Add endpointing (#54)

sherpa-onnx/csrc/online-recognizer.cc

@@ -37,7 +37,9 @@ std::string OnlineRecognizerConfig::ToString() const {
   os << "OnlineRecognizerConfig(";
   os << "feat_config=" << feat_config.ToString() << ", ";
   os << "model_config=" << model_config.ToString() << ", ";
-  os << "tokens=\"" << tokens << "\")";
+  os << "tokens=\"" << tokens << "\", ";
+  os << "endpoint_config=" << endpoint_config.ToString() << ", ";
+  os << "enable_endpoint=" << (enable_endpoint ? "True" : "False") << ")";
 
   return os.str();
 }
@@ -47,7 +49,8 @@ class OnlineRecognizer::Impl {
   explicit Impl(const OnlineRecognizerConfig &config)
       : config_(config),
         model_(OnlineTransducerModel::Create(config.model_config)),
-        sym_(config.tokens) {
+        sym_(config.tokens),
+        endpoint_(config_.endpoint_config) {
     decoder_ =
         std::make_unique<OnlineTransducerGreedySearchDecoder>(model_.get());
   }
@@ -64,7 +67,7 @@ class OnlineRecognizer::Impl {
            s->NumFramesReady();
   }
 
-  void DecodeStreams(OnlineStream **ss, int32_t n) {
+  void DecodeStreams(OnlineStream **ss, int32_t n) const {
     int32_t chunk_size = model_->ChunkSize();
     int32_t chunk_shift = model_->ChunkShift();
 
@@ -111,18 +114,44 @@ class OnlineRecognizer::Impl {
     }
   }
 
-  OnlineRecognizerResult GetResult(OnlineStream *s) {
+  OnlineRecognizerResult GetResult(OnlineStream *s) const {
     OnlineTransducerDecoderResult decoder_result = s->GetResult();
     decoder_->StripLeadingBlanks(&decoder_result);
 
     return Convert(decoder_result, sym_);
   }
 
+  bool IsEndpoint(OnlineStream *s) const {
+    if (!config_.enable_endpoint) return false;
+    int32_t num_processed_frames = s->GetNumProcessedFrames();
+
+    // frame shift is 10 milliseconds
+    float frame_shift_in_seconds = 0.01;
+
+    // subsampling factor is 4
+    int32_t trailing_silence_frames = s->GetResult().num_trailing_blanks * 4;
+
+    return endpoint_.IsEndpoint(num_processed_frames, trailing_silence_frames,
+                                frame_shift_in_seconds);
+  }
+
+  void Reset(OnlineStream *s) const {
+    // reset result and neural network model state,
+    // but keep the feature extractor state
+
+    // reset result
+    s->SetResult(decoder_->GetEmptyResult());
+
+    // reset neural network model state
+    s->SetStates(model_->GetEncoderInitStates());
+  }
+
  private:
   OnlineRecognizerConfig config_;
   std::unique_ptr<OnlineTransducerModel> model_;
   std::unique_ptr<OnlineTransducerDecoder> decoder_;
   SymbolTable sym_;
+  Endpoint endpoint_;
 };
 
 OnlineRecognizer::OnlineRecognizer(const OnlineRecognizerConfig &config)
@@ -137,12 +166,18 @@ bool OnlineRecognizer::IsReady(OnlineStream *s) const {
   return impl_->IsReady(s);
 }
 
-void OnlineRecognizer::DecodeStreams(OnlineStream **ss, int32_t n) {
+void OnlineRecognizer::DecodeStreams(OnlineStream **ss, int32_t n) const {
   impl_->DecodeStreams(ss, n);
 }
 
-OnlineRecognizerResult OnlineRecognizer::GetResult(OnlineStream *s) {
+OnlineRecognizerResult OnlineRecognizer::GetResult(OnlineStream *s) const {
   return impl_->GetResult(s);
 }
 
+bool OnlineRecognizer::IsEndpoint(OnlineStream *s) const {
+  return impl_->IsEndpoint(s);
+}
+
+void OnlineRecognizer::Reset(OnlineStream *s) const { impl_->Reset(s); }
+
 }  // namespace sherpa_onnx