[FFmpeg-trac] #5951(undetermined:new): Problem with accurate seeking

[FFmpeg]

#5951: Problem with accurate seeking
-------------------------------------+-------------------------------------
             Reporter:  hanky        |                     Type:  defect
               Status:  new          |                 Priority:  normal
            Component:               |                  Version:
  undetermined                       |  unspecified
             Keywords:  seeking      |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 I want to extract an image frame at a certain time.
 I'm using the following command:
 {{{
 % ffmpeg -ss 00:05:00 -i V0000754.mpg -frames:v 1 out_1.jpg
 }}}
 The [https://trac.ffmpeg.org/wiki/Seeking#Inputseeking Seeking] article
 says that prefix version of '-ss' parameter should be frame-accurate. But
 the result I get is different from the postfix version:
 {{{
 % ffmpeg -i V0000754.mpg -ss 00:05:00 -frames:v 1 out_2.jpg
 }}}

 Video info:
 {{{
 % ffprobe V0000754.mpg
 ffprobe version 3.1.1-static http://johnvansickle.com/ffmpeg/  Copyright
 (c) 2007-2016 the FFmpeg developers
   built with gcc 5.4.0 (Debian 5.4.0-4) 20160609
   configuration: --enable-gpl --enable-version3 --enable-static --disable-
 debug --enable-libmp3lame --enable-libx264 --enable-libx265 --enable-
 libwebp --enable-libspeex --enable-libvorbis --enable-libvpx --enable-
 libfreetype --enable-fontconfig --enable-libxvid --enable-libopencore-
 amrnb --enable-libopencore-amrwb --enable-libtheora --enable-libvo-
 amrwbenc --enable-gray --enable-libopenjpeg --enable-libopus --enable-
 libass --enable-gnutls --enable-libvidstab --enable-libsoxr --enable-
 frei0r --enable-libfribidi --disable-indev=sndio --disable-outdev=sndio
 --enable-librtmp --enable-libmfx --enable-libzimg --cc=gcc
   libavutil      55. 28.100 / 55. 28.100
   libavcodec     57. 48.101 / 57. 48.101
   libavformat    57. 41.100 / 57. 41.100
   libavdevice    57.  0.101 / 57.  0.101
   libavfilter     6. 47.100 /  6. 47.100
   libswscale      4.  1.100 /  4.  1.100
   libswresample   2.  1.100 /  2.  1.100
   libpostproc    54.  0.100 / 54.  0.100
 [h264 @ 0x4b2a480] mmco: unref short failure
 [h264 @ 0x4b2a480] number of reference frames (0+4) exceeds max (3;
 probably corrupt input), discarding one
 [h264 @ 0x4b2a480] Increasing reorder buffer to 2
 Input #0, mpeg, from 'V0000754.mpg':
   Duration: 00:15:05.55, start: 48367.196511, bitrate: 2324 kb/s
     Stream #0:0[0x1c0]: Audio: mp2, 48000 Hz, stereo, s16p, 192 kb/s
     Stream #0:1[0x1e0]: Video: h264 (Main), yuv420p(tv, bt470bg), 720x576
 [SAR 12:11 DAR 15:11], 25 fps, 25 tbr, 90k tbn, 50 tbc
 }}}

 Should the results of those two commands be identical?

--
Ticket URL: <https://trac.ffmpeg.org/ticket/5951>
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