Subler

Subler builds and edits MP4 files: it imports tracks from MOV, MP4 and MKV sources, adds chapters and closed captions, and creates the tx3g subtitle tracks that Apple players understand. Metadata such as artwork, episode details and descriptions can be looked up from TMDb, TVDB and the iTunes Store.

It is a long-standing companion to encoders such as HandBrake for preparing files for the Apple TV app. Most of the code is GPLv2, with some LGPL and permissive files, and the combined app is distributed under GPLv2.