Put audio from one vhs tape onto another video? how?

[darter99]

I am using Ubunutu 22. I would like to transfer audio from vhs tape A to tape B and sync the audio from A to the video motion on tape B. Both of these have been captured as mp4s. Any simple tools for this ? (So B will have new audio from A) Thanks.

[october262]

I am using Ubunutu 22. I would like to transfer audio from vhs tape A to tape B and sync the audio from A to the video motion on tape B. Both of these have been captured as mp4s. Any simple tools for this ? (So B will have new audio from A) Thanks.

use ffmpeg -- extract audio from tape A with ffmpeg -i input-video.mp4 -vn -acodec copy output-audio.aac
remove audio from tape B with ffmpeg -i tape B.mp4 -c copy -an out.mp4
add the new audio to tape B with ffmpeg -i input.mp4 -i input.aac -c copy -map 0:v:0 -map 1:a:0 output.mp4

[darter99]

This looks helpful. Thanks for the instructions. I am just wondering how I would know how much offset there might be to correct for to get the two sources in sync. So if one is 5 milliseconds behind the other, how would I know that value? Trial and error maybe? I will be trying this.