Merge branch 'k2-fsa:master' into gigaspeech_recipe

.flake8

@@ -14,4 +14,5 @@ per-file-ignores =
 exclude =
   .git,
   **/data/**,
-  icefall/shared/make_kn_lm.py
+  icefall/shared/make_kn_lm.py,
+  icefall/__init__.py

.github/workflows/style_check.yml

@@ -45,7 +45,9 @@ jobs:
 
       - name: Install Python dependencies
         run: |
-          python3 -m pip install --upgrade pip black==21.6b0 flake8==3.9.2
+          python3 -m pip install --upgrade pip black==21.6b0 flake8==3.9.2 click==8.0.4
+          # See https://github.com/psf/black/issues/2964
+          # The version of click should be selected from 8.0.0, 8.0.1, 8.0.2, 8.0.3, and 8.0.4
 
       - name: Run flake8
         shell: bash

docs/source/installation/index.rst

@@ -27,9 +27,21 @@ Installation
 ``icefall`` depends on `k2 <https://github.com/k2-fsa/k2>`_ and
 `lhotse <https://github.com/lhotse-speech/lhotse>`_.
 
-We recommend you to install ``k2`` first, as ``k2`` is bound to
+We recommend you to use the following steps to install the dependencies.
-a specific version of PyTorch after compilation. Install ``k2`` also
+
-installs its dependency PyTorch, which can be reused by ``lhotse``.
+- (0) Install PyTorch and torchaudio
+- (1) Install k2
+- (2) Install lhotse
+
+.. caution::
+
+  Installation order matters.
+
+(0) Install PyTorch and torchaudio
+----------------------------------
+
+Please refer `<https://pytorch.org/>`_ to install PyTorch
+and torchaudio.
 
 
 (1) Install k2
@@ -54,14 +66,15 @@ to install ``k2``.
 Please refer to `<https://lhotse.readthedocs.io/en/latest/getting-started.html#installation>`_
 to install ``lhotse``.
 
-.. HINT::
 
-  Install ``lhotse`` also installs its dependency `torchaudio <https://github.com/pytorch/audio>`_.
+.. hint::
 
-.. CAUTION::
+    We strongly recommend you to use::
+
+      pip install git+https://github.com/lhotse-speech/lhotse
+
+    to install the latest version of lhotse.
 
-  If you have installed ``torchaudio``, please consider uninstalling it before
-  installing ``lhotse``. Otherwise, it may update your already installed PyTorch.
 
 (3) Download icefall
 --------------------

egs/aishell/ASR/prepare.sh

@@ -70,7 +70,7 @@ if [ $stage -le 0 ] && [ $stop_stage -ge 0 ]; then
   #     |-- lexicon.txt
   #     `-- speaker.info
 
-  if [ ! -d $dl_dir/aishell/data_aishell/wav ]; then
+  if [ ! -d $dl_dir/aishell/data_aishell/wav/train ]; then
     lhotse download aishell $dl_dir
   fi
 

egs/aishell/ASR/transducer_stateless_modified-2/pretrained.py

@@ -55,18 +55,17 @@ from typing import List
 
 import kaldifeat
 import torch
-import torch.nn as nn
 import torchaudio
-from beam_search import beam_search, greedy_search, modified_beam_search
+from beam_search import (
-from conformer import Conformer
+    beam_search,
-from decoder import Decoder
+    greedy_search,
-from joiner import Joiner
+    greedy_search_batch,
-from model import Transducer
+    modified_beam_search,
+)
 from torch.nn.utils.rnn import pad_sequence
+from train import get_params, get_transducer_model
 
-from icefall.env import get_env_info
 from icefall.lexicon import Lexicon
-from icefall.utils import AttributeDict
 
 
 def get_parser():
@@ -111,6 +110,13 @@ def get_parser():
         "The sample rate has to be 16kHz.",
     )
 
+    parser.add_argument(
+        "--sample-rate",
+        type=int,
+        default=16000,
+        help="The sample rate of the input sound file",
+    )
+
     parser.add_argument(
         "--beam-size",
         type=int,
@@ -137,70 +143,6 @@ def get_parser():
     return parser
 
