Minor fixes on decode stream

egs/librispeech/ASR/pruned_transducer_stateless/decode_stream.py

@@ -52,13 +52,17 @@ class DecodeStream(object):
 
         # It contains a 2-D tensors representing the feature frames.
         self.features: torch.Tensor = None
+
+        self.num_frames: int = 0
         # how many frames have been processed. (before subsampling).
         # we only modify this value in `func:get_feature_frames`.
-        self.num_frames = 0
         self.num_processed_frames: int = 0
+
         self._done: bool = False
+
         # The transcript of current utterance.
         self.ground_truth: str = ""
+
         # The decoding result (partial or final) of current utterance.
         self.hyp: List = []
 
@@ -94,30 +98,28 @@ class DecodeStream(object):
     ) -> None:
         """Set features tensor of current utterance."""
         assert features.dim() == 2, features.dim()
-        self.num_frames = features.size(0)
-        # tail padding
         self.features = torch.nn.functional.pad(
             features,
             (0, 0, 0, self.pad_length),
             mode="constant",
             value=self.LOG_EPS,
         )
+        self.num_frames = self.features.size(0)
 
     def get_feature_frames(self, chunk_size: int) -> Tuple[torch.Tensor, int]:
         """Consume chunk_size frames of features"""
-        # plus 3 here because we subsampling features with
-        # lengths = ((x_lens - 1) // 2 - 1) // 2
-        update_length = min(
-            self.num_frames - self.num_processed_frames, chunk_size
+        chunk_length = chunk_size + self.pad_length
+
+        ret_length = min(
+            self.num_frames - self.num_processed_frames, chunk_length
         )
-        ret_length = update_length + self.pad_length
 
         ret_features = self.features[
             self.num_processed_frames : self.num_processed_frames  # noqa
             + ret_length
         ]
 
-        self.num_processed_frames += update_length
+        self.num_processed_frames += chunk_size
         if self.num_processed_frames >= self.num_frames:
             self._done = True