Track token scores (k2-fsa#571)

* add export of per-token scores (ys, lm, context)

- for best path of the modified-beam-search decoding of transducer

* refactoring JSON export of OnlineRecognitionResult, extending pybind11 API of OnlineRecognitionResult

* export per-token scores also for greedy-search (online-transducer)

- export un-scaled lm_probs (modified-beam search, online-transducer)
- polishing

* fill lm_probs/context_scores only if LM/ContextGraph is present (make Result smaller)

Author: KarelVesely84

.gitignore

@@ -1,6 +1,7 @@
 build
 *.zip
 *.tgz
+*.sw?
 onnxruntime-*
 icefall-*
 run.sh

sherpa-onnx/csrc/hypothesis.h

@@ -29,9 +29,21 @@ struct Hypothesis {
   std::vector<int32_t> timestamps;
 
   // The acoustic probability for each token in ys.
-  // Only used for keyword spotting task.
+  // Used for keyword spotting task.
+  // For transducer mofified beam-search and greedy-search,
+  // this is filled with log_posterior scores.
   std::vector<float> ys_probs;
 
+  // lm_probs[i] contains the lm score for each token in ys.
+  // Used only in transducer mofified beam-search.
+  // Elements filled only if LM is used.
+  std::vector<float> lm_probs;
+
+  // context_scores[i] contains the context-graph score for each token in ys.
+  // Used only in transducer mofified beam-search.
+  // Elements filled only if `ContextGraph` is used.
+  std::vector<float> context_scores;
+
   // The total score of ys in log space.
   // It contains only acoustic scores
   double log_prob = 0;

sherpa-onnx/csrc/online-recognizer-transducer-impl.h

@@ -69,6 +69,10 @@ static OnlineRecognizerResult Convert(const OnlineTransducerDecoderResult &src,
     r.timestamps.push_back(time);
   }
 
+  r.ys_probs = std::move(src.ys_probs);
+  r.lm_probs = std::move(src.lm_probs);
+  r.context_scores = std::move(src.context_scores);
+
   r.segment = segment;
   r.start_time = frames_since_start * frame_shift_ms / 1000.;
 

sherpa-onnx/csrc/online-recognizer.cc

@@ -18,56 +18,50 @@
 
 namespace sherpa_onnx {
 
-std::string OnlineRecognizerResult::AsJsonString() const {
-  std::ostringstream os;
-  os << "{";
-  os << "\"is_final\":" << (is_final ? "true" : "false") << ", ";
-  os << "\"segment\":" << segment << ", ";
-  os << "\"start_time\":" << std::fixed << std::setprecision(2) << start_time
-     << ", ";
-
-  os << "\"text\""
-     << ": ";
-  os << "\"" << text << "\""
-     << ", ";
-
-  os << "\""
-     << "timestamps"
-     << "\""
-     << ": ";
-  os << "[";
-
+/// Helper for `OnlineRecognizerResult::AsJsonString()`
+template<typename T>
+std::string VecToString(const std::vector<T>& vec, int32_t precision = 6) {
+  std::ostringstream oss;
+  oss << std::fixed << std::setprecision(precision);
+  oss << "[ ";
   std::string sep = "";
-  for (auto t : timestamps) {
-    os << sep << std::fixed << std::setprecision(2) << t;
+  for (const auto& item : vec) {
+    oss << sep << item;
     sep = ", ";
   }
-  os << "], ";
-
-  os << "\""
-     << "tokens"
-     << "\""
-     << ":";
-  os << "[";
-
-  sep = "";
-  auto oldFlags = os.flags();
-  for (const auto &t : tokens) {
-    if (t.size() == 1 && static_cast<uint8_t>(t[0]) > 0x7f) {
-      const uint8_t *p = reinterpret_cast<const uint8_t *>(t.c_str());
-      os << sep << "\""
-         << "<0x" << std::hex << std::uppercase << static_cast<uint32_t>(p[0])
-         << ">"
-         << "\"";
-      os.flags(oldFlags);
-    } else {
-      os << sep << "\"" << t << "\"";
-    }
+  oss << " ]";
+  return oss.str();
+}
+
+/// Helper for `OnlineRecognizerResult::AsJsonString()`
+template<>  // explicit specialization for T = std::string
+std::string VecToString<std::string>(const std::vector<std::string>& vec,
+                                     int32_t) {  // ignore 2nd arg
+  std::ostringstream oss;
+  oss << "[ ";
+  std::string sep = "";
+  for (const auto& item : vec) {
+    oss << sep << "\"" << item << "\"";
     sep = ", ";
   }
-  os << "]";
-  os << "}";
+  oss << " ]";
+  return oss.str();
+}
 
