Add support for 24-bit and 32-bit audio output.

[AliceLR]

Patches necessary to actually use the 32-bit output support added by libxmp/libxmp#964 (see libxmp/libxmp#924). This is a work in progress and can be finished after libxmp 4.7.0 is out.

Drivers with 24-bit and 32-bit audio support:

• ALSA
• CoreAudio
• NetBSD
• OSS
• PulseAudio
• sndio
• WinMM
• Raw file
• WAV file

Skipped drivers (I do not have a testing environment):

• ALSA 0.5
• BSD

Drivers that do not support 24-bit or 32-bit:

• Sound Blaster

Drivers to verify:

• AHI
• AIFF file
• AIX
• BeOS
• DART
• HP-UX
• QNX
• SGI
• Solaris

[sezero]

Drivers with 24-bit and 32-bit audio support:

* [ ]  OSS

I think it's possible with new (4.x) oss versions, e.g. freebsd: See their sys/soundcard. h at https://cgit.freebsd.org/src/tree/sys/sys/soundcard.h#n175 for AFMT_S32_NE and AFMT_S24_NE, for e.g.

* [ ]  ALSA 0.5

Can't we just remove that prehistoric backend?

[AliceLR]

I think it's possible with new (4.x) oss versions, e.g. freebsd: See their sys/soundcard. h at https://cgit.freebsd.org/src/tree/sys/sys/soundcard.h#n175 for AFMT_S32_NE and AFMT_S24_NE, for e.g.

I think this is correct, but I didn't look that closely. The current lists were kind of just guessing based on the defines I could easily search. The only drivers I looked at with any depth are the ones that are updated and working, so far. (Also, I forgot to put WinMM in the list—seems that like WAV, it works but you need to use WAVEFORMATEXTENSIBLE?)

Can't we just remove that prehistoric backend?

Not sure; I think if that happens, it should wait for a later release. (I think anything that only supports ancient ALSA should also have OSS?)

[AliceLR]

SND_PCM_FORMAT_S8 played as if it was using the wrong signedness the last time I tested it, may need investigation. (This may be a PipeWire bug or something else, though.)

[AliceLR]

AFMT_S32_NE

Confirmed that this works in NetBSD. I will try the other BSDs too once I'm done with NetBSD (if only to see if anything actually supports AFMT_S24_NE...).

[AliceLR]

* [ ]  sndio

You need to use model=ac97 to even get this to work out of the box running in QEMU??? 🤨

Is there anything modern that supports the "BSD" driver or should I dig up older BSD releases?