FFmpeg concat filter

user_9257081 0
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I have 2 same videos. One of the videos doesn't have audio and I want to concat them.

video1 = 1 video stream + 1 audio stream.
video2 = 1 video stream.
the result should be 1(concatenated) video stream, 1 audio stream

I have tried 

ffmpeg -i videoonly.mov -i video+audio.mov -filter_complex "[0:v][0:a] [1:v] [1:a] concat=n=2:v=1:a=1 [v] [a]" -map "[v]" -map "[a]" out.mov

but it doesn't work and prints the error message 

Stream specifier ':a' in filtergraph description [0:v][0:a] [1:v] [1:a] concat=n=2:v=1:a=1 [v] [a] matches no streams.

I except this kind of error message because the second video doesn't have the audio and I sepcifyed the audio but the question is how to make it work or is it possible?

Thanks in advance.

video-processing concat filter concatenation ffmpeg
1 Answers

The concat filter expects matching pairs in each segment, so if one of the segment does not have audio, you should supply a dummy stream. Below, I use the anullsrc filter to generate one.

ffmpeg -i videoonly.mov -i video+audio.mov -f lavfi -t 1 -i anullsrc -filter_complex "[0:v][2:a] [1:v] [1:a] concat=n=2:v=1:a=1 [v] [a]" -map "[v]" -map "[a]" out.mov
user_57260270
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