Problem solved but I don't know what I did - can anyone explain?

[Chris Angelico]

On Tue, 10 Sept 2024 at 16:18, George Kiagiadakis <mail at gkiagia.gr> wrote:
> > On the previous installation, I would use the sink
> > "alsa_output.usb-Generic_USB_Audio-00.HiFi_7_1__hw_Audio_2__sink" to
> > send audio to the S/PDIF. Nothing I've done has made any such device
> > name appear.
>
> These profiles are made available by the ALSA UCM configuration files, which are being installed by some ALSA package. Perhaps you are missing those, or this new installation has a different version of those files (or something like that). These files describe how the various ALSA devices, subdevices and controls map to real inputs/outputs and use cases.
>

Thanks! That is definitely helpful. So it's possible that the
alsa-ucm-conf package may have been a part of this. It seems I have
version 1.2.8-1 on my new system, and 1.2.10 on the old, so there
could well be a discrepancy.

> Not sure what "as of now" means. These profile has been available for a long time. Unless you had a really old version of PipeWire running previously (or you were even using PulseAudio) and you just upgraded to a more recent one.
>

At time of writing. I don't know what changed that made it appear,
which is why I was asking. It's possible that I upgraded alsa-ucm-conf
and that's what made it appear.

> > My best guess is that installing OBS Studio build dependencies may
> > have done something. I'd previously been running OBS as installed from
> > Debian's repos, and now am about to start building from source,
> > although I hadn't actually done the build yet - just installed the
> > build deps and cloned the repo.
>
> OBS has nothing to do with this.
>

Yeah, I didn't think so, but was wondering if it dragged in a
dependency somewhere.

Thanks for your help. I can now, at very least, note down that the
version of alsa-ucm-conf could be relevant, and the
/usr/share/alsa/ucm2/conf.d directory.

ChrisA