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I've got a video in an MP4 container that I would like to replace the audio track in (not add another audio stream to, nor convert the audio format of).

Someone elsewhere online suggested to use VirtualDub to replace the audio track, but it wouldn't even open up the video file. Journeyman Geek suggested in chat that I use ffmpeg, but the documentation is pretty difficult for me to understand.

How can I accomplish this on Windows? I'll download/install external programs if I must.

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up vote 18 down vote accepted

I ended up scrutinizing the documentation for ffmpeg and worked out a solution:

ffmpeg.exe -i input_video.mp4 -i replacement_audio.m4a -vcodec copy -acodec copy -map 0:0 -map 1:0 output.mp4

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RTFM strikes again! – martineau Jun 2 '13 at 8:17

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