I am developing a service to concat a video (mine) with a another from a user (he/she upload it) and return to user.
First I tried to use Concat demuxer because I don't want to re-encode videos if it is not needed. It is supposed that with same codec it should concat videos almost immediately.
Users may upload different videos with different codecs so I will need to convert that video to a certain codec. The problem that I have now is that even having videos with same codec concat is not working well, so I would like to know what else is needed.
My mylist.txt
file './myVideo1.mp4'
file './userVideo1.mp4'
Command:
ffmpeg -f concat -i mylist.txt -c copy mergedVideo.mp4
It didn't work because there were different audio codecs (pcm_u8 vs aac) so I converted myVideo1 audio to aac with;
ffmpeg -i myVideo1.mp4 -map 0:0 -map 0:1 -acodec libfaac -vcodec copy myVideo1_aac.mp4
This was an intermediate task, I mention it because I had a warning:
Codec for stream 0 does not use global headers but container format requires global headers
At this point I have two videos with same audio and codec, lets see details:
I tried to concat videos as before...
ffmpeg -f concat -i mylist.txt -c copy mergedVideo.mp4
... and there were no errors shown, but when I played the video I saw first video normal however 2nd was super slow, only few frames per second, in fact mergedVideo.mp4 has 4 minutes and 34 seconds when it should have 39s (5.38 + 33.79).
Here is mergedVideo.mp4 info:
Can you tell me what is wrong?
