chore(processor): remove obsolete BleedGate filter

flexiondotorg · flexiondotorg · commit a933efb7fa11 · 2025-12-07T10:49:28.000Z
diff --git a/internal/logging/report.go b/internal/logging/report.go
@@ -670,8 +670,6 @@ func formatFilter(f *os.File, filterID processor.FilterID, cfg *processor.Filter
 		formatSpeechnormFilter(f, cfg, m, prefix)
 	case processor.FilterDynaudnorm:
 		formatDynaudnormFilter(f, cfg, prefix)
-	case processor.FilterBleedGate:
-		formatBleedGateFilter(f, cfg, m, prefix)
 	case processor.FilterAlimiter:
 		formatAlimiterFilter(f, cfg, prefix)
 	default:
@@ -1205,33 +1203,6 @@ func formatDynaudnormFilter(f *os.File, cfg *processor.FilterChainConfig, prefix
 	fmt.Fprintln(f, "        Mode: conservative fixed parameters (prevents artifacts)")
 }
 
-// formatBleedGateFilter outputs bleed gate filter details
-func formatBleedGateFilter(f *os.File, cfg *processor.FilterChainConfig, m *processor.AudioMeasurements, prefix string) {
-	if !cfg.BleedGateEnabled {
-		fmt.Fprintf(f, "%sbleedgate: DISABLED\n", prefix)
-		return
-	}
-
-	thresholdDB := linearToDb(cfg.BleedGateThreshold)
-	rangeDB := linearToDb(cfg.BleedGateRange)
-
-	fmt.Fprintf(f, "%sbleedgate: threshold %.1f dB, ratio %.1f:1\n", prefix, thresholdDB, cfg.BleedGateRatio)
-	fmt.Fprintf(f, "        Timing: attack %.0fms, release %.0fms\n", cfg.BleedGateAttack, cfg.BleedGateRelease)
-	fmt.Fprintf(f, "        Range: %.1f dB reduction, knee %.1f\n", rangeDB, cfg.BleedGateKnee)
-
-	// Show rationale
-	if m != nil && m.NoiseProfile != nil {
-		np := m.NoiseProfile
-		hasBleed := np.CrestFactor > 15.0 || (np.PeakLevel-np.MeasuredNoiseFloor) > 20.0
-		if hasBleed {
-			fmt.Fprintf(f, "        Rationale: bleed detected (crest %.1f dB, peak-floor %.1f dB)\n",
-				np.CrestFactor, np.PeakLevel-np.MeasuredNoiseFloor)
-		} else {
-			fmt.Fprintf(f, "        Rationale: noise amplification (predicted output above -40 dB)\n")
-		}
-	}
-}
-
 // formatAlimiterFilter outputs alimiter filter details
 func formatAlimiterFilter(f *os.File, cfg *processor.FilterChainConfig, prefix string) {
 	if !cfg.LimiterEnabled {
diff --git a/internal/processor/adaptive.go b/internal/processor/adaptive.go
@@ -248,19 +248,6 @@ const (
 	speechnormPeakTarget         = 0.95  // Headroom for limiter
 	speechnormSmoothingFast      = 0.001 // Fast response time
 
-	// Bleed gate parameters
-	// Catches bleed/crosstalk that was amplified by speechnorm/dynaudnorm
-	// Threshold is calculated from: predicted_output_bleed = silence_peak_level + worst_case_gain
-	bleedGateMarginDB          = 6.0   // dB above predicted bleed to set threshold (safety margin)
-	bleedGateEnableThresholdDB = -40.0 // dBFS - only enable if predicted output bleed is above this
-	bleedGateMinThresholdDB    = -50.0 // dBFS - minimum threshold (never gate below this)
-	bleedGateMaxThresholdDB    = -20.0 // dBFS - maximum threshold (never gate above this, would cut speech)
-	bleedGateDefaultRatio      = 4.0   // Gentler than pre-gate (suppress rather than cut)
-	bleedGateDefaultAttack     = 15.0  // ms - faster than pre-gate
-	bleedGateDefaultRelease    = 200.0 // ms - smooth release
-	bleedGateDefaultRange      = 0.125 // -18dB reduction (less aggressive than pre-gate)
-	bleedGateDefaultKnee       = 3.0   // Soft knee
-
 	// Mains hum filter parameters
 	humEntropyThreshold   = 0.7  // Below this = tonal noise detected (hum/buzz)
 	humFreq50Hz           = 50.0 // UK/EU mains fundamental frequency
@@ -482,7 +469,6 @@ func AdaptConfig(config *FilterChainConfig, measurements *AudioMeasurements) {
 	tuneLA2ACompressor(config, measurements)
 	tuneDynaudnorm(config)
 	tuneSpeechnorm(config, measurements, lufsGap)
-	tuneBleedGate(config, measurements, lufsGap) // Bleed gate for amplified bleed/crosstalk
 
