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/)
2026-01-20 19:36:13 +00:00
parent 63bd71202a
commit 5e127c3a3e
21 changed files with 6789 additions and 0 deletions
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+/**
+ * Game Boy Wave Channel
+ * 
+ * Implements the wave channel with:
+ * - 32-sample × 4-bit wavetable
+ * - GB-accurate frequency calculation
+ * - 4-level volume (mute, 100%, 50%, 25%)
+ * - Preset waveforms (bass, pad, lead, etc.)
+ * 
+ * Uses OscillatorNode with PeriodicWave for accurate pitch control
+ * (AudioBufferSourceNode playbackRate has issues at low frequencies).
+ */
+
+import { 
+  WaveTable, 
+  WAVE_PRESETS, 
+  VOLUME_MULTIPLIERS,
+  createPeriodicWaveFromTable,
+  type WavePreset, 
+  type WaveVolume 
+} from '../synthesis/WaveTable';
+import { calculateWaveFrequency } from '../synthesis/FrequencyCalc';
+
+export interface WaveNoteResult {
+  oscillator: OscillatorNode;
+  gainNode: GainNode;
+  stopTime: number;
+}
+
+export class WaveChannel {
+  private audioContext: AudioContext;
+  private waveTable: WaveTable;
+  private periodicWave: PeriodicWave | null = null;
+  private volume: WaveVolume = 1; // Default to 100%
+  private outputNode: GainNode;
+  private currentPreset: WavePreset;
+  
+  constructor(
+    audioContext: AudioContext,
+    outputNode: GainNode,
+    preset: WavePreset = 'bass'
+  ) {
+    this.audioContext = audioContext;
+    this.outputNode = outputNode;
+    this.currentPreset = preset;
+    
+    // Initialize wavetable with preset
+    this.waveTable = new WaveTable();
+    this.loadPreset(preset);
+  }
+  
+  /**
+   * Load a preset waveform.
+   */
+  loadPreset(preset: WavePreset): void {
+    this.currentPreset = preset;
+    const waveform = WAVE_PRESETS[preset]();
+    this.waveTable.loadFromBytes(Array.from(waveform));
+    
+    // Create PeriodicWave from the wavetable
+    this.periodicWave = createPeriodicWaveFromTable(
+      this.waveTable.getSamples(),
+      this.audioContext
+    );
+  }
+  
+  /**
+   * Load custom waveform data (32 samples, 0-15 each).
+   */
+  loadCustomWaveform(samples: number[]): void {
+    this.waveTable.loadFromBytes(samples);
+    this.periodicWave = createPeriodicWaveFromTable(
+      this.waveTable.getSamples(),
+      this.audioContext
+    );
+  }
+  
+  /**
+   * Set volume level (GB style: 0=mute, 1=100%, 2=50%, 3=25%).
+   */
+  setVolume(volume: WaveVolume): void {
+    this.volume = volume;
+  }
+  
+  /**
+   * Get current volume level.
+   */
+  getVolume(): WaveVolume {
+    return this.volume;
+  }
+  
+  /**
+   * Get current preset name.
+   */
+  getPreset(): WavePreset {
+    return this.currentPreset;
+  }
+  
+  /**
+   * Play a note on this channel.
+   * 
+   * @param midiNote - MIDI note number
+   * @param duration - Note duration in seconds
+   * @param velocity - Note velocity (0-127)
+   * @param startTime - When to start (audioContext.currentTime based)
+   */
+  playNote(
+    midiNote: number,
+    duration: number,
+    velocity: number = 100,
+    startTime?: number
+  ): WaveNoteResult {
+    const now = startTime ?? this.audioContext.currentTime;
+    
+    // Ensure we have a PeriodicWave
+    if (!this.periodicWave) {
+      this.periodicWave = createPeriodicWaveFromTable(
+        this.waveTable.getSamples(),
+        this.audioContext
+      );
+    }
+    
+    // Create oscillator with the wavetable's PeriodicWave
+    const oscillator = this.audioContext.createOscillator();
+    oscillator.setPeriodicWave(this.periodicWave);
+    
+    // Calculate GB frequency and set directly (no playback rate needed!)
