Sound.SC3.Lang.Control.Pitch

SC3 pitch model implementation.

Documentation

data Pitch a

The supercollider language pitch model is organised as a tree with three separate layers, and is designed to allow separate processes to manipulate aspects of the model independently.

The haskell variant implements Pitch as a labeled data type, with a default value such that scale degree 5 is the A above middle C.

 freq (defaultPitch {degree = 5}) == 440

The note is given as a degree, with a modal transposition, indexing a scale interpreted relative to an equally tempered octave divided into the indicated number of steps.

The midinote is derived from the note by adding the inidicated root, octave and gamut transpositions.

The frequency is derived by a chromatic transposition of the midinote, with a harmonic multiplier.

 let {p = defaultPitch
     ;n = p {stepsPerOctave = 12
            ,scale = [0,2,4,5,7,9,11]
            ,degree = 0
            ,mtranspose = 5}
     ;m = n {root = 0
            ,octave = 5
            ,gtranspose = 0}
     ;f = m {ctranspose = 0
            ,harmonic = 1}}
 in (note n,midinote m,freq f) == (9,69,440)

By editing the values of aspects of a pitch, processes can cooperate. Below one process controls the note by editing the modal transposition, a second edits the octave.

 let {edit_mtranspose p d = p {mtranspose = mtranspose p + d}
     ;edit_octave p o = p {octave = octave p + o}
     ;p = repeat defaultPitch
     ;q = zipWith edit_mtranspose p [0,2,4,3,5]
     ;r = zipWith edit_octave q [0,-1,0,1,0]}
 in (map midinote q,map midinote r)

Constructors

Pitch

Fields

mtranspose :: a

gtranspose :: a

ctranspose :: a

octave :: a

root :: a

scale :: [a]

degree :: a

stepsPerOctave :: a

detune :: a

harmonic :: a

freq_f :: Pitch a -> a

midinote_f :: Pitch a -> a

note_f :: Pitch a -> a

midi_cps :: Floating a => a -> a

Midi note number to cycles per second.

 midi_cps 69 == 440

defaultPitch :: (Floating a, RealFrac a) => Pitch a

A default Pitch value of middle C given as degree 0 of a C major scale.

 degree defaultPitch == 0
 scale defaultPitch == [0,2,4,5,7,9,11]
 stepsPerOctave defaultPitch == 12

default_freq_f :: Floating a => Pitch a -> a

The freq_f function for defaultPitch.

default_midinote_f :: Fractional a => Pitch a -> a

The midinote_f function for defaultPitch.

default_note_f :: RealFrac a => Pitch a -> a

The note_f function for defaultPitch.

degree_to_key :: RealFrac a => [a] -> a -> a -> a

Translate degree, scale and steps per octave to key.

 degree_to_key [0,2,4,5,7,9,11] 12 5 == 9

note :: Pitch a -> a

The note value of the pitch model.

 note (defaultPitch {degree = 5}) == 9

midinote :: Pitch a -> a

The midi note value of the pitch model.

 midinote (defaultPitch {degree = 5}) == 69

freq :: Pitch a -> a

The frequency value of the pitch model, excluding detune.

 freq (defaultPitch {degree = 5,detune = 10}) == 440

detunedFreq :: Num a => Pitch a -> a

The frequency value of the complete pitch model, including detune.

 detunedFreq (defaultPitch {degree = 5}) == 440