Merging is working but video is not running correctly. Only voice we can hear?
What is the cause?
mylist.txt
file '/path/to/file1.mp4'
file '/path/to/file2.mp4'
file '/path/to/file3.mp4'
ffmpeg -f concat -safe 0 -i mylist.txt -c copy output.mp4
If you have MP4 files, these could be losslessly concatenated by first transcoding them to MPEG-2 transport streams. With H.264 video and AAC audio, the following can be used:
ffmpeg -i input1.mp4 -c copy -bsf:v h264_mp4toannexb -f mpegts intermediate1.ts
ffmpeg -i input2.mp4 -c copy -bsf:v h264_mp4toannexb -f mpegts intermediate2.ts
ffmpeg -i "concat:intermediate1.ts|intermediate2.ts" -c copy -bsf:a aac_adtstoasc output.mp4