[xiph-rtp] header caching and chaining

[Ralph Giles]

On Thu, Feb 03, 2005 at 04:37:59PM -0800, Aaron Colwell wrote:

> Yes. Since SDP forces the number of streams to be constant, you can't support
> changing the number of logical streams unless you do SSRC multipexing over a
> single RTP channel. I'm fine with not supporting those types of stream since
> hopefully they are rare. For on-demand content you could support these files
> by figuring out the max number of Vorbis and Theora streams needed and 
> advertise that many streams. You just don't send data on some of the streams 
> when they aren't needed. This is basically how I support these types of files
> in the Helix Plugins.

Ok, thanks. That helps.

> For live this could be ok, but for on-demand, transcoding won't scale 
> eventhough audio is less expensive to transcode than video.

Is there a reason to use RTP instead of HTTP for on-demand work??

> I'm not sure what you mean about "a more expensive version of the fixed-info 
> packet config". I think it just means that if you want to support changes in
> the info header then you need to have the CRC cover the info header and 
> codebook. If you just want to switch out the codebook then it will work fine.
> Since the frame-rate info is in the ident header this would mean fixed 
> frame rate for video and fixed sample-rate and channels for audio.

That's what I mean. :-)

 -r