On Saturday 16 January 2010 19:17:18 Thomas Hummel wrote:
> Hello,
>
> I'm not really sure what the right list is since I cannot isolate the part
> of
> the system which cause the problem :
>
> I could use a little help on a weird sound issue I'm struggling with :
>
> 1. Description :
> ------------------------
>
> When playing audio files, the sound has from few to many
> "micro-interrupts"
> (less than 1/4 of a second), randomly but frequently (so this is not hard
> to
> reproduce). This seem to occur :
>
> . with any file (I can pick a random audio file to experience it)
> . with either mp3 or flaac encoded files
> . with mplayer (from the ports collection or hand compiled from svn),
> either with oss or sdl audio output (although sdl seems to have less
> "interrupts")
> . with vlc
>
> but
>
> . not with ffplay
> . apparently not with xine
> . apparently not with amarok
Amarok uses xine. All of the above ultimately use OSS to output the sound.
>
> -> so I doubt this may be a harware or a driver issue.
>
> and on a almost idle 4GB RAM machine running only KDE-4 and firefox-3
>
> no hints shows in /var/log/messages
>
> 2. Config :
> ------------
>
> I'm running :
>
> . 8.0-STABLE FreeBSD amd64
>
> . full zfs (no ufs) (files are on a "slow" disk pool (5400 rpm) but
> moving them to the "fast" system disk (7200 rpm) doesn't change anything
>
> . on a (bios up to date) P5Q3 ASUS motherboard
>
> . with snd_hda sound driver
[snip]
Try increasing the hw.snd.latency sysctl:
hw.snd.latency
Configure the buffering latency. Only affects applications that
do not explicitly request blocksize / fragments. This tunable
provides finer granularity than the hw.snd.latency_profile tun-
able. Possible values range between 0 (lowest latency) and 10
(highest latency).
Just thinking out loud here, but maybe you have some non-standard HZ
configured or powerd configured to clock the CPU back by an extreme amount,
both could theoretically cause buffer underruns.
- Pieter
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