+std::string OnlineRecognizerResult::AsJsonString() const {
+  std::ostringstream os;
+  os << "{ ";
+  os << "\"text\": " << "\"" << text << "\"" << ", ";
+  os << "\"tokens\": " << VecToString(tokens) << ", ";
+  os << "\"timestamps\": " << VecToString(timestamps, 2) << ", ";
+  os << "\"ys_probs\": " << VecToString(ys_probs, 6) << ", ";
+  os << "\"lm_probs\": " << VecToString(lm_probs, 6) << ", ";
+  os << "\"context_scores\": " << VecToString(context_scores, 6) << ", ";
+  os << "\"segment\": " << segment << ", ";
+  os << "\"start_time\": " << std::fixed << std::setprecision(2)
+     << start_time  << ", ";
+  os << "\"is_final\": " << (is_final ? "true" : "false");
+  os << "}";
   return os.str();
 }
 

sherpa-onnx/csrc/online-recognizer.h

@@ -40,6 +40,12 @@ struct OnlineRecognizerResult {
   /// timestamps[i] records the time in seconds when tokens[i] is decoded.
   std::vector<float> timestamps;
 
+  std::vector<float> ys_probs;  //< log-prob scores from ASR model
+  std::vector<float> lm_probs;  //< log-prob scores from language model
+                                //
+  /// log-domain scores from "hot-phrase" contextual boosting
+  std::vector<float> context_scores;
+
   /// ID of this segment
   /// When an endpoint is detected, it is incremented
   int32_t segment = 0;
@@ -58,6 +64,9 @@ struct OnlineRecognizerResult {
    *     "text": "The recognition result",
    *     "tokens": [x, x, x],
    *     "timestamps": [x, x, x],
+   *     "ys_probs": [x, x, x],
+   *     "lm_probs": [x, x, x],
+   *     "context_scores": [x, x, x],
    *     "segment": x,
    *     "start_time": x,
    *     "is_final": true|false

sherpa-onnx/csrc/online-transducer-decoder.cc

@@ -37,6 +37,10 @@ OnlineTransducerDecoderResult &OnlineTransducerDecoderResult::operator=(
   frame_offset = other.frame_offset;
   timestamps = other.timestamps;
 
+  ys_probs = other.ys_probs;
+  lm_probs = other.lm_probs;
+  context_scores = other.context_scores;
+
   return *this;
 }
 
@@ -60,6 +64,10 @@ OnlineTransducerDecoderResult &OnlineTransducerDecoderResult::operator=(
   frame_offset = other.frame_offset;
   timestamps = std::move(other.timestamps);
 
+  ys_probs = std::move(other.ys_probs);
+  lm_probs = std::move(other.lm_probs);
+  context_scores = std::move(other.context_scores);
+
   return *this;
 }
 

sherpa-onnx/csrc/online-transducer-decoder.h

@@ -26,6 +26,10 @@ struct OnlineTransducerDecoderResult {
   /// timestamps[i] contains the output frame index where tokens[i] is decoded.
   std::vector<int32_t> timestamps;
 
+  std::vector<float> ys_probs;
+  std::vector<float> lm_probs;
+  std::vector<float> context_scores;
+
   // Cache decoder_out for endpointing
   Ort::Value decoder_out;
 

sherpa-onnx/csrc/online-transducer-greedy-search-decoder.cc

@@ -71,9 +71,11 @@ void OnlineTransducerGreedySearchDecoder::StripLeadingBlanks(
   r->tokens = std::vector<int64_t>(start, end);
 }
 
+
 void OnlineTransducerGreedySearchDecoder::Decode(
     Ort::Value encoder_out,
     std::vector<OnlineTransducerDecoderResult> *result) {
+
   std::vector<int64_t> encoder_out_shape =
       encoder_out.GetTensorTypeAndShapeInfo().GetShape();
 
@@ -97,6 +99,7 @@ void OnlineTransducerGreedySearchDecoder::Decode(
       break;
     }
   }
+
   if (is_batch_decoder_out_cached) {
     auto &r = result->front();
     std::vector<int64_t> decoder_out_shape =
@@ -124,6 +127,7 @@ void OnlineTransducerGreedySearchDecoder::Decode(
       if (blank_penalty_ > 0.0) {
         p_logit[0] -= blank_penalty_;  // assuming blank id is 0
       }
+
       auto y = static_cast<int32_t>(std::distance(
           static_cast<const float *>(p_logit),
           std::max_element(static_cast<const float *>(p_logit),
@@ -138,6 +142,17 @@ void OnlineTransducerGreedySearchDecoder::Decode(
       } else {
         ++r.num_trailing_blanks;
       }
+
+      // export the per-token log scores
+      if (y != 0 && y != unk_id_) {
+        LogSoftmax(p_logit, vocab_size);  // renormalize probabilities,
+                                          // save time by doing it only for
+                                          // emitted symbols
+        const float *p_logprob = p_logit;  // rename p_logit as p_logprob,
+                                           // now it contains normalized
+                                           // probability
+        r.ys_probs.push_back(p_logprob[y]);
+      }
     }
     if (emitted) {
       Ort::Value decoder_input = model_->BuildDecoderInput(*result);

