I built my own parametric EQ with Puredata.

But, my problem is: How I can write a graphic image?
I try to explain...
My eq is working, I apply freq, Q, gain. But I have not a "visual image" showing me freq cuttings, Q envelope or gain reduction. I attach an example what I'm talking about and what I'm trying to do.

Any ideas will be appreciated. Thanks.

http://www.pdpatchrepo.info/hurleur/eq31.GIF

yeah, pd isn't too great when it comes to making graphical intefaces. but nothing is totally impossible, so here is one suggestion:

use a fairly large array to display the eq envelope shape, and then use individual sliders to control the various values. when you move the sliders, you would have to make some calculations in your patch to change the array.

(or, you could just not have a graphic display. that's how i prefer it anyway, because you use your ears more. )

Thanks Hardoff,

can you show me a little example?

I don't know how to start with this...

here's a VERY rough start. doesn't include Q though, because i don't know how to calculate its effect.

http://www.pdpatchrepo.info/hurleur/graphicEQ.pd

Q = sqrt(2^N) / (2 ^N -1)

Where N is the bandwidth in octave

N = log(( 2Q^2 + sqrt(4Q^2+1)+1) / 2Q^2) / log(2)

So if the gain is set at +1rms, the frequency at 200Hz and the N=1 then at 400Hz and 100Hz it should reach 0rms. If N=2 then at 800Hz and 50Hz it should reach 0rms.

Unless i'm wrong

http://en.wikipedia.org/wiki/Equalization_filter