Add v2 Game Boy sound engine (isolated from v1)

- Authentic DMG-CPU sound chip implementation:
  - 4 Pulse channels with duty cycle control (12.5%, 25%, 50%, 75%)
  - 2 Wave channels with 4-bit wavetables
  - 2 Noise channels with LFSR (7-bit and 15-bit modes)

- GameBoy Colorizer effect chain:
  - Low-pass filter (natural GB rolloff)
  - Bit-crushing (4-bit DAC simulation)
  - Sample rate reduction
  - Saturation and high-pass filter
  - Presets: DMG, GBC, GBA, Clean

- Intelligent MIDI processing:
  - Track analysis and role detection (bass, lead, drums, etc.)
  - Automatic channel mapping to GB channels
  - Chord arpeggiator for polyphony handling
  - GameBoy Arranger for fuller sound

- BitMidi search integration
- Completely isolated from v1 (no changes to src/)
This commit is contained in:
b1rdmania
2026-01-20 19:36:13 +00:00
parent 63bd71202a
commit 5e127c3a3e
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/**
* Game Boy APU (Audio Processing Unit) Coordinator
*
* This is the main audio engine for v2, coordinating 8 channels:
* - 4 Pulse channels (p1-p4) with duty cycle control
* - 2 Wave channels (w1-w2) with custom wavetables
* - 2 Noise channels (n1-n2) with LFSR noise
*
* This "Super Game Boy" configuration allows handling complex MIDIs
* while maintaining authentic GB sound character.
*/
import { PulseChannel } from './PulseChannel';
import { WaveChannel } from './WaveChannel';
import { NoiseChannel } from './NoiseChannel';
import { GameBoyColorizer, type ColorizerConfig } from '../effects/GameBoyColorizer';
import {
DEFAULT_V2_CONFIG,
type ChannelId,
type ChannelNote,
type ChannelState,
type PulseChannelId,
type WaveChannelId,
type NoiseChannelId,
type V2Config,
} from '../../types';
import type { DutyIndex } from '../synthesis/DutyCycle';
import type { WavePreset } from '../synthesis/WaveTable';
import type { LFSRMode } from '../synthesis/LFSR';
/**
* Channel configuration for the 8-channel setup
*/
const CHANNEL_CONFIG = {
pulse: [
{ id: 'p1' as const, hasSweep: true, defaultDuty: 2 as DutyIndex },
{ id: 'p2' as const, hasSweep: true, defaultDuty: 2 as DutyIndex },
{ id: 'p3' as const, hasSweep: false, defaultDuty: 1 as DutyIndex },
{ id: 'p4' as const, hasSweep: false, defaultDuty: 1 as DutyIndex },
],
wave: [
{ id: 'w1' as const, preset: 'bass' as WavePreset },
{ id: 'w2' as const, preset: 'pad' as WavePreset },
],
noise: [
{ id: 'n1' as const, mode: '7bit' as LFSRMode },
{ id: 'n2' as const, mode: '15bit' as LFSRMode },
],
};
export class GameBoyAPU {
private audioContext: AudioContext;
private config: V2Config;
// Master output chain
private masterGain: GainNode;
private colorizer: GameBoyColorizer;
// Individual channel instances
private pulseChannels: Map<PulseChannelId, PulseChannel> = new Map();
private waveChannels: Map<WaveChannelId, WaveChannel> = new Map();
private noiseChannels: Map<NoiseChannelId, NoiseChannel> = new Map();
// Per-channel gain nodes for mixing
private channelGains: Map<ChannelId, GainNode> = new Map();
// Channel state tracking
private channelStates: Map<ChannelId, ChannelState> = new Map();
// Note scheduling stats (no limit - Web Audio handles scheduling)
private scheduledNoteCount = 0;
constructor(audioContext?: AudioContext, config?: Partial<V2Config>) {
this.audioContext = audioContext || new AudioContext();
this.config = { ...DEFAULT_V2_CONFIG, ...config };
// Create colorizer with DMG preset for authentic sound
this.colorizer = new GameBoyColorizer(
this.audioContext,
GameBoyColorizer.createPreset('dmg')
);
// Create master gain
this.masterGain = this.audioContext.createGain();
this.masterGain.gain.value = this.config.masterVolume;
// Wire: master -> colorizer -> destination
this.masterGain.connect(this.colorizer.getInput());
this.colorizer.getOutput().connect(this.audioContext.destination);
// Initialize all channels
this.initializeChannels();
}
/**
* Initialize all 8 channels with their gain nodes.
