mp4box
mp4box
TLDR
Display information about an existing MP4 file
$ mp4box -info [path/to/file]
Add an SRT subtitle file into an MP4 file
$ mp4box -add [input_subs.srt]:lang=eng -add [input.mp4] [output.mp4]
Combine audio from one file and video from another
$ mp4box -add [input1.mp4]#audio -add [input2.mp4]#video [output.mp4]
