Audio track view asymmetry

[jade]

Hello,

I have a number of final mastered stereo audio tracks in which both left and right channels have somehow ended up asymmetrical about the center point of the y-axis in the audio view.  If this is what the waveform is really doing electrically, then it probably means some kind of unwanted distortion or at least reduced output, making the track quieter than it should be. 

I definitely didn't intend this, and the raw audio was correct many iterations ago. Any idea where it is going wrong and if it can be fixed?

I am wondering if the older cakewalk compressor might have limited the amplitudes on the +ve side of the y axis only...

Thanks

Edited September 17, 2022 by jade

[Lord Tim]

That's DC Offset. It's not particularly harmful, although it can affect how loud a track can be processed to a point as you mentioned.

To remove it, I'd recommend using something like Audacity (which is freeware). 

If this is part of a project inside Cakewalk, do this:

Find the offending clip by right-clicking it and choosing Associated Audio Files from the context menu, and make a note of the name and path to it.

Close Cakewalk, then go to where the file is, open it up in Audacity, and follow the instructions in the manual here: https://manual.audacityteam.org/man/dc_offset.html

Save the clip, re-open Cakewalk and it should load back in with the DC Offset removed.

IMPORTANT: This is a destructive process though, so once you do this, you're stuck with it. What is probably a better idea is to bounce down the offending track as an audio export, do the DC Offset work on that, then reimport that back in as a new track, and then archiving or deleting the original track. That way you have a safety net in case anything goes wrong.

... or, you know, just go to Process > Apply Effect > DC Offset rather than going through all of that. I keep forgetting that's been there for decades. ?

Honestly though, there's a good chance you'd never notice the difference if it's just a part of a mix. I'd be inclined to not worry about it.

Of course, if these are just exported stereo WAV files, it's easy just to open them up in Audacity directly and do the DC Offset work on them without needing to do most of those steps.

Edited September 20, 2022 by Lord Tim
Derp moment forgetting CbB has this built-in

[bvideo]

Besides DC offset it could also be an extreme low frequency component. Also, it could be the nature of the waveform, which could have equal energy but different maxima on the plus or minus side of center. There's some discussion about these things here.

[bitflipper]

An asymmetrical waveform isn't necessarily a problem, nor is it necessarily the result of a DC offset or excessive VLF content. 

First, determine if the waveform is truly asymmetrical versus just being offset. DC offset doesn't usually distort the waveform, but rather just shifts it above or below the zero crossing. As long as you have a bit of headroom, that won't result in asymmetry. If you suspect DC offset, insert a sharp (e.g. 48db/octave) HPF on the master with the cutoff around 100 Hz and see if the asymmetry is reduced. If it doesn't, then DC offset (or excessive subsonic content, essentially the same thing) is not the issue. 

If it does go away, then I'd start investigating where that DC or VLF content is coming from. In either case, start by examining each track for asymmetry. If you find one, put a low HPF on it and see if that changes the waveform. Start with synth tracks, as they are likely suspects. It's possible that none have it and it's some kind of interaction with an effect. If that's the case, bypass all effects and render the mix. If the asymmetry isn't in the export, start adding plugins back in one by one to see which one's doing it.

One thing it probably isn't is a malfunctioning compressor. Not that it can't ever happen - you can indeed distort waveforms with extremely fast attack times on low frequency content. Sometimes that's done intentionally to dirty up a bass track. The so-called "sync" effect in synthesizers does something similar. But in either case, you can easily hear the effect, as they generate gobs of harmonics. Neither of those situations necessarily results in asymmetrical waveforms.

 

[jade]

It seems to only be a problem on old cakewalk projects. It probably means reduced output more than anything because the track does not use the whole dynamic range.

Remove DC offset somehow did not correct this. However, VC32 final master mix did seem to correct it.

On a separate but related note is there a way of doing what used to be called relatively slow auto level adjust?

Sometimes the band plays louder and then quieter unintentionally during a 3 minutes song and it falls on me to equalize the volume.

Up to now I have been using splits and applying 0.5dB to 2dB boosts, but it is a coarse rough approach, risking sound glitches.

 

Edited September 30, 2022 by jade