+    const frequency = calculateWaveFrequency(midiNote);
+    oscillator.frequency.setValueAtTime(frequency, now);
+    
+    // Create gain node for volume control
+    const gain = this.audioContext.createGain();
+    
+    // Calculate final gain from velocity and GB volume level
+    const velocityGain = (velocity / 127) * 0.8;
+    const volumeMultiplier = VOLUME_MULTIPLIERS[this.volume];
+    const finalGain = velocityGain * volumeMultiplier;
+    
+    // Simple envelope for wave channel
+    const attackTime = 0.002;  // Very fast attack
+    const releaseTime = 0.01;  // Quick release
+    
+    gain.gain.setValueAtTime(0, now);
+    gain.gain.linearRampToValueAtTime(finalGain, now + attackTime);
+    
+    const releaseStart = now + Math.max(attackTime, duration - releaseTime);
+    gain.gain.setValueAtTime(finalGain, releaseStart);
+    
+    const stopTime = now + duration + releaseTime;
+    gain.gain.linearRampToValueAtTime(0.001, stopTime);
+    
+    // Connect nodes
+    oscillator.connect(gain);
+    gain.connect(this.outputNode);
+    
+    // Schedule playback
+    oscillator.start(now);
+    oscillator.stop(stopTime + 0.01);
+    
+    // Auto-cleanup
+    oscillator.onended = () => {
+      try {
+        oscillator.disconnect();
+        gain.disconnect();
+      } catch {
+        // Already disconnected
+      }
+    };
+    
+    return { oscillator, gainNode: gain, stopTime };
+  }
+  
+  /**
+   * Play a note with a specific preset (doesn't change default).
+   */
+  playNoteWithPreset(
+    midiNote: number,
+    duration: number,
+    velocity: number,
+    preset: WavePreset,
+    startTime?: number
+  ): WaveNoteResult {
+    const now = startTime ?? this.audioContext.currentTime;
+    
+    // Create temporary PeriodicWave for this preset
+    const waveform = WAVE_PRESETS[preset]();
+    const tempWave = createPeriodicWaveFromTable(waveform, this.audioContext);
+    
+    // Create oscillator with the preset's PeriodicWave
+    const oscillator = this.audioContext.createOscillator();
+    oscillator.setPeriodicWave(tempWave);
+    
+    const frequency = calculateWaveFrequency(midiNote);
+    oscillator.frequency.setValueAtTime(frequency, now);
+    
+    const gain = this.audioContext.createGain();
+    const velocityGain = (velocity / 127) * 0.8;
+    const volumeMultiplier = VOLUME_MULTIPLIERS[this.volume];
+    const finalGain = velocityGain * volumeMultiplier;
+    
+    const attackTime = 0.002;
+    const releaseTime = 0.01;
+    
+    gain.gain.setValueAtTime(0, now);
+    gain.gain.linearRampToValueAtTime(finalGain, now + attackTime);
+    
+    const releaseStart = now + Math.max(attackTime, duration - releaseTime);
+    gain.gain.setValueAtTime(finalGain, releaseStart);
+    
+    const stopTime = now + duration + releaseTime;
+    gain.gain.linearRampToValueAtTime(0.001, stopTime);
+    
+    oscillator.connect(gain);
+    gain.connect(this.outputNode);
+    
+    oscillator.start(now);
+    oscillator.stop(stopTime + 0.01);
+    
+    oscillator.onended = () => {
+      try {
+        oscillator.disconnect();
+        gain.disconnect();
+      } catch {
+        // Already disconnected
+      }
+    };
+    
+    return { oscillator, gainNode: gain, stopTime };
+  }
+  
+  /**
+   * Get the raw wavetable samples for visualization.
+   */
+  getWaveformSamples(): Uint8Array {
+    return this.waveTable.getSamples();
+  }
+}