(File created 2013-01-23, last updated 2013-03-22)

Type name: audio

Subtype names: EVRCNW1

Required parameters: None

Optional parameters:

These parameters apply to RTP transfer only.

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
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.
A value of 0 signals the support for wideband fixed rate (full or
half rate, depending on the value of 'fixedrate' parameter).  A value
of 1 signals narrowband fixed rate (full or half rate, depending on
the value of 'fixedrate' parameter).  Absence of this parameter
signals the mode 1.

ptime: see RFC 8866.

maxptime: see RFC 8866.

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
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 6838, Section 4.8) and
is defined for transfer of EVRC-NW encoded data via RTP using the
compact bundled packet format specified in RFC 4788.

Security considerations: See Section 16 of [RFC6884]

Interoperability considerations: None

Published specification:

The EVRC-NW vocoder is specified in 3GPP2 C.S0014-D.  The transfer
method with the compact bundled packet format via RTP is specified in
RFC 4788.

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:

Zheng Fang <zfang&qualcomm.com>

Intended usage: COMMON

Restrictions on usage:

This media type depends on RTP framing and hence is only defined
for transfer via RTP (RFC 3550).  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; instead, audio/EVRCNW SHALL be used.

Author:

Zheng Fang <zfang&qualcomm.com>

Change controller:

IETF Payload working group delegated from the IESG.