Senders, network elements, or receivers can suppress sending/forwarding/subscribing/decoding individual Media Partitions and still preserve perhaps suboptimal, but still useful, media quality.
One property of all Media Bitstreams relevant to this memo is that their Media Partitions have a well-defined usage relationship.
Status of This Memo This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements.
A new grouping type "DDP" -- decoding dependency -- is defined, to be used in conjunction with RFC 3388 entitled "Grouping of Media Lines in the Session Description Protocol".
In addition, an attribute is specified describing the relationship of the media streams in a "DDP" group indicated by media identification attribute(s) and media format description(s).
Usage of New Semantics in SDP ..................................10 6.1.
Usage with the SDP Offer/Answer Model .....................10 6.2.
In Multi- View Coding (MVC) [AVT-RTP-MVC], layered dependencies between views are used to increase the coding efficiency, and, therefore, the properties of MVC with respect to the SDP signaling are comparable to those of SVC.
The mechanisms defined herein are media transport protocol dependent, and applicable only in conjunction with the use of RTP [RFC3550].At present, this memo defines two decoding dependencies: layered coding and Multiple Description Coding.Layered coding dependency: Each Media Partition is only useful (i.e., can be decoded) when all of the Media Partitions it depends on are available.Today, if more than one "m=" lines exist indicating the same media type, a receiver cannot identify a specific relationship between those media.A Multiple Description Coding (MDC) or layered Media Bitstream contains, by definition, one or more Media Partitions that are conveyed in their own media stream.Abstract This memo defines semantics that allow for signaling the decoding dependency of different media descriptions with the same media type in the Session Description Protocol (SDP).