[FFmpeg-trac] #8035(undetermined:new): Issue with audio channel mapping

[FFmpeg]

#8035: Issue with audio channel mapping
-------------------------------------+-------------------------------------
             Reporter:  svihalekjan  |                     Type:  defect
               Status:  new          |                 Priority:  normal
            Component:               |                  Version:
  undetermined                       |  unspecified
             Keywords:               |               Blocked By:
  filter_complex amerge audio        |
  channel mapping                    |
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 '''WHAT I AM TRYING TO DO:
 '''
 I am encoding an HD mxf video file into other HD mxf video file (different
 parameters) - the video conversion is ok.
 I am also trying to encode the input file (that has 8 audio streams - each
 1 channel; 48 kHz, 24b PCM, more info in attached MediaInfo -
 input_file_mediainfo.txt) so that the output file will have 1 audio stream
 defined as follows:
 '''1 audio stream:'''
  -  1st channel = 1st channel of 1st audio stream of input file
  -  2nd channel = 1st channel of 2nd audio stream of input file
  -  3rd-8th channel = empty audio channel
 Input file media info can be found in '''input_file_mediainfo.txt'''.

 The issue happens with ffmpeg-20190327-681957b-win32-static build (and
 ffmpeg-20190411-3e10223-win64-static),
 but does not happen with ffmpeg-4.0-win32-static build
 (https://ffmpeg.zeranoe.com/builds/win32/static/ffmpeg-4.0-win32-static.zip)
 or
 https://ffmpeg.zeranoe.com/builds/win64/static/ffmpeg-4.0-win64-static.zip.
 (32b builds are being used on server; 64b builds used on local PC)


 '''PROBLEM ENCOUNTERED:'''
 The issue is with the fact that output audio sounds has some "dither"-like
 & noise feel after 1st minute.
 With some other files there are blank parts of audio within the
 channel(s).

 '''EXACT FFMPEG COMMAND:'''
 {{{
 % ffmpeg -v 9 -loglevel 99 -i "audio_channel_mapping_issue_2_22.mxf" -f
 lavfi -i anullsrc=r=48000:cl=mono -map 0:v -y -c:v mpeg2video -s 1920x1080
 -video_format pal -profile:v 0 -level:v 2 -r 25 -aspect 16:9 -flags +ildct
 -b:v 50000k -minrate 50000k -maxrate 50000k -filter_complex
 "[0:a:0][0:a:1][1:a:0][1:a:0][1:a:0][1:a:0][1:a:0][1:a:0]amerge=inputs=8[a]"
 -acodec pcm_s24le -map "[a]" "OUTPUT.mxf"
 }}}

 '''FULL CONSOLE OUTPUT (+OUTPUT FILE MEDIAINFO):'''
 new build (where the issue appears):
 '''ffmpeg-20190704-140832.log''' & '''newer_build_output_mediainfo.txt'''
 older build (without any issues):
 '''ffmpeg-20190704-145519.log''' & '''older_build_output_mediainfo.txt'''

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Ticket URL: <https://trac.ffmpeg.org/ticket/8035>
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