Structs for configuring audio processors used in the FDN. More...

Classes
struct	sfFDN::ScalarFeedbackMatrixOptions
	Options for configuring a scalar feedback matrix. More...

struct	sfFDN::CascadedFeedbackMatrixOptions
	Information structure for constructing a cascaded feedback matrix (also known as a filter feedback matrix). More...

struct	sfFDN::ModulationOptions
	Options for configuring signal modulation. More...

struct	sfFDN::TimeVaryingFeedbackMatrixOptions
	Options for configuring a TimeVaryingFeedbackMatrix. More...

struct	sfFDN::ParallelGainsOptions
	Options for configuring parallel gain processing. More...

struct	sfFDN::DelayOptions
	Options for configuring delays. More...

struct	sfFDN::DelayBankOptions
	Options for configuring a delay bank. More...

struct	sfFDN::DelayBankTimeVaryingOptions
	Options for configuring a time-varying delay bank. More...

struct	sfFDN::FilterCoefficients
	Coefficients for a digital IIR filter. More...

struct	sfFDN::AllpassFilterOptions
	Options for configuring an allpass filter. More...

struct	sfFDN::SparseFirOptions
	Options for configuring a sparse FIR filter. More...

struct	sfFDN::CascadedBiquadsOptions
	Options for configuring cascaded biquad filters. More...

struct	sfFDN::FirOptions
	Options for configuring a FIR filter. More...

struct	sfFDN::MultichannelFirOptions

struct	sfFDN::SchroederAllpassSectionOptions
	Options for configuring a Schroeder allpass section consisting of `N` Schroeder allpass in series or in parallel. More...

struct	sfFDN::MultichannelSchroederAllpassSectionOptions
	Options for configuring a multichannel bank of Schroeder allpass sections. More...

struct	sfFDN::TimeVaryingSchroederAllpassSectionOptions
	Options for configuring an energy-preserving time-varying Schroeder allpass section. More...

struct	sfFDN::MultichannelTimeVaryingSchroederAllpassSectionOptions
	Options for configuring a multichannel bank of time-varying Schroeder allpass sections. More...

struct	sfFDN::DattorroDelayOptions
	Options for configuring a Dattorro delay-line effect. More...

struct	sfFDN::MultichannelDattorroDelayOptions
	Options for configuring a multichannel bank of Dattorro delay-line effects. More...

struct	sfFDN::ControllableFullWaveRectifierOptions
	Options for configuring a controllable full-wave rectifier. More...

struct	sfFDN::MultichannelControllableFullWaveRectifierOptions
	Options for configuring a multichannel bank of controllable full-wave rectifiers. More...

struct	sfFDN::SignalDependentFractionalDelayOptions
	Options for configuring a signal-dependent fractional delay. More...

struct	sfFDN::MultichannelSignalDependentFractionalDelayOptions
	Options for configuring a multichannel bank of signal-dependent fractional delays. More...

struct	sfFDN::RingModulatorOptions
	Options for configuring a ring modulator. More...

struct	sfFDN::MultichannelRingModulatorOptions
	Options for configuring a multichannel bank of ring modulators. More...

struct	sfFDN::HomogenousFilterOptions
	Options for configuring a homogenous filter. More...

struct	sfFDN::TwoBandFilterOptions
	Options for configuring a two-band filter. More...

struct	sfFDN::ThreeBandFilterOptions
	Options for configuring a three-band filter. More...

struct	sfFDN::TenBandFilterOptions
	Options for configuring a ten-band filter. More...

struct	sfFDN::AttenuationFilterBankOptions
	Options for configuring an attenuation filter bank. More...

struct	sfFDN::GraphicEQOptions
	Options for configuring a graphic equalizer. More...

Typedefs
using	sfFDN::attenuation_filter_variant_t
	Variant type for holding different attenuation filter options.

using	sfFDN::feedback_matrix_variant_t
	Variant type for holding different feedback matrix options.

using	sfFDN::single_channel_processor_variant_t
	Variant type for holding different single-channel processor options.

using	sfFDN::multi_channel_processor_variant_t
	Variant type for holding different multi-channel processor options.

