- refactor input/output to be groups of arguments that are mutually exclusive; e.g., you specify a video file's sub track, a subtitle file, or a directory, but not more than one (currently you specify whatever and it just tries to do the right thing)
- add alternative subtitle syncing options
- shift forward/back by h:m:s:ms
- sync to audio
- sync to image subtitle file (PGS, etc)
- update arguments to allow selecting exactly one of the subtitle syncing options
- split add-dual-subs into add-synced-subs and add-dual-subs
- add command to do both of the above (add-and-combine-subs?)
- alternative sync solutions
- ffsubsync with no reference attempts to use audio
- https://github.com/oseiskar/autosubsync
- https://github.com/kaegi/alass
- https://github.com/sc0ty/subsync
- https://github.com/oseiskar/autosubsync
- https://github.com/pums974/srtsync