[alsa-devel] Adjust volume may cause audio playback corruption

cee1 fykcee1 at gmail.com
Thu May 17 11:15:24 CEST 2012


Thanks for reply.
2012/5/15 Takashi Iwai <tiwai at suse.de>
> At Tue, 15 May 2012 16:30:14 +0800,
> cee1 wrote:
> >
> > Witch a patch[1] of PA which dumps playback PCM data, I found the
> > dumped data(with ./wavformat.py[2] <dumpped_data> to convert to wav
> > file) is not corrupted.
> > Since PA uses mmap to transfer PCM data, the driver's DMA buffer
> > should also be "good".
> >
> > It seems related to HDA controller of SB710, I tried HDMI output, and
> > can reproduce the problem
> > too(http://dev.lemote.com/files/upload/software/PA-apc/HDMI-corrupted_sound.ogg).
> If you are using the recent kernel, try snoop=off option of
> snd-hda-intel driver.  The recent AMD and VIA controllers are known to
> work with the non-snooping mode.

I'm trying snd-hda-intel.snoop=0 under ubuntu10.10(32bit) with kernel
from ubuntu 12.04(32bit), I still can reproduce it.

BTW, what is difference between snoop and no snoop?
Enable no snoop mode will render no sound on our platform(which is
mips compatible).


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