Skip to content

SOUND_ENGINES.md

Latest commit

 

History

History
219 lines (178 loc) · 7.25 KB

SOUND_ENGINES.md

File metadata and controls

219 lines (178 loc) · 7.25 KB
Raw
              ☦
     ╔═════════════════════════╗
     ║  SOUND ENGINE MODULES   ║
     ║  Specifications         ║
     ╚═════════════════════════╝

Sound Engine Modules

Each sound engine is a self-contained module that can be assigned to a channel. Eight maximum channels total. Each channel gets ONE engine at a time.

1. Game Boy Sound Engine (DMG / GB APU Emulation)

Inspired by LSDj and Furnace Tracker's Game Boy support. Emulates the 4-bit resolution sound chip of the original Game Boy.

Channels (when using full GB mode, takes 4 of 8 channels)

Channel Type Description
PU1 Pulse Square wave with envelope AND sweep (freq sweep on PU1 only)
PU2 Pulse Square wave with envelope (no sweep)
WAV Wave Soft synth: 32-sample 4-bit wavetable, sample playback, speech synthesis
NOI Noise Noise generator with envelope and shape functions

Pulse Instrument Parameters

  • ENV: 3-stage amplitude envelope. Each value = 2 hex digits: amplitude + speed. Example: 32/AD/10 = attack from 3 fast, decay to A slow, sustain at 1 hold
  • WAVE: Duty cycle (12.5%, 25%, 50%, 75%)
  • SWEEP: Frequency sweep (PU1 only). First digit = time, second = increase/decrease
  • PU2 TSP: Transpose pulse channel 2 relative to PU1
  • FINETUNE: Detune between pulse channels for phase effects
  • LENGTH: Sound length (UNLIM = infinite)
  • OUTPUT: L/R/LR/OFF panning
  • PITCH: FAST (360Hz update), TICK (per tick), STEP (pitch change on P cmd), DRUM (log falloff)
  • TRANSP: ON/OFF - whether project/chain transpose affects this instrument
  • CMD/RATE: Command speed. 0=fastest, F=slowest
  • TABLE: Assign a table for per-tick automation

Wave Instrument Parameters

  • VOLUME: 0=0%, 1=25%, 2=50%, 3=100% (hardware limitation: only 4 levels)
  • WAVE: Select which wave to play from Wave screen
  • SYNTH: Select which synth sound (16 synths, each uses 10 waves)
  • PLAY: MANUAL, ONCE, LOOP, PINGPONG
  • SPEED: Synth playback speed
  • LENGTH: Synth sound length
  • LOOP POS: Loop point

Wave Synth Screen Parameters

  • SIGNAL: Square, saw tooth, triangle, custom wave, W.FX
  • FILTER: Low-pass, high-pass, band-pass, all-pass
  • DIST: CLIP, FOLD, WRAP distortion modes
  • PHASE: Waveform horizontal compression (PINCH, WARP, RESYNC, RESYN2)
  • VOLUME: Signal volume (start/end for morphing)
  • CUTOFF: Filter cutoff frequency (start/end)
  • Q: Resonance
  • VSHIFT: Vertical signal shift
  • LIMIT: Vertical limit using DIST mode
  • PHASE: Horizontal compression amount (start/end)

Noise Instrument Parameters

  • ENV: Same envelope system as Pulse
  • PITCH: FREE (pitch changes can randomly mute) or SAFE (restarts after pitch change)
  • LENGTH: UNLIM or timed
  • OUTPUT: L/R/LR/OFF
  • VIBRATO: Shape control
  • TABLE: Per-tick automation

Kit Instrument Parameters (Sample Playback via Wave Channel)

  • KIT: Select sample kit (two kits: left note column + right note column)
  • VOLUME: 0-3 levels + L/R output
  • OFFSET: Sample start loop point
  • LEN: ALL or partial
  • LOOP: OFF, ON (from offset), ATK (from beginning)
  • SPEED: Full or half speed
  • CLIP: HARD, SOFT, FOLD, WRAP (mixing behavior when layering two kits)

2. YM2612 FM Synthesis Engine

4-operator FM synthesis inspired by the Yamaha YM2612 (Sega Genesis / Mega Drive). As seen in Furnace Tracker and Deflemask.

