Finally: Digital AC-3 surround sound with pulseaudio (aka Surround Sound Awesomeness)

[oblib]

Here is the update to the old thread that somehow disappeared "HOWTO: A52 Encoded 5.1 Surround Sound Awesomeness with PulseAudio and ALSA on Hardy" thread (archived here). See also this bug report.

There are two steps here: add the a52 plugin, and tell pulseaudio to use it.

Step 1:
Go to a terminal and do the following:

sudo bash
echo "pcm.a52 {
  @args [CARD]
  @args.CARD {
    type string
  }
  type rate
  slave {
    pcm {
      type a52
      bitrate 448
      channels 6
      card $CARD
    }
  rate 48000 #required somehow, otherwise nothing happens in PulseAudio
  }
}
" > /etc/asound.conf
cd /tmp
apt-get source libasound2-plugins
apt-get build-dep libasound2-plugins
apt-get install libavcodec-dev
cd alsa-plugins-*
./configure
make
cd a52/.libs
cp libasound_module_pcm_a52.la libasound_module_pcm_a52.so /usr/lib/alsa-lib/
cd /tmp
rm alsa-plugins-* -rf

Step 2:
Either reboot or type the following (while still root):

alsa reload
killall pulseaudio

Pulse should come back on its own unless you disabled autospawn.

Now pulse should be aware of your digital surround output. Go to System -> Preferences -> Sound. Click on the "Hardware" tab and change the profile to one of the 'Digital Surround 5.1' profiles. Play some sound (I like to test with www.pandora.com) and enjoy!

If it doesn't show up, it probably means that alsa didn't create it correctly. To test if alsa sees the a52 device, type:

aplay -D a52:0

If it errors out (audio open error: No such file or directory) then that means it did not like your asound.conf settings. You might learn something by looking at the output of 'sudo alsa reload' or just 'aplay'.

To see if it works, you can test with this command:

speaker-test -Da52:0 -c6

One other useful debug tool is to disable autospawn in /etc/pulseaudio/client.conf (uncomment the autospawn line) and kill pulseaudio. Then if you run 'pulseaudio -vv' you can see what pulse is doing. Change the number of 'v's for more information.

Always double check alsamixer if things seem weird.

[craigcoffman]

This seems to be exactly what I'm looking for but I'm unsure as to whether I am to replace CARD with the card number, name or hw:0 or what? Also unsure as to whether all instances need to be replaced.

--
craig

[mgmeskill]

oblib! You are amazing! Your instructions worked perfectly for my ALC888 on-board sound connected via s/pdif (optical) to my Yamaha.

I followed your instructions verbatim on a freshly installed Ubuntu 10.10. 1 reboot later, digital 5.1 working.

You have really made my day! I hope you are enjoying the beverage of your choice right now!

-Mike

[craigcoffman]

Still no joy here. If I leave the asound.conf file verbatim as above, I do see the 5.1 surround setting appear in my pulseaudio configuration, but attempting to play any sound with either audacious or xine simply crashes pulseaudio & alsa. I have to do a alsa reload & kill pulseaudio & let it respawn. But still no sound.

Trying these items before crashing pulseaudio:

aplay -D a52:0 gives no errors (or any output at all)

speaker-test -D a52:0 -c6 likewise gives no errors, but produces no sounds.

syslog does show these errors:

Nov 2 06:32:09 sirguy pulseaudio[2258]: module-alsa-card.c: Failed to find a working profile.
Nov 2 06:32:09 sirguy pulseaudio[2258]: module.c: Failed to load module "module-alsa-card" (argument: "device_id="1" name="pci-0000_04_00.1" card_name="alsa_card.pci-0000_04_00.1" tsched=yes ignore_dB=no card_properties="module-udev-detect.discovered=1""): initialization failed.

[craigcoffman]

Alright,I figured out that the alsa side of thing WAS working.. after enabling the digital output in the alsamixer, I could hear the 5 speaker test fine. However, pulse audio still crashes if set to the new setting of Digital 5.1 surround.

Using audacious as my player, I am able to get SOME files to play directly to ALSA & I do hear 5.1 output there.. I gather that is a file-specification issue on the files that will not play.

