[FFmpeg-trac] #2912(FFmpeg:new): splitting the first minute from a wav file generated a slightly too long file (off by 160 samples)

[FFmpeg]

#2912: splitting the first minute from a wav file generated a slightly too long
file (off by 160 samples)
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             Reporter:  bernhard  |                     Type:  defect
               Status:  new       |                 Priority:  normal
            Component:  FFmpeg    |                  Version:  2.0.1
             Keywords:            |               Blocked By:
             Blocking:            |  Reproduced by developer:  0
Analyzed by developer:  0         |
----------------------------------+----------------------------------
 What you were trying to accomplish:

         split the first minute from a wav file

 The problem you encountered:

         the resulting file was not the exact length expected.
         I expected the file to have length 2646000 (= 60 * 44100) samples,
 but received length 2646160, i.e. 160 samples too many. I confirmed that
 sox generates a file of the expected length.

 The exact command line you were using:

         ffmpeg -i exil1211212315_02WaveGain.wav -ss 00:00:00 -t 00:01:00
 -acodec copy outffmpeg2.wav

 The full, uncut console output provided by ffmpeg -v 9 -loglevel 99 -i
         ffmpeg version 2.0.1 Copyright (c) 2000-2013 the FFmpeg developers
           built on Aug 15 2013 10:56:46 with llvm-gcc 4.2.1 (LLVM build
 2336.11.00)
           configuration: --prefix=/Volumes/Ramdisk/sw --enable-gpl
 --enable-pthreads --enable-version3 --enable-libspeex --enable-libvpx
 --disable-decoder=libvpx --enable-libmp3lame --enable-libtheora --enable-
 libvorbis --enable-libx264 --enable-avfilter --enable-libopencore_amrwb
 --enable-libopencore_amrnb --enable-filters --enable-libgsm --arch=x86_64
 --enable-runtime-cpudetect
           libavutil      52. 38.100 / 52. 38.100
           libavcodec     55. 18.102 / 55. 18.102
           libavformat    55. 12.100 / 55. 12.100
           libavdevice    55.  3.100 / 55.  3.100
           libavfilter     3. 79.101 /  3. 79.101
           libswscale      2.  3.100 /  2.  3.100
           libswresample   0. 17.102 /  0. 17.102
           libpostproc    52.  3.100 / 52.  3.100
         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 '-i' ... matched as input file with argument
 'exil1211212315_02WaveGain.wav'.
         Reading option '-ss' ... matched as option 'ss' (set the start
 time offset) with argument '00:00:00'.
         Reading option '-t' ... matched as option 't' (record or transcode
 "duration" seconds of audio/video) with argument '00:01:00'.
         Reading option '-acodec' ... matched as option 'acodec' (force
 audio codec ('copy' to copy stream)) with argument 'copy'.
         Reading option 'outffmpeg3.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
 exil1211212315_02WaveGain.wav.
         Successfully parsed a group of options.
         Opening an input file: exil1211212315_02WaveGain.wav.
         [wav @ 0x7fae6881a600] Format wav probed with size=2048 and
 score=99
         [wav @ 0x7fae6881a600] File position before
 avformat_find_stream_info() is 44
         [wav @ 0x7fae6881a600] parser not found for codec pcm_s24le,
 packets or times may be invalid.
             Last message repeated 1 times
         [wav @ 0x7fae6881a600] max_analyze_duration 5000000 reached at
 5010612 microseconds
         [wav @ 0x7fae6881a600] File position after
 avformat_find_stream_info() is 1338128
         Guessed Channel Layout for  Input Stream #0.0 : stereo
         Input #0, wav, from 'exil1211212315_02WaveGain.wav':
           Duration: 00:28:14.47, bitrate: 2116 kb/s
             Stream #0:0, 326, 1/44100: Audio: pcm_s24le ([1][0][0][0] /
 0x0001), 44100 Hz, stereo, s32, 2116 kb/s
         Successfully opened the file.
         Parsing a group of options: output file outffmpeg3.wav.
         Applying option ss (set the start time offset) with argument
 00:00:00.
         Applying option t (record or transcode "duration" seconds of
 audio/video) with argument 00:01:00.
         Applying option acodec (force audio codec ('copy' to copy stream))
 with argument copy.
         Successfully parsed a group of options.
         Opening an output file: outffmpeg3.wav.
         Successfully opened the file.
         Output #0, wav, to 'outffmpeg3.wav':
           Metadata:
             ISFT            : Lavf55.12.100
             Stream #0:0, 0, 1/44100: Audio: pcm_s24le ([1][0][0][0] /
 0x0001), 44100 Hz, stereo, 2116 kb/s
         Stream mapping:
           Stream #0:0 -> #0:0 (copy)
         Press [q] to stop, [?] for help
         No more output streams to write to, finishing.
         size=   15505kB time=00:01:00.00 bitrate=2116.8kbits/s
         video:0kB audio:15505kB subtitle:0 global headers:0kB muxing
 overhead 0.000642%
         0 frames successfully decoded, 0 decoding errors
         [AVIOContext @ 0x7fae684046a0] Statistics: 4 seeks, 3883 writeouts
         [AVIOContext @ 0x7fae68403e20] Statistics: 15892480 bytes read, 0
 seeks

 The input file is of this type, according to soxi:
         Input File     : 'exil1211212315_02WaveGain.wav'
         Channels       : 2
         Sample Rate    : 44100
         Precision      : 24-bit
         Duration       : 00:28:14.47 = 74726144 samples = 127085 CDDA
 sectors
         File Size      : 448M
         Bit Rate       : 2.12M
         Sample Encoding: 24-bit Signed Integer PCM

-- 
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/2912>
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