Enumerations
enum class	sfFDN::ScalarMatrixType : uint8_t { ScalarMatrixType::Identity = 0 , ScalarMatrixType::Random = 1 , ScalarMatrixType::Householder = 2 , ScalarMatrixType::RandomHouseholder = 3 , ScalarMatrixType::Hadamard = 4 , ScalarMatrixType::Circulant = 5 , ScalarMatrixType::Allpass = 6 , ScalarMatrixType::NestedAllpass = 7 , ScalarMatrixType::VariableDiffusion = 8 , Count = 9 }
	Represents the type of a scalar matrix. More...

enum class	sfFDN::DelayInterpolationType : uint8_t { DelayInterpolationType::None = 0 , DelayInterpolationType::Linear = 1 , DelayInterpolationType::Allpass = 2 , DelayInterpolationType::Lagrange = 3 , Count = 4 }
	Types of interpolation for fractional delay lengths. More...

enum class	sfFDN::DelayLengthType : uint8_t { DelayLengthType::Random = 0 , DelayLengthType::Gaussian = 1 , DelayLengthType::Primes = 2 , DelayLengthType::Uniform = 3 , DelayLengthType::PrimePower = 4 , DelayLengthType::SteamAudio = 5 , Count = 6 }
	Types of delay length distributions. More...

enum class	sfFDN::ParallelGainsMode : uint8_t { ParallelGainsMode::Split , ParallelGainsMode::Merge , ParallelGainsMode::Parallel }
	Enumeration for parallel gain processing modes. More...

enum class	sfFDN::TimeVaryingMatrixMode : uint8_t { TimeVaryingMatrixMode::Hadamard = 0 , TimeVaryingMatrixMode::RealSchur = 1 , TimeVaryingMatrixMode::Count = 2 }
	Construction modes for a TimeVaryingFeedbackMatrix. More...

enum class	sfFDN::DattorroEffectType : uint8_t { DattorroEffectType::Vibrato , DattorroEffectType::Flanger , DattorroEffectType::WhiteChorus , DattorroEffectType::Doubling , DattorroEffectType::Echo }
	Classic delay-line effects, as described in Table 1 of Jon Dattorro, "Effect Design Part 2: Delay-Line Modulation and Chorus", J. More...

Detailed Description

Structs for configuring audio processors used in the FDN.

Class Documentation

◆ sfFDN::ScalarFeedbackMatrixOptions

struct sfFDN::ScalarFeedbackMatrixOptions

Options for configuring a scalar feedback matrix.

Can be use to construct a ScalarFeedbackMatrix.

Class Members
optional< float >	arg {std::nullopt}	Optional argument for certain matrix types. For example, for the VariableDiffusion type, this could represent.
optional< vector< float > >	custom_matrix {std::nullopt}	Optional custom matrix values in row-major order: custom_matrix[row * matrix_size + column] is A[row, column], mapping source/input columns to destination/output rows (y = Ax). The size of the vector must be matrix_sizematrix_size. If this is set, `type` is ignored.
uint32_t	matrix_size {0}	Size of the feedback matrix.
uint32_t	rng_seed {0}	Optional. Seed for random number generation when type is Random or RandomHouseholder.
ScalarMatrixType	type {ScalarMatrixType::Random}	Type of the feedback matrix.

◆ sfFDN::CascadedFeedbackMatrixOptions

struct sfFDN::CascadedFeedbackMatrixOptions

Information structure for constructing a cascaded feedback matrix (also known as a filter feedback matrix).

A cascaded feedback matrix is composed of multiple stages, where each stage consists of a scalar feedback matrix followed by a bank of delay lines.

Can be used to construct a FilterFeedbackMatrix.

Class Members
float	gain_per_samples {1.f}	Gain per sample.
uint32_t	matrix_size {0}	Size of the feedback matrix.
float	sparsity {1.f}	Sparsity level (>= 1). A value of 1 corresponds to a fully dense matrix, while higher values correspond to sparser matrices.
uint32_t	stage_count {0}	Number of stages.
ScalarMatrixType	type	Type of the feedback matrix. The same type is used for all stages.

◆ sfFDN::ModulationOptions

struct sfFDN::ModulationOptions

Options for configuring signal modulation.

Class Members
float	amplitude {0.f}	For TimeVaryingFeedbackMatrix, normalized peak angular deviation with `\|amplitude\| <= 1`. It follows the AES paper's normalized `μ_A` convention and is multiplied by π exactly once internally: `amplitude = 0.7` means `0.7π`, approximately 2.2 radians, not 0.7 radians. The JASA paper instead expresses `μ_A` in radians, with `μ_A <= π`.
float	frequency {0.f}	Finite LFO frequency in cycles per sample, normalized by the sample rate. For example, 1 Hz at 48 kHz is `1.0f / 48000.0f`.
float	initial_phase {0.f}	Finite initial phase of the modulation, normalized to [0, 1].

