FFmpeg concat videos without decoding

# videos.txt
file 'input1.mp4'
file 'input2.mp4'
file 'input3.mp4'

# or

for f in *.mp4; do echo "file '$f'" >> videos.txt; done

First create a text file with a list of videos you want to join or create a file with the list of videos for larger numbers

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

Run the following command, the videos listed in that file will be merged. (concat demuxer)

ffmpeg -i "concat:input1.mp4|input2.mp4|input3.mp4" -c copy output.mp4

You can also merge videos with the concat protocol. The following code stitches four videos without re-encoding them. (concat protocol)