Store caption data in MP4s

[waldoj]

The downloaded MP4s have no embedded caption data. Merge the SRT-converted captions into the MP4 container before uploading them to the Internet Archive or to YouTube.

[waldoj]

The history of this can be found on the richmondsunlight.com repo.

[waldoj]

Looks like the options are gpac and mkvmerge. Both are good options.

[waldoj]

Huh. But not for the WebVTT format, instead of the SRT format. It looks like gpac is up to the task. I think mkvmerge, too. But look into this further.