[Icecast] Buffering / disconnect problem

Michael Smith msmith at xiph.org
Sun Dec 4 14:15:04 PST 2005


On 11/26/05, Lorenz Schoder <angro at gmx.de> wrote:
> hola
> We use IceS2 as source and Icecast 2.3.0 as servertool, streaming ogg
> vorbis in 128kbit/s, players: oggwinamp, vorbis player.
> We have got a new rented server (3ghz) with hardly any application
> running on it and a 100 mbit connection.
> We have 4 people testing the server and although they all got 2mbit
> connections without running any downloads/uploads all of us got
> bufferings, sometimes even we have to redo the authentification.
> Bufferings seem to happen more often the longer we have the server
> running, but I am not totally sure.
>
> Maybe it has nothing to do with it,
>                 -we transcode the ogg files
>                 -some commentlines of the id3 tags seem to be endless

Ogg Vorbis doesn't permit ID3 tags; if your files have ID3 tags they
will be ignored, and may cause problems, though this is unlikely to be
causing the particular issue you describe.

What client/player are your testers using?

It's actually normal for most 'simple' clients to underrun or overrun
their buffers eventually. This occurs because IceS2 (when streaming
preexisting data, rather than live) and icecast will send audio data
at precisely the correct rate (assuming your computer's system clock
is accurate). So, if your stream is 44.1kHz, it'll send it at that
rate.

However, your listening clients will be running at a slightly
different rate - usually just a fraction of a percent off perfect,
because the audio clock on the client computer will usually not be
perfectly accurate.

More advanced clients can compensate for this, but simpler ones can't,
so they eventually either fall too far behind because their buffers
are full, or read too quickly, and have to rebuffer.

Mike


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