I recently shot some footage with a GoPro, and realized after the fact the GoPro 'chapters' the footage around 4 GB, so I ended up with a number of 4 GB files, instead of one larger file. There are various reasons for this, but in the end, I really wanted one long file, so it would be easier to synchronize with footage from another camera and my audio recorder.
So I found this answer on StackOverflow, which had exactly the commands I needed:
ffmpeg -i 1.mp4 -c copy -bsf:v h264_mp4toannexb -f mpegts intermediate1.ts ffmpeg -i 2.mp4 -c copy -bsf:v h264_mp4toannexb -f mpegts intermediate2.ts ffmpeg -i 3.mp4 -c copy -bsf:v h264_mp4toannexb -f mpegts intermediate3.ts ffmpeg -i 4.mp4 -c copy -bsf:v h264_mp4toannexb -f mpegts intermediate4.ts ffmpeg -i "concat:intermediate1.ts|intermediate2.ts|intermediate3.ts|intermediate4.ts" -c copy -bsf:a aac_adtstoasc output.mp4
Note: If you use the 'High Efficiency' (HEVC) encoder for your GoPro videos, change
hevc_mp4toannexbin the above commands.