[FFmpeg-trac] #6106(undetermined:new): Some pcm wavs detected as eac3

FFmpeg trac at avcodec.org
Fri Jan 27 12:55:57 EET 2017


#6106: Some pcm wavs detected as eac3
-------------------------------------+-------------------------------------
             Reporter:  vlasbaard    |                     Type:  defect
               Status:  new          |                 Priority:  normal
            Component:               |                  Version:  git-
  undetermined                       |  master
             Keywords:  pcm ac3      |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 Summary of the bug:

 I use ffmpeg extensively to identify file formats.

 There are some pcm wavs that are mis-identified as varieties of ac3 -
 recompiling with --disable-demuxer=ac3 fixes it, but that's not nice if
 you also want to be able to deal with ac3 audio.

 This was not a case with a very old FFmpeg I have on a different machine
 (N-34304-gc0dbab9, built Oct 31 2011), but bisecting 5 years seems...
 unproductive.

 How to reproduce:

 Compile ffmpeg (git master) with default settings, and run ffmpeg -i with
 the file I'm supplying.

 {{{
 $ ./ffmpeg -i pcm_wav_misidentified_as_eac3.wav
 ffmpeg version N-83248-gb4a13d442a Copyright (c) 2000-2017 the FFmpeg
 developers
   built with Apple LLVM version 8.0.0 (clang-800.0.42.1)
   configuration:
   libavutil      55. 45.100 / 55. 45.100
   libavcodec     57. 75.100 / 57. 75.100
   libavformat    57. 65.100 / 57. 65.100
   libavdevice    57.  2.100 / 57.  2.100
   libavfilter     6. 70.100 /  6. 70.100
   libswscale      4.  3.101 /  4.  3.101
   libswresample   2.  4.100 /  2.  4.100
 Input #0, wav, from 'pcm_wav_misidentified_as_eac3.wav':
   Duration: 00:00:05.00, bitrate: 1411 kb/s
     Stream #0:0: Audio: eac3 ([1][0][0][0] / 0x0001), 48000 Hz, 5.0(side),
 fltp, 64 kb/s (visual impaired)
 At least one output file must be specified
 }}}

 Built Jan 25 13:03 CET.

 Additional comment:

 Based on what I read on http://soundfile.sapp.org/doc/WaveFormat/ the
 stream shouldn't even have to be interpreted by all different codecs as
 long as the AudioFormat field (at bytes 20-21) is 0x0001 ? Just a
 thought...

