73 lines
2.8 KiB
Go
73 lines
2.8 KiB
Go
 
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package synth
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import "math"
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// LFO is a low-frequency oscillator for modulating synthesis parameters.
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// Uses sine waveform. Rate is in Hz (typically 0.01-0.5 Hz for ambient feel).
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type LFO struct {
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phase float64
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rate float64 // Hz
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depth float64 // modulation depth (interpretation depends on usage)
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sr float64
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}
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// NewLFO creates an LFO at the given rate (Hz) and depth.
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func NewLFO(rate, depth float64, sampleRate int) *LFO {
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return &LFO{
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rate: rate,
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depth: depth,
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sr: float64(sampleRate),
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}
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}
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// Advance returns the current LFO value in [-depth, +depth] and advances the phase.
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func (l *LFO) Advance() float64 {
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val := math.Sin(2 * math.Pi * l.phase)
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l.phase += l.rate / l.sr
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if l.phase >= 1.0 {
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l.phase -= math.Floor(l.phase)
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}
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return val * l.depth
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}
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// PitchLFOFreq returns a pitch-modulated frequency given a base frequency
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// and an LFO value in semitones. For example, lfoVal=0.1 shifts pitch up by 0.1 semitones.
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func PitchLFOFreq(baseHz, lfoSemitones float64) float64 {
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return baseHz * math.Pow(2.0, lfoSemitones/12.0)
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}
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// LFOConfig holds LFO parameters for a synthesis layer.
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// Each protocol gets unique, incommensurable rates so modulation patterns never repeat.
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type LFOConfig struct {
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PitchRate float64 // Hz, typically 0.02-0.08
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PitchDepth float64 // semitones, typically 0.05-0.15
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TremoloRate float64 // Hz, typically 0.05-0.3
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TremoloDepth float64 // amplitude fraction, typically 0.05-0.2
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}
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// layerLFOConfigs provides unique incommensurable LFO rates per protocol group.
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// Rates chosen as non-integer ratios to avoid periodic sync (Eno technique).
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var groupLFOConfigs = map[string]LFOConfig{
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"Infrastructure": {PitchRate: 0.031, PitchDepth: 0.08, TremoloRate: 0.053, TremoloDepth: 0.12},
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"Web": {PitchRate: 0.043, PitchDepth: 0.10, TremoloRate: 0.071, TremoloDepth: 0.15},
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"Mail": {PitchRate: 0.037, PitchDepth: 0.07, TremoloRate: 0.059, TremoloDepth: 0.10},
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"Remote Access": {PitchRate: 0.029, PitchDepth: 0.12, TremoloRate: 0.047, TremoloDepth: 0.18},
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"File Transfer": {PitchRate: 0.041, PitchDepth: 0.09, TremoloRate: 0.067, TremoloDepth: 0.13},
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"Database": {PitchRate: 0.023, PitchDepth: 0.06, TremoloRate: 0.083, TremoloDepth: 0.10},
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"VoIP": {PitchRate: 0.019, PitchDepth: 0.05, TremoloRate: 0.091, TremoloDepth: 0.08},
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"Unknown": {PitchRate: 0.053, PitchDepth: 0.15, TremoloRate: 0.037, TremoloDepth: 0.20},
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}
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// DefaultLFOConfig is the fallback for groups not in the map.
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var DefaultLFOConfig = LFOConfig{
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PitchRate: 0.033, PitchDepth: 0.10, TremoloRate: 0.057, TremoloDepth: 0.15,
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}
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// LFOConfigForGroup returns the LFO config for a protocol group.
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func LFOConfigForGroup(group string) LFOConfig {
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if cfg, ok := groupLFOConfigs[group]; ok {
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return cfg
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}
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return DefaultLFOConfig
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}
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