Pitch conventions — Abjad v1.1.1 documentation

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# Pitch conventions

Abjad follows the following pitch conventions.

## Names

Abjad names pitches according to the LilyPond `english.ly` module.

Abjad names accidentals according to the table below.

> accidental | symbol
> --- | ---
> quarter sharp | ‘qs’
> quarter flat | ‘qf’
> sharp | ‘s’
> flat | ‘f’
> three-quarters sharp | ‘tqs’
> three-quarters flat | ‘tqf’
> double sharp | ‘ss’
> double flat | ‘ff’

## Numbers

Abjad sets middle C equal to 0. This follows the presentation of American pitch-class theory in, for example, [Morris1987] .

IRCAM / MIDI pitch numbers equal Abjad pitch numbers plus 60.

## Octaves

Abjad represents octaves with both numbers and ticks.

> Octave notation | Tick notation
> --- | ---
> C7 | c’‘’‘
> C6 | c’‘’
> C5 | c’‘
> C4 | c’
> C3 | c
> C2 | c,
> C1 | c,,

Abjad follows American usage and sets the octave of middle C equal to 4. usage.

Abjad uses ticks in LilyPond output only.

## Accidental spelling

Abjad chooses between enharmonic spellings at pitch-initialization time according to the following table.

> PC number | Default spelling
> --- | ---
> 0 | C
> 1 | C♯
> 2 | D
> 3 | E♭
> 4 | E
> 5 | F
> 6 | F♯
> 7 | G
> 8 | G♭
> 9 | A
> 10 | B♭
> 11 | B

For example:

    abjad> t = Staff([Note(n, (1, 8)) for n in range(12)])
    abjad> print t.format
    \new Staff {
            c'8
            cs'8
            d'8
            ef'8
            e'8
            f'8
            fs'8
            g'8
            af'8
            a'8
            bf'8
            b'8
    }

You can use `pitchtools.make_sharp()` and `pitchtools.make_flat()` to respell accidentals after initialization:

    abjad> pitchtools.make_sharp(t)
    abjad> print t.format
    \new Staff {
            c'8
            cs'8
            d'8
            ds'8
            e'8
            f'8
            fs'8
            g'8
            gs'8
            a'8
            as'8
            b'8
    }

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