I really would like to get pulse-audio to use the new setting though. Appreciate any follow-up ideas any one might have.

[oblib]

I've bolded the final advice I had, to check alsa mixer settings. craigcoffman, your next step should be to tell pulse to stop autospawning and run it verbosley from the terminal. See the second to last tip on how to do that. Hopefully pulse will tell you why it's crashing before it crashes.

[som21]

i tried to follow your guide;but it informed me the need to download 29MB file.when i pressed 'y' and enter,the process aborted.and now after rebooting ubuntu has no sound at all.please help me.thanks in advance

here is the terminal response:

root@som-laptop:~# echo "pcm.a52 {
>   @args [CARD]
>   @args.CARD {
>     type string
>   }
>   type rate
>   slave {
>     pcm {
>       type a52
>       bitrate 448
>       channels 6
>       card $CARD
>     }
>   rate 48000 #required somehow, otherwise nothing happens in PulseAudio
>   }
> }
> " > /etc/asound.conf
root@som-laptop:~# cd /tmp
root@som-laptop:/tmp# apt-get source libasound2-plugins
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Picking 'alsa-plugins' as source package instead of 'libasound2-plugins'
NOTICE: 'alsa-plugins' packaging is maintained in the 'Bzr' version control system at:
https://code.launchpad.net/~ubuntu-core-dev/alsa-plugins/ubuntu
Please use:
bzr get https://code.launchpad.net/~ubuntu-core-dev/alsa-plugins/ubuntu
to retrieve the latest (possibly unreleased) updates to the package.
Need to get 474kB of source archives.
Get:1 http://in.archive.ubuntu.com/ubuntu/ lucid/main alsa-plugins 1.0.22-0ubuntu6 (dsc) [2,181B]
Get:2 http://in.archive.ubuntu.com/ubuntu/ lucid/main alsa-plugins 1.0.22-0ubuntu6 (tar) [456kB]
Get:3 http://in.archive.ubuntu.com/ubuntu/ lucid/main alsa-plugins 1.0.22-0ubuntu6 (diff) [15.5kB]
Fetched 474kB in 1min 13s (6,417B/s)                                           
sh: dpkg-source: not found
Unpack command 'dpkg-source -x alsa-plugins_1.0.22-0ubuntu6.dsc' failed.
Check if the 'dpkg-dev' package is installed.
E: Child process failed
root@som-laptop:/tmp# apt-get build-dep libasound2-plugins
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Picking 'alsa-plugins' as source package instead of 'libasound2-plugins'
The following NEW packages will be installed:
  autotools-dev build-essential cvs debhelper diffstat dpkg-dev g++ g++-4.4
  gcc-4.4-multilib gcc-multilib gettext html2text intltool-debian lib64asound2
  lib64asound2-dev lib64gcc1 lib64gomp1 libasound2-dev libavahi-client-dev
  libavahi-common-dev libc6-amd64 libc6-dev-amd64 libdbus-1-dev libglib2.0-dev
  libice-dev libjack-dev libmail-sendmail-perl libpthread-stubs0
  libpthread-stubs0-dev libpulse-dev libsamplerate0-dev libsm-dev libspeex-dev
  libspeexdsp-dev libstdc++6-4.4-dev libsys-hostname-long-perl libx11-dev
  libxau-dev libxcb1-dev libxdmcp-dev libxt-dev po-debconf quilt
  x11proto-core-dev x11proto-input-dev x11proto-kb-dev xtrans-dev xz-utils
  zlib1g-dev
0 upgraded, 49 newly installed, 0 to remove and 0 not upgraded.
Need to get 29.5MB of archives.
After this operation, 84.6MB of additional disk space will be used.
Do you want to continue [Y/n]? Y
Abort.

please help me.there is no sound at all.i just now want to get back the sound.is it possible?or do i have to go for a fresh install?

[oblib]

som21, try deleting the asound.conf file and rebooting.

sudo rm /etc/asound.conf

That's the only system change you made, otherwise I can't imagine what went wrong.

[som21]

ok;i'll try and let you know.but why did it abort?any idea?

[som21]

ok;i'll try and let you know.but why did it abort?any idea?