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  1. I'm trying to join two video clips, the second with audio but the first without. The command I'm using is
    Code:
    ffmpeg -f concat -i JoinList.txt -c copy JOINED.mp4
    and the contents of the JoinList file are
    file silent.mp4
    file audible.mp4
    Unfortunately, this produces a joined file that's silent throughout. Switching the order of the files fixes it, but I need the silent part first. How can I do this (using ffmpeg)?

    Thanks!
    Last edited by wallywalters; 11th Jul 2015 at 16:14.
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  2. try adding a silent (blank) audio stream to silent.mp4 before appending
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  3. I've tried, but the audio stream keeps coming out at a different length than the video. This is my CLI. What am I doing wrong?
    Code:
    ffmpeg -f lavfi -i aevalsrc=0 -i silent_IN.mp4 -shortest -c:v copy -c:a libfdk_aac silent_OUT.mp4
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  4. Solved it. Making sure the audio frequency of the two clips matched did the trick. What finally worked was
    ffmpeg -i silent_IN.mp4 -f lavfi -i aevalsrc=0:s=48000 -c:v copy -shortest silent_OUT.mp4
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