 Full output:
 {{{
 $ ./ffmpeg -v 9 -loglevel 99 -report -i pcm_wav_misidentified_as_eac3.wav
 ffmpeg started on 2017-01-27 at 11:50:13
 Report written to "ffmpeg-20170127-115013.log"
 ffmpeg version N-83248-gb4a13d442a Copyright (c) 2000-2017 the FFmpeg
 developers
   built with Apple LLVM version 8.0.0 (clang-800.0.42.1)
   configuration:
   libavutil      55. 45.100 / 55. 45.100
   libavcodec     57. 75.100 / 57. 75.100
   libavformat    57. 65.100 / 57. 65.100
   libavdevice    57.  2.100 / 57.  2.100
   libavfilter     6. 70.100 /  6. 70.100
   libswscale      4.  3.101 /  4.  3.101
   libswresample   2.  4.100 /  2.  4.100
 Splitting the commandline.
 Reading option '-v' ... matched as option 'v' (set logging level) with
 argument '9'.
 Reading option '-loglevel' ... matched as option 'loglevel' (set logging
 level) with argument '99'.
 Reading option '-report' ... matched as option 'report' (generate a
 report) with argument '1'.
 Reading option '-i' ... matched as input url with argument
 'pcm_wav_misidentified_as_eac3.wav'.
 Finished splitting the commandline.
 Parsing a group of options: global .
 Applying option v (set logging level) with argument 9.
 Applying option report (generate a report) with argument 1.
 Successfully parsed a group of options.
 Parsing a group of options: input url pcm_wav_misidentified_as_eac3.wav.
 Successfully parsed a group of options.
 Opening an input file: pcm_wav_misidentified_as_eac3.wav.
 [file @ 0x7fb764d02680] Setting default whitelist 'file,crypto'
 Probing mp3 score:1 size:2048
 Probing wav score:99 size:2048
 [wav @ 0x7fb765800000] Format wav probed with size=2048 and score=99
 [wav @ 0x7fb765800000] Before avformat_find_stream_info() pos: 44 bytes
 read:65580 seeks:1 nb_streams:1
 [wav @ 0x7fb765800000] probing stream 0 pp:32
 Probing mp3 score:1 size:4096
 [wav @ 0x7fb765800000] Probe with size=4096, packets=2469 detected mp3
 with score=1
 [wav @ 0x7fb765800000] probing stream 0 pp:31
 Probing mp3 score:1 size:8192
 [wav @ 0x7fb765800000] Probe with size=8192, packets=2470 detected mp3
 with score=1
 [wav @ 0x7fb765800000] probing stream 0 pp:30
 [wav @ 0x7fb765800000] probing stream 0 pp:29
 Probing mp3 score:1 size:16384
 [wav @ 0x7fb765800000] Probe with size=16384, packets=2472 detected mp3
 with score=1
 [wav @ 0x7fb765800000] probing stream 0 pp:28
 [wav @ 0x7fb765800000] probing stream 0 pp:27
 [wav @ 0x7fb765800000] probing stream 0 pp:26
 [wav @ 0x7fb765800000] probing stream 0 pp:25
 [wav @ 0x7fb765800000] probing stream 0 pp:24
 [wav @ 0x7fb765800000] probing stream 0 pp:23
 [wav @ 0x7fb765800000] probing stream 0 pp:22
 [wav @ 0x7fb765800000] probing stream 0 pp:21
 [wav @ 0x7fb765800000] probing stream 0 pp:20
 [wav @ 0x7fb765800000] probing stream 0 pp:19
 [wav @ 0x7fb765800000] probing stream 0 pp:18
 [wav @ 0x7fb765800000] probing stream 0 pp:17
 Probing ac3 score:25 size:65536
 [wav @ 0x7fb765800000] Probe with size=65536, packets=2484 detected ac3
 with score=25
 [wav @ 0x7fb765800000] probing stream 0 pp:16
 [wav @ 0x7fb765800000] probing stream 0 pp:15
 [wav @ 0x7fb765800000] probing stream 0 pp:14
 [wav @ 0x7fb765800000] probing stream 0 pp:13
 [wav @ 0x7fb765800000] probing stream 0 pp:12
 [wav @ 0x7fb765800000] probing stream 0 pp:11
 [wav @ 0x7fb765800000] probing stream 0 pp:10
 [wav @ 0x7fb765800000] probing stream 0 pp:9
 [wav @ 0x7fb765800000] probing stream 0 pp:8
 [wav @ 0x7fb765800000] probing stream 0 pp:7
 [wav @ 0x7fb765800000] probing stream 0 pp:6
 [wav @ 0x7fb765800000] probing stream 0 pp:5
 [wav @ 0x7fb765800000] probing stream 0 pp:4
 [wav @ 0x7fb765800000] probing stream 0 pp:3
 [wav @ 0x7fb765800000] probing stream 0 pp:2
 [wav @ 0x7fb765800000] probing stream 0 pp:1
 Probing ac3 score:50 size:131072
 [wav @ 0x7fb765800000] Probe with size=131072, packets=2500 detected ac3
 with score=50
 [wav @ 0x7fb765800000] probed stream 0
 [wav @ 0x7fb765800000] stream 0: start_time: -209146758205323.719
 duration: 5.000
 [wav @ 0x7fb765800000] format: start_time: -9223372036854.775 duration:
 5.000 bitrate=1411 kb/s
 [wav @ 0x7fb765800000] After avformat_find_stream_info() pos: 882044 bytes
 read:947580 seeks:1 frames:16
 Input #0, wav, from 'pcm_wav_misidentified_as_eac3.wav':
   Duration: 00:00:05.00, bitrate: 1411 kb/s
     Stream #0:0, 16, 1/44100: Audio: eac3 ([1][0][0][0] / 0x0001), 48000
 Hz, 5.0(side), fltp, 64 kb/s (visual impaired)
 Successfully opened the file.
 At least one output file must be specified
 [AVIOContext @ 0x7fb764d028c0] Statistics: 947580 bytes read, 1 seeks
 }}}

--
Ticket URL: <https://trac.ffmpeg.org/ticket/6106>
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