Per-Operator Parameters

  • RATIO: Frequency ratio (0-15)
  • LEVEL: Output level (TL: 0-127)
  • ATTACK: Attack rate (AR: 0-31)
  • DECAY: First decay rate (D1R: 0-31)
  • SUSTAIN: Sustain level (SL: 0-15)
  • SUSTAIN RATE: Second decay rate (D2R: 0-31)
  • RELEASE: Release rate (RR: 0-15)
  • DETUNE: Detune amount (DT: 0-7)
  • MULTIPLE: Frequency multiple (MUL: 0-15)
  • KEY SCALE: Rate scaling (KS: 0-3)
  • AM ENABLE: Amplitude modulation on/off

Global FM Parameters

  • ALGORITHM: 0-7 (defines operator routing)
  • FEEDBACK: 0-7 (operator 1 self-feedback)
  • LFO FREQ: Low frequency oscillator speed
  • LFO AM DEPTH: Amplitude modulation depth
  • LFO FM DEPTH: Frequency modulation depth

TODO: Define exact algorithm diagrams for our 8 algorithms

3. 16-Bit Sample Playback Module

Simple, efficient sample player.

Constraints

  • Max samples per song: 16
  • Max sample size: 64KB each
  • Sample format: 16-bit PCM (mono or stereo)
  • Supported import formats: WAV, raw PCM
  • Total sample memory budget: 1MB max per song (16 x 64KB)

Per-Sample Parameters

  • START: Sample start point
  • END: Sample end point
  • LOOP: OFF, FORWARD, PINGPONG
  • LOOP START: Loop region start
  • LOOP END: Loop region end
  • ROOT NOTE: Base pitch (MIDI note)
  • FINETUNE: Fine pitch adjustment
  • VOLUME: 0-127
  • PAN: L-C-R (0-127)

Playback Features

  • Pitch-shifted playback (chromatic, follows note input)
  • Reverse playback
  • One-shot or looped modes
  • Half-speed mode for lo-fi effect

4. Noise Channel (Dynamic Noise Warping)

A dedicated noise synthesis engine that goes beyond simple white/pink noise. Dynamically warps noise through different bitrates and shapes.

Core Parameters

  • SHAPE: Noise shape selection
    • WHITE: Full spectrum white noise
    • PINK: -3dB/octave rolled off
    • BROWN: -6dB/octave rolled off (Brownian motion)
    • METALLIC: Short-loop periodic noise (like NES/GB metallic tones)
    • DIGITAL: Quantized/crushed noise
    • CUSTOM: User-defined noise via wavetable

Bitrate Warping

  • BITRATE: Dynamic bit depth (1-bit through 16-bit)
    • 1-bit: Harsh square-ish noise
    • 4-bit: Game Boy style noise
    • 8-bit: Classic digital noise
    • 16-bit: Full resolution
  • BITRATE can be automated via tables for dynamic warping over time

Frequency Bend Module (ADSR Mode)

  • FREQ START: Starting frequency/pitch of noise
  • FREQ END: Target frequency after envelope
  • BEND ATTACK: Time to reach peak frequency
  • BEND DECAY: Time from peak to sustain frequency
  • BEND SUSTAIN: Held frequency level
  • BEND RELEASE: Frequency on note release
  • BEND CURVE: LINEAR, EXPONENTIAL, LOGARITHMIC

Amplitude Envelope (Standard ADSR)

  • ATTACK: 0-127
  • DECAY: 0-127
  • SUSTAIN: 0-127
  • RELEASE: 0-127

Shape Modulation

  • SHAPE LFO: Morphs between noise shapes over time
  • BITRATE LFO: Warps bitrate with LFO
  • RING MOD: Ring modulate noise with another channel's output

Use Cases

  • Snare drums (white noise + freq bend down)
  • Hi-hats (metallic noise, short envelope)
  • Risers/falls (noise with long frequency sweep)
  • Texture pads (shaped noise with filter)
  • Glitch effects (rapid bitrate warping via table)

Channel Assignment

8 channels total. User assigns engines freely:

Example configurations:

[Full GB Mode + FM]
CH1: PU1    CH5: FM
CH2: PU2    CH6: FM
CH3: WAV    CH7: SAMPLE
CH4: NOI    CH8: NOISE

[FM Heavy]
CH1: FM     CH5: FM
CH2: FM     CH6: FM
CH3: FM     CH7: SAMPLE
CH4: FM     CH8: NOISE

[Hybrid]
CH1: PU1    CH5: SAMPLE
CH2: PU2    CH6: SAMPLE
CH3: FM     CH7: FM
CH4: NOISE  CH8: NOISE

Each channel can be reassigned per-song in the Project screen.