[FFmpeg-trac] #3327(avformat:new): libavformat fails to detect some mp3 files reliably

[FFmpeg]

#3327: libavformat fails to detect some mp3 files reliably
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             Reporter:  gjdfgh    |                     Type:  defect
               Status:  new       |                 Priority:  normal
            Component:  avformat  |                  Version:  git-master
             Keywords:            |               Blocked By:
             Blocking:            |  Reproduced by developer:  0
Analyzed by developer:  0         |
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 Summary of the bug:

 For a small number of mp3 files, libavformat detects them with a probe
 score of only 24. This is below the "reliable" and recommended minimum
 score (AFAIK AVPROBE_SCORE_MAX/4 + 1, which is 26), and causes problems
 for applications. Applications want to respect the recommended minimum
 score to avoid playing random non-media files as media files, which would
 result in rather crappy behavior compared to just rejecting the file.
 Thus, for reasonably non-broken mp3 files, this definitely should return a
 higher probe score.

 How to reproduce:
 {{{
 $ build_libs/bin/ffprobe /tmp/sample.mp3
 ffprobe version N-59969-g5295735 Copyright (c) 2007-2014 the FFmpeg
 developers
   built on Jan 19 2014 12:58:57 with gcc 4.8 (Debian 4.8.2-12)
   configuration: --prefix=/tmp/upstream_mpv/build_libs --enable-static
 --disable-shared --enable-gpl --enable-avresample --disable-debug
 --disable-doc
   libavutil      52. 62.100 / 52. 62.100
   libavcodec     55. 48.101 / 55. 48.101
   libavformat    55. 24.100 / 55. 24.100
   libavdevice    55.  5.102 / 55.  5.102
   libavfilter     4.  1.100 /  4.  1.100
   libavresample   1.  1.  0 /  1.  1.  0
   libswscale      2.  5.101 /  2.  5.101
   libswresample   0. 17.104 /  0. 17.104
   libpostproc    52.  3.100 / 52.  3.100
 [mp3 @ 0xa8b8880] Format mp3 detected only with low score of 24,
 misdetection possible!
 [mp3 @ 0xa8b8880] Estimating duration from bitrate, this may be inaccurate
 Input #0, mp3, from '/tmp/sample.mp3':
   Metadata:
     track           : 01
     genre           : Oldies
   Duration: 00:01:36.00, start: 0.000000, bitrate: 256 kb/s
     Stream #0:0: Audio: mp3, 44100 Hz, stereo, s16p, 256 kb/s
 }}}
 Patches should be submitted to the ffmpeg-devel mailing list and not this
 bug tracker.

--
Ticket URL: <https://trac.ffmpeg.org/ticket/3327>
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