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Audio Complex Helpers (audio-complex)

Overview

audio-complex factors out complex-number and unit-conversion math used by libaudio. It provides magnitude and phase helpers for complex values, MIDI frequency conversion, and linear-to-dB gain conversion.

This module is typically used by other audio modules (audio-fft, audio) rather than imported directly.

Import

{ complexMag: complexMag, phaseAt: phaseAt, freqToMidi: freqToMidi, linearToDb: linearToDb } := import('audio-complex')

Functions

complexMag(x, y)

Returns the magnitude (modulus) of the complex number x + yi.

complexMag(3, 4)  // => 5.0
complexMag(1, 0)  // => 1.0

phaseAt(x, y)

Returns the phase angle in radians for the complex number x + yi. Returns 0 for the zero vector.

phaseAt(1, 0)  // => 0.0
phaseAt(0, 1)  // => ~1.5708  (π/2)
phaseAt(0, 0)  // => 0

freqToMidi(freq)

Converts a frequency in Hz to the nearest MIDI note number. A4 (440 Hz) maps to note 69.

freqToMidi(440)   // => 69  (A4)
freqToMidi(261.63) // => 60  (C4, middle C)
freqToMidi(880)   // => 81  (A5)

linearToDb(gain)

Converts a linear gain factor to decibels (dB). Returns ? for zero or negative gain values.

linearToDb(1.0)  // => 0.0   (unity gain)
linearToDb(2.0)  // => ~6.02 (double amplitude)
linearToDb(0.5)  // => ~-6.02
linearToDb(0)    // => ?