*/
private initializeChannels(): void {
// Create pulse channels
for (const config of CHANNEL_CONFIG.pulse) {
const gain = this.createChannelGain(config.id, 0.25);
const channel = new PulseChannel(this.audioContext, gain, config.hasSweep);
channel.setDutyCycle(config.defaultDuty);
this.pulseChannels.set(config.id, channel);
this.initChannelState(config.id);
}
// Create wave channels (higher gain for bass)
for (const config of CHANNEL_CONFIG.wave) {
const gain = this.createChannelGain(config.id, 0.55); // Boosted for bass
const channel = new WaveChannel(this.audioContext, gain, config.preset);
this.waveChannels.set(config.id, channel);
this.initChannelState(config.id);
}
// Create noise channels
for (const config of CHANNEL_CONFIG.noise) {
const gain = this.createChannelGain(config.id, 0.3);
const channel = new NoiseChannel(this.audioContext, gain, config.mode);
this.noiseChannels.set(config.id, channel);
this.initChannelState(config.id);
}
}
/**
* Create a gain node for a channel and connect to master.
*/
private createChannelGain(id: ChannelId, defaultGain: number): GainNode {
const gain = this.audioContext.createGain();
gain.gain.value = defaultGain;
gain.connect(this.masterGain);
this.channelGains.set(id, gain);
return gain;
}
/**
* Initialize channel state tracking.
*/
private initChannelState(id: ChannelId): void {
this.channelStates.set(id, {
id,
isBusy: false,
busyUntil: 0,
currentGain: this.channelGains.get(id)?.gain.value || 0,
});
}
/**
* Get the AudioContext.
*/
getAudioContext(): AudioContext {
return this.audioContext;
}
/**
* Resume audio context if suspended.
*/
async resume(): Promise<void> {
if (this.audioContext.state === 'suspended') {
await this.audioContext.resume();
}
}
/**
* Schedule a note on a specific channel.
*
* Web Audio handles scheduling of future notes efficiently, so we don't
* limit the number of scheduled notes. The browser will automatically
* manage memory for nodes that have finished playing.
*/
scheduleNote(note: ChannelNote): void {
const { channel, midiNote, startTime, duration, velocity } = note;
if (channel.startsWith('p')) {
this.schedulePulseNote(channel as PulseChannelId, midiNote, duration, velocity, startTime);
} else if (channel.startsWith('w')) {
this.scheduleWaveNote(channel as WaveChannelId, midiNote, duration, velocity, startTime);
} else if (channel.startsWith('n')) {
this.scheduleNoiseNote(channel as NoiseChannelId, midiNote, duration, velocity, startTime);
}
// Update channel state
this.updateChannelBusy(channel, startTime + duration);
this.scheduledNoteCount++;
}
/**
* Schedule a pulse channel note.
*/
private schedulePulseNote(
channelId: PulseChannelId,
midiNote: number,
duration: number,
velocity: number,
startTime: number
): void {
const channel = this.pulseChannels.get(channelId);
if (!channel) return;
channel.playNote(midiNote, duration, velocity, startTime);
}
/**
* Schedule a wave channel note.
*/
private scheduleWaveNote(
channelId: WaveChannelId,
midiNote: number,
duration: number,
velocity: number,
startTime: number
): void {
const channel = this.waveChannels.get(channelId);
if (!channel) return;
channel.playNote(midiNote, duration, velocity, startTime);
}
/**
* Schedule a noise channel note.
*/
private scheduleNoiseNote(
channelId: NoiseChannelId,
midiNote: number,
duration: number,
velocity: number,
startTime: number
): void {
const channel = this.noiseChannels.get(channelId);
if (!channel) return;
channel.playNote(midiNote, duration, velocity, startTime);
}
/**
* Update channel busy state.
*/
private updateChannelBusy(channelId: ChannelId, busyUntil: number): void {
const state = this.channelStates.get(channelId);
if (state) {
state.isBusy = true;
state.busyUntil = Math.max(state.busyUntil, busyUntil);
}
}
/**
* Check if a channel is free at a given time.
