NCKitProcessor

NCKit inference engine. Create one instance per session and reuse it.

Requirements

Parameter	Value
Sample rate	48,000 Hz
Channels	1 (mono)
Format	Float32 in [-1.0, 1.0]
Hop size	frameLength (480 samples = 10 ms)

API

Swift

public final class NCKitProcessor {
    public let frameLength: Int

    public init(
        modelURL: URL,
        attenLimDb: Float = 100,
        postFilterBeta: Float = 0
    ) throws

    @discardableResult
    public func processFrame(
        input: UnsafeMutablePointer<Float>,
        output: UnsafeMutablePointer<Float>
    ) -> Float

    public func setAttenLim(_ db: Float)
    public func setPostFilterBeta(_ b: Float)
}

Create processor

Swift

import NCKit

let modelURL = try NCKitModelLocator.modelTarGzURL()
let processor = try NCKitProcessor(
    modelURL: modelURL,
    attenLimDb: 100,       // 100 = unlimited attenuation
    postFilterBeta: 0      // 0 = post-filter off
)

Process one hop (real-time)

Swift

let hop = processor.frameLength
var input  = [Float](repeating: 0, count: hop)
var output = [Float](repeating: 0, count: hop)

// Fill input[0..<hop] with 48 kHz mono samples from your audio source

input.withUnsafeMutableBufferPointer { inBuf in
    output.withUnsafeMutableBufferPointer { outBuf in
        let lsnr = processor.processFrame(
            input: inBuf.baseAddress!,
            output: outBuf.baseAddress!
        )
        // lsnr: local SNR estimate (dB), optional voice-activity hint
    }
}

Tune at runtime

Swift

processor.setAttenLim(60)          // lighter noise reduction
processor.setPostFilterBeta(0.02)  // stronger residual-noise suppression

Throws

Error	When
NCKitError.libraryInit / NCKitException.LibraryInit	Model failed to load
NCKitError.missingModel / NCKitException.MissingModel	Model file missing

Notes

• Not thread-safe — call processFrame from one serial queue / coroutine context only.
• setAttenLim / setPostFilterBeta are safe from any thread.
• Android: call close() (or use {}) when done to release native memory (~30 MB).
• Live audio: prefer NCKitStreamProcessor over manual processFrame hop accumulation.