sherpa-ncnn/swift-api-examples/decode-file.swift

import AVFoundation

extension AudioBuffer {
    func array() -> [Float] {
        return Array(UnsafeBufferPointer(self))
    }
}

extension AVAudioPCMBuffer {
    func array() -> [Float] {
        return self.audioBufferList.pointee.mBuffers.array()
    }
}

func run() {
    let encoderParam =
    "./sherpa-ncnn-conv-emformer-transducer-2022-12-06/encoder_jit_trace-pnnx.ncnn.param"
    let encoderBin =
    "./sherpa-ncnn-conv-emformer-transducer-2022-12-06/encoder_jit_trace-pnnx.ncnn.bin"
    let decoderParam =
    "./sherpa-ncnn-conv-emformer-transducer-2022-12-06/decoder_jit_trace-pnnx.ncnn.param"
    let decoderBin =
    "./sherpa-ncnn-conv-emformer-transducer-2022-12-06/decoder_jit_trace-pnnx.ncnn.bin"
    let joinerParam =
    "./sherpa-ncnn-conv-emformer-transducer-2022-12-06/joiner_jit_trace-pnnx.ncnn.param"
    let joinerBin = "./sherpa-ncnn-conv-emformer-transducer-2022-12-06/joiner_jit_trace-pnnx.ncnn.bin"
    let tokens = "./sherpa-ncnn-conv-emformer-transducer-2022-12-06/tokens.txt"

    let featConfig = sherpaNcnnFeatureExtractorConfig(
        sampleRate: 16000,
        featureDim: 80
    )

    let modelConfig = sherpaNcnnModelConfig(
        encoderParam: encoderParam,
        encoderBin: encoderBin,
        decoderParam: decoderParam,
        decoderBin: decoderBin,
        joinerParam: joinerParam,
        joinerBin: joinerBin,
        tokens: tokens,
        numThreads: 4)

    let decoderConfig = sherpaNcnnDecoderConfig(
        decodingMethod: "modified_beam_search",
        numActivePaths: 4
    )

    var config = sherpaNcnnRecognizerConfig(
        featConfig: featConfig,
        modelConfig: modelConfig,
        decoderConfig: decoderConfig
    )



    let recognizer = SherpaNcnnRecognizer(config: &config)

    let filePath = "./sherpa-ncnn-conv-emformer-transducer-2022-12-06/test_wavs/0.wav"
    let fileURL: NSURL = NSURL(fileURLWithPath: filePath)
    let audioFile = try! AVAudioFile(forReading: fileURL as URL)

    let audioFormat = audioFile.processingFormat
    assert(audioFormat.sampleRate == 16000)
    assert(audioFormat.channelCount == 1)
    assert(audioFormat.commonFormat == AVAudioCommonFormat.pcmFormatFloat32)

    let audioFrameCount = UInt32(audioFile.length)
    let audioFileBuffer = AVAudioPCMBuffer(pcmFormat: audioFormat, frameCapacity: audioFrameCount)

    try! audioFile.read(into: audioFileBuffer!)
    let array: [Float]! = audioFileBuffer?.array()
    recognizer.acceptWaveform(samples: array)

    let tailPadding = [Float](repeating: 0.0, count: 3200)
    recognizer.acceptWaveform(samples: tailPadding)

    recognizer.inputFinished()
    while (recognizer.isReady()) {
        recognizer.decode()
    }

    let result = recognizer.getResult()
    print("\nresult is:\n\(result.text)")
}

@main
struct App {
    static func main() {
        run()
    }
}