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Effect: FFT Noise reduction |
Description of
effect:
Reduces, or even removes, noise from a waveform.
Main benefit:
This effect uses a new approach to FFT noiseremoval. Usually,
this kind of effect is very sensitive to changes of the noise in
a sample, but in Pristine Sounds, there is a built-in adaptive
mechanism to work against that. This effect is also useful to
remove hissing-noises.
Description of
parameters:
NOTE! The noise reduction effect is two-part-operation! To
begin removing noise, Pristine sounds first have to know what it
IS CONSIDERED NOISE and what is not!
Image of noise spectra: An image describing how the noise look like. This is the spectra you previously scanned in with the right mouse button.
Strength sliders representing three different frequency bands. To preserve the properties of the original sound, several completely separate layers of noise removal are associated with each slider. Please experiment with the strength of the sliders to find the optimum result.
50 Hz checkbox. This is an option mainly intended for removing "vinyl-rumbling" or groove distortion. The pickup of the turntable very often records signals 20-40 Hz with very high amplitude. They can easily be seen in the waveform window. This option applies only on the frequencies below 50 Hz.
Release time slider. To gather statistical information about any given point of the waveform, a small analyze is done over a larger segment around it. This way, the algorithm gets a better idea about the musical content (at a global point of view) around the point in question. With a small release time the result may turn up "bubbly" or being fluttering. With a too long release time, the result may turn up sounding like a reverb. The default setting is usually a fit-all solution.
Find holes: Seldom used. This function will find "errors" and holes in the previous noise scan.
Load / Save: Enables you to save & load the current spectra to and from the database. When you are loading a spectra you are asked the question if you wish to replace or merge with the spectra.
Merging the spectra can be useful if you are combining two different sorts of noise; for example a groove spectra taken from a vinyl album and a white noise spectra taken from a tape recording.
Carving, option and slider. At some times, one can hear weak remains of noise being left after reduction. That noise was stronger than what the noise image predicted. By using the carving option you can hunt down those remaining pieces. This function tries to isolate noise from music, and making the noise a "little more tender" and the music "more rigid" and therefor affecting the noise more.
Preview: Press the 'Preview' button to test the effect to see if it is tuned properly. It is quicker than applying the effect and making an undo...
What could go
wrong
Almost like in quantum physics, this kind
of effect have certain "forbidden levels". In this case
that means that some settings do not produce good and expected
result. But opposed to quantum physics, all these special
settings are allowed, but highly unrecomended! For
example: One probably want to remove as much noise as possible,
and therefor using the setting that precisely removes everything.
This setting does however produce the most unwanted effects at
the same time. There is a contradictory element, that introduce a
strong amount of "bubbly noise" instead of just
"low noise". When most of the noise has been removed,
what is left has become very bad sounding.
Solution:
1) Remove LESS noise than before. This will make the remaining noise sound more natural.
2) Remove MORE noise than before. This will remove all the "bubbly noise" as well. But, by doing this may harm the remaining music, and is probably not the choice You make in the end.
One other thing that may confuse, is when You have analyzed (scanned) a noise image, that contain cracks and pops. These tiny little sounds contain very strong elements of noise under an extremely short time. But the strength of the noise will make the noise image far stronger.
Solution:
1) Lower the three sliders to only 5-10% if the noise-scan contains pops & crackle. This will be enough.
Text and graphics, Copyright © 1998 Michael
Ljunggren. All rights reserved.
You may freely quote anything in this online help document, if
You clearly state the origin.
For more information: info@pristinesounds.com