(registered by RFC3555, updated by RFC4587)

MIME media type name: video

MIME subtype name: H261

Required parameters: None

Optional parameters:

   CIF.  This parameter has the format of parameter=value.  It
   describes the maximum supported frame rate for CIF resolution.
   Permissible values are integer values 1 to 4, and it means that
   the maximum rate is 29.97/specified value.

   QCIF.  This parameter has the format of parameter=value.  It
   describes the maximum supported frame rate for QCIF resolution.
   Permissible values are integer values 1 to 4, and it means that
   the maximum rate is 29.97/specified value.

   D.  Specifies support for still image graphics according to H.261,
   annex D.  If supported, the parameter value SHALL be "1".  If not
   supported, the parameter SHOULD NOT be used or SHALL have the
   value "0".

Encoding considerations:

   This media type is framed and binary, see Section 4.8 in
   [RFC4288].

Security considerations: See Section 8

Interoperability considerations:

   These are receiver options; current implementations will not send
   any optional parameters in their SDP.  They will ignore the
   optional parameters and will encode the H.261 stream without annex
   D.  Most decoders support at least QCIF resolutions, and they are
   expected to be available in almost every H.261-based video
   application.

Published specification: RFC 4587

Applications that use this media type:

   Audio and video streaming and conferencing applications.

Additional information: None

Person and email address to contact for further information:

   Roni Even: roni.even&polycom.co.il

Intended usage: COMMON

Restrictions on usage:

   This media type depends on RTP framing and thus is only defined
   for transfer via RTP [RFC3550].  Transport within other framing
   protocols is not defined at this time.

Author: Roni Even

Change controller:

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