sdpdemux: add "rtcp-mode" property to disable RTCP and "media" property to filter audio/video streams
sdpdemux: add "rtcp-mode" property to disable RTCP
If we know there's only one stream we care about and we
don't have to synchronise audio and video, or send RRs,
we might just as well not hook up all the RTCP bits and
use fewer threads and sockets and simplify the pipeline.
sdpdemux: add "media" property to allow audio-only or video-only streaming