[Openal] Code Graphical Equalizer readonly

[Jason Daly]

Andreas Dolinsek wrote:
> Hello,
> i want to code a graphical equalizer from a mp3 stream with openAL 
> (split frquency in channels). can you give me some hints to for an 
> easy start (functions etc.)?
>
> thank you!

The only thing OpenAL will help you do here is play back the mp3 stream 
(after you've decoded it into a PCM stream by some other method).  
You'll probably want something like LAME for this 
(http://lame.sourceforge.net).

If you really mean to implement a graphic equalizer (controls that allow 
you to boost and/or attenuate audio at specific frequencies) you'll need 
to look up how to implement band-pass filters, or find a library that 
does this for you.  I don't know of any off the top of my head (try Google).

If you're really just after a spectrum analyzer (just showing the 
amplitude of the audio at specific component frequencies), you just need 
to run the audio through a Fast Fourier Transform as you decode it.  
Look up fftw for this (http://www.fftw.org).

Hope this helps,

--"J"