[Icecast] IceCast KH - question

"Thomas B. Rücker" thomas at ruecker.fi
Tue Jun 11 06:16:37 UTC 2013


On 06/10/2013 04:43 PM, Live Mix - Arvy wrote:
> Hello Thomas and Karl, thank you for your answer and time.
> […]
> We use SAM Broadcaster to encode AAC+ HE 48k. We're using the latest 
> IceCast KH version, Win32.

As I'm neither familiar with the KH version, nor with SAM I won't be of
much help.

> Other datail: all users have always "Lag: 0" on Admin interface

That doesn't need to be a problem, but without full understanding it's
hard to say.

> If you want to listen what happens, if you can and have time (very 
> appreciated) the stream is http://mp4.livemix.com.br/livemix - if 
> possible using WinAmp. Wait about 15-20 minutes to see the problem.

I've had this stream now running for about 1800s and have observed one
peculiar thing, the cache-fill went constantly down from an initial 20%
to now about 3%.
I let it run a bit longer and this is what I get:

Cache empty, {…}
A:1938.8 (32:18.8) of 0.0 (unknown) 1.4% 0%

I suspect that Winamp is signalling a low buffer by that red square.
So, yes, that's why the players drop, the bitrate is a tiny bit lower
than the playback rate. This means that over time a player will deplete
the cache and inevitably either rebuffer or start to stutter. You can
also force this to happen immediately if you disable buffering completely.
As to the root cause I can only speculate it could be some KH specific
feature or it can be that your source client has a problem.

I can only repeat that it would be beneficial to try (maybe not on your
production system) against vanilla Icecast. This would help narrow down
the source of your problem.
There is a windows build available of 2.4 beta3:
For further information, see here:

> Any ideas I really appreciate, because we have about 100-200 listeners 
> at same time we really don't know what to do :(

Personally I'd recommend to look at gradually switching to streaming
Opus, it is at least as efficient as AAC+ and it can be also played back
natively in Firefox and Opera using the <audio> HTML tag.

Also /please/ subscribe to the mailing list.



>> On 06/06/13 17:13, Live Mix - Arvy wrote:
>>> Hi there,
>>> we use IceCast KH on our webradio, no commercial. We have an issue that
>>> we dont know where to look. When listening using WinAmp (but in other
>>> players too like JW Player), after 70 or 90 minutes, we realize that the
>>> "green square" on top of WinAmp becomes a "red square". About 60 minutes
>>> after start, sometimes the "red square" blinks, and then more
>>> frequently. It happens with different internet connections and
>>> providers. Until 60 minutes, the broadcast is perfect.
>>> Can you give me an idea where to look or solve this issue? It's related
>>> to Icecast, or encoder, or internet connection, etc?
>> My initial guess would be the encoder sending rate being mismatched 
>> with the samplerate.  When a player reports an issue it needs to be 
>> clear on what it is relating to, but I suspect it will be down to a 
>> starvation of the incoming data.
>> Any issue within icecst here would should as an increased lag value 
>> for that listener on the admin page, icecast will send a lot faster 
>> than the source but is still subject to certain limits like CPU or may 
>> be a per-mount limit (limit-rate is set).
>> If it is affecting multiple listeners at different locations at a 
>> consistent offset into the stream then the sending rate from the 
>> source is suspect. May be a 44k/48k mismatch or a bad clock on the 
>> source client.
>> karl.
> Live Mix
> www.livemix.com.br
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> Icecast mailing list
> Icecast at xiph.org
> http://lists.xiph.org/mailman/listinfo/icecast

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