id,summary,reporter,owner,description,type,status,priority,component,version,resolution,keywords,cc,blockedby,blocking,reproduced,analyzed
2263,Read second SeekHead in Matroska files,eelco,,"I have an MKV file for which using -ss is very slow. It plays fine in players like VLC and MplayerX. 

Normally, FFmpeg jumps to the keyframe before the seeking point and starts decoding from there. With this file, it seems to start at the beginning.

The sample file included is the first 15MB of a larger file. Seeking to a later point in the file is even slower.

ffprobe information (note there is a keyframe at 10.427)
{{{
> ./ffprobe -of compact -show_frames ~/Desktop/ffmpeg-ss-bug/slow-ss.mkv | grep 'video|key_frame=1'
ffprobe version N-49823-g7ff1a4b Copyright (c) 2007-2013 the FFmpeg developers
  built on Feb 12 2013 15:45:24 with llvm-gcc 4.2.1 (LLVM build 2336.11.00)
  configuration: --prefix=/Users/eelco/Projects/Beamer/FFmpeg/build --enable-gpl --enable-version3 --enable-libx264 --disable-shared --enable-static --enable-libtheora --enable-libvorbis --enable-libvo-aacenc --disable-doc --extra-cflags='-DMACOSX_DEPLOYMENT_TARGET=10.6 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk -mmacosx-version-min=10.6 -I/Users/eelco/Projects/Beamer/FFmpeg/build/include' --extra-ldflags='-isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk -mmacosx-version-min=10.6 -L/Users/eelco/Projects/Beamer/FFmpeg/build/lib'
  libavutil      52. 17.101 / 52. 17.101
  libavcodec     54. 91.102 / 54. 91.102
  libavformat    54. 62.100 / 54. 62.100
  libavdevice    54.  3.103 / 54.  3.103
  libavfilter     3. 37.101 /  3. 37.101
  libswscale      2.  2.100 /  2.  2.100
  libswresample   0. 17.102 /  0. 17.102
  libpostproc    52.  2.100 / 52.  2.100
Input #0, matroska,webm, from '/Users/eelco/Desktop/ffmpeg-ss-bug/slow-ss.mkv':
  Metadata:
    creation_time   : 2012-12-09 16:32:15
  Duration: 01:33:24.19, start: 0.000000, bitrate: 21 kb/s
    Chapter #0.0: start 0.000000, end 316.316000
    Metadata:
      title           : 00:00:00.000
    Chapter #0.1: start 316.316000, end 651.985000
    Metadata:
      title           : 00:05:16.316
    Chapter #0.2: start 651.985000, end 1186.310000
    Metadata:
      title           : 00:10:51.985
    Chapter #0.3: start 1186.310000, end 1669.835000
    Metadata:
      title           : 00:19:46.310
    Chapter #0.4: start 1669.835000, end 1970.552000
    Metadata:
      title           : 00:27:49.835
    Chapter #0.5: start 1970.552000, end 2434.974000
    Metadata:
      title           : 00:32:50.552
    Chapter #0.6: start 2434.974000, end 2811.976000
    Metadata:
      title           : 00:40:34.974
    Chapter #0.7: start 2811.976000, end 3120.534000
    Metadata:
      title           : 00:46:51.976
    Chapter #0.8: start 3120.534000, end 3535.157000
    Metadata:
      title           : 00:52:00.534
    Chapter #0.9: start 3535.157000, end 3623.411000
    Metadata:
      title           : 00:58:55.157
    Chapter #0.10: start 3623.411000, end 3859.314000
    Metadata:
      title           : 01:00:23.411
    Chapter #0.11: start 3859.314000, end 4259.672000
    Metadata:
      title           : 01:04:19.314
    Chapter #0.12: start 4259.672000, end 4530.317000
    Metadata:
      title           : 01:10:59.672
    Chapter #0.13: start 4530.317000, end 4869.782000
    Metadata:
      title           : 01:15:30.317
    Chapter #0.14: start 4869.782000, end 4968.630000
    Metadata:
      title           : 01:21:09.782
    Chapter #0.15: start 4968.630000, end 5604.192000
    Metadata:
      title           : 01:22:48.630
    Stream #0:0(eng): Video: h264 (High), yuv420p, 1920x1080, SAR 1:1 DAR 16:9, 23.98 fps, 23.98 tbr, 1k tbn, 47.95 tbc (default)
    Stream #0:1(eng): Audio: truehd, 48000 Hz, 7.1, s32
    Metadata:
      title           : English TRUE-HD
    Stream #0:2(swe): Audio: ac3, 48000 Hz, 5.1(side), fltp, 640 kb/s (default)
    Metadata:
      title           : Swedish AC3
    Stream #0:3(swe): Subtitle: dvd_subtitle (default)
    Metadata:
      title           : Swedish
    Stream #0:4(eng): Subtitle: dvd_subtitle
    Metadata:
      title           : English
frame|media_type=video|key_frame=1|pkt_pts=0|pkt_pts_time=0.000000|pkt_dts=0|pkt_dts_time=0.000000|pkt_duration=N/A|pkt_duration_time=N/A|pkt_pos=6670|pkt_size=148182|width=1920|height=1080|pix_fmt=yuv420p|sample_aspect_ratio=1:1|pict_type=I|coded_picture_number=0|display_picture_number=0|interlaced_frame=0|top_field_first=0|repeat_pict=0|reference=3
frame|media_type=video|key_frame=1|pkt_pts=10427|pkt_pts_time=10.427000|pkt_dts=10427|pkt_dts_time=10.427000|pkt_duration=41|pkt_duration_time=0.041000|pkt_pos=13743718|pkt_size=99527|width=1920|height=1080|pix_fmt=yuv420p|sample_aspect_ratio=1:1|pict_type=I|coded_picture_number=250|display_picture_number=0|interlaced_frame=0|top_field_first=0|repeat_pict=0|reference=3
[matroska,webm @ 0x101806600] Read error
}}}

