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Delossifier can produce bad distortion in some cases
https://forums.stereotool.com/viewtopic.php?f=15&t=25151		 Page 1 of 1
Author:  All Night [ Thu Jul 12, 2018 10:51 pm ]
Post subject:  Delossifier can produce bad distortion in some cases
Delossifier works pretty great for the most part, but sometimes the spectral hole filler can add really weird, noisy, and unpleasant harmonics / distortion, when it shouldn't. It sounds like the kind of distortion you'd get from a broken speaker or bad tube.

Here's an example:

Image


This issue has been present for as far back as I could test. In this case I'm using 9.01 final.

Here's the track:

https://drive.google.com/open?id=1GDd7z ... O9Bov9HgYT

Stereo Tool settings file attached.

The settings really don't matter though, because all you have to do is turn Delossifier on at the defaults. The attached settings though with AutoEQ, Absolute Highs, etc. will certainly make the distortion more audible.

I want to point out, there is something about certain tracks that causes this to happen. I think it's tracks that have spectral qualities like the above, where it makes the spectral hole algorithm "think" that there's a hole due to lossy compression when it's actually supposed to be the way it is. I only have this happen to a small number of tracks.

Attachments:
FINAL901_User Default_(Compressors+Bass).sts [106.95 KiB]
Downloaded 315 times
Author:  hvz [ Tue Jul 17, 2018 11:34 am ]
Post subject:  Re: Delossifier can produce bad distortion in some cases
Ah! The good news is that the screenshot very clearly shows that what it's doing is completely wrong - it fill up small holes, not just overwrite half of the spectrum. So this should be relatively easy to fix.

(Oddly, I never tested with this type of music ;) )
Author:  hvz [ Wed Jul 18, 2018 5:24 pm ]
Post subject:  Re: Delossifier can produce bad distortion in some cases
Ok. This one isn't as easy to fix as I originally thought. Sure, I can hack something in to make this specific song come out right.. but that's hardly a solution and you'll probably find another problem song. Still thinking.... (The problem is that there are indeed also tracks where you actually WANT it to fill up a large part of the spectrum).
Author:  hvz [ Wed Jul 18, 2018 5:33 pm ]
Post subject:  Re: Delossifier can produce bad distortion in some cases
Enabling "Stonger flutter protection" helps a lot. It removes all that stuff in the highs. Unfortunately it also reduces the effect on tracks where it's actually needed. I'll see if I can at least make a version where it doesn't suddenly recover this type of huge areas. Maybe make it a slider instead of a checkbox.

Can you try the "Stronger flutter protection" on your end, and verify that it helps? (Also on other tracks).
Author:  All Night [ Thu Jul 19, 2018 10:20 am ]
Post subject:  Re: Delossifier can produce bad distortion in some cases
Checking the "Stronger Flutter" checkbox fixes it for me as well.

As I mentioned, this doesn't happen often. This is the track that I have where this problem is most pronounced. Maybe see if you can make it a slider or number setting, and see what the threshold is for the setting to stop it from happening on this particular track, and then see how that affects mp3 tracks with spectral holes, compared to the 9.01 default ("Stronger Flutter" disabled).

I already checked the current "Stronger Flutter" setting on some mp3 compressed tracks and the Spectral Hole Filler definitely doesn't do as good a job when the "Stronger Flutter" setting is enabled, even on midrange.
Author:  hvz [ Mon Jul 23, 2018 5:00 pm ]
Post subject:  Re: Delossifier can produce bad distortion in some cases
The latest version should fix it without "Stronger flutter".
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