What format is best for converting the audio file of an mp4 to remove noise with Audacity

I know the heading seems somewhat vague, but I didn’t know how to phrase my simple question. So this is it.

I need to remove noise from my audio track of an mp4 video file that I have from converting a VHS tape. I know how to do the things to accomplish this. However, my question is, what format should I use for the audio file when I use ffmpeg to create the audio file for Audacity?

I know wav will keep all the audio, but I’m not sure about putting a wav file in the mp4 when I have removed the noise.

My hope is some of you gurus who do this sort of thing on a regular basis will respond quickly, because I have a lot of videos on which I need to do this. Thanks for your help.

You need a video editor, (or VLC), to create a new video file which has the new audio.
[ Audacity only edits audio ].

There will be an audio quality setting in the video editor (kbps) when you make the new MP4.
Turn that up to the maximum for best audio quality, (at the expense of file size).

I use Shotcut to edit my video files. I know (and have done so in the past) I can add the de-noised audio file from Audacity to replace the original audio track. Doing it that way, I have to (or at least I do) re-encode the video file. I guess I was thinking I should maybe convert the wav file to something smaller (say aac) before I add the audio back to the video file in Shotcut. But then I thought about syncing things up and that might be a problem if I converted the wav to a compressed file.

Shotcut doesn’t seem to have a way of setting the audio quality. Perhaps I have misunderstood what the video editor (Shotcut in my case) does when encoding to mp4. It seems if I look at the video I created with the wav audio in VLC, the audio track is aac. So perhaps my ignorance has caused me to ask a question that is completely immaterial.

If you find my above remarks making any sense at all, then I will ask one more thing. After I run Noise Reduction in Audacity on the extracted audio file, should I set the DB rating in Audacity on Amplify to 0? When I did not do this the first time around, I found the volume could not be turned up as high as I would like.

I really do appreciate your timely response to this question. You have open my eyes where they were closed before. I have used Audacity for years with audio (both live and recorded), but this is my first time with video involved.

You’d just be unnecessarily adding compression artifacts: AAC is a lossy format. Just import the WAV into the video editor.

I’ve never used Shotcut, but apparently it does have quality settings …

Thank you very much. I am now good to go.

You can open your MP4 in Audacity… I do it all the time. Then export a .WAV.

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