[Icecast] ices-kh60: latency bug

Karl Heyes karl at xiph.org
Sun Dec 18 20:27:12 UTC 2005

Andy Baxter wrote:
> hello,
> I've just got ices-kh60 running with jack. It's working OK apart from a 
> problem where the latency on the stream creeps up from about 15-20 secs to 
> around 7 minutes. The stream plays OK, but the audio coming out is 7 minutes 
> behind what goes in. I'm not sure how this can be happening, seeing as I 
> don't think there are any buffers that long in the system, but it is. I've 
> checked that it's not a problem with the player app I'm using (amarok), and 
> it isn't - even if I reconnect the stream, there is still a long latency.
> I suspect the problem is caused by running the stream for long periods with no 
> audio input (zero sound level from an unconnected jack graph), as this is 
> what seems to cause it.

There are two places that spring to mind.

Icecast 2.2 did have a problem in certain cases when it came across 
digital silence. The problem manifested itself by increasing the burst 
at start-up (increasing latency), 2.3 did correct for this so doesn't 
suffer from it.

The data delivered to ices is regulated by jackd and it has been known 
that the jackd dummy driver has had next to useless timing, make sure 
you use the alsa driver in jackd.


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