 
-def get_params() -> AttributeDict:
-    params = AttributeDict(
-        {
-            # parameters for conformer
-            "feature_dim": 80,
-            "encoder_out_dim": 512,
-            "subsampling_factor": 4,
-            "attention_dim": 512,
-            "nhead": 8,
-            "dim_feedforward": 2048,
-            "num_encoder_layers": 12,
-            "vgg_frontend": False,
-            "env_info": get_env_info(),
-            "sample_rate": 16000,
-        }
-    )
-    return params
-
-
-def get_encoder_model(params: AttributeDict) -> nn.Module:
-    encoder = Conformer(
-        num_features=params.feature_dim,
-        output_dim=params.encoder_out_dim,
-        subsampling_factor=params.subsampling_factor,
-        d_model=params.attention_dim,
-        nhead=params.nhead,
-        dim_feedforward=params.dim_feedforward,
-        num_encoder_layers=params.num_encoder_layers,
-        vgg_frontend=params.vgg_frontend,
-    )
-    return encoder
-
-
-def get_decoder_model(params: AttributeDict) -> nn.Module:
-    decoder = Decoder(
-        vocab_size=params.vocab_size,
-        embedding_dim=params.encoder_out_dim,
-        blank_id=params.blank_id,
-        context_size=params.context_size,
-    )
-    return decoder
-
-
-def get_joiner_model(params: AttributeDict) -> nn.Module:
-    joiner = Joiner(
-        input_dim=params.encoder_out_dim,
-        output_dim=params.vocab_size,
-    )
-    return joiner
-
-
-def get_transducer_model(params: AttributeDict) -> nn.Module:
-    encoder = get_encoder_model(params)
-    decoder = get_decoder_model(params)
-    joiner = get_joiner_model(params)
-
-    model = Transducer(
-        encoder=encoder,
-        decoder=decoder,
-        joiner=joiner,
-    )
-    return model
-
-
 def read_sound_files(
     filenames: List[str], expected_sample_rate: float
 ) -> List[torch.Tensor]:
@@ -225,6 +167,7 @@ def read_sound_files(
     return ans
 
 
+@torch.no_grad()
 def main():
     parser = get_parser()
     args = parser.parse_args()
@@ -249,7 +192,7 @@ def main():
     model = get_transducer_model(params)
 
     checkpoint = torch.load(args.checkpoint, map_location="cpu")
-    model.load_state_dict(checkpoint["model"])
+    model.load_state_dict(checkpoint["model"], strict=False)
     model.to(device)
     model.eval()
     model.device = device
@@ -279,12 +222,22 @@ def main():
         features, batch_first=True, padding_value=math.log(1e-10)
     )
 
-    hyps = []
+    encoder_out, encoder_out_lens = model.encoder(
-    with torch.no_grad():
+        x=features, x_lens=feature_lens
-        encoder_out, encoder_out_lens = model.encoder(
+    )
-            x=features, x_lens=feature_lens
+    hyp_list = []
+    if params.method == "greedy_search" and params.max_sym_per_frame == 1:
+        hyp_list = greedy_search_batch(
+            model=model,
+            encoder_out=encoder_out,
         )
-
+    elif params.method == "modified_beam_search":
+        hyp_list = modified_beam_search(
+            model=model,
+            encoder_out=encoder_out,
+            beam=params.beam_size,
+        )
+    else:
         for i in range(encoder_out.size(0)):
             # fmt: off
             encoder_out_i = encoder_out[i:i+1, :encoder_out_lens[i]]
@@ -301,17 +254,15 @@ def main():
                     encoder_out=encoder_out_i,
                     beam=params.beam_size,
                 )
-            elif params.method == "modified_beam_search":
-                hyp = modified_beam_search(
-                    model=model,
-                    encoder_out=encoder_out_i,
-                    beam=params.beam_size,
-                )
             else:
                 raise ValueError(
                     f"Unsupported decoding method: {params.method}"
                 )
-            hyps.append([lexicon.token_table[i] for i in hyp])
+            hyp_list.append(hyp)
+
+    hyps = []
+    for hyp in hyp_list:
+        hyps.append([lexicon.token_table[i] for i in hyp])
 
     s = "\n"
     for filename, hyp in zip(params.sound_files, hyps):

egs/aishell/ASR/transducer_stateless_modified/pretrained.py

@@ -55,18 +55,17 @@ from typing import List
 
 import kaldifeat
 import torch
-import torch.nn as nn
 import torchaudio
-from beam_search import beam_search, greedy_search, modified_beam_search
+from beam_search import (
-from conformer import Conformer
+    beam_search,
-from decoder import Decoder
+    greedy_search,
-from joiner import Joiner
+    greedy_search_batch,
-from model import Transducer
+    modified_beam_search,
+)
 from torch.nn.utils.rnn import pad_sequence
+from train import get_params, get_transducer_model
 
-from icefall.env import get_env_info
 from icefall.lexicon import Lexicon
-from icefall.utils import AttributeDict
 
 
 def get_parser():
@@ -111,6 +110,13 @@ def get_parser():
         "The sample rate has to be 16kHz.",
     )
 
+    parser.add_argument(
+        "--sample-rate",
+        type=int,
+        default=16000,
+        help="The sample rate of the input sound file",
+    )
+
     parser.add_argument(
         "--beam-size",
         type=int,
@@ -137,70 +143,6 @@ def get_parser():
     return parser
 
