On Sun, Feb 7, 2010 at 11:07 AM, Jarkko Nikula <jhnikula@xxxxxxxxx> wrote: > On Sat, 6 Feb 2010 19:33:08 +0200 > Grazvydas Ignotas <notasas@xxxxxxxxx> wrote: > >> It's on powerdown, there is a faint pop. It appears its the amp (final >> part in the path), I tried to toggle it while playing /dev/zero >> manually and it always pops on powerdown. On powerup there is a small >> sound cutoff too, probably because of amp capacitors charging, but we >> decided to leave it instead of halting every sound playing program >> until the amp gets ready. >> > My side comment for the /dev/zero test. You may hear pops also > if /dev/zero is played as unsigned 8-bit samples on signed DAC since > then samples gets converted to maximum negative value. > > So there is a difference how the /dev/zero is played. First command > below produces a pop because it's playing a pop and second produces a > pop only if HW is producing it. > > aplay /dev/zero > aplay -f S16_LE /dev/zero I was testing with '-f cd' which should also be signed. Actually doing just 'aplay /dev/zero' makes matters worse, there is some additional 'squeek' noise audible when I turn the volume up. On Mon, Feb 8, 2010 at 1:39 PM, Mark Brown <broonie@xxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > If this goes off too much you might want to tweak the delay ASoC uses to > defer power down of DAPM widgets after streams stop. There's a command > line option pmdown_time, it really ought to have a sysfs file to tweak > but there's not been any demand. Yes we are already using that (set to 1 minute), and the sysfs file would be useful for us (we have a hack for that in our tree). _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
