[xiph-rtp] Difficulties with several RTP streams for a Vorbisstream.

[Ramón García]

I suspect that there has been a misunderstanding here. 

GStreamer, DirectShow and JMF are general multimedia frameworks, they
can handle audio and video from different sources at the same time,
and synchronize them. However, what would be complicated is having two
different RTP sessions for the same Vorbis stream (but there would be
no trouble in having one RTP session for audio and another for video).
It is IHMO against the spirit of RTP, becase RTP streams are intended
to transport time based media, and codebooks do not fit with this
definition.

Transport of codebooks via HTTP is simple. It has only two drawbacks.
It is not scalable: multiple clients requesting the same codebook
require dedicated TCP connections instead of a single multicast
connection. In addition, it would not work  in environments where the
flow of data is unidirectional, such as digital television through
satellite. I think that this application is important enough and
should not be missed.

The mechanism that I support is sending the codebooks inside the data
stream and clients can request codebooks through RTCP. This mechanism
is reliable, because if a codebook is missed the client can request it
again. It would be at server discretion whether to send codebooks
inconditionally, or only at client request (to acomodate
unidirectional environments).

Ramon