This repo contains some DSP filters used in audio. The list of the filters is the following:
- First order all-pass filter (fo_apf)
- First order high-pass filter (fo_hpf)
- First order low-pass filter (fo_lpf)
- First order high-shelving filter (fo_shelving_high)
- First order low-shelving filter (fo_shelving_low)
- Second order all-pass filter (so_apf)
- Second order band-pass filter (so_bpf)
- Second order band-stop filter (so_bsf)
- Second order Butterworth band-pass filter (so_butterworth_bpf)
- Second order Butterworth band-stop filter (so_butterworth_bsf)
- Second order Butterworth high-pass filter (so_butterworth_hpf)
- Second order Butterworth low-pass filter (so_butterworth_lpf)
- Second order high-pass filter (so_hpf)
- Second order Linkwitz-Riley high-pass filter (so_linkwitz_riley_hpf)
- Second order Linkwitz-Riley low-pass filter (so_linkwitz_riley_lpf)
- Second order Low-pass filter (so_lpf)
- Second order parametric/peaking boost filter with constant-Q (so_parametric_cq_boost)
- Second order parametric/peaking cut filter with constant-Q (so_parametric_cq_cut)
- Second order parametric/peaking filter with non-constant-Q (so_parametric_ncq)
The filters can be used in your C++ code in the part where the audio sample is about to be processed. You need to include the filter_common.h and filter_includes.h files and the create an object with filter(s) you want to apply and calculate the coefficients with the calculate_coeffs() function. Then in the sample processing function run the filter() function with the current sample as a parameter.
I've used RackAFX to test these filters.