sfFDN::RingModulator Class Reference

A ring modulator. More...

#include <nonlinear.h>

Inheritance diagram for sfFDN::RingModulator:

Collaboration diagram for sfFDN::RingModulator:

Public Member Functions
	RingModulator (const RingModulatorOptions &options={})
	Constructs a ring modulator.
float	GetFrequency () const noexcept SFFDN_NONBLOCKING
	Returns the modulation frequency, in cycles per sample.
float	GetAmplitude () const noexcept SFFDN_NONBLOCKING
	Returns the linear gain applied to the modulating sinusoid.
float	Tick (float input) noexcept SFFDN_NONBLOCKING
	Processes a single sample.
void	Process (const AudioBuffer &input, AudioBuffer &output) noexcept SFFDN_NONBLOCKING override
	Processes the audio buffer.
uint32_t	InputChannelCount () const noexcept SFFDN_NONBLOCKING override
	Returns the number of input channels this processor expects.
uint32_t	OutputChannelCount () const noexcept SFFDN_NONBLOCKING override
	Returns the number of output channels this processor produces.
void	Clear () override
	Restores the configured initial phase.
std::unique_ptr< AudioProcessor >	Clone () const override
	Creates a copy of the processor.
Public Member Functions inherited from sfFDN::AudioProcessor

Additional Inherited Members
Protected Member Functions inherited from sfFDN::AudioProcessor
	AudioProcessor (const AudioProcessor &)=default
AudioProcessor &	operator= (const AudioProcessor &)=default
	AudioProcessor (AudioProcessor &&) noexcept=default
AudioProcessor &	operator= (AudioProcessor &&) noexcept=default

Detailed Description

A ring modulator.

Implements equation (5) of the paper:

\[ y(n) = g_\mathrm{rm}\, x(n) \sin(2 \pi f_\mathrm{rm} n). \]

The multiplication replaces the spectrum of the input with two sidebands, shifted by \(\pm f_\mathrm{rm}\). Below about 20 Hz the effect is heard as a tremolo, and above it as a change of timbre: harmonic when the modulation frequency is an integer ratio of the input, and bell-like or metallic otherwise.

The average power of a unit-amplitude sinusoid is one half, so the default amplitude of \(\sqrt{2}\) makes the operation energy preserving on average. That is an average over a modulation period, not a bound: the instantaneous gain still reaches \(\sqrt{2}\) at the peaks of the modulator. In a network with short, strongly recirculating delay lines, or with a diagonally dominant feedback matrix, several channels can peak together for long enough to make the energy grow. Lower the amplitude if that happens.

Constructor & Destructor Documentation

RingModulator()

sfFDN::RingModulator::RingModulator ( const RingModulatorOptions & options = {} )

explicit

Constructs a ring modulator.

Parameters

options

The configuration options.

Exceptions

std::invalid_argument

if the frequency is negative or not finite, if the amplitude is not finite, or if the initial phase is not in [0, 1].

Member Function Documentation

Clear()

void sfFDN::RingModulator::Clear ( )

overridevirtual

Restores the configured initial phase.

Implements sfFDN::AudioProcessor.

Clone()

std::unique_ptr< AudioProcessor > sfFDN::RingModulator::Clone ( ) const

overridevirtual

Creates a copy of the processor.

The running modulation phase is carried over, not restarted.

Implements sfFDN::AudioProcessor.

InputChannelCount()

uint32_t sfFDN::RingModulator::InputChannelCount ( ) const

overridevirtualnoexcept

Returns the number of input channels this processor expects.

This is always 1.

Implements sfFDN::AudioProcessor.

OutputChannelCount()

uint32_t sfFDN::RingModulator::OutputChannelCount ( ) const

overridevirtualnoexcept

Returns the number of output channels this processor produces.

This is always 1.

Implements sfFDN::AudioProcessor.

Process()

void sfFDN::RingModulator::Process ( const AudioBuffer & input, AudioBuffer & output )

overridevirtualnoexcept

Processes the audio buffer.

Note

The input and output buffers must have one channel and the same number of samples.

Implements sfFDN::AudioProcessor.

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The documentation for this class was generated from the following file:

• include/sffdn/nonlinear.h