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

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.

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.

This wasn't working for me in Ubuntu 20.04.1 (Focal Fossa) until I configured /etc/pulse/daemon.conf and changed

; default-sample-rate = 44100 

to

 default-sample-rate = 48000

Don't forget this step! :)