[Bug 46996] New: Improvements to the 7.1 and 5.1 to stereo conversion

https://bugs.winehq.org/show_bug.cgi?id=46996

Bug ID: 46996
           Summary: Improvements to the 7.1 and 5.1 to stereo conversion
           Product: Wine
           Version: unspecified
          Hardware: x86
                OS: Linux
            Status: UNCONFIRMED
          Severity: trivial
          Priority: P2
         Component: directx-dsound
          Assignee: [e-mail]
          Reporter: [e-mail]
      Distribution: ---

Created attachment 64159
  --> https://bugs.winehq.org/attachment.cgi?id=64159
a tar file with all of the patches

The existing implementation of put_surround512stereo is a bit misleading
because it takes into account LFE (Low-Freq Effects) that most likely can't be
reproduced by stereo setups and should be just ignored. Source:
https://www.audiokinetic.com/library/edge/?source=Help&id=standard_confi...

Also the values for other channels emphasize more on the front L/R channels
than on anything else. This is why some surround effects are barely audible.
And instead of relying on a algorithm from pulseaudio to determine the values
for the downmixer we can use a standard table for downmixing. Source:
https://www.audiokinetic.com/library/edge/?source=Help&id=downmix_tables

NOTE: Back speakers apparently are subwoofers in the 5.1 and 7.1 spec. So the
documentation may be misleading as well.

I also would like if support for converting 7.1 to stereo to be added to the
dsound component, because games like Need for Speed: Rivals loose audio some
capabilities, fxp. in game dialog is non-existant without this and turn it into
a worse experience than on windows.

Since I already made these changes and tried them out for basic testing, I'll
attach my diffs.

Also any tips on contributing would be helpful,
Cheers