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VadSegmentationConfig

public struct VadSegmentationConfig {
    var minSpeechDuration: TimeInterval    // Default: 0.15s
    var minSilenceDuration: TimeInterval   // Default: 0.75s
    var maxSpeechDuration: TimeInterval    // Default: 14s
    var speechPadding: TimeInterval        // Default: 0.1s
    var silenceThresholdForSplit: Float    // Default: 0.3
    var negativeThreshold: Float?          // Default: nil (auto)
    var negativeThresholdOffset: Float     // Default: 0.15
    var minSilenceAtMaxSpeech: TimeInterval // Default: 0.098s
    var useMaxPossibleSilenceAtMaxSpeech: Bool // Default: true
}

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Parameters

ParameterDefaultDescription
minSpeechDuration0.15sMinimum speech to keep. Prevents clicks/coughs from being treated as speech.
minSilenceDuration0.75sSilence required to end a segment. Prevents early cut-offs during brief pauses.
maxSpeechDuration14sForce-split long segments to match ASR model limits.
speechPadding0.1sContext padding on both sides of each segment.
silenceThresholdForSplit0.3Probability below which audio is treated as silence for splitting.
negativeThresholdnilOverride for exit hysteresis threshold. If nil, computed as baseThreshold - negativeThresholdOffset.
negativeThresholdOffset0.15Gap between entry and exit thresholds. Creates a “sticky zone” to prevent rapid flipping.
minSilenceAtMaxSpeech0.098sMinimum silence at forced split points. Ensures splits don’t land mid-phoneme.
useMaxPossibleSilenceAtMaxSpeechtrueSplit at the longest silence near max duration for cleaner boundaries.

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Hysteresis

The entry/exit threshold system prevents rapid state toggling:
  • Enter speech when probability > baseThreshold
  • Exit speech when probability < negativeThreshold
  • Stay in current state when probability is between the two
The entry threshold defaults to VadConfig.defaultThreshold set when constructing VadManager.