Add C API for streaming HLG decoding (#734)

swift-api-examples/streaming-hlg-decode-file.swift

@@ -0,0 +1,79 @@
+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-streaming-zipformer-ctc-small-2024-03-18/test_wavs/8k.wav"
+  let model =
+    "./sherpa-onnx-streaming-zipformer-ctc-small-2024-03-18/ctc-epoch-30-avg-3-chunk-16-left-128.int8.onnx"
+  let tokens = "./sherpa-onnx-streaming-zipformer-ctc-small-2024-03-18/tokens.txt"
+  let zipfomer2CtcModelConfig = sherpaOnnxOnlineZipformer2CtcModelConfig(
+    model: model
+  )
+
+  let modelConfig = sherpaOnnxOnlineModelConfig(
+    tokens: tokens,
+    zipformer2Ctc: zipfomer2CtcModelConfig
+  )
+
+  let featConfig = sherpaOnnxFeatureConfig(
+    sampleRate: 16000,
+    featureDim: 80
+  )
+
+  let ctcFstDecoderConfig = sherpaOnnxOnlineCtcFstDecoderConfig(
+    graph: "./sherpa-onnx-streaming-zipformer-ctc-small-2024-03-18/HLG.fst",
+    maxActive: 3000
+  )
+
+  var config = sherpaOnnxOnlineRecognizerConfig(
+    featConfig: featConfig,
+    modelConfig: modelConfig,
+    ctcFstDecoderConfig: ctcFstDecoderConfig
+  )
+
+  let recognizer = SherpaOnnxRecognizer(config: &config)
+
+  let fileURL: NSURL = NSURL(fileURLWithPath: filePath)
+  let audioFile = try! AVAudioFile(forReading: fileURL as URL)
+
+  let audioFormat = audioFile.processingFormat
+  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, sampleRate: Int(audioFormat.sampleRate))
+
+  let tailPadding = [Float](repeating: 0.0, count: 3200)
+  recognizer.acceptWaveform(samples: tailPadding, sampleRate: Int(audioFormat.sampleRate))
+
+  recognizer.inputFinished()
+  while recognizer.isReady() {
+    recognizer.decode()
+  }
+
+  let result = recognizer.getResult()
+  print("\nresult is:\n\(result.text)")
+}
+
+@main
+struct App {
+  static func main() {
+    run()
+  }
+}