[FFmpeg-user] Extract images from concatenate .VOB

[Etienne Desautels]

Hi,

After more testing extracting images from DVD using dvd2concat, it looks like that when I use the seek option before the input, to have a fast extraction, only keyframes are extracted instead of the exact frames. I tried also by putting a second seek option after the input, to go fast near the good frame then go accurately to the good frame, but I got the same result, only keyframes are extracted.

I tried also adding the -accurate_seek option (should be the default anyway, but we never know) without improvement.

Here's the full output :

ffmpeg -f concat -safe 0 -ss 00:02:31.125 -i /tmp/dvd_concat.txt -y -an -f image2 -vframes 1 -q:v 4 frames1.jpg 
ffmpeg version 2.5.4 Copyright (c) 2000-2015 the FFmpeg developers
  built on Mar  3 2015 10:53:22 with gcc 4.2.1 (GCC) (Apple Inc. build 5666) (dot 3)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/2.5.4 --enable-shared --enable-pthreads --enable-gpl --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=gcc-4.2 --host-cflags= --host-ldflags= --enable-libx264 --enable-libmp3lame --enable-libvo-aacenc --enable-libxvid --enable-libfaac --enable-libfdk-aac --enable-nonfree --enable-vda
  libavutil      54. 15.100 / 54. 15.100
  libavcodec     56. 13.100 / 56. 13.100
  libavformat    56. 15.102 / 56. 15.102
  libavdevice    56.  3.100 / 56.  3.100
  libavfilter     5.  2.103 /  5.  2.103
  libavresample   2.  1.  0 /  2.  1.  0
  libswscale      3.  1.101 /  3.  1.101
  libswresample   1.  1.100 /  1.  1.100
  libpostproc    53.  3.100 / 53.  3.100
Input #0, concat, from '/tmp/dvd_concat.txt':
  Duration: 00:38:16.50, start: 0.000000, bitrate: 0 kb/s
    Stream #0:0: Video: mpeg2video (Main), yuv420p(tv, smpte170m), 704x480 [SAR 10:11 DAR 4:3], max. 9558 kb/s, 29.97 fps, 29.97 tbr, 90k tbn, 59.94 tbc
    Stream #0:1: Audio: ac3, 48000 Hz, stereo, fltp, 256 kb/s
[swscaler @ 0x102800600] deprecated pixel format used, make sure you did set range correctly
Output #0, image2, to 'frames1.jpg':
  Metadata:
    encoder         : Lavf56.15.102
    Stream #0:0: Video: mjpeg, yuvj420p(pc), 704x480 [SAR 10:11 DAR 4:3], q=2-31, 200 kb/s, 29.97 fps, 29.97 tbn, 29.97 tbc
    Metadata:
      encoder         : Lavc56.13.100 mjpeg
Stream mapping:
  Stream #0:0 -> #0:0 (mpeg2video (native) -> mjpeg (native))
Press [q] to stop, [?] for help
frame=    1 fps=0.0 q=0.0 Lsize=N/A time=00:00:00.03 bitrate=N/A dup=1 drop=1    
video:12kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown

Is this normal? How I can extract frame accurately from DVD in a fast way?

Regards,
Etienne Desautels