(RFC 3558 published July 2003, updated January 2007 per RFC4788)

Type name:  audio

Subtype names:  EVRC0

Required parameters:  none

Optional parameters:

   silencesupp:  see Section 6.1 for definition.  If this parameter
      is not present, the default value 1 MUST be assumed.

   dtxmax:  see Section 6.1

   dtxmin:  see Section 6.1

   hangover:  see Section 6.1

Encoding considerations:
   This media type is framed binary data (see RFC 4288, Section 4.8)
   and is only defined for transfer of EVRC-encoded data via RTP
   using the Header-Free packet format specified in Section 4.2 of
   RFC 3558.

Security considerations:  See Section 14, "Security Considerations",
   of RFC 3558.

Interoperability considerations:
   The DTX parameters are receiver options.  Existing RFC 3558
   implementations will not send any of the DTX parameters in their
   SDP and will ignore any DTX parameters they receive.  The adaptive
   DTX behavior of DTX-capable EVRC codecs (as detailed in [8],
   Section 4.3.5) ensures interoperability with non-DTX EVRC codecs.

Published specification:
   The EVRC vocoder is specified in 3GPP2 C.S0014 [2].  Transfer
   methods are specified in RFC 3558.

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:
   Qiaobing Xie <Qiaobing.Xie&motorola.com>

Intended usage:  COMMON

Restrictions on usage:
   This media type depends on RTP framing; hence, it is only defined
   for transfer via RTP (RFC 3550 [5]).  Transfer within other
   framing protocols is not defined at this time.

Author:
   Adam Li/Qiaobing Xie

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