Mute part of the audio in a video without re-encoding

[90sTV]

Is there a way to do that?

imovie allows you to do detach the audio and then split it and mute the split part, but then it won't export in the same resolution (480p), much less lossless.

[Brad]

You can definitely re-encode the audio while keeping the original video track with various tools, some of which should work on Mac.

On Windows, you can demux the tracks, losslessly edit with https://en.m.wikipedia.org/wiki/Mp3DirectCut if the format is supported and then remux to avoid re-encoding the audio. I don't know how you would do that on Mac.

You didn't tell us the specs of the file.

[netmask56]

Extract the audio track and then in an audio editor mute the section of sound you don't want to hear. Then remux back into the video. You don't give any information about the your file so that limits what advice can be given let alone solutions. We are not mind readers. Do the basics please like posting a MediaInfo report file at the very least...

[90sTV]

Extract the audio track and then in an audio editor mute the section of sound you don't want to hear. Then remux back into the video. You don't give any information about the your file so that limits what advice can be given let alone solutions. We are not mind readers. Do the basics please like posting a MediaInfo report file at the very least...

They're mp4 files.

AAC, H.264.

[netmask56]

Demux the audio track and mute the section not to be heard - save the new file and then remux back into the mp4 removing or untick the original file. If it was a MKV it would be easy but not sure of what software for the MAC that does it for mp4

[90sTV]

Demux the audio track and mute the section not to be heard - save the new file and then remux back into the mp4 removing or untick the original file. If it was a MKV it would be easy but not sure of what software for the MAC that does it for mp4

What if I were to remux the mp4 to MKV using VideoProc (which I have), then do what you said, and then remux back to mp4? That would be lossless, right?

What software does what you said for MKV?

[netmask56]

MKVToolNix https://www.macupdate.com/app/mac/16837/mkvtoolnix to remux and MKVCleaver https://macdownload.informer.com/mkvcleaver/ to extract any elements like audio or subtitles etc.

[netmask56]

I don't know anything about VideoProc whether it re-encodes etc. MKV does nothing to the video or audio and is very quick, a matter of minutes. Why not just give it a try?

[90sTV]

MKVToolNix https://www.macupdate.com/app/mac/16837/mkvtoolnix to remux and MKVCleaver https://macdownload.informer.com/mkvcleaver/ to extract any elements like audio or subtitles etc.

That MKVCleaver link doesn't seem to work as far as the download.

Do you know if you can do this somehow on AVIDemux?

So if I understand you correctly, what you are saying to do is to extract the audio stream, and then mute the portion of it I want muted (maybe in Audacity or something?), then save it, and then somehow mux that with the video, removing the old audio stream?

[netmask56]

MKVToolNix https://www.macupdate.com/app/mac/16837/mkvtoolnix to remux and MKVCleaver https://macdownload.informer.com/mkvcleaver/ to extract any elements like audio or subtitles etc.

That MKVCleaver link doesn't seem to work as far as the download.

Do you know if you can do this somehow on AVIDemux?

So if I understand you correctly, what you are saying to do is to extract the audio stream, and then mute the portion of it I want muted (maybe in Audacity or something?), then save it, and then somehow mux that with the video, removing the old audio stream?

Yes exactly, to mux back you you MKV ToolNix and just drag the new audio in and untick the old - I'm sorry if this sounds a little harsh but have you ever heard of searching for MKVCleaver on this site under software - anyway here go go holding hands https://www.videohelp.com/software/MKVcleaver.
Re AViDemux you probably can but I don't use that program and can't offer any advice.

[90sTV]

MKVToolNix https://www.macupdate.com/app/mac/16837/mkvtoolnix to remux and MKVCleaver https://macdownload.informer.com/mkvcleaver/ to extract any elements like audio or subtitles etc.

That MKVCleaver link doesn't seem to work as far as the download.

Do you know if you can do this somehow on AVIDemux?

So if I understand you correctly, what you are saying to do is to extract the audio stream, and then mute the portion of it I want muted (maybe in Audacity or something?), then save it, and then somehow mux that with the video, removing the old audio stream?

Yes exactly, to mux back you you MKV ToolNix and just drag the new audio in and untick the old - I'm sorry if this sounds a little harsh but have you ever heard of searching for MKVCleaver on this site under software - anyway here go go holding hands https://www.videohelp.com/software/MKVcleaver.
Re AViDemux you probably can but I don't use that program and can't offer any advice.

I did actually come across that but I don't see a Mac version on there for MKVCleaver.

[netmask56]

Sorry it appears development on the MAC version has ceased. As you appear to have Audacity there is another way to do it - simply load the original mp4 file into Audacity. It will load just the audio track. Select the area to mute and do so then save the file by going to Export and selecting Export Audio then select the file type probably .aac if that option is not available on your MAC then select MP3. Save.

You will now have your original mp4 file with video and audio, plus a new file of just the audio. Then load each file (select both) and drag into MKVToolNix. Deselect the original audio, ie untick leaving just the video and the new audio and the select Start multiplexing. You then should have a MKV file with the original video and the new audio.

If you want to try something clever you could leave both audio tracks and mark the one you want as the default track and then your media player should use that one, not guaranteed as different media players treat flags differently . If for any reason you want to go back to the original audio you just select the 2nd audio track

[90sTV]

Sorry it appears development on the MAC version has ceased. As you appear to have Audacity there is another way to do it - simply load the original mp4 file into Audacity. It will load just the audio track. Select the area to mute and do so then save the file by going to Export and selecting Export Audio then select the file type probably .aac if that option is not available on your MAC then select MP3. Save.

You will now have your original mp4 file with video and audio, plus a new file of just the audio. Then load each file (select both) and drag into MKVToolNix. Deselect the original audio, ie untick leaving just the video and the new audio and the select Start multiplexing. You then should have a MKV file with the original video and the new audio.

If you want to try something clever you could leave both audio tracks and mark the one you want as the default track and then your media player should use that one, not guaranteed as different media players treat flags differently . If for any reason you want to go back to the original audio you just select the 2nd audio track

When I go to export it as "M4A (AAC) Files (FFmpeg)" in Audacity, it has a setting asking what "quality" I want it in, going up to 320 kbps. Does this mean quality will be affected if I export it this way?

It doesn't have that pop up if I try to export it as mp3.

[netmask56]

Just choose 240 kbps for aac, more than adequate especially considering the source material.

[90sTV]

Just choose 240 kbps for aac, more than adequate especially considering the source material.

So it won't alter the quality any, or it will be so small it's imperceptible?

[netmask56]

No change to video - imperceptible change to audio. Really! rather than debating it in your mind why not just do it and check the results for yourself.

[niente0]

Hi all,
for this pourpose I make use of ffmpeg, this is the command line I use:

ffmpeg -i in.mp4 -af "volume=enable='between(t,3.200,3.500)':volume=0,volume=enable='between(t,7.5,8)':volume=0" -c:v copy out.mp4

In this example I have muted audio from 3.2 to 3.5 seconds and from 7.5 and 8 seconds, without video re-encoding.