*/
isChannelFree(channelId: ChannelId, atTime?: number): boolean {
const time = atTime ?? this.audioContext.currentTime;
const state = this.channelStates.get(channelId);
if (!state) return false;
return time >= state.busyUntil;
}
/**
* Find a free pulse channel.
*/
findFreePulseChannel(atTime?: number): PulseChannelId | null {
const time = atTime ?? this.audioContext.currentTime;
for (const id of ['p1', 'p2', 'p3', 'p4'] as PulseChannelId[]) {
if (this.isChannelFree(id, time)) {
return id;
}
}
return null;
}
/**
* Find a free wave channel.
*/
findFreeWaveChannel(atTime?: number): WaveChannelId | null {
const time = atTime ?? this.audioContext.currentTime;
for (const id of ['w1', 'w2'] as WaveChannelId[]) {
if (this.isChannelFree(id, time)) {
return id;
}
}
return null;
}
/**
* Find a free noise channel.
*/
findFreeNoiseChannel(atTime?: number): NoiseChannelId | null {
const time = atTime ?? this.audioContext.currentTime;
for (const id of ['n1', 'n2'] as NoiseChannelId[]) {
if (this.isChannelFree(id, time)) {
return id;
}
}
return null;
}
/**
* Set duty cycle for a pulse channel.
*/
setPulseDuty(channelId: PulseChannelId, duty: DutyIndex): void {
const channel = this.pulseChannels.get(channelId);
if (channel) {
channel.setDutyCycle(duty);
}
}
/**
* Set preset for a wave channel.
*/
setWavePreset(channelId: WaveChannelId, preset: WavePreset): void {
const channel = this.waveChannels.get(channelId);
if (channel) {
channel.loadPreset(preset);
}
}
/**
* Set mode for a noise channel.
*/
setNoiseMode(channelId: NoiseChannelId, mode: LFSRMode): void {
const channel = this.noiseChannels.get(channelId);
if (channel) {
channel.setMode(mode);
}
}
/**
* Set individual channel volume.
*/
setChannelVolume(channelId: ChannelId, volume: number): void {
const gain = this.channelGains.get(channelId);
if (gain) {
gain.gain.value = Math.max(0, Math.min(1, volume));
}
}
/**
* Set master volume.
*/
setMasterVolume(volume: number): void {
this.masterGain.gain.value = Math.max(0, Math.min(1, volume));
this.config.masterVolume = volume;
}
/**
* Get master volume.
*/
getMasterVolume(): number {
return this.config.masterVolume;
}
/**
* Get a pulse channel instance.
*/
getPulseChannel(id: PulseChannelId): PulseChannel | undefined {
return this.pulseChannels.get(id);
}
/**
* Get a wave channel instance.
*/
getWaveChannel(id: WaveChannelId): WaveChannel | undefined {
return this.waveChannels.get(id);
}
/**
* Get a noise channel instance.
*/
getNoiseChannel(id: NoiseChannelId): NoiseChannel | undefined {
return this.noiseChannels.get(id);
}
/**
* Get all channel states.
*/
getChannelStates(): Map<ChannelId, ChannelState> {
return new Map(this.channelStates);
}
/**
* Get current time from audio context.
*/
getCurrentTime(): number {
return this.audioContext.currentTime;
}
/**
* Reset all channel states.
*/
reset(): void {
for (const id of this.channelStates.keys()) {
this.initChannelState(id);
}
this.scheduledNoteCount = 0;
}
/**
* Get scheduled note count.
*/
getScheduledNoteCount(): number {
return this.scheduledNoteCount;
}
// ===== COLORIZER CONTROLS =====
/**
* Get the colorizer instance.
*/
getColorizer(): GameBoyColorizer {
return this.colorizer;
}
/**
* Set colorizer preset.
*/
setColorizerPreset(preset: 'dmg' | 'gbc' | 'gba' | 'clean'): void {
this.colorizer.setConfig(GameBoyColorizer.createPreset(preset));
}
/**
* Enable/disable the colorizer.
*/
setColorizerEnabled(enabled: boolean): void {
this.colorizer.setEnabled(enabled);
}
/**
* Initialize bit crusher (call after user interaction).
*/
initializeBitCrusher(): void {
this.colorizer.initializeBitCrusher();
}
}
// Re-export default config for convenience
export { DEFAULT_V2_CONFIG } from '../../types';