Support to choose transformer as encoder.

egs/librispeech/ASR/transducer_stateless/train.py

@@ -54,7 +54,7 @@ from torch import Tensor
 from torch.nn.parallel import DistributedDataParallel as DDP
 from torch.nn.utils import clip_grad_norm_
 from torch.utils.tensorboard import SummaryWriter
-from transformer import Noam
+from transformer import Noam, Transformer
 
 from icefall.checkpoint import load_checkpoint
 from icefall.checkpoint import save_checkpoint as save_checkpoint_impl
@@ -138,6 +138,13 @@ def get_parser():
         "2 means tri-gram",
     )
 
+    parser.add_argument(
+        "--encoder-type",
+        type=str,
+        default="conformer",
+        help="Type of the encoder. Valid values are: conformer and transformer",
+    )
+
     return parser
 
 
@@ -214,8 +221,16 @@ def get_params() -> AttributeDict:
 
 
 def get_encoder_model(params: AttributeDict):
-    # TODO: We can add an option to switch between Conformer and Transformer
+    if params.encoder_type == "conformer":
-    encoder = Conformer(
+        Encoder = Conformer
+    elif params.encoder_type == "transformer":
+        Encoder = Transformer
+    else:
+        raise ValueError(
+            f"Unsupported encoder type: {params.encoder_type}"
+            "\nPlease use conformer or transformer"
+        )
+    encoder = Encoder(
         num_features=params.feature_dim,
         output_dim=params.encoder_out_dim,
         subsampling_factor=params.subsampling_factor,
@@ -360,7 +375,8 @@ def compute_loss(
       params:
         Parameters for training. See :func:`get_params`.
       model:
-        The model for training. It is an instance of Conformer in our case.
+        The model for training. It is an instance of Conformer or Transformer
+        in our case.
       batch:
         A batch of data. See `lhotse.dataset.K2SpeechRecognitionDataset()`
         for the content in it.