Cockos Incorporated Forums - View Single Post - How to plot filter's frequency response using WDL_fft?

Nowhk · 01-31-2017, 01:42 AM

Hey boss, may I ask a further question?

Usually, when I change/filter the signal in some ways, I apply to the knob/modulation source a sort of smooth.
Else, when GUI param value change, I can hear clicks into the audio.
I think you know what I'm talking about: smoothing a param. I'm using a pretty basic (one pole) filter in my VST plugin, which process in this way:

Code:

inline double Process(double input) {
	z1L += a0 * (input - z1L);
	return z1L;
}

Using a0 = 0.01 it gives to me a nice smooth.

Well, my question is: what about changing Freq/Q/Gain of your Biquad filter? Should I need to apply 3 different param smooth for each knob?
That's won't really be a problem. The problem is that I need to calculate coefficients for every "slight" smooth value.

For example: if I change the gain from 0.6 to 0.7, it will calculate coefficients for the next 100 samples, stressing the CPU heavily.
How do you usually deal with this? It's not a Biquad filter problem I know: more a DSP common problem. But I believe you are the right person to asking this right here

Can you help me?
Thanks again!

01-31-2017, 01:42 AM	#33
Nowhk Human being with feelings Join Date: Mar 2016 Posts: 234	Hey boss, may I ask a further question? Usually, when I change/filter the signal in some ways, I apply to the knob/modulation source a sort of smooth. Else, when GUI param value change, I can hear clicks into the audio. I think you know what I'm talking about: smoothing a param. I'm using a pretty basic (one pole) filter in my VST plugin, which process in this way: Code: inline double Process(double input) { z1L += a0 * (input - z1L); return z1L; } Using a0 = 0.01 it gives to me a nice smooth. Well, my question is: what about changing Freq/Q/Gain of your Biquad filter? Should I need to apply 3 different param smooth for each knob? That's won't really be a problem. The problem is that I need to calculate coefficients for every "slight" smooth value. For example: if I change the gain from 0.6 to 0.7, it will calculate coefficients for the next 100 samples, stressing the CPU heavily. How do you usually deal with this? It's not a Biquad filter problem I know: more a DSP common problem. But I believe you are the right person to asking this right here Can you help me? Thanks again!