[pulseaudio-discuss] cracks and pops with intelHDA

[Lennart Poettering]

On Mon, 07.01.08 17:59, Erik Slagter (erik at slagter.name) wrote:

>> I was wondering if anybody was experiencing random cracks and pops (loud 
>> ones actually :( ) while using pulseaudio with intelHDA? I have the 
>> following configuration for my inbuilt intelHDA card and will be thankful 
>> if somebody helped me out here. I haven't observed cracks and pops on my 
>> other card (Griffin iMic). I am using pulseaudio 0.9.8 which is able to 
>> acquire realtime scheduling priority and a nice level of -11.
>
> If you have true realtime scheduling, you don't need "nice" levels. If a 
> process in the realtime queue is ready to run, it will run, even if there 
> are dozens of processes in the "normal" queue ready to run and even if they 
> are all nice'd -19 (the maximum).

While this is generally true, it's not really applicable to PA. In PA
every device has an RT thread. And then there is a global additional
"main" thread that does control and stuff like this, which is not RT,
but reniced. So, even if you enabled RT, you still need nice levels
for the main thread.

> Besides that, a properly designed sound system (software and hardware) 
> doesn't need a high priority to work smoothly.

If you don't have RT then having a negative nice level has a
measurably positive effect on the scheduling latency if your system is
busy. I strongly recommend to to enable renicing if RT is not possible,

> I have a similar problem in that a pulse stream plays for a few moments, 
> starts to hiccup and then stops altogether. It doesn't matter which program 
> I use. Using alsa directly there is no problem. On my other computer it 
> works like expected, though. I have no need to use pulse anymore (it 
> doesn't solve my problem) so my problem is gone ;-)

Please paste the output of pulseaudio -vv when this happens for cases
like this.

Lennart

-- 
Lennart Poettering                        Red Hat, Inc.
lennart [at] poettering [dot] net         ICQ# 11060553
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