Bilinear (First Order IIR) Filter

The 'bilinear-filter controller can be created using the following Lisp syntax:

The 'bilinear-filter controller takes four arguments:

• dimension: number of dimensions of the input and output controllers.
• period: the time between the updates of the controller. If zero is given then it updates every sample.
• coef_controller: a three-dimensional controller specifying the three bilinear filter coefficients.
• input_controller: filter input (a controller).

The number of dimensions should be the same as that of the input controller.

The coefficient controller should have 3 dimensions which represent the a0, a1 and b1 coefficients.

This filter implements a general first-order (one-pole one-zero) filter which can be used for a variety of purposes, including smoothing out envelopes, and filtering sound-file, signal or other controllers. The following example is shown in one of the graphs (with a 1 Hz cutoff) in the above image:

You should probably consider using it or the biquadratic-filter, instead of the older filtering functions. However, you will need to generate your own sets of coefficients from higher level parameters such as center/cutoff frequency, etc....

There are no special options for this controller.