Lost Audio After Using Compression Effect

When I use the compression effect on an MP3 input it trims out either some of the beginning or the end so I have to undo the compression copy the part it randomly removes, redo compression and then past in the random part. I have uninstalled and reinstalled, updated to a new version but nothing works. Any ideas would be much appreciated. I am running on Windows 10.

A workaround: if you duplicate approximately one second of audio at either end,
then apply compression, then delete the audio you added at the ends.
repeat ~1second at each end, then compress, then remove excess.gif

Thanks for the suggestion.

For anyone else who might be able to do a full fix, I am using Audacity 3.2.1

Which compression effect are you using, and what settings?

Please describe in more detail. Is it making the track shorter?

See: Compressor processes wrong audio selection in second clip on second track #3903
and: Compressor fails on multiple tracks #1687

Does yours fail on multiple tracks ? If not, please provide additional information, as Steve as requested.


I choose Effect > Volume and Compression > Compressor

Then I get the screen linked with those settings.

It only fails on one track, not all.

It seems to keep the track length the same except there is more silence (horizontal line) and less actual sound.

I was unable to reproduce your issue on 3.2.1. Mono or Stereo ? How long is the track?

Are there any other tracks in the project ? Can you upload the mp3?

I have had the problem before with one mono track and one stereo track. This one I sent the screen shot from had two mono tracks and one stereo track. It lasted overall around 46 mins.

The mono tracks around 45mins, the stereo (which it never effects) are less than a minute. I edit a podcast and the stereo is just short intro and outro music.

So I was unable to reproduce this issue in my testing. Perhaps you wish to upload a project which exhibits this problem.

Here’s the file on which the compression cuts some of the audio.


Your .aup3 file contains audio before time zero. You can tell this by the left-ward pointing arrows in the second track. When I apply the compressor to this track I can see that the compressor shifts the audio out of the negative area.

There is a report here: Compressor works incorrectly when selected audio is partly in negative time that describe this issue.

The developers have looked into the problem and on Jun 9, unfortunately, have closed this issue as not planned, saying “this is unlikely to get fixed any time soon, if at all - negative time is such a niche concept in an audio editor”

==> So, remove any audio before time zero and try running the compressor again. You can do this by Ctrl+A (select all), then grabbing the top of your track and sliding it until the yellow alignment bar appears.

Thanks for taking a look. I had no idea I was in negative time. I’ll try realigning it.

The visual cues that you have audio in negative time are somewhat subtle - see the arrows (that I have ringed in green) in this image:
Negative time visual cues.png

I’m having this same issue on Mac, Audacity 3.2.1 but without the negative audio issue. The two issues referenced earlier describe my exact issue.

So let’s cut to the chase. Zip up your .aup3 project file and upload it. Then post or PM me a link, along with instructions on how to replicate the problem.