music

Documentation

Overview

Package music generates short, perfectly-looping chiptune tracks from a small deterministic parameter set, rendered entirely through the gion synthesis core: every note is a gion.Params scheduled on a step grid and mixed into one buffer. The same Params always produce the same samples, so a game can ship a seed instead of an audio file.

The design follows the classic NES conventions: a square lead built from a short motif arranged in an AABA form over a chord progression, a triangle bass on chord roots, and noise percussion on euclidean patterns. Mood picks scale, progression, tempo and timbre together.

Index

• Constants
• Variables
• type Mood
• type Params
  • func New(mood Mood, seed int64) Params
  • func (p Params) Render(rate int) []int16

Constants

const (
	MuteLead = 1 << iota
	MuteEcho
	MuteBass
	MuteKick
	MuteSnare
	MuteHat
)

Mute bits: set a bit in Params.Mute to silence that instrument — for isolating a voice in the workbench, or shipping a reduced arrangement. The bit order matches the internal voice order.

Variables

var Moods = map[string]Mood{
	"upbeat": Upbeat,
	"heroic": Heroic,
	"dark":   Dark,
	"chill":  Chill,
	"battle": Battle,
	"boss":   Boss,
}

Moods maps the mood names to their values, for CLIs and UIs.

Types

type Mood

type Mood int

Mood selects the musical character: scale, chord progression, default tempo, lead timbre and swing.

const (
	Upbeat Mood = iota
	Heroic
	Dark
	Chill
	Battle
	Boss
)

type Params

type Params struct {
	Seed  int64
	Mood  Mood
	Tempo float64 // BPM; 0 = the mood's tempo
	Bars  int     // loop length; 0 = 16 (an AABA of 4-bar phrases)
	Root  float64 // tonic frequency in Hz; 0 = 220 (A3)
	Gain  float64 // output level (0..1); 0 = 0.6
	Mute  int     // bitmask of silenced instruments (MuteLead, MuteBass, ...)

	// Mixer levels per instrument group, multiplying the built-in balance.
	// 0 means 1.0 (unchanged); the workbench exposes them as sliders so the
	// mix can be set by ear and saved with the track.
	LeadVol float64
	BassVol float64
	DrumVol float64
}

Params describes one track. Zero fields fall back to the mood's defaults (or the package defaults for Bars, Root and Gain); use New for a ready set.

func New

func New(mood Mood, seed int64) Params

New returns the default track parameters for a mood and seed.

func (Params) Render

func (p Params) Render(rate int) []int16

Render composes and synthesizes the track as mono 16-bit samples at the given rate (gion.DefaultRate when rate <= 0). The sample count is derived from tempo and bars alone, and note tails wrap around to the start of the buffer, so the result loops seamlessly by construction.