[xiph-rtp] Interesting post on AVT list
Tor-Einar at Jarnbjo.de
Tue Sep 6 13:18:40 PDT 2005
Aaron Colwell schrieb:
> This solves the reliable delivery problem since the SDP must be reliably
> transmitted from the server to the client. This would require that all
> codebooks be known at SDP generation time. I'm pretty sure we've
> already agreed
> to that constraint though.
Yes, Colin was right that the 1k size limit for the SDP descriptor is
not related to RTSP or SIP. However, SDP descriptors are usually _not_
reliably transmitted. Embedding the codebook header in the SDP means
that the encapsulating UDP packet will exceed the path MTU for all
common Vorbis streams and/or network situations and you will also empose
a length restriction on the codebook header to somewhere around 65000
bytes. For Vorbis this might not be a great problem. What about Theora?
So still, my objections against unreliable codebook delivery are valid.
If we put the codebook into the SDP, we will not even have a possibility
to transmit the codebook fragments twice, just to assume that the client
will have received at least one of each fragment.
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