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How to replace the audio in a video file using an audio file using ffmpeg?

I imagine the command looks like:

ffmpeg -i v.mp4 -i a.wav -MAGIC video-new.mp4

This is very similar to How to replace an audio stream in a video file with multiple audio streams? but that question handles multiple audio tracks, which complicates it very much, making it unclear which part of the solution is enough for a simple audio swap.

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qubodup
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1 Answers1

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You will want to copy the video stream without re-encoding to save a lot of time but re-encoding the audio might help to prevent incompatibilities:

ffmpeg -i v.mp4 -i a.wav -c:v copy -map 0:v:0 -map 1:a:0 new.mp4

-map 0:v:0 maps the first (index 0) video stream from the input to the first (index 0) video stream in the output.

-map 1:a:0 maps the second (index 1) audio stream from the input to the first (index 0) audio stream in the output.

If the audio is longer than the video, you will want to add -shortest before the output file name.

Not specifying an audio codec, will automatically select a working one. You can specify one by for example adding -c:a libvorbis after -c:v copy. You can also use -c copy to avoid re-encoding the audio, but this has lead to compatibility and synchronization problems in my past.

qubodup
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    or directly `-c copy` to just re-mux audio and video without re-encoding any of the streams ^^ – Francesco Yoshi Gobbo Sep 03 '18 at 06:19
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    Do you know how to convert the new audio on the same format (with the same parameters) as it is in original video? I mean, I need the new audios to be encoded in the same way as it was the old audio. – Kostanos Jun 15 '19 at 19:34
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    Works like charm!! – Trect Aug 26 '19 at 11:32
  • @Kostanos not automatically but I would like to. Please ask another question. You can reference this one to clarify that yours is new. – qubodup Sep 04 '19 at 09:08
  • Please, help: [segmentation fault when trying to replace audio](https://stackoverflow.com/q/60779743/12141355) – cipricus Mar 20 '20 at 18:41
  • @FrancescoYoshiGobbo - could you expand on that? How much of the rest of the command remains after `-c copy`? Obviously the new filename - what else? If you could provide a complete revised command, that would be helpful. – almcnicoll Apr 01 '20 at 16:06
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    @almcnicoll - if the audio files we are going to substitute have the same or compatible codec, the re-encoding is not necessary and a `ffmpeg -i v.mp4 -i a.m4a -c copy -map 0:v:0 -map 1:a:0 new.mp4` would suffice. Or alternatively if the 2 streams are going to be muxed into an `.mkv` container, so on the code above we can substitute `.m4a` with the original `.wav` of the question and the `new.mp4` with `new.mkv`. – Francesco Yoshi Gobbo Apr 01 '20 at 19:16
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    I agree with Francesco to use `-c copy` instead of `-c:v copy`. `-c:v copy` means to copy the video only, which means re-encoding the audio. `-c copy` will copy both the video and audio, no re-encoding. – wisbucky May 30 '21 at 08:36
  • worked on ffmpeg v4.3 win10. Thanks! – Rinaldo Jonathan Sep 18 '21 at 18:53
  • Interestingly when trying to put wav into my h265 file I get: `Could not find tag for codec pcm_s16le in stream #1, codec not currently supported in container Could not write header for output file #0 (incorrect codec parameters` – Jamie Hutber Mar 31 '22 at 13:51
  • Needed to pull out the audio from a video, de-noise it, and re-insert it. This was perfect. – Aaron R. Apr 22 '22 at 22:35
  • I tried but the video is not visible. what is the reason? – Harshil Kulkarni Jun 23 '22 at 04:48
  • `-shortest` didn't work for me. It still kept the video as long as the audio. `-fflags shortest` worked instead. – Iulian Onofrei Aug 21 '23 at 06:37