 	// Final safety checks
 	sanitizeConfig(config)
@@ -1664,111 +1650,6 @@ func tuneSpeechnormDenoise(config *FilterChainConfig, expansion float64) {
 	}
 }
 
-// tuneBleedGate adapts the bleed gate based on predicted output bleed level.
-//
-// The bleed gate catches bleed/crosstalk that was amplified by speechnorm/dynaudnorm
-// after the denoisers have run. Denoisers preserve speech-like content (which is what
-// they're designed to do), but headphone bleed IS speech-like content from other speakers.
-//
-// Strategy:
-// - Use silence sample PEAK level (not noise floor) - captures bleed bursts, not just hiss
-// - Calculate worst-case gain: speechnorm normalises each half-cycle to peak target
-// - For silence with bleed, this can mean 40-50dB of gain applied
-// - Use crest factor to detect presence of bleed (high crest = impulsive content in silence)
-// - Adjust ratio/range based on how much bleed is detected
-//
-// Key insight: Speechnorm applies VARIABLE gain per half-cycle. For quiet sections
-// (like silence with bleed), it applies much more gain than the "expansion" factor
-// suggests. The actual gain on silence can be:
-//
-//	silence_input_peak → target_peak (0.95 = -0.45 dBFS)
-//
-// Measurements used:
-// - NoiseProfile.PeakLevel: captures the loudest bleed burst
-// - NoiseProfile.MeasuredNoiseFloor: captures the background hiss
-// - NoiseProfile.CrestFactor: high crest = impulsive content (bleed), low = steady hiss
-// - NoiseProfile.Entropy: low entropy = tonal (hum), high = broadband (hiss/bleed)
-func tuneBleedGate(config *FilterChainConfig, measurements *AudioMeasurements, lufsGap float64) {
-	// Respect user's intent: if filter is disabled, don't touch it
-	if !config.BleedGateEnabled {
-		return
-	}
-
-	// Need noise profile with measurements to calculate threshold
-	if measurements.NoiseProfile == nil {
-		config.BleedGateEnabled = false
-		return
-	}
-
-	np := measurements.NoiseProfile
-
-	// Calculate worst-case gain: speechnorm can apply gain to bring quiet content to peak
-	// The target peak is typically 0.95 (-0.45 dBFS)
-	targetPeakDB := -0.45 // 20 * log10(0.95)
-	if config.SpeechnormEnabled && config.SpeechnormPeak > 0 {
-		targetPeakDB = 20.0 * math.Log10(config.SpeechnormPeak)
-	}
-
-	// Worst-case gain = what's needed to bring silence peak to target peak
-	// This is the maximum gain speechnorm could apply to the silence content
-	worstCaseGainDB := targetPeakDB - np.PeakLevel
-
-	// Calculate predicted output level for the silence PEAK (the bleed content)
-	predictedOutputPeakDB := np.PeakLevel + worstCaseGainDB
-
-	// Calculate predicted output noise floor
-	predictedOutputNoiseDB := np.MeasuredNoiseFloor + worstCaseGainDB
-
-	// Detect bleed presence using crest factor and peak-to-floor ratio
-	// Crest factor = peak - RMS; high crest means impulsive content in silence
-	// For pure hiss, crest factor is ~10-12dB; for bleed it's typically 20-30dB
-	peakToFloorDB := np.PeakLevel - np.MeasuredNoiseFloor
-	hasSignificantBleed := np.CrestFactor > 15.0 || peakToFloorDB > 20.0
-
-	// Determine threshold strategy based on bleed detection
-	var thresholdDB float64
-	if hasSignificantBleed {
-		// Bleed detected - use peak-based threshold (more aggressive)
-		// Set threshold to catch the amplified bleed peaks
-		thresholdDB = predictedOutputPeakDB - 3.0 // 3dB below predicted peak
-	} else {
-		// No significant bleed - use noise floor based threshold (standard approach)
-		thresholdDB = predictedOutputNoiseDB + bleedGateMarginDB
-	}
-
-	// Only enable bleed gate if predicted output would be audible
-	if thresholdDB < bleedGateEnableThresholdDB {
-		config.BleedGateEnabled = false
-		return
-	}
-
-	// Enable bleed gate
-	config.BleedGateEnabled = true
-
-	// Clamp threshold to safety limits
-	thresholdDB = clamp(thresholdDB, bleedGateMinThresholdDB, bleedGateMaxThresholdDB)
-
-	// Convert to linear for agate filter
-	config.BleedGateThreshold = dbToLinear(thresholdDB)
-
-	// Adapt ratio and range based on bleed severity
-	if hasSignificantBleed {
-		// Significant bleed - use stronger settings
-		config.BleedGateRatio = 6.0   // Stronger ratio for bleed
-		config.BleedGateRange = 0.063 // -24dB reduction (more aggressive)
-		config.BleedGateAttack = 10.0 // Faster attack to catch bleed transients
-		config.BleedGateRelease = 150.0
-	} else {
-		// Mild bleed or just noise amplification - use gentler settings
-		config.BleedGateRatio = bleedGateDefaultRatio
-		config.BleedGateRange = bleedGateDefaultRange
-		config.BleedGateAttack = bleedGateDefaultAttack
-		config.BleedGateRelease = bleedGateDefaultRelease
-	}
-
-	config.BleedGateKnee = bleedGateDefaultKnee
-}
-
 // sanitizeConfig ensures no NaN or Inf values remain after adaptive tuning
 func sanitizeConfig(config *FilterChainConfig) {
 	// DS201-inspired highpass filter
@@ -1801,11 +1682,6 @@ func sanitizeConfig(config *FilterChainConfig) {
 	if config.DS201HumHarmonics < 1 || config.DS201HumHarmonics > 8 {
 		config.DS201HumHarmonics = defaultHumHarmonics
 	}
-
-	// BleedGateThreshold needs additional check for zero/negative (like pre-gate)
-	if math.IsNaN(config.BleedGateThreshold) || math.IsInf(config.BleedGateThreshold, 0) || config.BleedGateThreshold <= 0 {
-		config.BleedGateThreshold = ds201DefaultGateThreshold // Use same default as pre-gate
-	}
 }
 
