[alsa-devel] soc underrun problem

Takashi Iwai tiwai at suse.de
Wed Mar 18 07:25:29 CET 2009

At Tue, 17 Mar 2009 21:56:06 -0700,
dfoley wrote:
> I'm currently having a problem with playing wave files
> root at tsi-tpcxx:~# aplay /usr/share/sounds/alsa/Front_Center.wav
> Playing WAVE '/usr/share/sounds/alsa/Front_Center.wav' : Signed 16 bit Little Endian, Rate 48000 Hz, Mono
> mapped channel 10 to 2
> underrun!!! (at least 130.662 ms long)
> underrun!!! (at least 140.809 ms long)
> I've narrowed it down to the commit ed3da3d9a0ef13c6fe1414ec73c9c1be12747b62 in linux-next/sound-2.6-tiwai.git.
>    ALSA: Rewrite hw_ptr updaters
> The audio works fine, when I reverse this commit.

Could you build with CONFIG_SND_DEBUG_XRUN and set below?
	echo 1 > /proc/asound/card0/pcm0p/xrun_debug

It will show you why the playback skips.  It means usually the pointer
callback is unstable.  The commit changed the xrun check more


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