 
-def get_params() -> AttributeDict:
-    params = AttributeDict(
-        {
-            # parameters for conformer
-            "feature_dim": 80,
-            "encoder_out_dim": 512,
-            "subsampling_factor": 4,
-            "attention_dim": 512,
-            "nhead": 8,
-            "dim_feedforward": 2048,
-            "num_encoder_layers": 12,
-            "vgg_frontend": False,
-            "env_info": get_env_info(),
-            "sample_rate": 16000,
-        }
-    )
-    return params
-
-
-def get_encoder_model(params: AttributeDict) -> nn.Module:
-    encoder = Conformer(
-        num_features=params.feature_dim,
-        output_dim=params.encoder_out_dim,
-        subsampling_factor=params.subsampling_factor,
-        d_model=params.attention_dim,
-        nhead=params.nhead,
-        dim_feedforward=params.dim_feedforward,
-        num_encoder_layers=params.num_encoder_layers,
-        vgg_frontend=params.vgg_frontend,
-    )
-    return encoder
-
-
-def get_decoder_model(params: AttributeDict) -> nn.Module:
-    decoder = Decoder(
-        vocab_size=params.vocab_size,
-        embedding_dim=params.encoder_out_dim,
-        blank_id=params.blank_id,
-        context_size=params.context_size,
-    )
-    return decoder
-
-
-def get_joiner_model(params: AttributeDict) -> nn.Module:
-    joiner = Joiner(
-        input_dim=params.encoder_out_dim,
-        output_dim=params.vocab_size,
-    )
-    return joiner
-
-
-def get_transducer_model(params: AttributeDict) -> nn.Module:
-    encoder = get_encoder_model(params)
-    decoder = get_decoder_model(params)
-    joiner = get_joiner_model(params)
-
-    model = Transducer(
-        encoder=encoder,
-        decoder=decoder,
-        joiner=joiner,
-    )
-    return model
-
-
 def read_sound_files(
     filenames: List[str], expected_sample_rate: float
 ) -> List[torch.Tensor]:
@@ -225,6 +167,7 @@ def read_sound_files(
     return ans
 
 
+@torch.no_grad()
 def main():
     parser = get_parser()
     args = parser.parse_args()
@@ -279,12 +222,22 @@ def main():
         features, batch_first=True, padding_value=math.log(1e-10)
     )
 
-    hyps = []
+    encoder_out, encoder_out_lens = model.encoder(
-    with torch.no_grad():
+        x=features, x_lens=feature_lens
-        encoder_out, encoder_out_lens = model.encoder(
+    )
-            x=features, x_lens=feature_lens
+    hyp_list = []
+    if params.method == "greedy_search" and params.max_sym_per_frame == 1:
+        hyp_list = greedy_search_batch(
+            model=model,
+            encoder_out=encoder_out,
         )
-
+    elif params.method == "modified_beam_search":
+        hyp_list = modified_beam_search(
+            model=model,
+            encoder_out=encoder_out,
+            beam=params.beam_size,
+        )
+    else:
         for i in range(encoder_out.size(0)):
             # fmt: off
             encoder_out_i = encoder_out[i:i+1, :encoder_out_lens[i]]
@@ -301,17 +254,15 @@ def main():
                     encoder_out=encoder_out_i,
                     beam=params.beam_size,
                 )
-            elif params.method == "modified_beam_search":
-                hyp = modified_beam_search(
-                    model=model,
-                    encoder_out=encoder_out_i,
-                    beam=params.beam_size,
-                )
             else:
                 raise ValueError(
                     f"Unsupported decoding method: {params.method}"
                 )
-            hyps.append([lexicon.token_table[i] for i in hyp])
+            hyp_list.append(hyp)
+
+    hyps = []
+    for hyp in hyp_list:
+        hyps.append([lexicon.token_table[i] for i in hyp])
 
     s = "\n"
     for filename, hyp in zip(params.sound_files, hyps):

egs/librispeech/ASR/pruned_transducer_stateless/beam_search.py

@@ -17,14 +17,96 @@
 from dataclasses import dataclass
 from typing import Dict, List, Optional
 
