91.4 Video Concatenate or Join

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Two or more mp4 video files can be joined using mkvmerge to output a Matroska (mkv) file:

mkvmerge -o output.mkv input1.mp4 + input2.mp4 + input3.mp4

We can also use ffmpeg with the concat filter. This filter expects the argument to -i to name a text file which will list the files to be concatenated, like concat.txt

file 'input1.mp4'
file 'input2.mp4'
file 'input3.mp4'

Using -f to identify the filter as concat and -c to identify the encoder for the video and audio as a copy (i.e., no re-encoding).

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

Other options include using mencoder.

$ mencoder -ovc copy -oac copy video1.avi video2.avi -o video.avi

To join multiple avi files into one avi file we can utilise avimerge:

$ avimerge -i a1.avi a2.avi a3.avi -o a.avi

Experience with this latter approach has the audio of the second file out of sync!

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