This script reads a subrip subtitles file (a.k.a. a .srt file) and offsets the
timings in the file by a specified amount. Some media players provide this 
facility already, but some do not, so I thought it would be a useful tool to
develop.

Usage:
python fix_subtitles_timings.py <seconds_offset> <subtitles_file>

Examples:
python fix_subtitles_timings.py +5 film.srt     #  offset by +5 seconds
python fix_subtitles_timings.py -15 film.srt     #  offset by -15 seconds

seconds_offset can be a positive or a negative value
subtitles_file must be in the subrip format. It shouldn't be too hard to 
rewrite to accomodate other formats.