[libav-bugs] [Bug 827] New: MPEG-TS extraction using avconv -map 0:p:N selects wrong audio channel

bugzilla at aruru.libav.org bugzilla at aruru.libav.org
Wed Mar 4 20:58:50 CET 2015


https://bugzilla.libav.org/show_bug.cgi?id=827

            Bug ID: 827
           Summary: MPEG-TS extraction using avconv -map 0:p:N selects
                    wrong audio channel
           Product: Libav
           Version: 10
          Hardware: X86
                OS: BSD
            Status: NEW
          Severity: normal
          Priority: ---
         Component: utilities
          Assignee: bugzilla at libav.org
          Reporter: avcv at opal.com

Trying to extract MPEG-PS from an MPEG-TS.

Avprobe info is this:

avprobe version 10.2, Copyright (c) 2007-2014 the Libav developers
  built on Nov  6 2014 12:43:54 with FreeBSD clang version 3.3
(tags/RELEASE_33/final 183502) 20130610
Input #0, mpegts, from '2015_03_03_04_00.m2t':
  Duration: 19:30:23.06, start: 22496.216511, bitrate: 1988 kb/s
  Program 7 
    Stream #0.3[0x71]: Video: mpeg2video (Main), yuv420p, 1920x1080 [PAR 1:1
DAR 16:9], 24000 kb/s, 29.97 fps, 90k tbn, 59.94 tbc
    Stream #0.6[0x74](eng): Audio: ac3, 48000 Hz, stereo, fltp, 192 kb/s
    Stream #0.4[0x75](eng): Audio: ac3, 48000 Hz, stereo, fltp, 128 kb/s
(visual impaired)
  Program 4 
    Stream #0.0[0x41]: Video: mpeg2video (Main), yuv420p, 704x480 [PAR 10:11
DAR 4:3], 15000 kb/s, 29.97 fps, 90k tbn, 59.94 tbc
    Stream #0.1[0x44](eng): Audio: ac3, 48000 Hz, stereo, fltp, 192 kb/s
    Stream #0.2[0x45](eng): Audio: ac3, 48000 Hz, mono, fltp, 128 kb/s (visual
impaired)
  Program 5 
    Stream #0.7[0x51]: Video: mpeg2video (Main), yuv420p, 704x480 [PAR 10:11
DAR 4:3], 15000 kb/s, 29.97 fps, 90k tbn, 59.94 tbc
    Stream #0.5[0x54](eng): Audio: ac3, 48000 Hz, stereo, fltp, 192 kb/s
    Stream #0.8[0x55](eng): Audio: ac3, 48000 Hz, mono, fltp, 128 kb/s (visual
impaired)
# avprobe output

Conversion command is this:

avconv -i /var/db/freevo/tv/2015_03_03_04_00.m2t -map 0:p:7 -codec:v mpeg2video
-r 30000/1001 -b:v 1200k -s 1024x576 -codec:a ac3 -b:a 192k -ac 6 -af
volume=6dB -y /var/db/freevo/tv/2015_03_03_04_00.mpg

The result is that video stream 0.3 and audio 0.4 are extracted to the mpg.

This is not correct: it should be that streams 3 and 6 are extracted.

The alternative command:

avconv -i /var/db/freevo/tv/2015_03_03_04_00.m2t -map 0:3 -map 0:6 -codec:v
mpeg2video -r 30000/1001 -b:v 1200k -s 1024x576 -codec:a ac3 -b:a 192k -ac 6
-af volume=6dB -y /var/db/freevo/tv/2015_03_03_04_00.mpg

works as desired, but I think the default behavior of selection using 0:p:N
should be to use the first audio channel, not the lowest-numbered one.  Okay,
lowest numbered is generally first, but the sort should be on the hex 0xNN
field rather than the 0.N field.

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