[FFmpeg-trac] #9858(ffmpeg:new): Automatic stream selection doesn't work correctly

[FFmpeg]

#9858: Automatic stream selection doesn't work correctly
--------------------------------+---------------------------------------
             Reporter:  Ptaah   |                     Type:  defect
               Status:  new     |                 Priority:  normal
            Component:  ffmpeg  |                  Version:  unspecified
             Keywords:          |               Blocked By:
             Blocking:          |  Reproduced by developer:  0
Analyzed by developer:  0       |
--------------------------------+---------------------------------------
 Summary of the bug: Automatic stream selection doesn't work correctly on
 audio for one particular file.
 How to reproduce:
 {{{
 % ffmpeg.exe -y -i noisemeter.mov -f lavfi -i anullsrc=cl=mono -vcodec
 copy -acodec copy -t 2 test.mov
 ffmpeg version n5.1-3-g80d1b8938e-20220801
 built with gcc 12.1.0 (crosstool-NG 1.25.0.55_3defb7b)
 }}}

 According to ffmpeg documentation regarding automatic stream selection:

 It will select that stream based upon the following criteria:

 - for video, it is the stream with the highest resolution,
 '''- for audio, it is the stream with the most channels,'''
 - for subtitles, it is the first subtitle stream found but there’s a
 caveat. The output format’s default subtitle encoder can be either text-
 based or image-based, and only a subtitle stream of the same type will be
 chosen.

 This is, however, not the case in this example.

 {{{
 Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'noisemeter.mov':
   Metadata:
     major_brand     : qt
     minor_version   : 537199360
     compatible_brands: qt
     creation_time   : 2022-07-13T14:21:10.000000Z
   Duration: 00:02:52.51, start: 0.000000, bitrate: 947309 kb/s
   Stream #0:0[0x1](eng): Video: qtrle (rle  / 0x20656C72),
 argb(progressive), 3840x2160, 945725 kb/s, SAR 1:1 DAR 16:9, 23.98 fps,
 23.98 tbr, 24k tbn (default)
     Metadata:
       creation_time   : 2022-07-13T14:21:10.000000Z
       handler_name    : Apple Video Media Handler
       vendor_id       : appl
       encoder         : Animation
       timecode        : 00:00:00:00
   Stream #0:1[0x2](eng): Audio: pcm_s16le (sowt / 0x74776F73), 48000 Hz,
 stereo, s16, 1536 kb/s (default)
     Metadata:
       creation_time   : 2022-07-13T14:21:10.000000Z
       handler_name    : Apple Sound Media Handler
       vendor_id       :
       timecode        : 00:00:00:00
   Stream #0:2[0x3](eng): Data: none (tmcd / 0x64636D74) (default)
     Metadata:
       creation_time   : 2022-07-13T14:21:10.000000Z
       handler_name    : Time Code Media Handler
       timecode        : 00:00:00:00
 Input #1, lavfi, from 'anullsrc=cl=mono':
   Duration: N/A, start: 0.000000, bitrate: 352 kb/s
   Stream #1:0: Audio: pcm_u8, 44100 Hz, mono, u8, 352 kb/s
 Output #0, mov, to 'test.mov':
   Metadata:
     major_brand     : qt
     minor_version   : 537199360
     compatible_brands: qt
     encoder         : Lavf59.27.100
   Stream #0:0(eng): Video: qtrle (rle  / 0x20656C72), argb(progressive),
 3840x2160 [SAR 1:1 DAR 16:9], q=2-31, 945725 kb/s, 23.98 fps, 23.98 tbr,
 24k tbn (default)
     Metadata:
       creation_time   : 2022-07-13T14:21:10.000000Z
       handler_name    : Apple Video Media Handler
       vendor_id       : appl
       encoder         : Animation
       timecode        : 00:00:00:00
   Stream #0:1: Audio: pcm_u8 (raw  / 0x20776172), 44100 Hz, mono, u8, 352
 kb/s
 Stream mapping:
   Stream #0:0 -> #0:0 (copy)
   Stream #1:0 -> #0:1 (copy)
 }}}

 For some reason, ffmpeg selects mono silence generated by anullsrc,
 instead of stereo pcm_s16le from source file. Now here is the really weird
 thing. It only does this for this particular file. If I try to make the
 file smaller (with vcodec copy, acodec copy), it works file. And since
 it's RLE + uncompressed video, it's size is 20 GB.

 For those really brave and patient, here is the mov file:
 https://mega.nz/file/8tRQFTZa#K02DK2QSRlm2DTvcwYHBXm4cbDilhhVvu4vTkqZUzI4
-- 
Ticket URL: <https://trac.ffmpeg.org/ticket/9858>
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