FFmpeg-An audio/video conversion tool.

FFmpeg is a free and open-source software project consisting of a large suite of libraries and programs for handling video, audio, and other multimedia files and streams.

• FFmpeg cheat sheet

Basic conversion

ffmpeg -i in.mov out.mp4

Combine multiple videos into one

First, make a text file, touch list.txt.

file 'in1.mp4'
file 'in2.mp4'
file 'in3.mp4'
file 'in4.mp4'

ffmpeg -f concat -i list.txt -c copy out.mp4