mp4box

MPEG-4 Systems Toolbox: muxe streams into MP4 container. More information: https://gpac.wp.imt.fr/mp4box.

• 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}}