[vorbis-dev] Update on Vorbis RTP I-D

Ralph Giles giles at xiph.org
Tue Feb 11 05:39:49 PST 2003

On Tuesday, February 11, 2003, at 12:57 pm, Phil Kerr wrote:

> Keeping it at 64k gives us extra headroom if needed and I'll adjust the
> text at the start of the I-D to highlight this.  Should the main Vorbis
> documentation make a note of this?

I would agree that 64k is a save compromise.

The vorbis documentation will certainly include the rtp profile 
(already does, actually) but yes, once issues like this are finalized, 
a note about the restriction should be added to the main text.

>> Codebook delivery is, of course, the largest problem in terms of 
>> practical
>> implementations. Perhaps have multiple methods with flag(s) to 
>> indicate which
>> are available for a specific stream?
> That's sort of built-in now with the VORB message, the overflow and
> SDP.  I've been discussing the TCP option with one of the AVT guys and
> although the specs for this delivery mechanism are available they are
> not 100% developed and work is still ongoing in this area.  This method
> would provide the reliable solution we need.  Any further ideas in this
> area would be welcomed.

One (not new) idea that I've liked is to add a 'codebooks by reference' 
feature to vorbis, where instead of transmitting actual codebooks, 
there's an entry with e.g. a checksum or hash of the codebooks (for 
both verification and cache lookup) and a pointer to where they can be 
retrieved if the decoder doesn't already have them. In an host-based 
application, I could imagine this working very well where the pointer 
is just a url where the headers can be retrieved over normal TCP.

Given the state of things, I would reinterate Mike's suggestion that we 
leave room for a variety of methods.

> I don't think it's essential but it can be useful to specify which 
> ports
> the server will bind to.  It certainly helps with firewalls and network
> admin.

It seems to me these requirements are more relevent to rtp-streamed 
media in general. What do quicktime and realaudio use?


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