Pitchy provides a simple way to get a music pitch from a frequency. Other than that it has a bunch of useful data structures, calculators and helper functions to work with notes, octaves and acoustic waves.
From Wikipedia:
Pitch is a perceptual property of sounds that allows their ordering on a frequency-related scale, or more commonly, pitch is the quality that makes it possible to judge sounds as "higher" and "lower" in the sense associated with musical melodies.
- Get lower, higher and closest pitch offsets from a specified frequency.
- Get an acoustic wave with wavelength, period and harmonics.
- Create a note from a pitch index, frequency or a letter with octave number.
- Calculate a frequency, note letter and octave from a pitch index
- Find a pitch index from a specified frequency or a note letter with octave.
- Convert a frequency to wavelength and vice versa.
- Convert a wavelength to time period and vice versa.
Create Pitch struct with a specified frequency to get lower, higher and
closest pitch offsets:
do {
// Frequency = 445 Hz
let pitch = try Pitch(frequency: 445.0)
let pitchOffsets = pitch.offsets
print(pitchOffsets.lower.frequency) // 5 Hz
print(pitchOffsets.lower.percentage) // 19.1%
print(pitchOffsets.lower.note.index) // 0
print(pitchOffsets.lower.cents) // 19.56
print(pitchOffsets.higher.frequency) // -21.164 Hz
print(pitchOffsets.higher.percentage) // -80.9%
print(pitchOffsets.higher.note.index) // 1
print(pitchOffsets.higher.cents) // -80.4338
print(pitchOffsets.closest.note.string) // "A4"
// You could also use acoustic wave
print(pitch.wave.wavelength) // 0.7795 meters
} catch {
// Handle errors
}Get an acoustic wave with wavelength, period and harmonics.
do {
// AcousticWave(wavelength: 0.7795)
// AcousticWave(period: 0.00227259)
let wave = try AcousticWave(frequency: 440.0)
print(wave.frequency) // 440 Hz
print(wave.wavelength) // 0.7795 meters
print(wave.period) // 0.00227259 s
print(wave.harmonics[0]) // 440 Hz
print(wave.harmonics[1]) // 880 Hz
} catch {
// Handle errors
}Note could be created with a corresponding frequency, letter + octave number or a pitch index.
do {
// Note(frequency: 261.626)
// Note(letter: .C, octave: 4)
let note = try Note(index: -9)
print(note.index) // -9
print(note.letter) // .C
print(note.octave) // 4
print(note.frequency) // 261.626 Hz
print(note.string) // "C4"
print(try note.lower().string) // "B3"
print(try note.higher().string) // "C#4"
} catch {
// Handle errors
}Calculators are used in the initialization of Pitch, AcousticWave
and Note, but also are included in the public API.
do {
// PitchCalculator
let pitchOffsets = try PitchCalculator.offsets(445.0)
let cents = try PitchCalculator.cents(
frequency1: 440.0,
frequency2: 440.0
) // 19.56
// NoteCalculator
let frequency1 = try NoteCalculator.frequency(forIndex: 0) // 440.0 Hz
let letter = try NoteCalculator.letter(forIndex: 0) // .A
let octave = try NoteCalculator.octave(forIndex: 0) // 4
let index1 = try NoteCalculator.index(forFrequency: 440.0) // 0
let index2 = try NoteCalculator.index(forLetter: .A, octave: 4) // 0
// WaveCalculator
let f = try WaveCalculator.frequency(forWavelength: 0.7795) // 440.0 Hz
let wl1 = try WaveCalculator.wavelength(forFrequency: 440.0) // 0.7795 meters
let wl2 = try WaveCalculator.wavelength(forPeriod: 0.00227259) // 0.7795 meters
let period = try WaveCalculator.period(forWavelength: 0.7795) // 0.00227259 s
} catch {
// Handle errors
}With a help of FrequencyValidator it's possible to adjust minimum and
maximum frequencies that are used for validations in all calculations:
FrequencyValidator.minimumFrequency = 20.0
FrequencyValidator.maximumFrequency = 4190.0Almost everything is covered with tests, but it's important to pass valid values, such as frequencies and pitch indexes. That's why there a re a list of errors that should be handled properly.
enum Error: ErrorType {
case InvalidFrequency
case InvalidWavelength
case InvalidPeriod
case InvalidPitchIndex
case InvalidOctave
}Pitchy is available through CocoaPods. To install it, simply add the following line to your Podfile:
pod 'Pitchy'Pitchy is also available through Carthage. To install just write into your Cartfile:
github "vadymmarkov/Pitchy"Vadym Markov, markov.vadym@gmail.com
Check the CONTRIBUTING file for more info.
Pitchy is available under the MIT license. See the LICENSE file for more info.