Pops and clicks in ALSA audio playback

[Andreas Gustafsson]

I'm running Ubuntu 7.04 on Fujitsu Amilo Pro V3205 laptop and I'm experiencing
problems with pops and clicks in various audio applications.

In an attempt to come up with a minimal test case, I compiled the PCM playback
test program from the alsa-lib distribution, and found that it also suffers from the
same problem: when run with its default settings (no command line options),
there are loud clicks and pops once every few seconds.

To reproduce:

  apt-get source alsa-lib
  cd alsa-lib-1.0.13/test/
  cc pcm.c -lasound -o pcm
. /pcm

[Andreas Gustafsson (gson)]

I just upgraded to 7.10 and the pops and clicks are still there.
To reproduce:

  apt-get source alsa-lib
  cd alsa-lib-1.0.14/test/
  cc pcm.c -lasound -o pcm
  . /pcm

[Andreas Gustafsson (gson)]

Now where did that space come from? The last line of the commands to
reproduce should of course be "./pcm", not ". /pcm".

[Tim Gardner (timg-tpi)]

You should try the Gutsy live CD to see if audio works any better. Audio issues in Feisty don't meet the Stable Release Update requirements.

[Andreas Gustafsson (gson)]

> You should try the Gutsy live CD to see if audio works any better

Did you miss the part saying "I just upgraded to 7.10 and the pops and clicks are still there"?

[Tim Gardner (timg-tpi)]

Indeed I did. The next thing you could try is linux-backports-modules which is not installed by default and does contain ALSA 1.0.15rc3.

[Andreas Gustafsson (gson)]

> The next thing you could try is linux-backports-modules
> which is not installed by default and does contain ALSA 1.0.15rc3.

Can you be more specific about how to do that? I ran the command

  sudo apt-get install linux-backports-modules

and rebooted, but I'm unsure as to whether that actually installed anything;
"dpkg-query -L linux-backports-modules" only lists files in /usr/share/doc,
and I see no change in the output of "modinfo snd-hda-intel". How can I
verify that I'm in fact running the new ALSA code?

[Andreas Gustafsson (gson)]

The pops and clicks still occur with the Hardy alpha 4 live CD.
Here are the exact commands needed to reproduce the issue
after booting from the live CD:

sudo apt-get install dpkg-dev
sudo apt-get install libc6-dev
sudo apt-get install libasound2-dev
apt-get source alsa-lib
cd alsa-lib-1.0.15/test
cc pcm.c -lasound -o pcm
./pcm

[Andreas Gustafsson (gson)]

I have now repeated the test using the ALSA "pcm" test program
in 8.04 and 8.10 beta. The pops and clicks are still there in 8.04,
but they are gone in 8.10 beta.

For the 8.10 beta test, I booted the 8.10 beta i386 desktop live
CD (in safe graphics mode, because the machine locks up during
boot otherwise), and ran the following commands:

sudo apt-get install dpkg-dev
sudo apt-get install libc6-dev
sudo apt-get install libasound2-dev
apt-get source alsa-lib
cd alsa-lib-1.0.17a/test
cc pcm.c -lasound -o pcm
./pcm