[xiph-rtp] Interesting post on AVT list

[Tor-Einar Jarnbjo]

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.

Tor