+import k2
 import torch
 from model import Transducer
 
+from icefall.decode import one_best_decoding
+from icefall.utils import get_texts
+
+
+def fast_beam_search(
+    model: Transducer,
+    decoding_graph: k2.Fsa,
+    encoder_out: torch.Tensor,
+    encoder_out_lens: torch.Tensor,
+    beam: float,
+    max_states: int,
+    max_contexts: int,
+) -> List[List[int]]:
+    """It limits the maximum number of symbols per frame to 1.
+
+    Args:
+      model:
+        An instance of `Transducer`.
+      decoding_graph:
+        Decoding graph used for decoding, may be a TrivialGraph or a HLG.
+      encoder_out:
+        A tensor of shape (N, T, C) from the encoder.
+      encoder_out_lens:
+        A tensor of shape (N,) containing the number of frames in `encoder_out`
+        before padding.
+      beam:
+        Beam value, similar to the beam used in Kaldi..
+      max_states:
+        Max states per stream per frame.
+      max_contexts:
+        Max contexts pre stream per frame.
+    Returns:
+      Return the decoded result.
+    """
+    assert encoder_out.ndim == 3
+
+    context_size = model.decoder.context_size
+    vocab_size = model.decoder.vocab_size
+
+    B, T, C = encoder_out.shape
+
+    config = k2.RnntDecodingConfig(
+        vocab_size=vocab_size,
+        decoder_history_len=context_size,
+        beam=beam,
+        max_contexts=max_contexts,
+        max_states=max_states,
+    )
+    individual_streams = []
+    for i in range(B):
+        individual_streams.append(k2.RnntDecodingStream(decoding_graph))
+    decoding_streams = k2.RnntDecodingStreams(individual_streams, config)
+
+    for t in range(T):
+        # shape is a RaggedShape of shape (B, context)
+        # contexts is a Tensor of shape (shape.NumElements(), context_size)
+        shape, contexts = decoding_streams.get_contexts()
+        # `nn.Embedding()` in torch below v1.7.1 supports only torch.int64
+        contexts = contexts.to(torch.int64)
+        # decoder_out is of shape (shape.NumElements(), 1, decoder_out_dim)
+        decoder_out = model.decoder(contexts, need_pad=False)
+        # current_encoder_out is of shape
+        # (shape.NumElements(), 1, encoder_out_dim)
+        # fmt: off
+        current_encoder_out = torch.index_select(
+            encoder_out[:, t:t + 1, :], 0, shape.row_ids(1)
+        )
+        # fmt: on
+        logits = model.joiner(
+            current_encoder_out.unsqueeze(2), decoder_out.unsqueeze(1)
+        )
+        logits = logits.squeeze(1).squeeze(1)
+        log_probs = logits.log_softmax(dim=-1)
+        decoding_streams.advance(log_probs)
+    decoding_streams.terminate_and_flush_to_streams()
+    lattice = decoding_streams.format_output(encoder_out_lens.tolist())
+
+    best_path = one_best_decoding(lattice)
+    hyps = get_texts(best_path)
+    return hyps
+
 
 def greedy_search(
     model: Transducer, encoder_out: torch.Tensor, max_sym_per_frame: int
 ) -> List[int]:
-    """
+    """Greedy search for a single utterance.
     Args:
       model:
         An instance of `Transducer`.
@@ -96,6 +178,68 @@ def greedy_search(
     return hyp
 
 
+def greedy_search_batch(
+    model: Transducer, encoder_out: torch.Tensor
+) -> List[List[int]]:
+    """Greedy search in batch mode. It hardcodes --max-sym-per-frame=1.
+    Args:
+      model:
+        The transducer model.
+      encoder_out:
+        Output from the encoder. Its shape is (N, T, C), where N >= 1.
+    Returns:
+      Return a list-of-list of token IDs containing the decoded results.
+      len(ans) equals to encoder_out.size(0).
+    """
+    assert encoder_out.ndim == 3
+    assert encoder_out.size(0) >= 1, encoder_out.size(0)
+
+    device = model.device
+
+    batch_size = encoder_out.size(0)
+    T = encoder_out.size(1)
+
+    blank_id = model.decoder.blank_id
+    context_size = model.decoder.context_size
+
+    hyps = [[blank_id] * context_size for _ in range(batch_size)]
+
+    decoder_input = torch.tensor(
+        hyps,
+        device=device,
+        dtype=torch.int64,
+    )  # (batch_size, context_size)
+
+    decoder_out = model.decoder(decoder_input, need_pad=False)
+    # decoder_out: (batch_size, 1, decoder_out_dim)
+    for t in range(T):
+        current_encoder_out = encoder_out[:, t : t + 1, :].unsqueeze(2)  # noqa
+        # current_encoder_out's shape: (batch_size, 1, 1, encoder_out_dim)
+        logits = model.joiner(current_encoder_out, decoder_out.unsqueeze(1))
+        # logits'shape (batch_size, 1, 1, vocab_size)
+
+        logits = logits.squeeze(1).squeeze(1)  # (batch_size, vocab_size)
+        assert logits.ndim == 2, logits.shape
+        y = logits.argmax(dim=1).tolist()
+        emitted = False
+        for i, v in enumerate(y):
+            if v != blank_id:
+                hyps[i].append(v)
+                emitted = True
+        if emitted:
+            # update decoder output
+            decoder_input = [h[-context_size:] for h in hyps]
+            decoder_input = torch.tensor(
+                decoder_input,
+                device=device,
+                dtype=torch.int64,
+            )
+            decoder_out = model.decoder(decoder_input, need_pad=False)
+
+    ans = [h[context_size:] for h in hyps]
+    return ans
+
+
 @dataclass
 class Hypothesis:
     # The predicted tokens so far.
@@ -222,13 +366,156 @@ class HypothesisList(object):
         return ", ".join(s)
 
