Support files with VOBSUB resolution different from video resolution

[Giovanni Musto]

Some video files with embedded VOBSUB subtitles have different resolutions set for the video and the subtitles track itself. This results in non-showing subtitles because they are rendered off-screen (or misplaced if the resolution of the subtitles is smaller than the video). Using the scale filer on the VOBSUB track with ffmpeg solves the problem.

Attached there's a sample file.

[Giovanni Musto]

Additional samples: https://drive.google.com/open?id=0B27-Q3Won2AhSHJHRDhURTRoeGM

[Petr Nejedly]

This applies to internal or external vobsub streams / files.