[vorbis-dev] UDP streaming vorbis

[Petr Tomasek]

On Wed, Sep 10, 2003 at 08:19:00PM +0300, Beni Cherniavsky wrote:
> eross+vorbis-dev at disc.ucn.cl wrote on 2003-09-10:
> 
> > Hello..
> >
> > I've searching the mailing lists archives for udp streaming, but i
> > only found some references to using rtp, but it doesnt answer all my
> > questions..,
> >
> > I'm trying to implement a vorbis client/server for doing streaming
> > over udp. Currently, using the examples in the vorbis source code I
> > managed to make it work. (BTW, im using multicast, and it works
> > fine).
> 
> Are you sure you want to use UDP?  It'll sort-of-work for a LAN (I
> guess that's how you tested it) but it will break horribly in the
> large.  In particular, consider that the order of packets can change.
> I'm not sure what guarantees RTP gives but UDP sounds like really
> saking for trouble.
> 
> > The problem is that the clients must connect from the begining of
> > the stream, or they will not recieve the first packets and complain
> > about the stream not being ogg/vorbis.
> >
> Vorbis requires the first packets, not only to nkow it's Vorbis but
> also because they contain a lot of info necessary for decoding the
> rest.  All streaming schemes include some way to recieve the headers
> when you connect and the data from the point you connected.
> 
> > In some post, someone told that he was re-transmitting these packets every
> > N seconds.
> >
> > Is there some alternative to this ? I'd like to make a client that can
> > connect in any time to the server.
> >
> If you use multicast, all clients get the same bits (or corrupted
> subsets of them).  So you can't send the headers with UDP, excpet for
> the scheme of re-sending every X seconds.  It has an inconveneint
> joining latency (unless X is very small but then you waste
> considerable bandwidth) but for really heavy multicast it's the most
> scalable way...

You can also retransmit the headers on user request via the main (multicast)
channel...


--
Petr Tomasek, http://www.etf.cuni.cz/~tomasek/

<p>--- >8 ----
List archives:  http://www.xiph.org/archives/
Ogg project homepage: http://www.xiph.org/ogg/
To unsubscribe from this list, send a message to 'vorbis-dev-request at xiph.org'
containing only the word 'unsubscribe' in the body.  No subject is needed.
Unsubscribe messages sent to the list will be ignored/filtered.