Swift API for keyword spotting. (#1027)

@@ -7,6 +7,10 @@ echo "pwd: $PWD"
 cd swift-api-examples
 ls -lh
 
+./run-keyword-spotting-from-file.sh
+rm ./keyword-spotting-from-file
+rm -rf sherpa-onnx-kws-*
+
 ./run-streaming-hlg-decode-file.sh
 rm ./streaming-hlg-decode-file
 rm -rf sherpa-onnx-streaming-zipformer-ctc-small-2024-03-18

@@ -8,3 +8,4 @@ sherpa-onnx-paraformer-zh-2023-09-14
 !*.sh
 *.bak
 streaming-hlg-decode-file
+keyword-spotting-from-file

@@ -832,3 +832,111 @@ class SherpaOnnxSpokenLanguageIdentificationWrapper {
     return SherpaOnnxSpokenLanguageIdentificationResultWrapper(result: result)
   }
 }
+
+// keyword spotting
+
+class SherpaOnnxKeywordResultWrapper {
+  /// A pointer to the underlying counterpart in C
+  let result: UnsafePointer<SherpaOnnxKeywordResult>!
+
+  var keyword: String {
+    return String(cString: result.pointee.keyword)
+  }
+
+  var count: Int32 {
+    return result.pointee.count
+  }
+
+  var tokens: [String] {
+    if let tokensPointer = result.pointee.tokens_arr {
+      var tokens: [String] = []
+      for index in 0..<count {
+        if let tokenPointer = tokensPointer[Int(index)] {
+          let token = String(cString: tokenPointer)
+          tokens.append(token)
+        }
+      }
+      return tokens
+    } else {
+      let tokens: [String] = []
+      return tokens
+    }
+  }
+
+  init(result: UnsafePointer<SherpaOnnxKeywordResult>!) {
+    self.result = result
+  }
+
+  deinit {
+    if let result {
+      DestroyKeywordResult(result)
+    }
+  }
+}
+
+func sherpaOnnxKeywordSpotterConfig(
+  featConfig: SherpaOnnxFeatureConfig,
+  modelConfig: SherpaOnnxOnlineModelConfig,
+  keywordsFile: String,
+  maxActivePaths: Int = 4,
+  numTrailingBlanks: Int = 1,
+  keywordsScore: Float = 1.0,
+  keywordsThreshold: Float = 0.25
+) -> SherpaOnnxKeywordSpotterConfig {
+  return SherpaOnnxKeywordSpotterConfig(
+    feat_config: featConfig,
+    model_config: modelConfig,
+    max_active_paths: Int32(maxActivePaths),
+    num_trailing_blanks: Int32(numTrailingBlanks),
+    keywords_score: keywordsScore,
+    keywords_threshold: keywordsThreshold,
+    keywords_file: toCPointer(keywordsFile)
+  )
+}
+
+class SherpaOnnxKeywordSpotterWrapper {
+  /// A pointer to the underlying counterpart in C
+  let spotter: OpaquePointer!
+  var stream: OpaquePointer!
+
+  init(
+    config: UnsafePointer<SherpaOnnxKeywordSpotterConfig>!
+  ) {
+    spotter = CreateKeywordSpotter(config)
+    stream = CreateKeywordStream(spotter)
+  }
+
+  deinit {
+    if let stream {
+      DestroyOnlineStream(stream)
+    }
+
+    if let spotter {
+      DestroyKeywordSpotter(spotter)
+    }
+  }
+
+  func acceptWaveform(samples: [Float], sampleRate: Int = 16000) {
+    AcceptWaveform(stream, Int32(sampleRate), samples, Int32(samples.count))
+  }
+
+  func isReady() -> Bool {
+    return IsKeywordStreamReady(spotter, stream) == 1 ? true : false
+  }
+
+  func decode() {
+    DecodeKeywordStream(spotter, stream)
+  }
+
+  func getResult() -> SherpaOnnxKeywordResultWrapper {
+    let result: UnsafePointer<SherpaOnnxKeywordResult>? = GetKeywordResult(
+      spotter, stream)
+    return SherpaOnnxKeywordResultWrapper(result: result)
+  }
+
+  /// Signal that no more audio samples would be available.
+  /// After this call, you cannot call acceptWaveform() any more.
+  func inputFinished() {
+    InputFinished(stream)
+  }
+}

