-stream_loop option

ffmpeg -stream_loop 3 -i input.mp4 -c copy output.mp4

• This can avoid re-encoding because it can use stream copy.
• 0 means no loop, -1 means infinite loop.
• This may not work with anything older than FFmpeg 4.0.

concat demuxer

The concat demuxer allows you to loop an input without needing to re-encode because it can use stream copy.

1. Make a text file. Contents of an example text file to repeat 4 times.

    file 'input.mp4'
    file 'input.mp4'
    file 'input.mp4'
    file 'input.mp4'
   

2. Then run ffmpeg:

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

If you want to add additional inputs make sure they all have the same attributes.

Automatically make list.txt in Linux/macOS

This example is the same as above but you don't have to manually make list.txt:

for i in {1..4}; do printf "file '%s'\n" input.mp4 >> list.txt; done
ffmpeg -f concat -i list.txt -c copy output.mp4

With most commonly-used modern shells, you can even avoid the creation of the list.txt file entirely. For example, with bash:

ffmpeg -f concat -i <(for i in {1..4}; do printf "file '%s'\n" input.mp4; done) -c copy output.mp4