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Resister
Apr 23, 2012, 02:56 PM
Hello,

Does anyone know and/or have an example of how to build and equalizer like that in iTunes ? I don't mean a graphical one, I want to make one like this:
http://hints.macworld.com/images/eq_big.jpg

Appreciate the help. :D

Thanks.



robvas
Apr 23, 2012, 06:01 PM
It's just a bunch of Slider controls. The audio 'brains' behind what an EQ actually does are probably complicated.

http://en.wikipedia.org/wiki/Equalization_(audio)

Resister
Apr 23, 2012, 07:21 PM
Yeah, I'm just wanting to know if anyone has any code for the "brains" of it.

I've read that Apple's AudioUnits would need to be used, but thats a bit above me.

gnasher729
Apr 24, 2012, 07:29 AM
Yeah, I'm just wanting to know if anyone has any code for the "brains" of it.

I've read that Apple's AudioUnits would need to be used, but thats a bit above me.

A digital equaliser requires some rather complex maths, FFTs, manipulating the frequencies, transforming back, doing everything very carefully to avoid audible glitches, so I think going through the documentation for audio units is your best chance.

BTW. If you find something in there that allows changing playback speed without changing pitch I would be interested in hearing about that, just out of curiosity.

cMacSW
Apr 24, 2012, 09:30 AM
You may want to look at CoreAudio (http://developer.apple.com/library/mac/#documentation/MusicAudio/Conceptual/CoreAudioOverview/Introduction/Introduction.html%23//apple_ref/doc/uid/TP40003577-CH1-SW1)

ghellquist
Apr 24, 2012, 11:21 AM
You might want to search for free open software doing audio editing. Reading the source code might help in understanding how the algorithms work. You might also have a starting point for experiments.

The projects coming to my mind are
Audacity -- I believe it only runs equalizer in "batch" mode
Ardour -- source code available

//gunnar

firewood
Apr 24, 2012, 02:21 PM
BTW. If you find something in there that allows changing playback speed without changing pitch I would be interested in hearing about that, just out of curiosity.

Core Audio on Mac OS X includes the AUTimePitch Audio Unit.

On iOS, Dirac reportedly sells a commercial time pitch library.

chown33
Apr 24, 2012, 02:52 PM
BTW. If you find something in there that allows changing playback speed without changing pitch I would be interested in hearing about that, just out of curiosity.

Audacity > Effect > Change Tempo