Support raw evo subtitle files

[Carl Eugen Hoyos]

​http://thread.gmane.org/gmane.comp.video.ffmpeg.user/43279
A user uploaded an evo file and a "sup" file that eac3to exports to externally save the subtitles.

$ ffmpeg -analyzeduration 70M -probesize 30M -i Scanner.evo
ffmpeg version N-49161-g4e69237 Copyright (c) 2000-2013 the FFmpeg developers
  built on Jan 23 2013 10:09:13 with gcc 4.7 (SUSE Linux)
  configuration: --enable-gpl --disable-indev=jack
  libavutil      52. 15.100 / 52. 15.100
  libavcodec     54. 90.100 / 54. 90.100
  libavformat    54. 61.103 / 54. 61.103
  libavdevice    54.  3.102 / 54.  3.102
  libavfilter     3. 33.100 /  3. 33.100
  libswscale      2.  2.100 /  2.  2.100
  libswresample   0. 17.102 /  0. 17.102
  libpostproc    52.  2.100 / 52.  2.100
[mpeg @ 0x34976e0] Stream #3: not enough frames to estimate rate; consider increasing probesize
[mpeg @ 0x34976e0] Stream #4: not enough frames to estimate rate; consider increasing probesize
[mpeg @ 0x34976e0] Stream #5: not enough frames to estimate rate; consider increasing probesize
Input #0, mpeg, from 'Scanner.evo':
  Duration: 00:02:21.39, start: 0.038011, bitrate: 12978 kb/s
    Stream #0:0[0xfd55]: Video: vc1 (Advanced), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], 30.17 fps, 29.97 tbr, 90k tbn, 59.94 tbc
    Stream #0:1[0xc1]: Audio: eac3, 48000 Hz, stereo, fltp, 192 kb/s
    Stream #0:2[0xc0]: Audio: eac3, 48000 Hz, 5.1(side), fltp, 640 kb/s
    Stream #0:3[0x22]: Subtitle: dvd_subtitle
    Stream #0:4[0x23]: Subtitle: dvd_subtitle
    Stream #0:5[0x21]: Subtitle: dvd_subtitle
At least one output file must be specified

The sup file cannot be read

$ ffmpeg -i Scanner.sup
ffmpeg version N-49161-g4e69237 Copyright (c) 2000-2013 the FFmpeg developers
  built on Jan 23 2013 10:09:13 with gcc 4.7 (SUSE Linux)
  configuration: --enable-gpl --disable-indev=jack
  libavutil      52. 15.100 / 52. 15.100
  libavcodec     54. 90.100 / 54. 90.100
  libavformat    54. 61.103 / 54. 61.103
  libavdevice    54.  3.102 / 54.  3.102
  libavfilter     3. 33.100 /  3. 33.100
  libswscale      2.  2.100 /  2.  2.100
  libswresample   0. 17.102 /  0. 17.102
  libpostproc    52.  2.100 / 52.  2.100
Scanner.sup: Invalid data found when processing input