Enable (unmute) HDMI audio outputs by default

[Danté]

On a good number of Ubuntu devices, Ubuntu fails to deliver sound through HDMI; however the fix is simple; in the terminal, if you run 'alsamixer' you should see a few entries; S/PDIF, S/PDIF Def and S/PDIF 1. They are, for some odd reason, muted by default. Unmuting them (and setting sound prefernces to output through HDMI) gives you sound.

I suggest unmuting these channels.

[Daniel T Chen (crimsun)]

This requires a change to either the deprecated initscript or (preferably) the init db. In the case of the latter, converting the udev rule to use alsactl init instead of start would suffice.

[Chris Wilson (notgary-deactivatedaccount)]

With hardware vendors confirming the phasing out of all VGA support by a specified date in favour of DisplayPort and HDMI, any problems encountered with either of these connections will have a massive impact on the user experience so I am confirming this as a papercut.

[David Henningsson (diwic)]

Hmm, wouldn't changing the profile/connector in PulseAudio automatically unmute these items? Or are you talking about non-pulseaudio applications here?

[Danté (dante-ashton)]

PulseAudio (at least with the 4 TV's I've tried it with) does NOT unmute these channels regardless of the profile chosen. Sound simply silently fails.

What would be perhaps far more interesting (and user friendly) would be some sort of mechanism that offers to switch sound through a new device; a sort of 'plug 'n' play for speakers. But I fear that might be out of the scope of the Papercuts project.

[David Henningsson (diwic)]

@Danté, ok, it seems you're right, there are no mixer paths specified for HDMI in pulseaudio. Perhaps we should add one and let that one turn spdif and iec958 on?

As for "plug'n'play for HDMI", we're currently missing jack detection support both in PulseAudio and the HDA HDMI module, so yes, that would be more than a papercut project can handle.