Subtitlefs presents a filesystem where textual subtitles embedded in video
files are presented as files with the name of the video file and extension
of the subtitle format.  This is useful for media servers which expect the
subs for a movie to be presented this way.

* Currently only matroska format is supported.

Requires:
 * python-fuse
 * mkvtoolnix
 * sqlite3dbm (optional)

Usage:
  subtitlefs.py -o root=/media/path/to/movies/dir /mount/point

Authors
 * Glenn Washburn <crass@berlios.de>

KNOWN ISSUES:
 * Currently directory traversal is very slow. Paths must be stat'ed in
   order to determine their type (file or directory).  Since stat must
   return the file size, we must extract the subtitle to get its size.
   An improvement might be to have a background thread creating a cache
   of these subtitles.
 * Currently subtitle files are read with direct_io, bypassing the fs cache
   because going through the fs cache is causing an EIO error after a
   couple consecutive reads. If each read is preceded by a seek, then the
   EIO never shows up.  It seems like its always the last read which fails.
   Is this a bug in fuse?
   * This might be related to fuse/kernel not knowing the file size:
     http://sourceforge.net/apps/mediawiki/fuse/index.php?title=FAQ#I_can_not_know_the_file_size_in_advance.2C_how_do_I_force_EOF_from_fs_read.28.29_to_be_seen_in_the_application.3F

TODO:
 * Support more subtitle formats
 * Support other video formats with subtitles
 * Natively read matroska (instead of using mkvtoolnix)
 * use inotify to be aware of when file path changes
 * Implement caching of subtitles with mapping back to file path
   * keep hueristic identifier of file, to determine when the contents
     change. Maybe just subtitle track uid. Right now using mtime of video
     file.
 * Do error handling and validation on language arg. Allow for ISO639-1 and
   ISO639-2 codes.
 * Add support for converting subtitle formats (eg. the file contains ssa,
   but you want srt)
 * Add option for multi-subtitle mode, where multiple subtitles can be
   shown.  The idea is to present multiple video files, each which
   correspond to a different subtitle (eg. a.mkv with 2 subs, would present
   a.1.mkv a.1.srt a.2.mkv a.2.srt)
 * Add tests