Filter sweep effect in MATLAB

1
votes

I know how to create and apply a lowpass filter with a given cutoff-frequency on an audio input-file by using the functions butter and filter. Now I want to increase the cutoff-frequency with time to create the well-known "filter-sweep effect". My naive approach would be to loop over the audio vector and apply the filter for each sample (or group of samples), but this seems very inefficient. What is the "correct" of accomplishing this in MATLAB?

PS. By the title, it seems this question is similar, but in my opinion it doesn't answer my specific question.

1
matlabfilteringsignal-processing

1 Answers

0
votes

If you have the DSP toolbox, have a look at dsp.IIRFilter since it was designed to do real-time filtering.

You can create this object:

iir = dsp.IIRFilter;

Assign your filter coefficients:

iir.Numerator = B;
iir.Denominator = A;

Filter a frame (stereo audio for example):

iir(randn(1024,2));

Rinse and repeat.