◆ sfFDN::TimeVaryingFeedbackMatrixOptions

struct sfFDN::TimeVaryingFeedbackMatrixOptions

Options for configuring a TimeVaryingFeedbackMatrix.

Supply either no modulation configurations to disable modulation, or exactly one configuration for each 2x2 rotation block (matrix_size / 2). matrix_size must be even; Hadamard mode additionally requires a power of two.

Class Members
uint32_t	matrix_size {0}	Dimension of the square feedback matrix. Must be even and at least two.
TimeVaryingMatrixMode	mode {TimeVaryingMatrixMode::Hadamard}	Construction mode for the orthogonal matrix.
uint32_t	rng_seed {0}	Seed for the RealSchur random orthogonal basis. In RealSchur mode, zero selects a fixed seed so configurations are reproducible; Hadamard mode ignores it.
vector< ModulationOptions >	time_varying_config	One LFO configuration per rotation block, or empty to disable modulation.

◆ sfFDN::ParallelGainsOptions

struct sfFDN::ParallelGainsOptions

Options for configuring parallel gain processing.

Class Members
vector< float >	gains	Gain values for each channel. The size of the vector determines the number of channels.
ParallelGainsMode	mode {ParallelGainsMode::Split}	Mode of parallel gain processing.
vector< ModulationOptions >	time_varying_config	Optional time-varying modulation configuration for each channel. The size of the vector must match the size of `gains` if provided.

◆ sfFDN::DelayOptions

struct sfFDN::DelayOptions

Options for configuring delays.

Class Members
float	delay {256.f}
DelayInterpolationType	interp_type
optional< ModulationOptions >	lfo_config
uint32_t	max_delay {512}

◆ sfFDN::DelayBankOptions

struct sfFDN::DelayBankOptions

Options for configuring a delay bank.

Class Members
uint32_t	block_size {kDefaultBlockSize}
vector< float >	delays
DelayInterpolationType	interpolation_type

◆ sfFDN::DelayBankTimeVaryingOptions

struct sfFDN::DelayBankTimeVaryingOptions

Options for configuring a time-varying delay bank.

Class Members
vector< float >	delays
DelayInterpolationType	interpolation_type
uint32_t	max_delay {0}
vector< ModulationOptions >	time_varying_config

◆ sfFDN::AllpassFilterOptions

struct sfFDN::AllpassFilterOptions

Options for configuring an allpass filter.

Class Members
float	coeff {0.f}	The coefficient for the allpass filter.

◆ sfFDN::SparseFirOptions

struct sfFDN::SparseFirOptions

Options for configuring a sparse FIR filter.

Class Members
vector< pair< uint32_t, float > >	coeffs

◆ sfFDN::CascadedBiquadsOptions

struct sfFDN::CascadedBiquadsOptions

Options for configuring cascaded biquad filters.

Class Members
vector< FilterCoefficients >	coeffs

◆ sfFDN::FirOptions

struct sfFDN::FirOptions

Options for configuring a FIR filter.

Class Members
vector< float >	coeffs {1.f}

◆ sfFDN::MultichannelFirOptions

struct sfFDN::MultichannelFirOptions

Class Members
vector< vector< float > >	coeffs

◆ sfFDN::SchroederAllpassSectionOptions

struct sfFDN::SchroederAllpassSectionOptions

Options for configuring a Schroeder allpass section consisting of N Schroeder allpass in series or in parallel.

Class Members
vector< float >	delays
vector< float >	gains
bool	parallel {false}

◆ sfFDN::MultichannelSchroederAllpassSectionOptions

struct sfFDN::MultichannelSchroederAllpassSectionOptions

Options for configuring a multichannel bank of Schroeder allpass sections.

Each section processes one channel of audio.

Class Members
vector< SchroederAllpassSectionOptions >	sections

◆ sfFDN::TimeVaryingSchroederAllpassSectionOptions

struct sfFDN::TimeVaryingSchroederAllpassSectionOptions

Options for configuring an energy-preserving time-varying Schroeder allpass section.

Each stage uses a fixed integer delay and modulates its gain coefficient. time_varying_config must contain one non-zero modulation entry per stage. The complete gain range must remain strictly inside (-1, 1).

