Filters

Audio-rate filters.

4 objects. Every entry is pulled directly from the engine source via the ADD_DESCRIPTION / INLET_DOC / OUTLET_DOC / PARAM_DOC macros (see YseEngine/patcher/pObject.h). The ~ prefix marks DSP / audio-rate objects; . marks control-rate objects.

~bp

Bandpass filter. Passes a frequency band centered on ‘frequency’ with bandwidth shaped by ‘Q’ (resonance).

Kind:

DSP (audio-rate)

The center frequency is in Hz; below 0.001 Hz, including the default 0, the filter uses 10 Hz. A higher Q makes the band narrower; the default is 1. A tone at the center frequency comes out at the input’s level for every Q. A Q low enough to open the band fully (below 0.001, or below about 2 * pi * frequency / samplerate) turns filtering off and passes the input unchanged.

Inlets

#	Label	Accepts	Range	Description
0	in	BUFFER	-1.0 to 1.0	Audio input buffer.
1	freq	FLOAT	0-20000 Hz	Center frequency in Hz.
2	Q	FLOAT	0.1-100	Resonance / inverse bandwidth — higher narrows the band.

Outlets

#	Label	Type	Range	Description
0	out	BUFFER	-1.0 to 1.0	Filtered audio output.

Parameters

Name	Default	Range	Description
frequency	0	0-20000 Hz	Initial center frequency in Hz.
Q	1	0.1-100	Initial Q / resonance.

~hp

Single-pole highpass filter. Attenuates content below the cutoff frequency.

Kind:

DSP (audio-rate)

At 0 Hz, the default, the input passes unchanged. As for ~lp, the cutoff is an approximation that holds well at low frequencies; from about a sixth of the sample rate up, the output is the difference between successive samples.

Inlets

#	Label	Accepts	Range	Description
0	in	BUFFER	-1.0 to 1.0	Audio input buffer.
1	cutoff	FLOAT	0-20000 Hz	Cutoff frequency in Hz.

Outlets

#	Label	Type	Range	Description
0	out	BUFFER	-1.0 to 1.0	Filtered audio output.

Parameters

Name	Default	Range	Description
frequency	0	0-20000 Hz	Initial cutoff frequency in Hz.

~lp

Single-pole lowpass filter. Attenuates content above the cutoff frequency.

Kind:

DSP (audio-rate)

The cutoff argument defaults to 0 Hz, where the filter lets nothing through: give it a cutoff (~lp 800). The cutoff is an approximation that holds well at low frequencies. From about a sixth of the sample rate up (about 7 kHz at 44.1 kHz), the filter is fully open and passes the input unchanged.

Inlets

#	Label	Accepts	Range	Description
0	in	BUFFER	-1.0 to 1.0	Audio input buffer.
1	cutoff	FLOAT	0-20000 Hz	Cutoff frequency in Hz.

Outlets

#	Label	Type	Range	Description
0	out	BUFFER	-1.0 to 1.0	Filtered audio output.

Parameters

Name	Default	Range	Description
frequency	0	0-20000 Hz	Initial cutoff frequency in Hz.

~vcf

Resonant bandpass filter whose center frequency is a signal, so it can sweep at audio rate. Sharpness sets how narrow the band is.

Kind:

DSP (audio-rate)

Unlike ~bp, the center frequency comes in as a signal, in Hz, so it can be swept smoothly or modulated at audio rate. Feed it from ~line or an oscillator scaled to a frequency range.

sharpness sets how narrow the band is: higher is narrower. At 0, the default, the left outlet passes the input unchanged and the right outlet is silent.

Nothing comes out unless both the audio input and the center frequency are connected.

Inlets

#	Label	Accepts	Range	Description
0	in	BUFFER	-1.0 to 1.0	Audio input.
1	center	BUFFER	0-20000 Hz	Center frequency in Hz, as a signal. Both signal inlets must be connected for the filter to run.
2	sharpness	FLOAT	0+	How narrow the band is: higher is narrower. 0 turns filtering off.

Outlets

#	Label	Type	Range	Description
0	real	BUFFER	-1.0 to 1.0	The bandpass output.
1	imag	BUFFER	-1.0 to 1.0	The imaginary part of the resonator, a lowpass-like response.

Parameters

Name	Default	Range	Description
sharpness	0	0+	Initial sharpness.