FEATURE REQUEST: Fix misaligned, unbalanced Waveform

Hi, there.

Take a good look at this image. I believe everyone here already knows this problem. But, how to solve it with Audacity?

The audio has DC Offset perfectly at ZERO, but the waveform curves (two people using different microphones) are sometimes more up than down and vice versa.

I know a friend who has a professional studio, and he uses iZotope RX 10, the Phase tool (Adaptive Phase Rotation) to correct this unbalanced waveform problem. But the problem is that the iZotope RX 10 costs me an eye and a kidney.

I believe that a function like this in our beloved Audacity would be very very very useful.

The free reaper plugins bundle includes a phase rotator which works in Audacity 2 & 3 …

phase-rotator-

Another way would be simply to put on a high-pass filter. A waveform slowly shifting around is the same as a very low frequency sine wave being added to the signal. If you’re dealing with speech, there’s no useful frequencies below around 80Hz anyway, so a highpass at 80Hz is always useful to filter out rustles and such. Many mics even come with that built-in.

A high-pass filter is worth a try, however …

soundonsound wrote:
natural waveform asymmetry cannot be ‘corrected’ with a high-pass filter,
and a rather more complicated solution is required called a ‘phase rotator’.
https://www.soundonsound.com/sound-advice/q-why-do-waveforms-sometimes-look-lop-sided

I downloaded, installed, updated the plugin list… But it simply doesn’t appear in Audacity 3.4.2. What is the “magic” I must do to make Reaper appear in the Effect menu?

Please, Audacity developers, make a built-in plugin for Phase correction of asymmetrical (misaligned) waveforms

The phase rotator is part of “Real JS” which should be extracted into

C:\Program Files\Common Files\VST2

Real JS

1 Like

Very thank you, Trebor.

But the problem is that the plugin does not detect how many degrees the waveform is asymmetric. I have to experiment with trial and error. And after applying the plugin (rendering to a new track) a shift to the left (or right) is noticeable. In other words, it does not preserve the waveform in its temporal position. So I can’t use this plugin. Thank you very much for your effort in helping me, but I will have to look for another solution to this problem.

I really wish the Audacity developers would create a built-in effect to fix this very common problem. Do they read our suggestions on the forums?

That’s correctable: use the time shift tool to drag the new track so it matches the original.

drag timeline

[many old plugins require this PITA manual time correction ]