Fourier Pitch/Tempo Control
===========================
Winamp used to provide a Pitch/Tempo control in it's earlier versions. I was rather disappointed when I did not find it in the last version I installed. Then I remembered it was there in the SDK tutorial, and I thought I would just compile it for myself. I started to play with the code, and ultimately added ability to transform pitch or tempo independently, using a mathematical magic called Fourier Transformations.

The module actually contains two subroutines - one for changing the pitch independent of tempo (which actually uses the Fourier Transformation), and one for changing the tempo keeping the pitch/tempo ratio constant. Sometimes one or both of the subroutines may not be necessary. Then they will be turned off automatically, and a star (*) will appear beside the name.

You can mimic the Nullsoft Pitch/Tempo control by fixing the Pitch/Tempo ratio at 1.

Note: If you want to do fourier transformations by the book in a program it is going to be much too slow. Fortunately, there is an ingenious algorithm (or rather, collection of algorithms) available, called the Fast Fourier Transform (FFT). This is what is used in this plugin. The credit for the FFT source goes to Don Cross <dcross@intersrv.com> - thanks Don.

Echo & Chorus
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This module provides Reverbed Echo and Chorus. I wrote this plugin long back (01/01/2000) just to get myself aquainted with writing a .dll for the first time. Below I quote whatever I wrote in that plugin's accompanying .txt file.

Reverbed Echo
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The echo plugin supplied with Winamp (dsp_ns2.dll) is not Reverbed, and it's quality is also not good enough. It was created only as a test, and a tutorial for those who want to play with the Plugin SDKs (however, the Pitch/Temp Control provided there is just great!). So I just decided to create a good echo plugin (before somebody else creates it ;-) ).

*Reverbation* means that the echo will repeat infinitely many times, each time being fader and fader. Turning Reverbed Echo off will cause the echo feature to be turned off. There is no means by which you can turn off Reverbation only.

The *First Slider* adjusts the time delay. The text below shows the time delay / how much away the wall should be to produce that much delay. You should set it to match the rithm of the song, ie. it should be set as a multiple of the time difference between 'beats' in the song for best results.

The *Second Slider* adjust the intensity. Each time the original volume will be decreased to the value set in intensity while echoing. WARNING: Don't go too much near 100%!

Chorus
------
This feature works best with solo only. It will produce annoying noise if too many instruments are playing.

Contacting me
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Email: <hirak_99@myrealbox.com>
Also if you want you might visit my website http://geocities.com/hirak_99 which contains some other free softwares by me.

- Arnab, March 2003.