Type name: audio

Subtype name: G7291

Required parameters: none

Optional parameters:

maxbitrate:  the absolute maximum codec bit rate for the session, in
   bits per second.  Permissible values are 8000, 12000, 14000,
   16000, 18000, 20000, 22000, 24000, 26000, 28000, 30000, and 32000.
   32000 is implied if this parameter is omitted.  The maxbitrate
   restricts the range of bit rates which can be used.  The bit rates
   indicated by FT and MBS fields in the RTP packets MUST NOT exceed
   maxbitrate.

mbs:  the current maximum codec bit rate supported as a receiver, in
   bits per second.  Permissible values are in the same set as for
   the maxbitrate parameter, with the constraint that mbs MUST be
   lower or equal to maxbitrate.  If the mbs parameter is omitted, it
   is set to the maxbitrate value.  So if both mbs and maxbitrate are
   omitted, they are both set to 32000.  The mbs parameter
   corresponds to a MBS value in the RTP packets as per table in
   Section 5.2 of RFC 4749.  Note that this parameter may be
   dynamically updated by the MBS field of the RTP packets sent; it
   is not an absolute value for the session.

ptime:  the recommended length of time (in milliseconds) represented
   by the media in a packet.  See Section 6 of RFC 4566.

maxptime:  the maximum length of time (in milliseconds) that can be
   encapsulated in a packet.  See Section 6 of RFC 4566

dtx: indicates that Discontinuous Transmission (DTX) is used or
   preferred. Permissible values are 0 and 1. 0 means no DTX. 1
   means DTX support, as described in Annex C of ITU-T Recommendation
   G.729.1. 0 is implied if this parameter is omitted.

   When DTX is turned off, the RTP payload must not contain a
   Silence Insertion Descriptor (SID), and the frame type (FT) value 14
   must not be used.

Encoding considerations: This media type is framed and contains
   binary data; see Section 4.8 of RFC 4288.

Security considerations: See Section 8 of RFC 4749

Interoperability considerations: none

Published specification: RFC 4749

Applications which use this media type: Audio and video conferencing
   tools.

Additional information: none

Person & email address to contact for further information:
   Aurelien Sollaud, aurelien.sollaud&orange-ftgroup.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].

Author: Aurelien Sollaud

Change controller: IETF Audio/Video Transport working group delegated
   from the IESG