 
+def _get_hyps_shape(hyps: List[HypothesisList]) -> k2.RaggedShape:
+    """Return a ragged shape with axes [utt][num_hyps].
+
+    Args:
+      hyps:
+        len(hyps) == batch_size. It contains the current hypothesis for
+        each utterance in the batch.
+    Returns:
+      Return a ragged shape with 2 axes [utt][num_hyps]. Note that
+      the shape is on CPU.
+    """
+    num_hyps = [len(h) for h in hyps]
+
+    # torch.cumsum() is inclusive sum, so we put a 0 at the beginning
+    # to get exclusive sum later.
+    num_hyps.insert(0, 0)
+
+    num_hyps = torch.tensor(num_hyps)
+    row_splits = torch.cumsum(num_hyps, dim=0, dtype=torch.int32)
+    ans = k2.ragged.create_ragged_shape2(
+        row_splits=row_splits, cached_tot_size=row_splits[-1].item()
+    )
+    return ans
+
+
 def modified_beam_search(
     model: Transducer,
     encoder_out: torch.Tensor,
     beam: int = 4,
+) -> List[List[int]]:
+    """Beam search in batch mode with --max-sym-per-frame=1 being hardcoded.
+
+    Args:
+      model:
+        The transducer model.
+      encoder_out:
+        Output from the encoder. Its shape is (N, T, C).
+      beam:
+        Number of active paths during the beam search.
+    Returns:
+      Return a list-of-list of token IDs. ans[i] is the decoding results
+      for the i-th utterance.
+    """
+    assert encoder_out.ndim == 3, encoder_out.shape
+
+    batch_size = encoder_out.size(0)
+    T = encoder_out.size(1)
+
+    blank_id = model.decoder.blank_id
+    context_size = model.decoder.context_size
+    device = model.device
+    B = [HypothesisList() for _ in range(batch_size)]
+    for i in range(batch_size):
+        B[i].add(
+            Hypothesis(
+                ys=[blank_id] * context_size,
+                log_prob=torch.zeros(1, dtype=torch.float32, device=device),
+            )
+        )
+
+    for t in range(T):
+        current_encoder_out = encoder_out[:, t : t + 1, :].unsqueeze(2)  # noqa
+        # current_encoder_out's shape is (batch_size, 1, 1, encoder_out_dim)
+
+        hyps_shape = _get_hyps_shape(B).to(device)
+
+        A = [list(b) for b in B]
+        B = [HypothesisList() for _ in range(batch_size)]
+
+        ys_log_probs = torch.cat(
+            [hyp.log_prob.reshape(1, 1) for hyps in A for hyp in hyps]
+        )  # (num_hyps, 1)
+
+        decoder_input = torch.tensor(
+            [hyp.ys[-context_size:] for hyps in A for hyp in hyps],
+            device=device,
+            dtype=torch.int64,
+        )  # (num_hyps, context_size)
+
+        decoder_out = model.decoder(decoder_input, need_pad=False).unsqueeze(1)
+        # decoder_output is of shape (num_hyps, 1, 1, decoder_output_dim)
+
+        # Note: For torch 1.7.1 and below, it requires a torch.int64 tensor
+        # as index, so we use `to(torch.int64)` below.
+        current_encoder_out = torch.index_select(
+            current_encoder_out,
+            dim=0,
+            index=hyps_shape.row_ids(1).to(torch.int64),
+        )  # (num_hyps, 1, 1, encoder_out_dim)
+
+        logits = model.joiner(
+            current_encoder_out,
+            decoder_out,
+        )  # (num_hyps, 1, 1, vocab_size)
+
+        logits = logits.squeeze(1).squeeze(1)  # (num_hyps, vocab_size)
+
+        log_probs = logits.log_softmax(dim=-1)  # (num_hyps, vocab_size)
+
+        log_probs.add_(ys_log_probs)
+
+        vocab_size = log_probs.size(-1)
+
+        log_probs = log_probs.reshape(-1)
+
+        row_splits = hyps_shape.row_splits(1) * vocab_size
+        log_probs_shape = k2.ragged.create_ragged_shape2(
+            row_splits=row_splits, cached_tot_size=log_probs.numel()
+        )
+        ragged_log_probs = k2.RaggedTensor(
+            shape=log_probs_shape, value=log_probs
+        )
+
+        for i in range(batch_size):
+            topk_log_probs, topk_indexes = ragged_log_probs[i].topk(beam)
+
+            topk_hyp_indexes = (topk_indexes // vocab_size).tolist()
+            topk_token_indexes = (topk_indexes % vocab_size).tolist()
+
+            for k in range(len(topk_hyp_indexes)):
+                hyp_idx = topk_hyp_indexes[k]
+                hyp = A[i][hyp_idx]
+
+                new_ys = hyp.ys[:]
+                new_token = topk_token_indexes[k]
+                if new_token != blank_id:
+                    new_ys.append(new_token)
+
+                new_log_prob = topk_log_probs[k]
+                new_hyp = Hypothesis(ys=new_ys, log_prob=new_log_prob)
+                B[i].add(new_hyp)
+
+    best_hyps = [b.get_most_probable(length_norm=True) for b in B]
+    ans = [h.ys[context_size:] for h in best_hyps]
+
+    return ans
+
+
+def _deprecated_modified_beam_search(
+    model: Transducer,
+    encoder_out: torch.Tensor,
+    beam: int = 4,
 ) -> List[int]:
     """It limits the maximum number of symbols per frame to 1.
 
