[FFmpeg-user] How to concat two videos with same size but different source?

[pehache]

Le 08/10/2022 à 10:31, Bo Berglund a écrit :
> I have two mp4 videos both at 480p resolution, which I want to concat.
> They are together about 80 minutes long.
> 
> When I do this using the common way with this command:
> 
> ffmpeg -f concat -safe 0 -i join.txt -c copy joinedfile.mp4
> 
> using a file specifying the video sections to concatenate the result plays very
> poorly and has many artifacts.
> 
> And at the border between the two videos the output video becomes unplayable.
> 
> So I tried to re-encode using this command instead:
> 
> ffmpeg -hide_banner -i video.1.mp4 -i video.2.mp4 \
> -filter_complex "[0:v] [0:a] [1:v] [1:a] concat=n=2:v=1:a=1 [v] [a]" \
> -map "[v]" -map "[a]" video.mp4
> 
> This command was started before bedtime yesterday and had not finished this
> morning 8 hours later...
> 
> The video output file size was about 1.5 GB when I interrupted the process.
> The two videos are 101 and 238 MB in size respectively. They are downloaded
> videos from the Internet.
> 
> What ffmpeg command can I use to concatenate these two files in a safe way?
> 
> 

First I advice reading this: https://trac.ffmpeg.org/wiki/Concatenate

Second, when you have commands that do not give the expected results, it 
can often help to show the messages they print in the terminal.