[libav-bugs] [Bug 370] New: Combining -filter_complex and -map results in unrequested audio track

bugzilla-daemon at aruru.libav.org bugzilla-daemon at aruru.libav.org
Tue Sep 18 03:04:25 CEST 2012


http://bugzilla.libav.org/show_bug.cgi?id=370

           Summary: Combining -filter_complex and -map results in
                    unrequested audio track
           Product: Libav
           Version: git HEAD
          Platform: X86
        OS/Version: Mac OS
            Status: NEW
          Severity: normal
          Priority: Normal
         Component: utilities
        AssignedTo: bugzilla at libav.org
        ReportedBy: tdskywalker at gmail.com


I have a file with two audio tracks:

https://dl.dropbox.com/u/37259775/libav/af_aformat/filter_complex_aformat_map.mkv

I'd like to encode the second audio track to Stereo WAV, using the aformat
filter to downmix.

I tried placing -map before and after -filter_complex, but neither seems to
give the results I'm expecting. For some reason there are two (!) audio tracks
in the output.

--------------------------
1) -map before -filter_complex

avconv -i filter_complex_aformat_map.mkv -map 0:2 -filter_complex
aformat="channel_layouts=stereo" ~/Desktop/test.wav
avconv version v0.8-3125-g2a8a860, Copyright (c) 2000-2012 the Libav developers
  built on Sep 18 2012 02:31:55 with llvm-gcc 4.2.1 (LLVM build 2336.11.00)
Input #0, matroska,webm, from 'filter_complex_aformat_map.mkv':
  Duration: 00:00:14.00, start: 0.000000, bitrate: N/A
    Stream #0.0(eng): Video: h264 (High), yuv420p, 1280x720 [PAR 1:1 DAR 16:9],
24 fps, 24 tbr, 1k tbn, 48 tbc (default)
    Stream #0.1(eng): Audio: dca (DTS), 48000 Hz, 5.0, s16, 768 kb/s (default)
    Stream #0.2(eng): Audio: dca (DTS), 48000 Hz, 5.1, s16, 768 kb/s
Output #0, wav, to '/Users/tim/Desktop/test.wav':
  Metadata:
    encoder         : Lavf54.16.1
    Stream #0.0: Audio: pcm_s16le, 48000 Hz, stereo, s16, 1536 kb/s (default)
    Stream #0.1(eng): Audio: pcm_s16le, 48000 Hz, 5.1, s16, 4608 kb/s
Stream mapping:
  Stream #0:1 (dca) -> aformat (graph 0)
  aformat (graph 0) -> Stream #0:0 (pcm_s16le)
  Stream #0:2 -> #0:1 (dca -> pcm_s16le)
Press ctrl-c to stop encoding
size=    9944kB time=11.53 bitrate=7065.4kbits/s    
video:0kB audio:9944kB global headers:0kB muxing overhead 0.000452%
--------------------------------------------------------------

--------------------------
2) -map after -filter_complex

avconv -i filter_complex_aformat_map.mkv -filter_complex
aformat="channel_layouts=stereo" -map 0:2 ~/Desktop/test.wav
avconv version v0.8-3125-g2a8a860, Copyright (c) 2000-2012 the Libav developers
  built on Sep 18 2012 02:31:55 with llvm-gcc 4.2.1 (LLVM build 2336.11.00)
Input #0, matroska,webm, from 'filter_complex_aformat_map.mkv':
  Duration: 00:00:14.00, start: 0.000000, bitrate: N/A
    Stream #0.0(eng): Video: h264 (High), yuv420p, 1280x720 [PAR 1:1 DAR 16:9],
24 fps, 24 tbr, 1k tbn, 48 tbc (default)
    Stream #0.1(eng): Audio: dca (DTS), 48000 Hz, 5.0, s16, 768 kb/s (default)
    Stream #0.2(eng): Audio: dca (DTS), 48000 Hz, 5.1, s16, 768 kb/s
Output #0, wav, to '/Users/tim/Desktop/test.wav':
  Metadata:
    encoder         : Lavf54.16.1
    Stream #0.0: Audio: pcm_s16le, 48000 Hz, stereo, s16, 1536 kb/s (default)
    Stream #0.1(eng): Audio: pcm_s16le, 48000 Hz, 5.1, s16, 4608 kb/s
Stream mapping:
  Stream #0:1 (dca) -> aformat (graph 0)
  aformat (graph 0) -> Stream #0:0 (pcm_s16le)
  Stream #0:2 -> #0:1 (dca -> pcm_s16le)
Press ctrl-c to stop encoding
size=    9944kB time=11.53 bitrate=7065.4kbits/s    
video:0kB audio:9944kB global headers:0kB muxing overhead 0.000452%
--------------------------------------------------------------

In both cases, the aformat filter is applied to the first audio track (which I
did not ask for) and the second track is not downmixed.

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