sherpa-onnx/csrc/online-transducer-modified-beam-search-decoder.cc

@@ -59,6 +59,12 @@ void OnlineTransducerModifiedBeamSearchDecoder::StripLeadingBlanks(
   std::vector<int64_t> tokens(hyp.ys.begin() + context_size, hyp.ys.end());
   r->tokens = std::move(tokens);
   r->timestamps = std::move(hyp.timestamps);
+
+  // export per-token scores
+  r->ys_probs = std::move(hyp.ys_probs);
+  r->lm_probs = std::move(hyp.lm_probs);
+  r->context_scores = std::move(hyp.context_scores);
+
   r->num_trailing_blanks = hyp.num_trailing_blanks;
 }
 
@@ -180,6 +186,28 @@ void OnlineTransducerModifiedBeamSearchDecoder::Decode(
         new_hyp.log_prob = p_logprob[k] + context_score -
                            prev_lm_log_prob;  // log_prob only includes the
                                               // score of the transducer
+        // export the per-token log scores
+        if (new_token != 0 && new_token != unk_id_) {
+          const Hypothesis& prev_i = prev[hyp_index];
+          // subtract 'prev[i]' path scores, which were added before
+          // getting topk tokens
+          float y_prob = p_logprob[k] - prev_i.log_prob - prev_i.lm_log_prob;
+          new_hyp.ys_probs.push_back(y_prob);
+
+          if (lm_) {  // export only when LM is used
+            float lm_prob = new_hyp.lm_log_prob - prev_lm_log_prob;
+            if (lm_scale_ != 0.0) {
+              lm_prob /= lm_scale_;  // remove lm-scale
+            }
+            new_hyp.lm_probs.push_back(lm_prob);
+          }
+
+          // export only when `ContextGraph` is used
+          if (ss != nullptr && ss[b]->GetContextGraph() != nullptr) {
+            new_hyp.context_scores.push_back(context_score);
+          }
+        }
+
         hyps.Add(std::move(new_hyp));
       }  // for (auto k : topk)
       cur.push_back(std::move(hyps));

sherpa-onnx/python/csrc/online-recognizer.cc

@@ -28,7 +28,26 @@ static void PybindOnlineRecognizerResult(py::module *m) {
           [](PyClass &self) -> float { return self.start_time; })
       .def_property_readonly(
           "timestamps",
-          [](PyClass &self) -> std::vector<float> { return self.timestamps; });
+          [](PyClass &self) -> std::vector<float> { return self.timestamps; })
+      .def_property_readonly(
+          "ys_probs",
+          [](PyClass &self) -> std::vector<float> { return self.ys_probs; })
+      .def_property_readonly(
+          "lm_probs",
+          [](PyClass &self) -> std::vector<float> { return self.lm_probs; })
+      .def_property_readonly(
+          "context_scores",
+          [](PyClass &self) -> std::vector<float> {
+            return self.context_scores;
+      })
+      .def_property_readonly(
+          "segment",
+          [](PyClass &self) -> int32_t { return self.segment; })
+      .def_property_readonly(
+          "is_final",
+          [](PyClass &self) -> bool { return self.is_final; })
+      .def("as_json_string", &PyClass::AsJsonString,
+            py::call_guard<py::gil_scoped_release>());
 }
 
 static void PybindOnlineRecognizerConfig(py::module *m) {

sherpa-onnx/python/sherpa_onnx/online_recognizer.py

@@ -503,6 +503,9 @@ def is_ready(self, s: OnlineStream) -> bool:
     def get_result(self, s: OnlineStream) -> str:
         return self.recognizer.get_result(s).text.strip()
 
+    def get_result_as_json_string(self, s: OnlineStream) -> str:
+        return self.recognizer.get_result(s).as_json_string()
+
     def tokens(self, s: OnlineStream) -> List[str]:
         return self.recognizer.get_result(s).tokens
 
@@ -512,6 +515,15 @@ def timestamps(self, s: OnlineStream) -> List[float]:
     def start_time(self, s: OnlineStream) -> float:
         return self.recognizer.get_result(s).start_time
 
+    def ys_probs(self, s: OnlineStream) -> List[float]:
+        return self.recognizer.get_result(s).ys_probs
+
+    def lm_probs(self, s: OnlineStream) -> List[float]:
+        return self.recognizer.get_result(s).lm_probs
+
+    def context_scores(self, s: OnlineStream) -> List[float]:
+        return self.recognizer.get_result(s).context_scores
+
     def is_endpoint(self, s: OnlineStream) -> bool:
         return self.recognizer.is_endpoint(s)