These shouldn't be enabled by default, because they cannot be
autodetected, and if the configuration is not a supported one, they
produce loud BRRRT at 100% volume and ALSA errors.
It is sometimes useful to add a custom profile-set.
For that, e.g. `default.conf` needs to be modified.
(at least, i have not succeeded in just adding a new file)
But that change gets overridden when the package is updated,
which could be *extremely* dangerous, e.g. if said profile
changed the `volume-limit`.
By shipping an "empty" `9999-custom.conf`,
the update becomes less problematic,
because one can now use e.g. `dpkg-divert` on said file.
Refs. https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1050293
This is a follow-up to d5390c7, where we switched to the 'PCM' mixer controls
on Sound Blaster Audigy devices, since the ones we used before only work in the
stereo-to-all-speakers mirroring mode.
It turns out we do use that mode after all, but only in a couple of profiles.
Since returning those profiles to the default mixer path yields uneven volume
steps similar to #2934, we instead add a new mixer path just for that mode.
Creative Labs Sound Blaster Audigy cards (snd_emu10k1 driver) expose
mixer controls named 'PCM Front', 'PCM Rear', etc. in addition to the
more common 'Front', 'Rear', etc. The latter seem to be intended for
a stereo-to-all-speakers mirroring mode that we do not use, and have
no effect when we adjust them.
https://docs.kernel.org/sound/cards/audigy-mixer.html
We therefore define a custom mixer path for Audigy devices, using the
PCM mixer controls.
This has been tested on an Audigy 5/Rx. Based on a brief look at the
ALSA driver, I think all Audigy devices (vendor 0x1102, device 0x0004
or 0x0008) have the same PCM controls, making this change probably safe
for our existing Audigy udev rules.
Relevant kernel files:
sound/pci/emu10k1/emu10k1_main.c
sound/pci/emu10k1/emufx.c
include/sound/emu10k1.h
Fixes#2934
Motu M4 has four inputs (two line-in inputs, and two complete ones
with gain and XLR and whatnot), as well as four outputs (two monitor
pairs, and an unnaccounted headphone).
Sadly, like a few other interfaces, it wasn't being given an input
profile, since the matching code goes through default.conf testing
each config, and ends up selecting 'analog-surround-40', which does
not have input mapping. The inputs would fallback to 'multichannel-
input', which also doesn't have input paths.
Add input paths to all analog-surround-* mappings, and remove their
'direction=output' fields since they handle both out and in.