+    It decodes only one utterance at a time. We keep it only for reference.
+    The function :func:`modified_beam_search` should be preferred as it
+    supports batch decoding.
+
+
     Args:
       model:
         An instance of `Transducer`.

egs/librispeech/ASR/pruned_transducer_stateless/decode.py

@@ -42,6 +42,17 @@ Usage:
         --max-duration 100 \
         --decoding-method modified_beam_search \
         --beam-size 4
+
+(4) fast beam search
+./pruned_transducer_stateless/decode.py \
+        --epoch 28 \
+        --avg 15 \
+        --exp-dir ./pruned_transducer_stateless/exp \
+        --max-duration 1500 \
+        --decoding-method fast_beam_search \
+        --beam 4 \
+        --max-contexts 4 \
+        --max-states 8
 """
 
 
@@ -49,13 +60,20 @@ import argparse
 import logging
 from collections import defaultdict
 from pathlib import Path
-from typing import Dict, List, Tuple
+from typing import Dict, List, Optional, Tuple
 
+import k2
 import sentencepiece as spm
 import torch
 import torch.nn as nn
 from asr_datamodule import LibriSpeechAsrDataModule
-from beam_search import beam_search, greedy_search, modified_beam_search
+from beam_search import (
+    beam_search,
+    fast_beam_search,
+    greedy_search,
+    greedy_search_batch,
+    modified_beam_search,
+)
 from train import get_params, get_transducer_model
 
 from icefall.checkpoint import (
@@ -80,27 +98,28 @@ def get_parser():
         "--epoch",
         type=int,
         default=28,
-        help="It specifies the checkpoint to use for decoding."
+        help="""It specifies the checkpoint to use for decoding.
-        "Note: Epoch counts from 0.",
+        Note: Epoch counts from 0.
+        You can specify --avg to use more checkpoints for model averaging.""",
     )
+
+    parser.add_argument(
+        "--iter",
+        type=int,
+        default=0,
+        help="""If positive, --epoch is ignored and it
+        will use the checkpoint exp_dir/checkpoint-iter.pt.
+        You can specify --avg to use more checkpoints for model averaging.
+        """,
+    )
+
     parser.add_argument(
         "--avg",
         type=int,
         default=15,
         help="Number of checkpoints to average. Automatically select "
         "consecutive checkpoints before the checkpoint specified by "
-        "'--epoch'. ",
+        "'--epoch' and '--iter'",
-    )
-
-    parser.add_argument(
-        "--avg-last-n",
-        type=int,
-        default=0,
-        help="""If positive, --epoch and --avg are ignored and it
-        will use the last n checkpoints exp_dir/checkpoint-xxx.pt
-        where xxx is the number of processed batches while
-        saving that checkpoint.
-        """,
     )
 
     parser.add_argument(
@@ -125,6 +144,7 @@ def get_parser():
           - greedy_search
           - beam_search
           - modified_beam_search
+          - fast_beam_search
         """,
     )
 
@@ -132,8 +152,35 @@ def get_parser():
         "--beam-size",
         type=int,
         default=4,
+        help="""An interger indicating how many candidates we will keep for each
+        frame. Used only when --decoding-method is beam_search or
+        modified_beam_search.""",
+    )
+
+    parser.add_argument(
+        "--beam",
+        type=float,
+        default=4,
+        help="""A floating point value to calculate the cutoff score during beam
+        search (i.e., `cutoff = max-score - beam`), which is the same as the
+        `beam` in Kaldi.
+        Used only when --decoding-method is fast_beam_search""",
+    )
+
+    parser.add_argument(
+        "--max-contexts",
+        type=int,
+        default=4,
         help="""Used only when --decoding-method is
-        beam_search or modified_beam_search""",
+        fast_beam_search""",
+    )
+
+    parser.add_argument(
+        "--max-states",
+        type=int,
+        default=8,
+        help="""Used only when --decoding-method is
+        fast_beam_search""",
     )
 
