[FFmpeg-trac] #2852(avcodec:new): dcadec internal default downmix is not normalised and reduces stereo separation by cross mixing L* and R*.

[FFmpeg]

#2852: dcadec internal default downmix is not normalised and reduces stereo
separation by cross mixing L* and R*.
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             Reporter:  AndyF       |                    Owner:
                 Type:  defect      |                   Status:  new
             Priority:  normal      |                Component:  avcodec
              Version:  git-master  |               Resolution:
             Keywords:  dca         |               Blocked By:
             Blocking:              |  Reproduced by developer:  0
Analyzed by developer:  0           |
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Comment (by AndyF):

 Replying to [comment:1 cehoyos]:
 > Does the output change if you change the default matrix in dcadata.h?

 Yes I just tried below and the results were as I expected = no cross
 mixing and center/surround at -3dB but still not normalised.

 diff --git a/libavcodec/dcadata.h b/libavcodec/dcadata.h
 index 15df49e..55f9c33 100644
 --- a/libavcodec/dcadata.h
 +++ b/libavcodec/dcadata.h
 @@ -7566,7 +7566,7 @@ static const uint8_t dca_default_coeffs[10][5][2] =
 {
      { {  0, 25 }, { 25,  0 }, { 13, 13 },                         },
      { {  6,  6 }, {  0, 25 }, { 25,  0 }, { 13, 13 },             },
      { {  0, 25 }, { 25,  0 }, {  0, 13 }, { 13,  0 },             },
 -    { {  6,  6 }, {  0, 25 }, { 25,  0 }, {  0, 13 }, { 13,  0 }, },
 +    { {  13,  13 }, {  0, 64 }, { 64,  0 }, {  13, 64 }, { 64,  13 }, },
  };

  /* downmix coeffs

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Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/2852#comment:2>
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