[FFmpeg-trac] #2590(avformat:new): Inaccurate seek in mp3

FFmpeg trac at avcodec.org
Sun May 19 13:44:50 CEST 2013


#2590: Inaccurate seek in mp3
------------------------------------+------------------------------------
             Reporter:  eleventeen  |                    Owner:
                 Type:  defect      |                   Status:  new
             Priority:  normal      |                Component:  avformat
              Version:  git-master  |               Resolution:
             Keywords:              |               Blocked By:
             Blocking:              |  Reproduced by developer:  0
Analyzed by developer:  0           |
------------------------------------+------------------------------------

Comment (by eleventeen):

 The same problem in ffmpeg.

 ./ffmpeg -v 9 -loglevel 99 -ss 227 -i Underworld_sample.mp3 o.wav
 ffmpeg version 1.1.git Copyright (c) 2000-2013 the FFmpeg developers
   built on May 19 2013 12:16:24 with gcc 4.6 (Ubuntu/Linaro
 4.6.3-1ubuntu5)
   configuration: --disable-yasm --enable-debug
   libavutil      52. 33.100 / 52. 33.100
   libavcodec     55. 10.101 / 55. 10.101
   libavformat    55.  7.100 / 55.  7.100
   libavdevice    55.  0.100 / 55.  0.100
   libavfilter     3. 68.101 /  3. 68.101
   libswscale      2.  3.100 /  2.  3.100
   libswresample   0. 17.102 /  0. 17.102
 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 '-ss' ... matched as option 'ss' (set the start time
 offset) with argument '227'.
 Reading option '-i' ... matched as input file with argument
 'Underworld_sample.mp3'.
 Reading option 'o.wav' ... matched as output file.
 Finished splitting the commandline.
 Parsing a group of options: global .
 Applying option v (set logging level) with argument 9.
 Successfully parsed a group of options.
 Parsing a group of options: input file Underworld_sample.mp3.
 Applying option ss (set the start time offset) with argument 227.
 Successfully parsed a group of options.
 Opening an input file: Underworld_sample.mp3.
 [mp3 @ 0x178c8a0] Format mp3 probed with size=8192 and score=51
 [mp3 @ 0x178c8a0] id3v2 ver:3 flags:00 len:2416
 [mp3 @ 0x178c8a0] pad 576 1932
 [mp3 @ 0x178c8a0] File position before avformat_find_stream_info() is 3052
 [mp3 @ 0x178c8a0] max_analyze_duration 5000000 reached at 5015510
 microseconds
 [mp3 @ 0x178c8a0] File position after avformat_find_stream_info() is
 125932
 Input #0, mp3, from 'Underworld_sample.mp3':
   Metadata:
     artist          : Lilith
     album           : Underworld
     genre           : Gothic Metal
     date            : 2007
   Duration: 00:42:36.63, start: 0.000000, bitrate: 32 kb/s
     Stream #0:0, 194, 1/14112000: Audio: mp3, 44100 Hz, stereo, s16p, 192
 kb/s
 Successfully opened the file.
 Parsing a group of options: output file o.wav.
 Successfully parsed a group of options.
 Opening an output file: o.wav.
 Successfully opened the file.
 [graph 0 input from stream 0:0 @ 0x17903c0] Setting 'time_base' to value
 '1/44100'
 [graph 0 input from stream 0:0 @ 0x17903c0] Setting 'sample_rate' to value
 '44100'
 [graph 0 input from stream 0:0 @ 0x17903c0] Setting 'sample_fmt' to value
 's16p'
 [graph 0 input from stream 0:0 @ 0x17903c0] Setting 'channel_layout' to
 value '0x3'
 [graph 0 input from stream 0:0 @ 0x17903c0] tb:1/44100 samplefmt:s16p
 samplerate:44100 chlayout:0x3
 [audio format for output stream 0:0 @ 0x17904c0] Setting 'sample_fmts' to
 value 's16'
 [audio format for output stream 0:0 @ 0x17904c0] auto-inserting filter
 'auto-inserted resampler 0' between the filter 'Parsed_anull_0' and the
 filter 'audio format for output stream 0:0'
 [AVFilterGraph @ 0x178f880] query_formats: 4 queried, 9 merged, 3 already
 done, 0 delayed
 [auto-inserted resampler 0 @ 0x1791fe0] ch:2 chl:stereo fmt:s16p r:44100Hz
 -> ch:2 chl:stereo fmt:s16 r:44100Hz
 Output #0, wav, to 'o.wav':
   Metadata:
     IART            : Lilith
     IPRD            : Underworld
     IGNR            : Gothic Metal
     ICRD            : 2007
     ISFT            : Lavf55.7.100
     Stream #0:0, 0, 1/44100: Audio: pcm_s16le ([1][0][0][0] / 0x0001),
 44100 Hz, stereo, s16, 1411 kb/s
 Stream mapping:
   Stream #0:0 -> #0:0 (mp3 -> pcm_s16le)
 Press [q] to stop, [?] for help
 incomplete frametime=00:02:47.78 bitrate=1600.2kbits/s
 Error while decoding stream #0:0: Invalid data found when processing input
 [output stream 0:0 @ 0x17901a0] EOF on sink link output stream
 0:0:default.
 No more output streams to write to, finishing.
 size=   39087kB time=00:03:24.43 bitrate=1566.3kbits/s
 video:0kB audio:39087kB subtitle:0 global headers:0kB muxing overhead
 0.000380%
 8686 frames successfully decoded, 1 decoding errors
 [AVIOContext @ 0x178d880] Statistics: 4 seeks, 8689 writeouts
 [AVIOContext @ 0x1794f20] Statistics: 5577342 bytes read, 1 seeks

-- 
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/2590#comment:3>
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