+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 filePath = "./sherpa-onnx-kws-zipformer-wenetspeech-3.3M-2024-01-01/test_wavs/3.wav"
+  let encoder =
+    "./sherpa-onnx-kws-zipformer-wenetspeech-3.3M-2024-01-01/encoder-epoch-12-avg-2-chunk-16-left-64.onnx"
+  let decoder =
+    "./sherpa-onnx-kws-zipformer-wenetspeech-3.3M-2024-01-01/decoder-epoch-12-avg-2-chunk-16-left-64.onnx"
+  let joiner =
+    "./sherpa-onnx-kws-zipformer-wenetspeech-3.3M-2024-01-01/joiner-epoch-12-avg-2-chunk-16-left-64.onnx"
+  let tokens =
+    "./sherpa-onnx-kws-zipformer-wenetspeech-3.3M-2024-01-01/tokens.txt"
+  let keywordsFile =
+    "./sherpa-onnx-kws-zipformer-wenetspeech-3.3M-2024-01-01/test_wavs/test_keywords.txt"
+  let transducerConfig = sherpaOnnxOnlineTransducerModelConfig(
+    encoder: encoder,
+    decoder: decoder,
+    joiner: joiner
+  )
+
+  let modelConfig = sherpaOnnxOnlineModelConfig(
+    tokens: tokens,
+    transducer: transducerConfig
+  )
+
+  let featConfig = sherpaOnnxFeatureConfig(
+    sampleRate: 16000,
+    featureDim: 80
+  )
+  var config = sherpaOnnxKeywordSpotterConfig(
+    featConfig: featConfig,
+    modelConfig: modelConfig,
+    keywordsFile: keywordsFile
+  )
+
+  let spotter = SherpaOnnxKeywordSpotterWrapper(config: &config)
+
+  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()
+  spotter.acceptWaveform(samples: array)
+
+  let tailPadding = [Float](repeating: 0.0, count: 3200)
+  spotter.acceptWaveform(samples: tailPadding)
+
+  spotter.inputFinished()
+  while spotter.isReady() {
+    spotter.decode()
+    let keyword = spotter.getResult().keyword
+    if keyword != "" {
+      print("Detected: \(keyword)")
+    }
+  }
+}
+
+@main
+struct App {
+  static func main() {
+    run()
+  }
+}

+#!/usr/bin/env bash
+
+set -ex
+
+if [ ! -d ../build-swift-macos ]; then
+  echo "Please run ../build-swift-macos.sh first!"
+  exit 1
+fi
+
+if [ ! -d ./sherpa-onnx-kws-zipformer-wenetspeech-3.3M-2024-01-01 ]; then
+  curl -SL -O https://github.com/k2-fsa/sherpa-onnx/releases/download/kws-models/sherpa-onnx-kws-zipformer-wenetspeech-3.3M-2024-01-01.tar.bz2
+  tar xf sherpa-onnx-kws-zipformer-wenetspeech-3.3M-2024-01-01.tar.bz2
+  rm sherpa-onnx-kws-zipformer-wenetspeech-3.3M-2024-01-01.tar.bz2
+fi
+
+if [ ! -e ./keyword-spotting-from-file ]; then
+  # Note: We use -lc++ to link against libc++ instead of libstdc++
+  swiftc \
+    -lc++ \
+    -I ../build-swift-macos/install/include \
+    -import-objc-header ./SherpaOnnx-Bridging-Header.h \
+    ./keyword-spotting-from-file.swift  ./SherpaOnnx.swift \
+    -L ../build-swift-macos/install/lib/ \
+    -l sherpa-onnx \
+    -l onnxruntime \
+    -o keyword-spotting-from-file
+
+  strip keyword-spotting-from-file
+else
+  echo "./keyword-spotting-from-file exists - skip building"
+fi
+
+export DYLD_LIBRARY_PATH=$PWD/../build-swift-macos/install/lib:$DYLD_LIBRARY_PATH
+./keyword-spotting-from-file