Fix the error of BLSTM forward state and force turn off use_dynamic_c…

…hunk during bias module training

wenet/bin/train.py

@@ -276,14 +276,16 @@ def main():
     num_params = sum(p.numel() for p in model.parameters())
     print('the number of model params: {:,d}'.format(num_params)) if local_rank == 0 else None  # noqa
 
-    # Freeze other parts of the model during training context bias module
     if 'context_module_conf' in configs:
+        # Freeze other parts of the model during training context bias module
         for p in model.parameters():
             p.requires_grad = False
         for p in model.context_module.parameters():
             p.requires_grad = True
         for p in model.context_module.context_decoder_ctc_linear.parameters():
             p.requires_grad = False
+        # Turn off dynamic chunk because it will affect the training of bias
+        model.encoder.use_dynamic_chunk = False
 
     # !!!IMPORTANT!!!
     # Try to export the model by script, if fails, we should refine

wenet/transformer/context_module.py

@@ -51,8 +51,8 @@ def forward(self, sen_batch, sen_lengths):
         _, last_state = self.sen_rnn(pack_seq)
         laste_h = last_state[0]
         laste_c = last_state[1]
-        state = torch.cat([laste_h[-1, :, :], laste_h[0, :, :],
-                          laste_c[-1, :, :], laste_c[0, :, :]], dim=-1)
+        state = torch.cat([laste_h[-1, :, :], laste_h[-2, :, :],
+                          laste_c[-1, :, :], laste_c[-2, :, :]], dim=-1)
         return state