     parser.add_argument(
@@ -146,7 +193,7 @@ def get_parser():
     parser.add_argument(
         "--max-sym-per-frame",
         type=int,
-        default=3,
+        default=1,
         help="""Maximum number of symbols per frame.
         Used only when --decoding_method is greedy_search""",
     )
@@ -159,6 +206,7 @@ def decode_one_batch(
     model: nn.Module,
     sp: spm.SentencePieceProcessor,
     batch: dict,
+    decoding_graph: Optional[k2.Fsa] = None,
 ) -> Dict[str, List[List[str]]]:
     """Decode one batch and return the result in a dict. The dict has the
     following format:
@@ -181,6 +229,9 @@ def decode_one_batch(
         It is the return value from iterating
         `lhotse.dataset.K2SpeechRecognitionDataset`. See its documentation
         for the format of the `batch`.
+      decoding_graph:
+        The decoding graph. Can be either a `k2.trivial_graph` or HLG, Used
+        only when --decoding_method is fast_beam_search.
     Returns:
       Return the decoding result. See above description for the format of
       the returned dict.
@@ -199,36 +250,74 @@ def decode_one_batch(
         x=feature, x_lens=feature_lens
     )
     hyps = []
-    batch_size = encoder_out.size(0)
 
-    for i in range(batch_size):
+    if params.decoding_method == "fast_beam_search":
-        # fmt: off
+        hyp_tokens = fast_beam_search(
-        encoder_out_i = encoder_out[i:i+1, :encoder_out_lens[i]]
+            model=model,
-        # fmt: on
+            decoding_graph=decoding_graph,
-        if params.decoding_method == "greedy_search":
+            encoder_out=encoder_out,
-            hyp = greedy_search(
+            encoder_out_lens=encoder_out_lens,
-                model=model,
+            beam=params.beam,
-                encoder_out=encoder_out_i,
+            max_contexts=params.max_contexts,
-                max_sym_per_frame=params.max_sym_per_frame,
+            max_states=params.max_states,
-            )
+        )
-        elif params.decoding_method == "beam_search":
+        for hyp in sp.decode(hyp_tokens):
-            hyp = beam_search(
+            hyps.append(hyp.split())
-                model=model, encoder_out=encoder_out_i, beam=params.beam_size
+    elif (
-            )
+        params.decoding_method == "greedy_search"
-        elif params.decoding_method == "modified_beam_search":
+        and params.max_sym_per_frame == 1
-            hyp = modified_beam_search(
+    ):
-                model=model, encoder_out=encoder_out_i, beam=params.beam_size
+        hyp_tokens = greedy_search_batch(
-            )
+            model=model,
-        else:
+            encoder_out=encoder_out,
-            raise ValueError(
+        )
-                f"Unsupported decoding method: {params.decoding_method}"
+        for hyp in sp.decode(hyp_tokens):
-            )
+            hyps.append(hyp.split())
-        hyps.append(sp.decode(hyp).split())
+    elif params.decoding_method == "modified_beam_search":
+        hyp_tokens = modified_beam_search(
+            model=model,
+            encoder_out=encoder_out,
+            beam=params.beam_size,
+        )
+        for hyp in sp.decode(hyp_tokens):
+            hyps.append(hyp.split())
+    else:
+        batch_size = encoder_out.size(0)
+
+        for i in range(batch_size):
+            # fmt: off
+            encoder_out_i = encoder_out[i:i+1, :encoder_out_lens[i]]
+            # fmt: on
+            if params.decoding_method == "greedy_search":
+                hyp = greedy_search(
+                    model=model,
+                    encoder_out=encoder_out_i,
+                    max_sym_per_frame=params.max_sym_per_frame,
+                )
+            elif params.decoding_method == "beam_search":
+                hyp = beam_search(
+                    model=model,
+                    encoder_out=encoder_out_i,
+                    beam=params.beam_size,
+                )
+            else:
+                raise ValueError(
+                    f"Unsupported decoding method: {params.decoding_method}"
+                )
+            hyps.append(sp.decode(hyp).split())
 
     if params.decoding_method == "greedy_search":
         return {"greedy_search": hyps}
+    elif params.decoding_method == "fast_beam_search":
+        return {
+            (
+                f"beam_{params.beam}_"
+                f"max_contexts_{params.max_contexts}_"
+                f"max_states_{params.max_states}"
+            ): hyps
+        }
     else:
-        return {f"beam_{params.beam_size}": hyps}
+        return {f"beam_size_{params.beam_size}": hyps}
 
 
 def decode_dataset(
@@ -236,6 +325,7 @@ def decode_dataset(
     params: AttributeDict,
     model: nn.Module,
     sp: spm.SentencePieceProcessor,
+    decoding_graph: Optional[k2.Fsa] = None,
 ) -> Dict[str, List[Tuple[List[str], List[str]]]]:
     """Decode dataset.
 
