Audio

I should have included all the necessaries but you might need to check specific drivers depending on OEM.

The idea is that all this config is at the top of the script so you can easily modify.

HDMI Ouput

Go to settings select "Audio Pro", toggle a device and press the test button.

aplay -l to check devices or xrandr --listmonitors

Then you can xrandr --output HDMI-A-1 --auto replacing with your values.

Can also use lspci and wpctl to configure further.

ps aux | grep pulse to check that its running.

Pavucontrol

This app can let you easily manage these things with a GUI and advanced features but depends on quite a bit of things so I didn't include by default as we have alsamixer.

Alsamixer

alsamixer this weird terminal app you will need to open with usershell.

Note: Careful that if you select x11 you will need to do alsamixer (usershell) again.

Then unmute channels that are not green. This was my issue. To do so f6 select the card. Then activate ones that are not green mine was something like PDIFx then simply "M" to mute/unmute. You can also go back to settings and rename your devices to HMDI or appropriate. From alpine wiki:

nano /usr/share/alsa/alsa.conf

Scroll down until you find the lines that start with defaults.ctl.card and defaults.pcm.card and put the number (you found in the F6 context menu of the alsamixer command for the soundcard you want as your default) at the end of those lines separated by a space for each. For example, if the default sound card you want is "1".

Contents of /usr/share/alsa/alsa.conf
...
defaults.ctl.card 1
defaults.pcm.card 1
...

Save your nano work by pressing Ctrl+O and confirm the changes by pressing Enter. Then exit nano by pressing Ctrl+X.

Try turning up the volume of Master and the device(s) such as speakers or microphones that you need with the alsamixer command, and audio should work. 

For older hardware you might need more like ucm-conf or more utils/firmware...