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

Type name: audio

Subtype names: EVRCNW

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 {0,1,2,3,4,5,6,7} (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.  Absence of this parameter signals the
mode set {1,2,3,4,5,6,7}.

ptime: see RFC 8866.

maxptime: see RFC 8866.

maxinterleave: Maximum number for interleaving length (field LLL in
the Interleaving Octet)[0..7].  The interleaving lengths used in the
entire session MUST NOT exceed this maximum value.  If not signaled,
the maxinterleave length MUST be 5.

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
interleaved/bundled packet format specified in RFC 3558.

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 interleaved/bundled packet format via RTP is
specified in RFC 3558.  See Section 6 of [RFC6884] for details for
EVRC-NW.  

Applications that use this media type:

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

Additional information:

The following applies to stored-file transfer methods:

Magic number: #!EVRCNW\n (see Section 8)

File extensions: enw, ENW

Macintosh file type code: None

Object identifier or OID: None

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
"audio/3gpp2" or "video/3gpp2" registered by RFC 4393.

Person & email address to contact for further information:

Zheng Fang <zfang&qualcomm.com>

Intended usage: COMMON

Restrictions on usage:

This media type can be used with the file format defined in Section 8
of [RFC6884] in contexts other than RTP.  In context of transfers over 
RTP, the RTP payload format specified in Section 4.1 of RFC 3558 is 
used for this media type.  

Author:

Zheng Fang <zfang&qualcomm.com>

Change controller:

IETF Payload working group delegated from the IESG.