Ubuntu: Problem with 5.1 AC-3 through Alsa, Pulseaudio on SPDIF, Ubuntu 14.04


I have Ubuntu 14.04 installed (i386 Architecture) on Zotac ZBOX-ID18.

I am trying to output digital surround audio through digital SPDIF output, I understand that the default SPDIF output is on PCM format which is stereo only (not 5.1 surround).

I did install the AC3 plugin using the below as a reference, however even after selecting "Digital 5.1 Output" profile, I don't get any audio output at all.


I tried forcing this profile from default.pa and from pavucontrol but still no luck :(

Also tried running aplay -D a52:0 but not getting any output.

In some random cases I was able to output digital surround by playing test videos but it happened only few cases and couldn't relate this cases with any other events or config changes, it was pure random.


Finally managed to set this permanently, I had to add the following command in the startup applications.

pacmd set-card-profile 0 output:iec958-ac3-surround-51

To verify the name of you sound profile, run following command, u'll get all available profiled for ur sound card.

pacmd info

For some reason adding this default device in default.pa didn't work, but adding it as a startup command is working, now I don't need to open pavucontrol every time I reboot my machine.


I eventually had luck by doing the weirdest thing. Leaving pavucontrol up. That's right - I just don't close it. As long as I select one of the two Digital Surround 5.1 profile options (one includes Analog input) under the built-in audio section under the configuration tab of pavucontrol then DON'T CLOSE that app, I get working 5.1 audio in all other programs. If I close it, I go back to wonky issues including my receiver freaking out trying to decode whatever my computer is outputting and not knowing what to do.


Same issue as John N, trying to get SPDIF working on a Zotac box, using Ubuntu 14.10. I walked through the same steps, and got 5.1 channel sound selected, but when trying to play videos without pavucontrol open the videos would freeze and the AV receiver would show intermittent signal being received. Leaving pavucontrol open did indeed enable playback of any video, through mplayer, VLC, or XBMC.

Trying the pacmd command in startup applications, however, did not solve the problem. Neither the example given nor any relevant variation worked, and I'd welcome input on configuring that command.

Ultimately what I did was simply add pavucontrol to the startup applications and leave it running in the background or minimised while using XBMC or other playback utilities. Not elegant, but effective, especially since no future user can accidentally forget to run pavucontrol before trying to play a file.

Note:If u also have question or solution just comment us below or mail us on toontricks1994@gmail.com
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