[FFmpeg-trac] #3455(ffmpeg:new): aresample=matrix_encoding=dplii doesn't downmix backleft and center correctly

FFmpeg trac at avcodec.org
Wed Mar 12 23:02:40 CET 2014


#3455: aresample=matrix_encoding=dplii doesn't downmix backleft and center
correctly
-------------------------------------+-------------------------------------
             Reporter:  Peter        |                     Type:  defect
               Status:  new          |                 Priority:  normal
            Component:  ffmpeg       |                  Version:  git-
             Keywords:  aresample    |  master
  matrix_encoding dplii              |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 Summary of the bug: DPLII files have too-loud right channel.
 Seems to be some problem with the interaction of back left and center
 channel
 How to reproduce:
 {{{
 ffmpeg -i surround_blbrc.wav -af "aresample=matrix_encoding=dplii" -ac 2
 dplii_blbrc.wav
 ffmpeg version git-2014-03-09-8dfd0e6
 built on Mar  9 2014 22:53:26 with gcc 4.8.2 (Gentoo 4.8.2 p1.3r1,
 pie-0.5.8r1)
 }}}
 You can see the problem easiest by crafting a 5.1 surround wave file with
 empty channels except the center channel with noise and the two back
 channels, first half of the back left with noise and the second half of
 the back right with noise. However, all surround files that use the bl and
 center channels at the same time will be too loud in the resulting file's
 right channel.

 Can provide example files if you like.

--
Ticket URL: <https://trac.ffmpeg.org/ticket/3455>
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