Concatenating videos on macOS

Sometimes I’m out and I record many videos on my GoPro and then I import them on my Mac, but then I want to have a single big video for a day, instead of multiple videos.

I really don’t want to edit, hate editing videos.

So what I do is, I put them all in a folder, I go into it, then I run this command:

ls -t *.MP4 | sort | awk '{print "file \x27"$0"\x27"}' > list.txt && ffmpeg -f concat -safe 0 -i list.txt -c copy output.mp4

This concatenates all .MP4 videos, rather quickly, to an output.mp4 file.

It uses ffmpeg, so you’ve got to have it installed, with Homebrew use brew install ffmpeg

One time I ran this and videos were encoded badly and footage resulted faster than the original, and the end of the video was just black.

You might see a warning in this case, something like “ Non-monotonic DTS; ……… This may result in incorrect timestamps in the output file.”

I have no idea why this happened, I wasn’t able to fix this with ffmpeg but I used the native macOS QuickTime Player app, basically you open the first video file and drag and drop the second. Then the third, and so on. You’ll see an interface show up that shows you the file is being appended.

Then you export that file to a 4K video.