFC 4566.
fixedrate: Indicates the EVRC-NW rate of the session while in single fixedrate: Indicates the EVRC-NW 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 RFC 4788. silencesupp: see Section 6.1 in RFC 4788.
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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 [5], the RTP payload format specified in Section 4 transfer via RTP [5], the RTP payload format specified in Section 4
of RFC 4788 SHALL be used. This media type SHALL NOT be used for of RFC 4788 SHALL be used. This media type SHALL NOT be used for
storage or file transfer, instead audio/EVRCNW SHALL be used. storage or file transfer, instead audio/EVRCNW SHALL be used.
Author: Author:
Zheng Fang Zheng Fang <zfang@qualcomm.com>
Change controller: Change controller:
IETF Audio/Video Transport working group delegated from the IESG. IETF Payload working group delegated from the IESG.
10. SDP mode attributes for EVRC-NW 10. SDP mode attributes for EVRC-NW
'mode-set-recv' can be used by a decoder to inform an encoder of its 'mode-set-recv' can be used by a decoder to inform an encoder of its
preference to operate in a specified subset of modes. Note that preference to operate in a specified subset of modes. Note that
indicating a preference, implicitly indicates support for that indicating a preference, implicitly indicates support for that
capability. Conversely, if mode 0 is not preferred, then there is no capability. Conversely, if mode 0 is not preferred, then there is no
indication that mode 0 is supported. indication that mode 0 is supported.
1. To inform the capability of wideband mode support: A decoder can 1. To inform the capability of wideband mode support: A decoder can
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partner complements the mode set information in mode-set-recv. A partner complements the mode set information in mode-set-recv. A
mode request with MMM=0 from a communication partner is an implicit mode request with MMM=0 from a communication partner is an implicit
indication of the partner's EVRCNW wideband decoding capability and indication of the partner's EVRCNW wideband decoding capability and
preference. An EVRCNW wideband capable node receiving the request preference. An EVRCNW wideband capable node receiving the request
can operate in wideband mode. A mode request with MMM=1, 2, ..., or can operate in wideband mode. A mode request with MMM=1, 2, ..., or
7 from a communication partner is an implicit indication of the 7 from a communication partner is an implicit indication of the
partner's EVRCNW narrowband decoding preference. The encoder of an partner's EVRCNW narrowband decoding preference. The encoder of an
EVRCNW node receiving the request should honor the request and EVRCNW node receiving the request should honor the request and
operate in narrowband mode. operate in narrowband mode.
'sendmode' is used as a SDP mode attribute in EVRC [6], EVRC-B [2]
and EVRC-WB [3]. However it is deprecated in EVRC-NW.
11. Mapping EVRC-NW media type parameters into SDP 11. Mapping EVRC-NW 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) [9], mapping to fields in the Session Description Protocol (SDP) [10],
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-NW encoded speech, the mapping is as specify sessions employing EVRC-NW 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 ("EVRCNW", "EVRCNW0" or "EVRCNW1") goes in SDP o The media subtype ("EVRCNW", "EVRCNW0" or "EVRCNW1") 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
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attributes, respectively. attributes, respectively.
o Any remaining parameters (for subtypes EVRCNW, EVRCNW0 and o Any remaining parameters (for subtypes EVRCNW, EVRCNW0 and
EVRCNW1) go in the SDP "a=fmtp" attribute by copying them from the EVRCNW1) 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. Offer-Answer Model Considerations for EVRC-NW 12. Offer-Answer Model Considerations for EVRC-NW
The following considerations apply when using the SDP offer-answer The following considerations apply when using the SDP offer-answer
procedures of RFC 3264 [11] to negotiate the use of EVRC-NW payload procedures of RFC 3264 [12] to negotiate the use of EVRC-NW payload
in RTP: in RTP:
o Since EVRC-NW is an extension of both EVRC-B and EVRC-WB, the o Since EVRC-NW is an extension of both EVRC-B and EVRC-WB, the
offerer SHOULD also announce EVRC-B and EVRC-WB support in its offerer SHOULD also announce EVRC-B and EVRC-WB support in its
"m=audio" lines, with EVRC-NW as the preferred codec. This will "m=audio" lines, with EVRC-NW as the preferred codec. This will
allow interoperability with an answerer which supports only EVRC-B allow interoperability with an answerer which supports only EVRC-B
and/or EVRC-WB. and/or EVRC-WB.
Below is an example of such an offer: Below is an example of such an offer:
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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. However, a remote sender shall not assume the other requests. However, a remote sender shall not assume the other
side can support mode 0, unless the offer includes mode 0 side can support mode 0, unless the offer includes mode 0
explicitly in 'mode-set-recv'. explicitly in 'mode-set-recv'.
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 RFC 3264 [11]. handling of the 'ptime' parameter is described in RFC 3264 [12].
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, 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 When using EVRCNW1, the entire session MUST use the same fixed o When using EVRCNW1, the entire session MUST use the same fixed
rate and mode (0-Wideband or 1-Narrowband). rate and mode (0-Wideband or 1-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 RFC 4788 [2]. parameters, see Section 6.8 in RFC 4788 [2].
skipping to change at page 22, line 5 skipping to change at page 21, line 21
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 14. see Section 14.
o The usage of unidirectional receive only parameters, such as
'mode-set-recv', should be excluded in any declarations, since
these parameters are meaningless in one-way streaming
applications.
14. Examples 14. Examples
Some example SDP session descriptions utilizing EVRC-NW encodings Some example SDP session descriptions utilizing EVRC-NW encodings
follow. In these examples, long a=fmtp lines are folded to meet the follow. In these examples, long a=fmtp lines are folded to meet the
column width constraints of this document. The backslash ("\") at column width constraints of this document. The backslash ("\") at
the end of a line and the carriage return that follows it should be the end of a line and the carriage return that follows it should be
ignored. Note that media subtype names are case-insensitive. ignored. Note that media subtype names are case-insensitive.
Parameter names are case-insensitive both in media types and in the Parameter names are case-insensitive both in media types and in the
mapping to the SDP a=fmtp attribute. mapping to the SDP a=fmtp attribute.
skipping to change at page 25, line 10 skipping to change at page 25, line 10
Answer: Answer:
m=audio 55954 RTP/AVP 98 99 m=audio 55954 RTP/AVP 98 99
a=rtpmap:98 EVRCWB0/16000 a=rtpmap:98 EVRCWB0/16000
15. Security Considerations 15. 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 [12]. Implementations using the considerations specified in RFC 3558 [6]. 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 [12], RFC 3550 [5] and any considerations discussed in RFC 3558 [6], RFC 3550 [5] and any
appropriate profile (for example RFC 3551 [6]). appropriate profile (for example RFC 3551 [7]).
16. References 16. References
16.1. Normative References 16.1. 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. and R. Kapoor, "Enhancements to RTP Payload Formats for [2] Xie, Q. and R. Kapoor, "Enhancements to RTP Payload Formats for
EVRC Family Codecs", RFC 4788, January 2007. EVRC Family Codecs", RFC 4788, January 2007.
skipping to change at page 26, line 27 skipping to change at page 26, line 27
Updates for EVRC-B Codec", RFC 5188, February 2008. Updates for EVRC-B Codec", RFC 5188, February 2008.
[4] "Enhanced Variable Rate Codec, Speech Service Options 3, 68, [4] "Enhanced Variable Rate Codec, Speech Service Options 3, 68,
70, and 73 for Wideband Spread Spectrum Digital Systems", 70, and 73 for Wideband Spread Spectrum Digital Systems",
3GPP2 C.S0014-D v1.0, May 2009. 3GPP2 C.S0014-D v1.0, May 2009.
[5] Schulzrinne, H., Casner, S., Frederick, R., and V. Jacobson, [5] Schulzrinne, H., Casner, S., Frederick, R., and V. Jacobson,
"RTP: A Transport Protocol for Real-Time Applications", STD 64, "RTP: A Transport Protocol for Real-Time Applications", STD 64,
RFC 3550, July 2003. RFC 3550, July 2003.
[6] Schulzrinne, H. and S. Casner, "RTP Profile for Audio and Video [6] Li, A., "RTP Payload Format for Enhanced Variable Rate Codecs
(EVRC) and Selectable Mode Vocoders (SMV)", RFC 3558,
July 2003.
[7] Schulzrinne, H. and S. Casner, "RTP Profile for Audio and Video
Conferences with Minimal Control", STD 65, RFC 3551, July 2003. Conferences with Minimal Control", STD 65, RFC 3551, July 2003.
[7] Casner, S., "Media Type Registration of RTP Payload Formats", [8] Casner, S., "Media Type Registration of RTP Payload Formats",
RFC 4855, February 2007. RFC 4855, February 2007.
[8] Freed, N. and J. Klensin, "Media Type Specifications and [9] Freed, N. and J. Klensin, "Media Type Specifications and
Registration Procedures", BCP 13, RFC 4288, December 2005. Registration Procedures", BCP 13, RFC 4288, December 2005.
[9] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session [10] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
Description Protocol", RFC 4566, July 2006. Description Protocol", RFC 4566, July 2006.
[10] Garudadri, H., "MIME Type Registrations for 3GPP2 Multimedia [11] Garudadri, H., "MIME Type Registrations for 3GPP2 Multimedia
Files", RFC 4393, March 2006. Files", RFC 4393, March 2006.
[11] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model with [12] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model with
Session Description Protocol (SDP)", RFC 3264, June 2002. Session Description Protocol (SDP)", RFC 3264, June 2002.
[12] Li, A., "RTP Payload Format for Enhanced Variable Rate Codecs
(EVRC) and Selectable Mode Vocoders (SMV)", RFC 3558,
July 2003.
16.2. Informative References 16.2. Informative References
[13] Handley, M., Perkins, C., and E. Whelan, "Session Announcement [13] Handley, M., Perkins, C., and E. Whelan, "Session Announcement
Protocol", RFC 2974, October 2000. Protocol", RFC 2974, October 2000.
[14] Schulzrinne, H., Rao, A., and R. Lanphier, "Real Time Streaming [14] Schulzrinne, H., Rao, A., and R. Lanphier, "Real Time Streaming
Protocol (RTSP)", RFC 2326, April 1998. Protocol (RTSP)", RFC 2326, April 1998.
Author's Address Author's Address
 End of changes. 36 change blocks. 
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