timing of -ss (about 6-8x slower than other MKVs)
{{{
> time ./ffmpeg ""-ss"" ""11"" ""-i"" ~/Desktop/ffmpeg-ss-bug/slow-ss.mkv  ""-f"" ""image2"" ""-vframes"" ""1"" /dev/null
ffmpeg version N-49823-g7ff1a4b Copyright (c) 2000-2013 the FFmpeg developers
  built on Feb 12 2013 15:45:24 with llvm-gcc 4.2.1 (LLVM build 2336.11.00)
  configuration: --prefix=/Users/eelco/Projects/Beamer/FFmpeg/build --enable-gpl --enable-version3 --enable-libx264 --disable-shared --enable-static --enable-libtheora --enable-libvorbis --enable-libvo-aacenc --disable-doc --extra-cflags='-DMACOSX_DEPLOYMENT_TARGET=10.6 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk -mmacosx-version-min=10.6 -I/Users/eelco/Projects/Beamer/FFmpeg/build/include' --extra-ldflags='-isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk -mmacosx-version-min=10.6 -L/Users/eelco/Projects/Beamer/FFmpeg/build/lib'
  libavutil      52. 17.101 / 52. 17.101
  libavcodec     54. 91.102 / 54. 91.102
  libavformat    54. 62.100 / 54. 62.100
  libavdevice    54.  3.103 / 54.  3.103
  libavfilter     3. 37.101 /  3. 37.101
  libswscale      2.  2.100 /  2.  2.100
  libswresample   0. 17.102 /  0. 17.102
  libpostproc    52.  2.100 / 52.  2.100
Input #0, matroska,webm, from '/Users/eelco/Desktop/ffmpeg-ss-bug/slow-ss.mkv':
  Metadata:
    creation_time   : 2012-12-09 16:32:15
  Duration: 01:33:24.19, start: 0.000000, bitrate: 21 kb/s
    Chapter #0.0: start 0.000000, end 316.316000
    Metadata:
      title           : 00:00:00.000
    Chapter #0.1: start 316.316000, end 651.985000
    Metadata:
      title           : 00:05:16.316
    Chapter #0.2: start 651.985000, end 1186.310000
    Metadata:
      title           : 00:10:51.985
    Chapter #0.3: start 1186.310000, end 1669.835000
    Metadata:
      title           : 00:19:46.310
    Chapter #0.4: start 1669.835000, end 1970.552000
    Metadata:
      title           : 00:27:49.835
    Chapter #0.5: start 1970.552000, end 2434.974000
    Metadata:
      title           : 00:32:50.552
    Chapter #0.6: start 2434.974000, end 2811.976000
    Metadata:
      title           : 00:40:34.974
    Chapter #0.7: start 2811.976000, end 3120.534000
    Metadata:
      title           : 00:46:51.976
    Chapter #0.8: start 3120.534000, end 3535.157000
    Metadata:
      title           : 00:52:00.534
    Chapter #0.9: start 3535.157000, end 3623.411000
    Metadata:
      title           : 00:58:55.157
    Chapter #0.10: start 3623.411000, end 3859.314000
    Metadata:
      title           : 01:00:23.411
    Chapter #0.11: start 3859.314000, end 4259.672000
    Metadata:
      title           : 01:04:19.314
    Chapter #0.12: start 4259.672000, end 4530.317000
    Metadata:
      title           : 01:10:59.672
    Chapter #0.13: start 4530.317000, end 4869.782000
    Metadata:
      title           : 01:15:30.317
    Chapter #0.14: start 4869.782000, end 4968.630000
    Metadata:
