(RFC 5188 published February 2008, subtype last updated February 2008)

Type name: audio

Subtype name: EVRCWB1

Required parameters: None

Optional parameters:

These parameters apply to RTP transfer only.

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
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
of modes.  A value of 0 signals the support for wideband fixed rate
(full or half rate, depending on the value of the 'fixedrate'
parameter).  A value of 4 signals narrowband fixed full rate.  A
value of 7 signals narrowband fixed half rate.  Absence of this
parameter signals mode 0.

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
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
value of the 'fixedrate' parameter). 'sendmode' with value 4 signals
narrowband fixed full-rate operation. 'sendmode' with value 7 signals
narrowband fixed half-rate operation.  The 'fixedrate' parameter MUST
NOT be present when the 'sendmode' value is 4 or 7.  Absence of this
parameter signals mode 0.

ptime: See RFC 8866.

maxptime: See RFC 8866.

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 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.

silencesupp: See Section 6.1 in RFC 4788.

dtxmax: See Section 6.1 in RFC 4788.

dtxmin: See Section 6.1 in RFC 4788.

hangover: See Section 6.1 in RFC 4788.

Encoding considerations:

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
compact bundle packet format specified in RFC 4788.

Security considerations: See Section 18 of RFC 5188.

Interoperability considerations: None

Published specification:

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
RFC 4788 and RFC 5188.

3GPP2 C.S0050-B, 3GPP2 File Formats for Multimedia Services.

3GPP2 specifications are publicly accessible at http://www.3gpp2.org

Applications that use this media type:

It is expected that many VoIP applications (as well as mobile
applications) will use this type.

Additional information: None

Person & email address to contact for further information:

Harikishan Desineni <hd&qualcomm.com>

Intended usage: COMMON

Restrictions on usage:

This media type depends on RTP framing and hence is only defined for
transfer via RTP [6]; the RTP payload format specified in Section 4
of RFC 4788 SHALL be used.  This media type SHALL NOT be used for
storage or file transfer using the file format defined in Section 8
of RFC 5188; instead, audio/EVRCWB SHALL be used.

Author:

Harikishan Desineni

Change controller:

IETF Audio/Video Transport working group delegated from the IESG.