Add custom audio hardware settings

[dsborets]

Custom settings for ALSA in case of multiple sound cards (hardware) installed in the system.
Background:
In my Pycroft I installed HifiBerry AMP HiFi tas5713 sound card and it's visible in the system as a card no 1

card 0: Headphones [bcm2835 Headphones], device 0: bcm2835 Headphones [bcm2835 Headphones]
card 1: sndrpihifiberry [snd_rpi_hifiberry_amp], device 0: HifiBerry AMP HiFi tas5713.1-001b-0 [HifiBerry AMP HiFi tas5713.1-001b-0]
...

and what is more important it has two different volume controls: Master and Channels
in my case I decided to use Channels to control a volume.

I think these settings will be useful for some customers

[ken-mycroft]

Looks good.

[krisgesling]

Hey Denis, this looks like a great feature, thanks!

The challenge at the moment is that currently when Skill settings definitions are modified, the home.mycroft.ai backend see's that as a new block of settings and hence any existing settings are effectively reset to the default. Using this Skill as example, if we push this change out then anyone who had changed their "duck while listening" setting, would suddenly have that reverted.

We're talking about if we can prioritize the work to fix this at the moment. That would mean we can safely merge this in without impacting users who have changed their ducking setting. So please bear with us for a moment.

[dsborets]

Hi Kris. Sure, I understand. Do you have an link to that issue?

[krisgesling]

I don't think we had a public ticket for it previously so I've added one here:
MycroftAI/selene-backend#260