      title           : 01:21:09.782
    Chapter #0.15: start 4968.630000, end 5604.192000
    Metadata:
      title           : 01:22:48.630
    Stream #0:0(eng): Video: h264 (High), yuv420p, 1920x1080, SAR 1:1 DAR 16:9, 23.98 fps, 23.98 tbr, 1k tbn, 47.95 tbc (default)
    Stream #0:1(eng): Audio: truehd, 48000 Hz, 7.1, s32
    Metadata:
      title           : English TRUE-HD
    Stream #0:2(swe): Audio: ac3, 48000 Hz, 5.1(side), fltp, 640 kb/s (default)
    Metadata:
      title           : Swedish AC3
    Stream #0:3(swe): Subtitle: dvd_subtitle (default)
    Metadata:
      title           : Swedish
    Stream #0:4(eng): Subtitle: dvd_subtitle
    Metadata:
      title           : English
Output #0, image2, to '/dev/null':
  Metadata:
    encoder         : Lavf54.62.100
    Chapter #0.0: start 0.000000, end 305.316000
    Metadata:
      title           : 00:00:00.000
    Chapter #0.1: start 305.316000, end 640.985000
    Metadata:
      title           : 00:05:16.316
    Chapter #0.2: start 640.985000, end 1175.310000
    Metadata:
      title           : 00:10:51.985
    Chapter #0.3: start 1175.310000, end 1658.835000
    Metadata:
      title           : 00:19:46.310
    Chapter #0.4: start 1658.835000, end 1959.552000
    Metadata:
      title           : 00:27:49.835
    Chapter #0.5: start 1959.552000, end 2423.974000
    Metadata:
      title           : 00:32:50.552
    Chapter #0.6: start 2423.974000, end 2800.976000
    Metadata:
      title           : 00:40:34.974
    Chapter #0.7: start 2800.976000, end 3109.534000
    Metadata:
      title           : 00:46:51.976
    Chapter #0.8: start 3109.534000, end 3524.157000
    Metadata:
      title           : 00:52:00.534
    Chapter #0.9: start 3524.157000, end 3612.411000
    Metadata:
      title           : 00:58:55.157
    Chapter #0.10: start 3612.411000, end 3848.314000
    Metadata:
      title           : 01:00:23.411
    Chapter #0.11: start 3848.314000, end 4248.672000
    Metadata:
      title           : 01:04:19.314
    Chapter #0.12: start 4248.672000, end 4519.317000
    Metadata:
      title           : 01:10:59.672
    Chapter #0.13: start 4519.317000, end 4858.782000
    Metadata:
      title           : 01:15:30.317
    Chapter #0.14: start 4858.782000, end 4957.630000
    Metadata:
      title           : 01:21:09.782
    Chapter #0.15: start 4957.630000, end 5593.192000
    Metadata:
      title           : 01:22:48.630
    Stream #0:0(eng): Video: mjpeg, yuvj420p, 1920x1080 [SAR 1:1 DAR 16:9], q=2-31, 200 kb/s, 90k tbn, 23.98 tbc (default)
Stream mapping:
  Stream #0:0 -> #0:0 (h264 -> mjpeg)
Press [q] to stop, [?] for help
frame=    1 fps=0.5 q=0.0 Lsize=N/A time=00:00:00.04 bitrate=N/A dup=0 drop=262    
video:47kB audio:0kB subtitle:0 global headers:0kB muxing overhead -100.045473%
        2.20 real         6.15 user         0.13 sys
}}}

See also #2245.",enhancement,open,wish,avformat,git-master,,mkv h264,,,,1,0