How do I replace the audio in an MP4 file without re-encoding?

Question

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.

score 48 · Accepted Answer · answered Jun 02 '13 at 01:27

48

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

answered Jun 02 '13 at 01:27

nc4pk

9,257
14
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score 14 · Answer 2 · answered Jul 02 '16 at 21:35

An addition to the current solution: If the audio file does not match the video container's format, just avoid the -acodec parameter:

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

Now, only the audio gets encoded in order to match the container.

T.Todua · Answer 3 · 2019-08-27T06:39:25.050

3

There are several free software for this:

and many others at videohelp.com

edited Aug 27 '19 at 06:39

answered Mar 02 '17 at 17:45

T.Todua

4,053

score 0 · Answer 4 · answered May 27 '21 at 07:36

0

I'm surprised that no one mentioned onlineconverter.com. In addition to many other goodies, their site allows to add or replace audio in a video file.

Trying it out, replacing the audio in a sample video file does not seem to affect the video.

answered May 27 '21 at 07:36

Shlomi A

101

How do I replace the audio in an MP4 file without re-encoding?

4 Answers4