$ ./ffmpeg -ss 00:10:01.01 -i /media/music/summer.mkv -y -f image2 -vframes 1 screenshot6.png
ffmpeg version N-53359-gc54a156 Copyright (c) 2000-2013 the FFmpeg developers
  built on May 23 2013 05:13:11 with gcc 4.6 (Debian 4.6.3-1)
  configuration: --prefix=/root/ffmpeg-static/32bit --arch=x86_32 --extra-cflags='-m32 -I/root/ffmpeg-static/32bit/include -static' --extra-ldflags='-m32 -L/root/ffmpeg-static/32bit/lib -static' --extra-libs='-lxml2 -lexpat -lfreetype' --enable-static --disable-shared --disable-ffserver --disable-doc --enable-bzlib --enable-zlib --enable-postproc --enable-runtime-cpudetect --enable-libx264 --enable-gpl --enable-libtheora --enable-libvorbis --enable-libmp3lame --enable-gray --enable-libass --enable-libfreetype --enable-libopenjpeg --enable-libspeex --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-version3 --enable-libvpx
  libavutil      52. 33.100 / 52. 33.100
  libavcodec     55. 10.101 / 55. 10.101
  libavformat    55.  7.100 / 55.  7.100
  libavdevice    55.  1.101 / 55.  1.101
  libavfilter     3. 69.100 /  3. 69.100
  libswscale      2.  3.100 /  2.  3.100
  libswresample   0. 17.102 /  0. 17.102
  libpostproc    52.  3.100 / 52.  3.100
Input #0, matroska,webm, from '/media/music/summer.mkv':
  Duration: 01:21:46.44, start: 0.000000, bitrate: 2859 kb/s
    Chapter #0.0: start 0.000000, end 540.760000
    Metadata:
      title           : Chapter  1
    Chapter #0.1: start 540.760000, end 1387.120000
    Metadata:
      title           : Chapter  2
    Chapter #0.2: start 1387.120000, end 2223.760000
    Metadata:
      title           : Chapter  3
    Chapter #0.3: start 2223.760000, end 2767.000000
    Metadata:
      title           : Chapter  4
    Chapter #0.4: start 2767.000000, end 3574.120000
    Metadata:
      title           : Chapter  5
    Chapter #0.5: start 3574.120000, end 4261.840000
    Metadata:
      title           : Chapter  6
    Chapter #0.6: start 4261.840000, end 4814.680000
    Metadata:
      title           : Chapter  7
    Chapter #0.7: start 4814.680000, end 4906.440000
    Metadata:
      title           : Chapter  8
    Stream #0:0(eng): Video: h264 (High), yuv420p, 712x572 [SAR 64:45 DAR 11392:6435], SAR 253:178 DAR 23:13, 25 fps, 25 tbr, 1k tbn, 50 tbc (default)
    Stream #0:1(fre): Audio: ac3, 48000 Hz, 5.1(side), fltp, 384 kb/s (default)
Output #0, image2, to 'screenshot6.png':
  Metadata:
    encoder         : Lavf55.7.100
    Chapter #0.0: start 0.000000, end 786.110000
    Metadata:
      title           : Chapter  2
    Chapter #0.1: start 786.110000, end 1622.750000
    Metadata:
      title           : Chapter  3
    Chapter #0.2: start 1622.750000, end 2165.990000
    Metadata:
      title           : Chapter  4
    Chapter #0.3: start 2165.990000, end 2973.110000
    Metadata:
      title           : Chapter  5
    Chapter #0.4: start 2973.110000, end 3660.830000
    Metadata:
      title           : Chapter  6
    Chapter #0.5: start 3660.830000, end 4213.670000
    Metadata:
      title           : Chapter  7
    Chapter #0.6: start 4213.670000, end 4305.430000
    Metadata:
      title           : Chapter  8
    Stream #0:0(eng): Video: png, rgb24, 712x572 [SAR 253:178 DAR 23:13], q=2-31, 200 kb/s, 90k tbn, 25 tbc (default)
Stream mapping:
  Stream #0:0 -> #0:0 (h264 -> png)
Press [q] to stop, [?] for help
frame=    1 fps=0.0 q=0.0 Lsize=N/A time=00:00:00.04 bitrate=N/A dup=0 drop=43
video:821kB audio:0kB subtitle:0 global headers:0kB muxing overhead -100.002617%