webaudio.lib

An implementation of the WebAudio API filters (https://www.w3.org/TR/webaudio/). Its official prefix is wa.

This library implement WebAudio filters, using their C++ version as a starting point, taken from Mozilla Firefox implementation.

References

(wa.)lowpass2

Standard second-order resonant lowpass filter with 12dB/octave rolloff. Frequencies below the cutoff pass through, frequencies above it are attenuated.

Usage

_ : lowpass2(f0, Q, dtune) : _

Where:

  • f0: cutoff frequency in Hz
  • Q: the quality factor
  • dtune: detuning of the frequency in cents

Test

wa = library("webaudio.lib");
os = library("oscillators.lib");
lowpass2_test = os.osc(440) : wa.lowpass2(1000, 0.707, 0);

References

(wa.)highpass2

Standard second-order resonant highpass filter with 12dB/octave rolloff. Frequencies below the cutoff are attenuated, frequencies above it pass through.

Usage

_ : highpass2(f0, Q, dtune) : _

Where:

  • f0: cutoff frequency in Hz
  • Q: the quality factor
  • dtune: detuning of the frequency in cents

Test

wa = library("webaudio.lib");
os = library("oscillators.lib");
highpass2_test = os.osc(440) : wa.highpass2(1000, 0.707, 0);

References

(wa.)bandpass2

Standard second-order bandpass filter. Frequencies outside the given range of frequencies are attenuated, the frequencies inside it pass through.

Usage

_ : bandpass2(f0, Q, dtune) : _

Where:

  • f0: cutoff frequency in Hz
  • Q: the quality factor
  • dtune: detuning of the frequency in cents

Test

wa = library("webaudio.lib");
os = library("oscillators.lib");
bandpass2_test = os.osc(440) : wa.bandpass2(1000, 1, 0);

References

(wa.)notch2

Standard notch filter, also called a band-stop or band-rejection filter. It is the opposite of a bandpass filter: frequencies outside the give range of frequencies pass through, frequencies inside it are attenuated.

Usage

_ : notch2(f0, Q, dtune) : _

Where:

  • f0: cutoff frequency in Hz
  • Q: the quality factor
  • dtune: detuning of the frequency in cents

Test

wa = library("webaudio.lib");
os = library("oscillators.lib");
notch2_test = os.osc(440) : wa.notch2(1000, 1, 0);

References

(wa.)allpass2

Standard second-order allpass filter. It lets all frequencies through, but changes the phase-relationship between the various frequencies.

Usage

_ : allpass2(f0, Q, dtune) : _

Where:

  • f0: cutoff frequency in Hz
  • Q: the quality factor
  • dtune: detuning of the frequency in cents

Test

wa = library("webaudio.lib");
os = library("oscillators.lib");
allpass2_test = os.osc(440) : wa.allpass2(1000, 1, 0);

References

(wa.)peaking2

Frequencies inside the range get a boost or an attenuation, frequencies outside it are unchanged.

Usage

_ : peaking2(f0, gain, Q, dtune) : _

Where:

  • f0: cutoff frequency in Hz
  • gain: the gain in dB
  • Q: the quality factor
  • dtune: detuning of the frequency in cents

Test

wa = library("webaudio.lib");
os = library("oscillators.lib");
peaking2_test = os.osc(440) : wa.peaking2(1000, 3, 1, 0);

References

(wa.)lowshelf2

Standard second-order lowshelf filter. Frequencies lower than the frequency get a boost, or an attenuation, frequencies over it are unchanged.

_ : lowshelf2(f0, gain, dtune) : _

Where:

  • f0: cutoff frequency in Hz
  • gain: the gain in dB
  • dtune: detuning of the frequency in cents

Test

wa = library("webaudio.lib");
os = library("oscillators.lib");
lowshelf2_test = os.osc(440) : wa.lowshelf2(500, 6, 0);

References

(wa.)highshelf2

Standard second-order highshelf filter. Frequencies higher than the frequency get a boost or an attenuation, frequencies lower than it are unchanged.

_ : highshelf2(f0, gain, dtune) : _

Where:

  • f0: cutoff frequency in Hz
  • gain: the gain in dB
  • dtune: detuning of the frequency in cents

Test

wa = library("webaudio.lib");
os = library("oscillators.lib");
highshelf2_test = os.osc(440) : wa.highshelf2(2000, -6, 0);

References