Audacity Forum

Could someone explain the difference between using the gain control in the track label and using the amplify filter?

Obviously with the filter the change is permanent and can be applied to just a part of the track. But all else being equal, is there a big difference in practice?

My specific situation is that I was editing a multi track podcast with voice tracks and background music. I realized too late that the voice tracks were recorded too low after I split them into different tracks. Normally I would have used the amplify feature. But instead I just went through all of them and increased the gain from the track label. In this situation there was no danger from clipping because the signal was so low.

I'm really just looking for a general answer, especially if there is some big problem by using one and not the other.

Track gain has the advantage that it can be adjusted in real-time: as the track is playing,
(which is not the case with amplify).
Amplify can be applied to multiple tracks at once, whereas track gain is a per-track.

So a related question would be about enveloping. Again, is the output the same with enveloping as it would be with using amplify?

I did discover that with enveloping you can't fade out completely.

Also, adjusting the track gain doesn't seem to have a protection against clipping. So that makes it a much more dangerous option. Unless I'm missing some setting that would stop clipping.

Thanks for the reply!

snowbird wrote: ↑

Tue Jun 04, 2019 5:30 am

I did discover that with enveloping you can't fade out completely.

That's true, and is because envelopes are logarithmic (the log of zero is "undefined").
However, you can fade down to -140 dB, which is well below the smallest 16-bit number.

snowbird wrote: ↑

Tue Jun 04, 2019 5:30 am

adjusting the track gain doesn't seem to have a protection against clipping. So that makes it a much more dangerous option. Unless I'm missing some setting that would stop clipping.

This is a much trickier problem than it might first appear:

Audacity projects can contain audio in multiple tracks. When exporting, the tracks are mixed (added) together. If tracks overlap, then the mix "may" be greater than 0 dB, even though all of the overlapping tracks may themselves be well below 0 dB. There's no way that a program can determine what the peak level of a mix will be, without mixing the tracks and then looking for the peak level.

With a single track project the problem is not so bad, because you can enable "Show Clipping" in the View menu.

For mult-track projects, I would very highly recommend mixing down the project and Normalizing the mix before exporting.
Tip: "Export to New Track", then Normalize the Mix track, the "Export Selection" to export the mix track only, then delete the mix track and save the multi-track project.

Dear Steve,

Thank you so much for your thoughtful answer. And thank you for all the other useful contributions you have made on the forum. It's a great service.