SoundFonts

SoundFonts (.sf2 / .sf3) are bundled instrument banks, usually General MIDI piano, strings, brass, drums. The soundfont() builtin plays a pattern through a chosen preset of a chosen SoundFont file. nkido ships with three GM banks: gm (small, preloaded), gm_medium (FluidR3Mono), and gm_large (MuseScore General).

soundfont

SoundFont playback - Polyphonic playback of a pattern through a SoundFont preset.

Param	Type	Default	Description
pattern	pattern	-	Pattern producing gate / freq / velocity events
file	string	-	SoundFont filename (string literal)
preset	number	-	Preset index within the SoundFont (number literal)

The pattern provides gate, frequency, and velocity signals. The file is resolved at compile time. The preset is the GM program number: 0 is Acoustic Grand Piano, 40 is Violin, etc.

// Piano on a chord progression
chord("C Em Am G") |> soundfont(@, "gm", 0) |> out(@)

gm

The General MIDI bank, preloaded on engine startup. Filename "gm" resolves to TimGM6mb.sf3, a small, fast-loading set of GM presets covering the standard 128 instruments plus drum kits.

// Acoustic Grand Piano (preset 0)
pat("c4 e4 g4 c5") |> soundfont(@, "gm", 0) |> out(@)

preset

The preset index picks an instrument within the SoundFont. For GM banks: 0 Acoustic Grand Piano, 4 Electric Piano, 24 Acoustic Guitar, 40 Violin, 56 Trumpet, 73 Flute, 81 Lead Synth, 128 (channel 10) Drum Kit. See the General MIDI specification for the full table.

// Strings ensemble (preset 48)
chord("Am F C G") |> soundfont(@, "gm", 48) |> out(@)

voice

soundfont() is polyphonic: multiple notes from a chord pattern play simultaneously, each on its own voice. Voice allocation is automatic; use a chord(...) or poly(pat, ...) input pattern to get parallel notes.

// Polyphonic chord voicing
chord("Cmaj7 Fmaj7 G7 Cmaj7") |> soundfont(@, "gm", 0) |> out(@)

polyphonic

Voice count is managed internally by the SoundFont engine. There’s no explicit voice limit at the akkado level; the engine steals the oldest voice when the budget is exhausted, which is typical SoundFont behavior.

instrument

Different presets within a SoundFont give different instruments. Routing the same pattern through different preset values gives you, for example, piano, brass, and string versions of the same melody, which is handy for layering.

// Layered piano + strings
melody = chord("Am F C G")
melody |> soundfont(@, "gm", 0) +
melody |> soundfont(@, "gm", 48) |> out(@)

Related: samplers, samples-loading, poly