update export.py and pretrained_ctc.py

egs/librispeech/ASR/zipformer/ctc_decode.py

@@ -73,6 +73,29 @@
     --nbest-scale 1.0 \
     --lm-dir data/lm \
     --decoding-method whole-lattice-rescoring
+
+(6) attention-decoder-rescoring-no-ngram
+./zipformer/ctc_decode.py \
+    --epoch 30 \
+    --avg 15 \
+    --exp-dir ./zipformer/exp \
+    --use-ctc 1 \
+    --use-attention-decoder 1 \
+    --max-duration 100 \
+    --decoding-method attention-decoder-rescoring-no-ngram
+
+(7) attention-decoder-rescoring-with-ngram
+./zipformer/ctc_decode.py \
+    --epoch 30 \
+    --avg 15 \
+    --exp-dir ./zipformer/exp \
+    --use-ctc 1 \
+    --use-attention-decoder 1 \
+    --max-duration 100 \
+    --hlg-scale 0.6 \
+    --nbest-scale 1.0 \
+    --lm-dir data/lm \
+    --decoding-method attention-decoder-rescoring-with-ngram
 """
 
 
@@ -101,10 +124,10 @@
     nbest_decoding,
     nbest_oracle,
     one_best_decoding,
-    rescore_with_n_best_list,
-    rescore_with_whole_lattice,
     rescore_with_attention_decoder_no_ngram,
     rescore_with_attention_decoder_with_ngram,
+    rescore_with_n_best_list,
+    rescore_with_whole_lattice,
 )
 from icefall.lexicon import Lexicon
 from icefall.utils import (
@@ -214,6 +237,10 @@ def get_parser():
         - (6) nbest-oracle. Its WER is the lower bound of any n-best
           rescoring method can achieve. Useful for debugging n-best
           rescoring method.
+        - (7) attention-decoder-rescoring-no-ngram. Extract n paths from the decoding
+          lattice, rescore them with the attention decoder.
+        - (8) attention-decoder-rescoring-with-ngram. Extract n paths from the LM
+          rescored lattice, rescore them with the attention decoder.
         """,
     )
 

egs/librispeech/ASR/zipformer/export.py

@@ -404,6 +404,7 @@ def main():
 
     token_table = k2.SymbolTable.from_file(params.tokens)
     params.blank_id = token_table["<blk>"]
+    params.sos_id = params.eos_id = token_table["<sos/eos>"]
     params.vocab_size = num_tokens(token_table) + 1
 
     logging.info(params)
@@ -466,8 +467,6 @@ def main():
                     device=device,
                 )
             )
-        elif params.avg == 1:
-            load_checkpoint(f"{params.exp_dir}/epoch-{params.epoch}.pt", model)
         else:
             assert params.avg > 0, params.avg
             start = params.epoch - params.avg

egs/librispeech/ASR/zipformer/pretrained_ctc.py

@@ -81,6 +81,15 @@
   --sample-rate 16000 \
   /path/to/foo.wav \
   /path/to/bar.wav
+
+(5) attention-decoder-rescoring-no-ngram
+./zipformer/pretrained_ctc.py \
+  --checkpoint ./zipformer/exp/pretrained.pt \
+  --tokens data/lang_bpe_500/tokens.txt \
+  --method attention-decoder-rescoring-no-ngram \
+  --sample-rate 16000 \
+  /path/to/foo.wav \
+  /path/to/bar.wav
 """
 
 import argparse
@@ -100,6 +109,7 @@
 from icefall.decode import (
     get_lattice,
     one_best_decoding,
+    rescore_with_attention_decoder_no_ngram,
     rescore_with_n_best_list,
     rescore_with_whole_lattice,
 )
@@ -172,6 +182,8 @@ def get_parser():
             decoding lattice and then use 1best to decode the
             rescored lattice.
             We call it HLG decoding + whole-lattice n-gram LM rescoring.
+        (4) attention-decoder-rescoring-no-ngram. Extract n paths from the decoding
+          lattice, rescore them with the attention decoder.
         """,
     )
 
@@ -276,6 +288,7 @@ def main():
     token_table = k2.SymbolTable.from_file(params.tokens)
     params.vocab_size = num_tokens(token_table) + 1  # +1 for blank
     params.blank_id = token_table["<blk>"]
+    params.sos_id = params.eos_id = token_table["<sos/eos>"]
     assert params.blank_id == 0
 
     logging.info(f"{params}")
@@ -333,16 +346,13 @@ def main():
         dtype=torch.int32,
     )
 
-    if params.method == "ctc-decoding":
-        logging.info("Use CTC decoding")
+    if params.method in ["ctc-decoding", "attention-decoder-rescoring-no-ngram"]:
         max_token_id = params.vocab_size - 1
-
         H = k2.ctc_topo(
             max_token=max_token_id,
             modified=False,
             device=device,
         )
-
         lattice = get_lattice(
             nnet_output=ctc_output,
             decoding_graph=H,
@@ -354,9 +364,23 @@ def main():
             subsampling_factor=params.subsampling_factor,
         )
 
-        best_path = one_best_decoding(
-            lattice=lattice, use_double_scores=params.use_double_scores
-        )
+        if params.method == "ctc-decoding":
+            logging.info("Use CTC decoding")
+            best_path = one_best_decoding(
+                lattice=lattice, use_double_scores=params.use_double_scores
+            )
+        else:
+            logging.info("Use attention decoder rescoring without ngram")
+            best_path_dict = rescore_with_attention_decoder_no_ngram(
+                lattice=lattice,
+                num_paths=params.num_paths,
+                attention_decoder=model.attention_decoder,
+                encoder_out=encoder_out,
+                encoder_out_lens=encoder_out_lens,
+                nbest_scale=params.nbest_scale,
+            )
+            best_path = next(iter(best_path_dict.values()))
+
         token_ids = get_texts(best_path)
         hyps = [[token_table[i] for i in ids] for ids in token_ids]
     elif params.method in [
@@ -430,7 +454,7 @@ def main():
         raise ValueError(f"Unsupported decoding method: {params.method}")
 
     s = "\n"
-    if params.method == "ctc-decoding":
+    if params.method in ["ctc-decoding", "attention-decoder-rescoring-no-ngram"]:
         for filename, hyp in zip(params.sound_files, hyps):
             words = "".join(hyp)
             words = words.replace("▁", " ").strip()

egs/librispeech/ASR/zipformer/train.py

@@ -1199,8 +1199,7 @@ def run(rank, world_size, args):
 
     # <blk> is defined in local/train_bpe_model.py
     params.blank_id = sp.piece_to_id("<blk>")
-    params.eos_id = sp.piece_to_id("<sos/eos>")
-    params.sos_id = sp.piece_to_id("<sos/eos>")
+    params.sos_id = params.eos_id = sp.piece_to_id("<sos/eos>")
     params.vocab_size = sp.get_piece_size()
 
     if not params.use_transducer: