(RFC4788 published January 2007, updated February 2008 per RFC 5188)

Type name: audio

Subtype name: EVRCB

Required parameters: None

Optional parameters:

These parameters apply to RTP transfer only.

recvmode: A mode of the EVRC-B codec.  A decoder can use this
attribute to inform an encoder of its preference to operate in a
specified mode.  Possible values are 0..7 (see the encoder operating
point column in Table 2-6 of 3GPP2 C.S0014-B).

sendmode: A mode of the EVRC-B codec.  An encoder can use this to
signal its current mode of operation.  Possible values are 0..7 (see
encoder operating point column in Table 2-6 of 3GPP2 C.S0014-B).

ptime: See RFC 8866.

maxptime: See RFC 8866.

maxinterleave: Maximum number for interleaving length (field LLL in
the Interleaving Octet).  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 of RFC 4788 for a definition.  If this
parameter is not present, the default value 1 MUST be assumed.

dtxmax: See Section 6.1 of RFC 4788.

dtxmin: See Section 6.1 of RFC 4788.

hangover: See Section 6.1 of RFC 4788.

Encoding considerations:

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
interleaved/bundled packet format specified in RFC 3558.

Security considerations: See Section 9 of RFC 4788.

Interoperability considerations: None

Published specification:

The EVRC-B vocoder is specified in 3GPP2 C.S0014-B.  The transfer
method with the interleaved/bundled packet format via RTP is
specified in RFC 3558, RFC 4788, and RFC 5188.

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 information applies for the
storage format only.

Magic number: #!EVRC-B\n (see Section 5 of RFC 4788)

File extensions: evb, EVB

Macintosh file type code: None

Object identifier or OID: None

Person & email address to contact for further information:

Harikishan Desineni <hd&qualcomm.com>

Intended usage: COMMON

Restrictions on usage:

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
used.  In all other contexts, the file format defined in Section 5 of
RFC 4788 SHALL be used.

Author:

Qiaobing Xie / Harikishan Desineni

Change controller:

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