Add vad clear api for better performance (#366)

* Add vad clear api for better performance

* rename to make naming consistent and remove macro

* Fix linker error

* Fix Vad.kt

swift-api-examples/SherpaOnnx.swift

@@ -551,7 +551,7 @@ class SherpaOnnxVoiceActivityDetectorWrapper {
     return SherpaOnnxVoiceActivityDetectorEmpty(vad) == 1
   }
 
-  func isDetected() -> Bool {
+  func isSpeechDetected() -> Bool {
     return SherpaOnnxVoiceActivityDetectorDetected(vad) == 1
   }
 
@@ -559,6 +559,10 @@ class SherpaOnnxVoiceActivityDetectorWrapper {
     SherpaOnnxVoiceActivityDetectorPop(vad)
   }
 
+  func clear() {
+    SherpaOnnxVoiceActivityDetectorClear(vad)
+  }
+
   func front() -> SherpaOnnxSpeechSegmentWrapper {
     let p: UnsafePointer<SherpaOnnxSpeechSegment>? = SherpaOnnxVoiceActivityDetectorFront(vad)
     return SherpaOnnxSpeechSegmentWrapper(p: p)

swift-api-examples/generate-subtitles.swift

@@ -174,32 +174,31 @@ func run() {
 
   var segments: [SpeechSegment] = []
 
-  while array.count > windowSize {
-    // todo(fangjun): avoid extra copies here
-    vad.acceptWaveform(samples: [Float](array[0..<windowSize]))
-    array = [Float](array[windowSize..<array.count])
-
-    while !vad.isEmpty() {
-      let s = vad.front()
-      vad.pop()
-      let result = recognizer.decode(samples: s.samples)
-
-      segments.append(
-        SpeechSegment(
-          start: Float(s.start) / Float(sampleRate),
-          duration: Float(s.samples.count) / Float(sampleRate),
-          text: result.text))
-
-      print(segments.last!)
-
-    }
+  for offset in stride(from: 0, to: array.count, by: windowSize) {
+      let end = min(offset + windowSize, array.count)
+      vad.acceptWaveform(samples: [Float](array[offset ..< end]))
   }
 
-  let srt = zip(segments.indices, segments).map { (index, element) in
+  var index: Int = 0
+  while !vad.isEmpty() {
+    let s = vad.front()
+    vad.pop()
+    let result = recognizer.decode(samples: s.samples)
+
+    segments.append(
+      SpeechSegment(
+        start: Float(s.start) / Float(sampleRate),
+        duration: Float(s.samples.count) / Float(sampleRate),
+        text: result.text))
+
+    print(segments.last!)
+  }
+
+  let srt: String = zip(segments.indices, segments).map { (index, element) in
     return "\(index+1)\n\(element)"
   }.joined(separator: "\n\n")
 
-  let srtFilename = filePath.stringByDeletingPathExtension + ".srt"
+  let srtFilename: String = filePath.stringByDeletingPathExtension + ".srt"
   do {
     try srt.write(to: srtFilename.fileURL, atomically: true, encoding: .utf8)
   } catch {