Saved here for my own reference, and possibly others’ if they should stumble across it: the easiest workflow I’ve found yet for converting DVDs or Blu-Rays (if you have a Blu-Ray reader, of course) for personal use on OS X, including OCR conversion of subtitles in either VOBSUB (DVD) or PGS (Blu-Ray) format to text-based .srt files suitable for use as soft subtitles, either as a sidecar file or included in the final movie file.
The flow diagram to the right gives an overview of the process I’ve landed on. Here’s a slightly more detailed breakdown.
- Use MakeMKV to rip the DVD or BluRay disc to an .mkv file (if I run into a stubborn DVD, or one with a lot of multiplexing, I’ll use RipIt to create a disk image first, then run that image through MakeMKV). To save space, you can select only the primary audio track for inclusion, or you can select others if you want other languages or commentary tracks archived as well (though this will require more storage space). I also select all available English-language subtitle tracks, as some discs will include both standard subtitles and subtitles for the hearing impaired or closed captions, which include some extra information on who is speaking and background sounds, or occasionally even transcriptions of commentary tracks.
- Use Subler to OCR and export the subtitle files. This takes two runs through Subler to complete.
- First run; drag the .mkv file onto Subler, and only select the subtitle track(s). Pop that into the export queue, and after a few minutes of processing (this is when the OCR process happens) Subler will output a tiny .m4v file.
- Second run; drag that file back onto Subler, click on the subtitle track, and choose File > Export… to save the .srt file(s). The tiny .m4v file can then be deleted.
Now, the OCR process is not perfect, and the resulting .srt file(s) are virtually guaranteed to have some errors. How many and how intrusive they are depends on the source. BluRay subs seem to come out better than DVD subs (likely due to the higher resolution of the format giving better quality text for the OCR process to scan), DVD subs are also affected by the chosen font and whether or not italics were used. For correction, I use one of two methods.
- For a quick-and-dirty “good enough for now” run, I use BBEdit (but just about any other text editor would work) to do a quick spellcheck, identifying common errors and using search-and-replace to fix them in batches.
- For a real quality fix, I use Aegisub to go through line-by-line, comparing the text to the original audio, adding italics when appropriate, and so on.
Of course, these two processes can be combined, done at different times, or skipped entirely; right now, I’m just living with the OCR errors, because I can always go back and use Subler to extract the .srt files for cleanup later on when I have more time.
- Use HandBrake to re-encode and convert the .mkv file (which at this point will be fairly large, straight off the source media) to a smaller .m4v file. You can either embed the .srt files at this point, under HandBrake’s ‘Subtitles’ tab, or if you prefer…
- …you can use Subler to .srt files into into the .m4v: Drag the .m4v file from HandBrake on to Subler, drag the .srt file(s) into the window that opens, and then drop that into the queue for final remuxing (optionally, before adding the files to the queue, use Subler’s metadata search tools to add the description, artwork, and other metadata). Then run the queue to output the final file.
And that’s it. Now, you should have a .m4v file with embedded text-based soft subtitles for programs that support that (VLC, Plex, etc.), or you can just use the .srt file(s) created by Subler earlier as a sidecar file for programs that don’t read the embedded .srt.