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View Full Version : Levelizer peculiarity



Cary B. Cornett
05-25-2005, 01:02 PM
I have really been enjoying the use of the latest updated Levelizer.

Today I was working with using Levelizer in an output track for parallel compression and limiting, which it turns out to do very well, thanks in part to the auto-magic delay compensation for Saw Native plugs. If there is a track or a group of tracks that I need to do this with, I assign those tracks both to the "master" output AND to another output track (which I might label something like "drum sqz") with this added track assigned back to the master. I then insert a Levelizer pre-fade into the "squeeze" output track.

In this case I was fattening up some rhythm guitar tracks, and wanted to both compress and limit using Levelizer in the "squeeze" output track. I also used the gate. I set the compressor to grab AFTER the attack (30) and release quickly (90) with a low threshold (-20 or so), leaving the peaks alone for the limiter. I would set each function by itself, then engage both once I had the settings. This all works fine, except that, when I turned the limiter off during playback, I could hear comb filtering, which went away again when I re-engaged the limiter.

With playback running, I can switch either the gate or the compressor on and off, in any combination, with no problem. I can also engage (right clicking in the threshold window) the limiter with playback running, and all is fine UNTIL, with playback still running, I release the limiter, at which time I get comb filtering. The comb filtering only happens if I disengage the limiter while playback is running. Disengaging the limiter with playback stopped does NOT lead to comb filtering.

The weird part is, if I START the limiter with playback running, it will not cause comb filtering UNLESS I stop the limiter WHILE playback is running.

Start playback with limit OFF. No problem.
Engage limiting while playback is running. No problem.
Disengage limiting whild playback is running. Comb filtering starts.
Re-engage limiting with playback running, comb filtering stops.
Disengage limiting again with playback running, comb filtering resumes.
Stop and restart playback, comb filtering is gone.

It works this way every time.

I can work with Levelizer this way, but it would be nice if this cute little bug went away. :rolleyes:

Bob L
05-25-2005, 03:52 PM
That cute litle bug is an effect of how things work with the Limit function... once you engage the Limiter, you are varying the size of each buffer according to zero cross points... this is completely random based on the audio material and how these points cross the buffer boundaries based on buffer size, audio material and where you started playback.

When you disengage the Limiter during playback, your out track is now short or long by x number of samples, which can no longer be made up or compensated for, because you have disengaged the routine that makes the adjustments.

This is normally not a problem while auditioning the Limit function in a single processing path... but your use of parrallel processing paths will cause two signal paths slightly shifted from each other to be mixed together causing phasing or comb filtering effects.

I would say... don't do this. :)

Bob L

Cary B. Cornett
05-26-2005, 07:51 AM
When you disengage the Limiter during playback, your out track is now short or long by x number of samples, which can no longer be made up or compensated for, because you have disengaged the routine that makes the adjustments.

Bob L

Your explanation was basically what I figured, except for the last bit I quoted.

I wonder if there is a way to have the routine "re-adjust" to the fixed buffer length "one more time" when disengaging the limiter? I bet there IS a way that you could do this. After all, most of the various "under the hood" operations of Saw Studio operate so transparently, which is part of what makes the program such a joy to use. Seems to me that you have made a number of such "tweaks" along the way. ;)

Bob L
05-26-2005, 09:01 AM
OK... the new Levelizer 2.4 has been adjusted to give back any withheld samples and resync the buffers when the Limit or Bypass functions are toggled.

This will fix the comb filter issue when its patched as in Cary's example.

The update will release at the same time as the SAWStudio 3.9e update... hopefully today or tommorrow.

Bob L

Cary B. Cornett
05-26-2005, 09:11 AM
OK... the new Levelizer 2.4 has been adjusted to give back any withheld samples and resync the buffers when the Limit or Bypass functions are toggled.

This will fix the comb filter issue when its patched as in Cary's example.
Bob L

Ah, actually I was using 2.4 when I discovered this (you sent it to me to test the fix of a different bug).

Bob L
05-26-2005, 01:52 PM
Cary... 2.4 has not been officially released... what I sent you was a test of the bug fix... so... I added this new code to the update that will go out shortly... definitely download it when it comes out.

Bob L

mako
05-26-2005, 02:44 PM
The magic strikes again :) :) :)

Great work Bob

cheers

mako

Carl G.
05-26-2005, 10:18 PM
OK... the new Levelizer 2.4 has been adjusted to give back any withheld samples and resync the buffers when the Limit or Bypass functions are toggled.

This will fix the comb filter issue when its patched as in Cary's example.

The update will release at the same time as the SAWStudio 3.9e update... hopefully today or tommorrow.

Bob L
Very nice addition, Bob!
Thanks!

Cary B. Cornett
05-27-2005, 07:53 AM
Cary... 2.4 has not been officially released... what I sent you was a test of the bug fix... so... I added this new code to the update that will go out shortly... definitely download it when it comes out.

Bob L

I will, thanks!