Class Members
vector< float >	delays	Fixed delay values in samples. Every value must be a positive integer.
vector< float >	gains	Base gain values. The size must match `delays`.
bool	parallel {false}	If true, process stages in parallel. Otherwise, process them in series.
vector< ModulationOptions >	time_varying_config	Gain modulation per stage. `amplitude` is the non-zero peak gain deviation.

◆ sfFDN::MultichannelTimeVaryingSchroederAllpassSectionOptions

struct sfFDN::MultichannelTimeVaryingSchroederAllpassSectionOptions

Options for configuring a multichannel bank of time-varying Schroeder allpass sections.

Class Members
vector< TimeVaryingSchroederAllpassSectionOptions >	sections

◆ sfFDN::DattorroDelayOptions

struct sfFDN::DattorroDelayOptions

Options for configuring a Dattorro delay-line effect.

blend, feedforward and feedback are the three knobs of the effect. See DattorroDelay for the topology and MakeDattorroDelayOptions() for the settings of the classic effects.

Collaboration diagram for sfFDN::DattorroDelayOptions:

[legend]

Class Members
float	blend {0.7071f}
DelayOptions	delay_config	Configuration of the delay line. `delay` is the nominal delay, which sets the position of the fixed feedback tap and the center of the modulated feedforward tap. `lfo_config`, if present, modulates the feedforward tap only. Note The default interpolation type suits a static delay. `DelayInterpolationType::Linear` is the cheaper choice for a modulated insert effect and `DelayInterpolationType::Allpass` the correct one inside a feedback loop; see DattorroDelay for why.
float	feedback {0.7071f}
float	feedforward {1.f}

◆ sfFDN::MultichannelDattorroDelayOptions

struct sfFDN::MultichannelDattorroDelayOptions

Options for configuring a multichannel bank of Dattorro delay-line effects.

Each entry processes one channel of audio.

See MakeMultichannelDattorroDelayOptions() for a decorrelated preset, and MakeMultichannelDattorroDelay() to build the processor.

Class Members
vector< DattorroDelayOptions >	delays

◆ sfFDN::ControllableFullWaveRectifierOptions

struct sfFDN::ControllableFullWaveRectifierOptions

Options for configuring a controllable full-wave rectifier.

Implements equation (3) of G. Dal Santo, X. Pi, K. Prawda, S. J. Schlecht and V. Välimäki, "Shimmer Reverberation with Nonlinear Feedback Delay Networks", DAFx26.

Class Members
float	alpha {1.f}	Distortion amount, in [0, 1]. Zero passes the input through unchanged, one is a full-wave rectifier, and one half is a half-wave rectifier.
bool	antialiasing {true}	If true, approximate the rectifier with first-order antiderivative antialiasing, equation (4) of the paper. This attenuates the aliased components that fold back from the even harmonics.
bool	dc_block {true}	If true, follow the rectifier with a dc blocker with energy compensation, equations (7) and (8) of the paper. The rectifier produces a dc component that would otherwise accumulate in a feedback loop.
float	sample_rate {static_cast<float>(kDefaultSampleRate)}	Sample rate in Hz. Only used to set the time constants of the dc blocker, so it is irrelevant when `dc_block` is false.

◆ sfFDN::MultichannelControllableFullWaveRectifierOptions

struct sfFDN::MultichannelControllableFullWaveRectifierOptions

Options for configuring a multichannel bank of controllable full-wave rectifiers.

Each entry processes one channel of audio, and a std::nullopt entry leaves its channel unprocessed.

Class Members
vector< optional< ControllableFullWaveRectifierOptions > >	channels

◆ sfFDN::SignalDependentFractionalDelayOptions

struct sfFDN::SignalDependentFractionalDelayOptions

Options for configuring a signal-dependent fractional delay.

Implements the filter of Fig. 5 of the DAFx26 shimmer paper, after V. Välimäki, T. Tolonen and M. Karjalainen, "Signal-dependent nonlinearities for physical models using time-varying fractional delay filters", ICMC 1998.

Class Members
float	d {1.f}	Interpolation weight, in [0, 1]. The positive half-wave component is delayed by `1 + d` samples and the negative one by `1 - d` samples, so zero is a plain one-sample delay and larger values distort the waveform more strongly around its zero crossings.

