[vorbis-dev] Re: [vorbis] packetizing an ogg stream

[Jeroen Vreeken]

On 2001.08.16 16:56:03 +0200 rillian wrote:
> On Wednesday, August 15, 2001, at 04:31 , Jeroen Vreeken wrote:
> 
> > I am looking for some pointers on how to packetize an ogg stream.
> > My idea is to use udp packets for transport, so I would need a way that
> > would minimalize the impact of lost packets.
> 
> There's an rtp payload draft format at 
> http://www.xiph.org/ogg/vorbis/doc/draft-moffitt-vorbis-rtp-00.txt (and 
> it's expired :) Comments welcome.

I don't know if it is really oppropriate for my situation, I am looking for
a way to connect radio amateur repeaters. My idea was to use short ogg
files (due to the simplex nature usually short messages are transmitted)
and cut them in about 1k pieces and send those over udp packets.
I am also thinking about using some higher level protocol to prevent
redundant streams from being send to the same router/node so it will be a
hybrid of multicast/unicast.
(No real specs yet, just brainstorming)
Your protocol is vorbis specific, but I prever to use a general solution
since we might also want to interconnect tv repeaters at a later time (if
'tarking' becomes usable and we upgrade our infrastructure).

> The unresolved issue is how to send the three header packets (including 
> the codebooks) which must be made available immediately to new connects 
> and transmitted losslessly. There's also been some discussion regarding 
> the codebook header being prohibitively large in applications with many 
> short segments (like commercial radio advertising) or contrariwise, how 
> to change metadata independently of the codebooks, if that issue is 
> handled by compression as a continuous stream.
> 

Although prefered delivery doesn't need to be 100% reliable since the
nature of the conversations will permit a transmission to be lost.
The reason I asked is that I would like to minimize any damage by using a
smart way of cutting so that if a frame goes missing the audio decoder
would suffer the minimum and might still decode the stream.
 

> > Are there any code examples out there for this?
> 
> Not that I'm aware of. Two programs that would be good places to start 
> are icecast2 (which does http vorbis streaming) and Apple's Darwin 
> Streaming Server (which does quicktime over rtp).
> 
>   -r
> 
> p.s. vorbis-dev is the more appropriate list for this question. I've 
> cc'd.

Jeroen

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