 // sanitizeFloat returns defaultVal if val is NaN or Inf
diff --git a/internal/processor/filters.go b/internal/processor/filters.go
@@ -44,7 +44,6 @@ const (
 	FilterDeesser        FilterID = "deesser"
 	FilterSpeechnorm     FilterID = "speechnorm"
 	FilterDynaudnorm     FilterID = "dynaudnorm"
-	FilterBleedGate      FilterID = "bleedgate" // Catches amplified bleed/crosstalk after normalisation
 	FilterAlimiter       FilterID = "alimiter"
 )
 
@@ -71,7 +70,6 @@ var Pass1FilterOrder = []FilterID{
 // - Deesser: after compression (which emphasises sibilance)
 // - Speechnorm: cycle-level normalisation for speech
 // - Dynaudnorm: frame-level normalisation for final consistency
-// - BleedGate: catches amplified bleed/crosstalk after normalisation
 // - Alimiter: brick-wall safety net
 // - Analysis: measures output for comparison with Pass 1
 // - Resample: standardises output format (44.1kHz/16-bit/mono)
@@ -88,7 +86,6 @@ var Pass2FilterOrder = []FilterID{
 	FilterDeesser,
 	FilterSpeechnorm,
 	FilterDynaudnorm,
-	FilterBleedGate,
 	FilterAlimiter,
 	FilterAnalysis,
 	FilterResample,
@@ -298,18 +295,6 @@ type FilterChainConfig struct {
 	LimiterAttack  float64 // ms, attack time
 	LimiterRelease float64 // ms, release time
 
-	// Bleed Gate (bleedgate) - catches amplified bleed/crosstalk after normalisation
-	// Positioned AFTER speechnorm/dynaudnorm to gate content that denoisers missed
-	// (denoisers preserve speech-like content, but headphone bleed IS speech-like)
-	// Uses gentler ratio than pre-gate to suppress rather than hard-cut
-	BleedGateEnabled   bool    // Enable bleed gate
-	BleedGateThreshold float64 // Activation threshold (0.0-1.0, linear) - calculated from predicted output bleed level
-	BleedGateRatio     float64 // Reduction ratio (gentler than pre-gate, e.g., 4:1)
-	BleedGateAttack    float64 // Attack time (ms)
-	BleedGateRelease   float64 // Release time (ms)
-	BleedGateRange     float64 // Level of gain reduction below threshold (0.0-1.0)
-	BleedGateKnee      float64 // Knee curve softness (1.0-8.0)
-
 	// Filter chain order - controls the sequence of filters in the processing chain
 	// Use DefaultFilterOrder or customise for experimentation
 	FilterOrder []FilterID
@@ -462,15 +447,6 @@ func DefaultFilterConfig() *FilterChainConfig {
 		ArnnDnEnabled: false,
 		ArnnDnMix:     0.35, // Initial mix (will be tuned adaptively based on measurements)
 