◆ sfFDN::MultichannelSignalDependentFractionalDelayOptions

struct sfFDN::MultichannelSignalDependentFractionalDelayOptions

Options for configuring a multichannel bank of signal-dependent fractional delays.

Each entry processes one channel of audio, and a std::nullopt entry leaves its channel unprocessed.

Class Members
vector< optional< SignalDependentFractionalDelayOptions > >	channels

◆ sfFDN::RingModulatorOptions

struct sfFDN::RingModulatorOptions

Options for configuring a ring modulator.

Implements equation (5) of the DAFx26 shimmer paper.

Note: Unlike ModulationOptions::amplitude, amplitude here is a plain linear gain and is never multiplied by pi.

Class Members
float	amplitude {std::numbers::sqrt2_v<float>}	Linear gain applied to the modulating sinusoid. The default of `sqrt(2)` compensates for the average power of a unit-amplitude sinusoid and makes the operation approximately energy preserving. Lower values are safer inside a strongly recirculating feedback loop.
float	frequency {0.f}	Modulation frequency in cycles per sample, normalized by the sample rate. For example, 100 Hz at 96 kHz is `100.0f / 96000.0f`. Must be finite and non-negative.
float	initial_phase {0.f}	Initial phase of the modulating sinusoid, normalized to [0, 1].

◆ sfFDN::MultichannelRingModulatorOptions

struct sfFDN::MultichannelRingModulatorOptions

Options for configuring a multichannel bank of ring modulators.

Each entry processes one channel of audio, and a std::nullopt entry leaves its channel unprocessed.

Class Members
vector< optional< RingModulatorOptions > >	channels

◆ sfFDN::HomogenousFilterOptions

struct sfFDN::HomogenousFilterOptions

Options for configuring a homogenous filter.

The homogenous filter has the same attenuation characteristics across all frequencies.

Class Members
float	delay {1.f}
float	sample_rate = kDefaultSampleRate
float	t60 = 1.f

◆ sfFDN::TwoBandFilterOptions

struct sfFDN::TwoBandFilterOptions

Options for configuring a two-band filter.

The two-band filter allows for specifying a target t60 at DC and Nyquist. The filter is implemented as a one-pole filter based on [1].

[1] Jot, J. M., & Chaigne, A. (1991). Digital delay networks for designing artificial reverberators (pp. 1-12). Presented at the Proc. Audio Eng. Soc. Conv., Paris, France.

Class Members
float	delay {0.f}
float	sample_rate = kDefaultSampleRate
array< float, 2 >	t60s {1.f, 0.5f}	Target T60 values for the low and high bands.

◆ sfFDN::ThreeBandFilterOptions

struct sfFDN::ThreeBandFilterOptions

Options for configuring a three-band filter.

The three-band filter is composed of a 2nd order low shelf and a 2nd order high shelf filter in series and allows control of the T60 over three bands with the first band being [0, freq[0]], the second band [freq[0], freq[1]], and the third band [freq[1], Nyquist].

Class Members
float	delay {0.f}
array< float, 2 >	freqs {800.f, 8000.f}
float	q = 1.f / std::numbers::sqrt2_v<float>
float	sample_rate = kDefaultSampleRate
array< float, 3 >	t60s {1.f, 0.5f, 0.25f}

◆ sfFDN::TenBandFilterOptions

struct sfFDN::TenBandFilterOptions

Options for configuring a ten-band filter.

The ten-band filter allows control of the T60 over ten bands. The bands of the filter are set to {32, 64, 125, 250, 500, 1k, 2k, 4k, 8k, 16k} Hz.

The filter is implemented as a cascade of second-order biquad filters following the design method described in [1]. [1] V. Välimäki, K. Prawda, and S. J. Schlecht, "Two-Stage Attenuation Filter for Artificial Reverberation," IEEE Signal Processing Letters, vol. 31, pp. 391–395, 2024, doi: 10.1109/LSP.2024.3352510.

Class Members
float	delay {0.f}	Delay in samples for the delay line preceding the filter. If set to <= 0, it will be updated automatically when accessed from `CreateFDNFromConfig()`
float	sample_rate = kDefaultSampleRate	Sample rate in Hz. This is used to calculate the filter coefficients based on the specified T60 values.
float	shelf_cutoff = 8000.f	Cutoff frequency for the shelf filters.
array< float, 10 >	t60s = {1.f, 0.9f, 0.8f, 0.7f, 0.6f, 0.5f, 0.4f, 0.3f, 0.2f, 0.1f}	Target T60 values for the ten bands.

