[Bug 52512] New: Skyrim Legendary Edition regression in Wine 6.21: some in-game sounds no longer work

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=52512

Bug ID: 52512
           Summary: Skyrim Legendary Edition regression in Wine 6.21: some
                    in-game sounds no longer work
           Product: Wine
           Version: 6.21
          Hardware: x86-64
                OS: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: -unknown
          Assignee: [e-mail]
          Reporter: [e-mail]
                CC: [e-mail], [e-mail]
   Regression SHA1: babaf916ab12c7a9128409f717878919ccc5826b
      Distribution: Ubuntu

Created attachment 71813
  --> https://bugs.winehq.org/attachment.cgi?id=71813
Wine output log at commit babaf916ab12c7a9128409f717878919ccc5826b

Starting with Wine 6.21, some in-game audio no longer works, including game
music, all NPC voices, and player's voice during attacks. Other sounds still
work normally, such as GUI sounds, weapon sounds, magic casting, footsteps and
doors opening and closing. It's as if the game only plays a single audio
channel. The bug is reproducible in any game area, for example by starting a
new game or loading an existing save.

I did a regression test, and it seems that the bug was actually introduced
earlier in Wine 6.20, with the following commit:
> d8be85863fedf6982944d06ebd1ce5904cb3d4e1
> xaudio: Use the bundled FAudio and build with msvcrt.

However, in that version the game crashes immediately after the intro sequence
with error:
> Assertion failed: (voice->src.wmadec != NULL && (pBufferWMA != NULL || voice->src.format->wFormatTag == FAUDIO_FORMAT_XMAUDIO2)) || 
> (voice->src.wmadec == NULL && (pBufferWMA == NULL && voice->src.format->wFormatTag != FAUDIO_FORMAT_XMAUDIO2)), file ../wine-git/lib
> s/faudio/src/FAudio.c, line 2456

Then, this seems to have been fixed immediately in the next release 6.21, in
commit:
> babaf916ab12c7a9128409f717878919ccc5826b
> faudio: Build with -DNDEBUG.

After this the game works, but it behaves as described above. The attached log
was made using the second commit. The bug is still present in the current
latest 7.1 release.

I've CC'ed the authors of both commits like mentioned on the regression testing
wiki page, I'm uncertain which one should be considered more relevant for the
bug. My interpretation is that the newly introduced bundled version of the
faudio library is built or configured differently than the previous
distro-provided shared dependency, and disabling debug assertions just made the
message go away but there's still an issue, so I guess both are relevant.

Additional info:
OS: Ubuntu Focal 20.04.3 LTS
Kernel: 5.13.0-27-generic x86_64
Wine Prefix: 32 bit, clean
GPU: NVIDIA Corporation GF108 [GeForce GT 730] (rev a1)
Graphics Driver: Proprietary NVIDIA ver. 390.144