-		// Bleed Gate - catches amplified bleed/crosstalk after normalisation
-		BleedGateEnabled:   false,
-		BleedGateThreshold: 0.01,  // -40dBFS default (will be calculated from predicted output bleed level)
-		BleedGateRatio:     4.0,   // 4:1 ratio (gentler than pre-gate, suppresses rather than cuts)
-		BleedGateAttack:    15,    // 15ms attack (faster than pre-gate to catch transient bleed)
-		BleedGateRelease:   200,   // 200ms release (smooth, natural decay)
-		BleedGateRange:     0.125, // -18dB reduction (less aggressive than pre-gate's -24dB)
-		BleedGateKnee:      3.0,   // Soft knee for smooth engagement
-
 		// Limiter - brick-wall safety net with soft knee (via ASC)
 		LimiterEnabled: false,
 		LimiterCeiling: 0.84, // -1.5dBTP (actual limiting target)
@@ -1002,29 +978,6 @@ func (cfg *FilterChainConfig) buildArnnDnFilter() string {
 	return fmt.Sprintf("arnndn=m=%s:mix=%.2f", modelPath, cfg.ArnnDnMix)
 }
 
-// buildBleedGateFilter builds the bleed gate filter specification.
-// Positioned AFTER speechnorm/dynaudnorm to catch bleed/crosstalk that was amplified
-// during normalisation. Uses gentler ratio (4:1) compared to pre-gate (2:1) because
-// it's suppressing rather than cleaning inter-speech gaps.
-//
-// This filter addresses the "headphone bleed" problem where normalisation amplifies
-// low-level content (like bleed from headphones) that denoisers couldn't remove because
-// it's speech-like content that they're designed to preserve.
-func (cfg *FilterChainConfig) buildBleedGateFilter() string {
-	if !cfg.BleedGateEnabled {
-		return ""
-	}
-	return fmt.Sprintf(
-		"agate=threshold=%.6f:ratio=%.1f:attack=%.0f:release=%.0f:range=%.4f:knee=%.1f",
-		cfg.BleedGateThreshold,
-		cfg.BleedGateRatio,
-		cfg.BleedGateAttack,
-		cfg.BleedGateRelease,
-		cfg.BleedGateRange,
-		cfg.BleedGateKnee,
-	)
-}
-
 // buildAlimiterFilter builds the alimiter (true peak limiter) filter specification.
 // Brick-wall safety net using lookahead and ASC for smooth, musical limiting.
 func (cfg *FilterChainConfig) buildAlimiterFilter() string {
@@ -1066,7 +1019,6 @@ func (cfg *FilterChainConfig) BuildFilterSpec() string {
 		FilterDeesser:        cfg.buildDeesserFilter,
 		FilterSpeechnorm:     cfg.buildSpeechnormFilter,
 		FilterArnndn:         cfg.buildArnnDnFilter,
-		FilterBleedGate:      cfg.buildBleedGateFilter,
 		FilterDynaudnorm:     cfg.buildDynaudnormFilter,
 		FilterAlimiter:       cfg.buildAlimiterFilter,
 	}
@@ -1252,7 +1204,6 @@ func buildNoiseProfileFilterSpec(noiseDuration time.Duration, config *FilterChai
 		FilterDeesser:        config.buildDeesserFilter,
 		FilterSpeechnorm:     config.buildSpeechnormFilter,
 		FilterDynaudnorm:     config.buildDynaudnormFilter,
-		FilterBleedGate:      config.buildBleedGateFilter,
 		FilterAlimiter:       config.buildAlimiterFilter,
 	}
 
diff --git a/internal/processor/filters_test.go b/internal/processor/filters_test.go
@@ -33,7 +33,6 @@ func newTestConfig() *FilterChainConfig {
 		DynaudnormEnabled: false,
 		SpeechnormEnabled: false,
 		ArnnDnEnabled:     false,
-		BleedGateEnabled:  false,
 		LimiterEnabled:    false,
 
 		// Sensible defaults for parameters (used when filter is enabled)
@@ -84,13 +83,6 @@ func newTestConfig() *FilterChainConfig {
 
 		ArnnDnMix: 0.8,
 
-		BleedGateThreshold: 0.01,
-		BleedGateRatio:     4.0,
-		BleedGateAttack:    15,
-		BleedGateRelease:   200,
-		BleedGateRange:     0.125,
-		BleedGateKnee:      3.0,
-
 		LimiterCeiling: 0.84,
 		LimiterAttack:  5.0,
 		LimiterRelease: 50.0,
@@ -1040,7 +1032,6 @@ func TestPass2FilterOrder(t *testing.T) {
 			FilterDeesser,
 			FilterSpeechnorm,
 			FilterDynaudnorm,
-			FilterBleedGate,
 			FilterAlimiter,
 			FilterAnalysis,
 			FilterResample,