◆ sfFDN::AttenuationFilterBankOptions

struct sfFDN::AttenuationFilterBankOptions

Options for configuring an attenuation filter bank.

Class Members
vector< attenuation_filter_variant_t >	filter_configs	Vector of attenuation filter configurations.

◆ sfFDN::GraphicEQOptions

struct sfFDN::GraphicEQOptions

Options for configuring a graphic equalizer.

Class Members
array< float, 10 >	freqs {}	Frequency values for the ten bands in Hz.
array< float, 10 >	gains_db {}	Target gains for the ten bands in dB.
float	sample_rate = kDefaultSampleRate	Sample rate in Hz.

Typedef Documentation

◆ attenuation_filter_variant_t

using sfFDN::attenuation_filter_variant_t

Initial value:

std::variant<HomogenousFilterOptions, TwoBandFilterOptions, ThreeBandFilterOptions, TenBandFilterOptions>

Variant type for holding different attenuation filter options.

◆ feedback_matrix_variant_t

using sfFDN::feedback_matrix_variant_t

Initial value:

std::variant<CascadedFeedbackMatrixOptions, ScalarFeedbackMatrixOptions, TimeVaryingFeedbackMatrixOptions>

Variant type for holding different feedback matrix options.

◆ multi_channel_processor_variant_t

using sfFDN::multi_channel_processor_variant_t

Initial value:

 
    std::variant<ParallelGainsOptions, MultichannelSchroederAllpassSectionOptions,
                 MultichannelTimeVaryingSchroederAllpassSectionOptions, MultichannelDattorroDelayOptions,
                 AttenuationFilterBankOptions, DelayBankOptions, DelayBankTimeVaryingOptions,
                 CascadedFeedbackMatrixOptions, ScalarFeedbackMatrixOptions, MultichannelFirOptions,
                 MultichannelControllableFullWaveRectifierOptions, MultichannelSignalDependentFractionalDelayOptions,
                 MultichannelRingModulatorOptions>

Variant type for holding different multi-channel processor options.

◆ single_channel_processor_variant_t

using sfFDN::single_channel_processor_variant_t

Initial value:

 
    std::variant<SchroederAllpassSectionOptions, TimeVaryingSchroederAllpassSectionOptions, AllpassFilterOptions,
                 CascadedBiquadsOptions, FirOptions, DelayOptions, GraphicEQOptions, DattorroDelayOptions,
                 ControllableFullWaveRectifierOptions, SignalDependentFractionalDelayOptions, RingModulatorOptions>

Variant type for holding different single-channel processor options.

Enumeration Type Documentation

◆ DattorroEffectType

enum class sfFDN::DattorroEffectType : uint8_t

strong

Classic delay-line effects, as described in Table 1 of Jon Dattorro, "Effect Design Part 2: Delay-Line Modulation and Chorus", J.

Audio Eng. Soc., Vol. 45, No. 10, 1997.

Enumerator
Vibrato	Fully wet, modulated delay.
Flanger	Short modulated delay with negative feedback.
WhiteChorus	Medium modulated delay with positive feedback.
Doubling	Long modulated delay without feedback.
Echo	Long unmodulated delay with feedback.

◆ DelayInterpolationType

enum class sfFDN::DelayInterpolationType : uint8_t

strong

Types of interpolation for fractional delay lengths.

Enumerator
None	No interpolation. The delay length will be rounded to the nearest integer value.
Linear	Linear interpolation.
Allpass	Allpass interpolation.
Lagrange	Third-order Lagrange interpolation.

◆ DelayLengthType

enum class sfFDN::DelayLengthType : uint8_t

strong

Types of delay length distributions.

Enumerator
Random	Delay lengths are generated randomly within the specified range based on a uniform distribution.
Gaussian	Delay lengths are generated based on a Gaussian distribution within the specified range.
Primes	Delay lengths are selected randomly from a list of prime numbers within the specified range.
Uniform	Delay lengths are uniformly distributed within the specified range.
PrimePower	Delay lengths are generated as powers of prime numbers within the specified range. Based on https://ccrma.stanford.edu/~jos/pasp/Prime_Power_Delay_Line_Lengths.html.
SteamAudio	Delay lengths are generated using the algorithm from the SteamAudio library.

◆ ParallelGainsMode

enum class sfFDN::ParallelGainsMode : uint8_t

strong

Enumeration for parallel gain processing modes.

