Hello, biquad~ formula in the PD help-patch is : y(n) = ff1 * w(n) + ff2 * w(n-1) + ff3 * w(n-2) w(n) = x(n) + fb1 * w(n-1) + fb2 * w(n-2)
biquad~ formula in Jmax is : y[n] = c1*x[n] + c2*x[n-1] + c3*x[n-2] - c4*y[n-1] - c5*y[n-2]
What is the mathematical relation between these two formulae (so between Pd and Jmax coefficients) ?
I found a nice document that explains how to get the right coeffs for different filters : http://www.harmony-central.com/Computer/Programming/Audio-EQ-Cookbook.txt and I'm not sure how to use it with PD biquad~ object.
nicolas
hi Nicolas and all,
I believe it's:
ff1 = c1 ff2 = c2 ff3 = c3 fb1 = -c4 fb5 = -c5
cheers Miller
On Thu, Jan 03, 2002 at 05:16:46AM +0100, Nicolas Lhommet wrote:
Hello, biquad~ formula in the PD help-patch is : y(n) = ff1 * w(n) + ff2 * w(n-1) + ff3 * w(n-2) w(n) = x(n) + fb1 * w(n-1) + fb2 * w(n-2)
biquad~ formula in Jmax is : y[n] = c1*x[n] + c2*x[n-1] + c3*x[n-2] - c4*y[n-1] - c5*y[n-2]
What is the mathematical relation between these two formulae (so between Pd and Jmax coefficients) ?
I found a nice document that explains how to get the right coeffs for different filters : http://www.harmony-central.com/Computer/Programming/Audio-EQ-Cookbook.txt and I'm not sure how to use it with PD biquad~ object.
nicolas
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Miller Puckette -
Nicolas Lhommet