Class SynthMath

Namespace

NAudio.Dsp

Assembly

NAudio.Core.dll

Conversions between the musical / MIDI domain and the DSP domain that a sampler or synthesiser needs: note numbers, frequencies, cents, timecents and centibels. These are the units SoundFont generators and SFZ opcodes are expressed in, but the helpers are deliberately format-neutral so any instrument can share them.

public static class SynthMath

Inheritance

object

SynthMath

Inherited Members

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

object.ToString()

Fields

MidiNote0Frequency

Frequency in Hz of MIDI note 0 (C-1), i.e. the reference used by the SoundFont "absolute cents" pitch scale. Equal to 440 * 2^((0-69)/12).

public const double MidiNote0Frequency = 8.175798915643707

Field Value

double

Methods

AbsoluteCentsToHertz(double)

Converts a SoundFont "absolute cents" value to a frequency in Hz. Used for filter cutoff and LFO/envelope-to-pitch destinations. 6900 absolute cents = 440 Hz.

public static double AbsoluteCentsToHertz(double absoluteCents)

Parameters

absoluteCents double

Returns

double

AttenuationCentibelsToGain(double)

Converts a SoundFont attenuation in centibels to a linear gain multiplier. Attenuation reduces level, so 0 cB = unity gain and larger values are quieter (gain = 10^(-cB/200)).

public static double AttenuationCentibelsToGain(double centibels)

Parameters

centibels double

Returns

double

CentibelsToGain(double)

Converts a level expressed in centibels (1/10th of a decibel) to a linear gain multiplier, where positive centibels mean louder.

public static double CentibelsToGain(double centibels)

Parameters

centibels double

Returns

double

CentsToRatio(double)

Converts a pitch offset in cents (1/100th of a semitone) to a linear frequency ratio. 1200 cents = one octave = a ratio of 2.

public static double CentsToRatio(double cents)

Parameters

cents double

Returns

double

DecibelsToGain(double)

Converts a level in decibels to a linear gain multiplier.

public static double DecibelsToGain(double decibels)

Parameters

decibels double

Returns

double

FrequencyToMidiNote(double)

Converts a frequency in Hz to a (fractional) MIDI note number.

public static double FrequencyToMidiNote(double frequency)

Parameters

frequency double

Returns

double

GainToDecibels(double)

Converts a linear gain multiplier to decibels.

public static double GainToDecibels(double gain)

Parameters

gain double

Returns

double

HertzToAbsoluteCents(double)

Converts a frequency in Hz to SoundFont "absolute cents".

public static double HertzToAbsoluteCents(double hertz)

Parameters

hertz double

Returns

double

MidiNoteToFrequency(double)

Converts a MIDI note number to a frequency in Hz (A4 = note 69 = 440 Hz). The note may be fractional to express detuning.

public static double MidiNoteToFrequency(double midiNote)

Parameters

midiNote double

Returns

double

RatioToCents(double)

Converts a frequency ratio to a pitch offset in cents.

public static double RatioToCents(double ratio)

Parameters

ratio double

Returns

double

ResonanceCentibelsToQ(double)

Converts a SoundFont filter resonance (initialFilterQ) in centibels to a linear biquad Q value. The input is clamped to the spec range of 0..960 cB (SF2.04 §8.1.2 gen 8) so malformed values cannot reach float infinity. 0 cB means a flat, non-resonant response, so the mapping subtracts 3.01 dB before converting — Q = 10^((cB/10 - 3.01)/20) — giving the Butterworth Q of ~0.707 at 0 cB (the convention FluidSynth also documents for this generator).

public static double ResonanceCentibelsToQ(double centibels)

Parameters

centibels double

Returns

double

SecondsToTimecents(double)

Converts a duration in seconds to timecents.

public static double SecondsToTimecents(double seconds)

Parameters

seconds double

Returns

double

TimecentsToSeconds(double)

Converts a duration expressed in timecents to seconds. Timecents are the units SoundFont envelope stages (delay/attack/hold/decay/release) use: seconds = 2^(timecents/1200), so 0 timecents = 1 second.

public static double TimecentsToSeconds(double timecents)

Parameters

timecents double

Returns

double