Csound.Air.Filter

Filters

Documentation

Arguemnts are inversed to get most out of curruing. First come parameters and the last one is the signal.

First order filters

lp1 :: Sig -> Sig -> Sig

First order low pass filter (tone in Csound, 6 dB)

lp1 centerFreq asig

hp1 :: Sig -> Sig -> Sig

First order high pass filter (atone in Csound, 6 dB)

hp1 centerFreq asig

Simple filters

lp :: Sig -> Sig -> Sig -> Sig

Low-pass filter.

lp cutoff resonance sig

hp :: Sig -> Sig -> Sig -> Sig

High-pass filter.

hp cutoff resonance sig

bp :: Sig -> Sig -> Sig -> Sig

Band-pass filter.

bp cutoff resonance sig

br :: Sig -> Sig -> Sig -> Sig

Band-reject filter.

br cutoff resonance sig

alp :: Sig -> Sig -> Sig -> Sig

All-pass filter.

alp cutoff resonance sig

bp2 :: Sig -> Sig -> Sig -> Sig

Resonance band pass filter (yet another implementation, it's reson in Csound)

bp2 centerFreq q asig

br2 :: Sig -> Sig -> Sig -> Sig

Resonance band reject filter (yet another implementation, it's areson in Csound)

br2 centerFreq q asig

Butterworth filters

blp :: Sig -> Sig -> Sig

Low-pass filter.

blp cutoff sig

bhp :: Sig -> Sig -> Sig

High-pass filter.

bhp cutoff sig

bbp :: Sig -> Sig -> Sig -> Sig

Band-pass filter.

bbp cutoff bandwidth sig

bbr :: Sig -> Sig -> Sig -> Sig

Band-regect filter.

bbr cutoff bandwidth sig

Filter order

type ResonFilter = Sig -> Sig -> Sig -> Sig

Resonant filter.

f centerFreq q asig

type FlatFilter = Sig -> Sig -> Sig

Filter without a resonance.

f centerFreq q asig

filt :: Int -> ResonFilter -> ResonFilter

Applies a filter n-times. The n is given in the first rgument.

flatFilt :: Int -> FlatFilter -> FlatFilter

Applies a flat filter (without resonance) n-times. The n is given in the first rgument.

Specific filters

Moog filters

mlp :: Sig -> Sig -> Sig -> Sig

Moog's low-pass filter.

mlp centerFrequency qResonance signal

mlp2 :: Sig -> Sig -> Sig -> Sig

Another implementation of moog low pass filter (it's moogladder in Csound). The arguments have are just like in the mlp filter.

mlp3 :: Sig -> Sig -> Sig -> Sig

Mooglowpass filter with 18 dB.

lp18 :: Sig -> Sig -> Sig -> Sig -> Sig

Low pass filter 18 dB with built in distortion module.

lp18 distortion centerFreq resonance asig

• distortion's range is 0 to 1
• resonance's range is 0 to 1

Formant filters

formant :: ResonFilter -> [(Sig, Sig)] -> Sig -> Sig

Formant filter.

formant bandPassFilter formants asig

It expects a band pass filter, a list of formants and processed signal. The signal is processed with each filter the result is a sum of all proceessed signals. Formant filters are used to mimic the vocalization of the sound.

singA :: Sig -> Sig

Formant filter that sings an A.

singO :: Sig -> Sig

Formant filter that sings an O.

singE :: Sig -> Sig

Formant filter that sings an E.

singU :: Sig -> Sig

Formant filter that sings an U.

singO2 :: Sig -> Sig

Formant filter that sings an O.

Making the smooth lines

smooth :: Sig -> Sig -> Sig

Produces smooth transitions between values in the signals. The first value defines a duration in seconds for a transition from one value to another in piecewise constant signals.

slide :: Sig -> Sig -> Sig

Makes slides between values in the signals. The first value defines a duration in seconds for a transition from one value to another in piecewise constant signals.

Analog filters

Requires Csound 6.07 or higher

alp1 :: Sig -> Sig -> Sig -> Sig

Analog-like low-pass filter

alpf1 centerFrequency resonance asig

alp2 :: Sig -> Sig -> Sig -> Sig

Analog-like low-pass filter

alpf2 centerFrequency resonance asig

alp3 :: Sig -> Sig -> Sig -> Sig

Analog-like low-pass filter

alpf3 centerFrequency resonance asig

alp4 :: Sig -> Sig -> Sig -> Sig

Analog-like low-pass filter

alpf4 centerFrequency resonance asig

ahp :: Sig -> Sig -> Sig

Analog-like high-pass filter

ahp centerFrequency asig

Low level analog filters

mvchpf :: Sig -> Sig -> Sig

Moog ladder lowpass filter.

Moogladder is an new digital implementation of the Moog ladder filter based on the work of Antti Huovilainen, described in the paper "Non-Linear Digital Implementation of the Moog Ladder Filter" (Proceedings of DaFX04, Univ of Napoli). This implementation is probably a more accurate digital representation of the original analogue filter.

asig  moogladder  ain, kcf, kres[, istor]

csound doc: http://www.csounds.com/manual/html/moogladder.html

Emulator of analog high pass filter.

mvchpf asig xfreq

mvclpf1 :: Sig -> Sig -> Sig -> Sig

Emulators of analog filters (requires Csound >= 6.07).

mvclpf1 asig xfreq xresonance 

mvclpf2 :: Sig -> Sig -> Sig -> Sig

Emulators of analog filters.

mvclpf2 asig xfreq xresonance 

mvclpf3 :: Sig -> Sig -> Sig -> Sig

Emulators of analog filters.

mvclpf3 asig xfreq xresonance 

mvclpf4 :: Sig -> Sig -> Sig -> Sig

Emulators of analog filters.

mvclpf4 asig xfreq xresonance