Enumerator
Split	Process input as a single channel and output to multiple channels.
Merge	Process each input channel separately and output to one channel.
Parallel	Process each input channel separately and output to the same number of channels.

◆ ScalarMatrixType

enum class sfFDN::ScalarMatrixType : uint8_t

strong

Represents the type of a scalar matrix.

[1] D. Rocchesso and J. O. Smith, “Circulant and elliptic feedback delay networks for artificial reverberation,” IEEE Transactions on Speech and Audio Processing, vol. 5, no. 1, pp. 51–63, Jan. 1997, doi: 10.1109/89.554269.
[2] S. J. Schlecht, “FDNTB: the feedback delay network toolbox,” 23rd International Conference on Digital Audio Effects (DAFx2020), 2020.
[3] O. Das, E. K. Canfield-Dafilou, and J. S. Abel, “On The Behavior of Delay Network Reverberator Modes,” in 2019 IEEE Workshop on Applications of Signal Processing to Audio and Acoustics (WASPAA), Oct. 2019, pp. 50–54. doi: 10.1109/WASPAA.2019.8937260.

Enumerator
Identity	Identity matrix.
Random	Random orthogonal matrix.
Householder	Householder matrix.
RandomHouseholder	Random Householder matrix.
Hadamard	Hadamard matrix.
Circulant	Circulant matrix as described in [1].
Allpass	Allpass matrix. See [2]
NestedAllpass	Nested Allpass matrix. See [2]
VariableDiffusion	Variable diffusion matrix as described in [3].

◆ TimeVaryingMatrixMode

enum class sfFDN::TimeVaryingMatrixMode : uint8_t

strong

Construction modes for a TimeVaryingFeedbackMatrix.

Both modes construct an orthogonal matrix at every sample by modulating independent 2x2 rotation blocks.

Enumerator

Hadamard

Uses H^T * blockdiag(R(theta)) * H.

Requires a power-of-two matrix_size.

RealSchur

Uses V * blockdiag(R(theta)) * V^T.

Accepts any even matrix_size.

Count

Number of time-varying matrix modes.

Classes

Typedefs

Enumerations

Detailed Description

Class Documentation

◆ sfFDN::ScalarFeedbackMatrixOptions

◆ sfFDN::CascadedFeedbackMatrixOptions

◆ sfFDN::ModulationOptions

◆ sfFDN::TimeVaryingFeedbackMatrixOptions

◆ sfFDN::ParallelGainsOptions

◆ sfFDN::DelayOptions

◆ sfFDN::DelayBankOptions

◆ sfFDN::DelayBankTimeVaryingOptions

◆ sfFDN::AllpassFilterOptions

◆ sfFDN::SparseFirOptions

◆ sfFDN::CascadedBiquadsOptions

◆ sfFDN::FirOptions

◆ sfFDN::MultichannelFirOptions

◆ sfFDN::SchroederAllpassSectionOptions

◆ sfFDN::MultichannelSchroederAllpassSectionOptions

◆ sfFDN::TimeVaryingSchroederAllpassSectionOptions

◆ sfFDN::MultichannelTimeVaryingSchroederAllpassSectionOptions

◆ sfFDN::DattorroDelayOptions

◆ sfFDN::MultichannelDattorroDelayOptions

◆ sfFDN::ControllableFullWaveRectifierOptions

◆ sfFDN::MultichannelControllableFullWaveRectifierOptions

◆ sfFDN::SignalDependentFractionalDelayOptions

◆ sfFDN::MultichannelSignalDependentFractionalDelayOptions

◆ sfFDN::RingModulatorOptions

◆ sfFDN::MultichannelRingModulatorOptions

◆ sfFDN::HomogenousFilterOptions

◆ sfFDN::TwoBandFilterOptions

◆ sfFDN::ThreeBandFilterOptions

◆ sfFDN::TenBandFilterOptions

◆ sfFDN::AttenuationFilterBankOptions

◆ sfFDN::GraphicEQOptions

Typedef Documentation

◆ attenuation_filter_variant_t

◆ feedback_matrix_variant_t

◆ multi_channel_processor_variant_t

◆ single_channel_processor_variant_t

Enumeration Type Documentation

◆ DattorroEffectType

◆ DelayInterpolationType

◆ DelayLengthType

◆ ParallelGainsMode

◆ ScalarMatrixType

◆ TimeVaryingMatrixMode