@@ -248,6 +338,9 @@ def decode_dataset(
         The neural model.
       sp:
         The BPE model.
+      decoding_graph:
+        The decoding graph. Can be either a `k2.trivial_graph` or HLG, Used
+        only when --decoding_method is fast_beam_search.
     Returns:
       Return a dict, whose key may be "greedy_search" if greedy search
       is used, or it may be "beam_7" if beam size of 7 is used.
@@ -275,6 +368,7 @@ def decode_dataset(
             params=params,
             model=model,
             sp=sp,
+            decoding_graph=decoding_graph,
             batch=batch,
         )
 
@@ -355,13 +449,24 @@ def main():
     assert params.decoding_method in (
         "greedy_search",
         "beam_search",
+        "fast_beam_search",
         "modified_beam_search",
     )
     params.res_dir = params.exp_dir / params.decoding_method
 
-    params.suffix = f"epoch-{params.epoch}-avg-{params.avg}"
+    if params.iter > 0:
-    if "beam_search" in params.decoding_method:
+        params.suffix = f"iter-{params.iter}-avg-{params.avg}"
-        params.suffix += f"-beam-{params.beam_size}"
+    else:
+        params.suffix = f"epoch-{params.epoch}-avg-{params.avg}"
+
+    if "fast_beam_search" in params.decoding_method:
+        params.suffix += f"-beam-{params.beam}"
+        params.suffix += f"-max-contexts-{params.max_contexts}"
+        params.suffix += f"-max-states-{params.max_states}"
+    elif "beam_search" in params.decoding_method:
+        params.suffix += (
+            f"-{params.decoding_method}-beam-size-{params.beam_size}"
+        )
     else:
         params.suffix += f"-context-{params.context_size}"
         params.suffix += f"-max-sym-per-frame-{params.max_sym_per_frame}"
@@ -387,8 +492,20 @@ def main():
     logging.info("About to create model")
     model = get_transducer_model(params)
 
-    if params.avg_last_n > 0:
+    if params.iter > 0:
-        filenames = find_checkpoints(params.exp_dir)[: params.avg_last_n]
+        filenames = find_checkpoints(params.exp_dir, iteration=-params.iter)[
+            : params.avg
+        ]
+        if len(filenames) == 0:
+            raise ValueError(
+                f"No checkpoints found for"
+                f" --iter {params.iter}, --avg {params.avg}"
+            )
+        elif len(filenames) < params.avg:
+            raise ValueError(
+                f"Not enough checkpoints ({len(filenames)}) found for"
+                f" --iter {params.iter}, --avg {params.avg}"
+            )
         logging.info(f"averaging {filenames}")
         model.to(device)
         model.load_state_dict(average_checkpoints(filenames, device=device))
@@ -408,6 +525,11 @@ def main():
     model.eval()
     model.device = device
 
+    if params.decoding_method == "fast_beam_search":
+        decoding_graph = k2.trivial_graph(params.vocab_size - 1, device=device)
+    else:
+        decoding_graph = None
+
     num_param = sum([p.numel() for p in model.parameters()])
     logging.info(f"Number of model parameters: {num_param}")
 
@@ -428,6 +550,7 @@ def main():
             params=params,
             model=model,
             sp=sp,
+            decoding_graph=decoding_graph,
         )
 
         save_results(

egs/librispeech/ASR/pruned_transducer_stateless/decoder.py

@@ -61,6 +61,7 @@ class Decoder(nn.Module):
 
         assert context_size >= 1, context_size
         self.context_size = context_size
+        self.vocab_size = vocab_size
         if context_size > 1:
             self.conv = nn.Conv1d(
                 in_channels=embedding_dim,

egs/librispeech/ASR/pruned_transducer_stateless/pretrained.py

@@ -50,7 +50,12 @@ import kaldifeat
 import sentencepiece as spm
 import torch
 import torchaudio
-from beam_search import beam_search, greedy_search, modified_beam_search
+from beam_search import (
+    beam_search,
+    greedy_search,
+    greedy_search_batch,
+    modified_beam_search,
+)
 from torch.nn.utils.rnn import pad_sequence
 from train import get_params, get_transducer_model
 
@@ -122,7 +127,7 @@ def get_parser():
     parser.add_argument(
         "--max-sym-per-frame",
         type=int,
-        default=3,
+        default=1,
         help="""Maximum number of symbols per frame. Used only when
         --method is greedy_search.
         """,
@@ -224,28 +229,43 @@ def main():
     if params.method == "beam_search":
         msg += f" with beam size {params.beam_size}"
     logging.info(msg)
-    for i in range(num_waves):
+    if params.method == "modified_beam_search":
-        # fmt: off
+        hyp_tokens = modified_beam_search(
-        encoder_out_i = encoder_out[i:i+1, :encoder_out_lens[i]]
+            model=model,
-        # fmt: on
+            encoder_out=encoder_out,
-        if params.method == "greedy_search":
+            beam=params.beam_size,
-            hyp = greedy_search(
+        )
-                model=model,
-                encoder_out=encoder_out_i,
-                max_sym_per_frame=params.max_sym_per_frame,
-            )
-        elif params.method == "beam_search":
-            hyp = beam_search(
-                model=model, encoder_out=encoder_out_i, beam=params.beam_size
-            )
-        elif params.method == "modified_beam_search":
-            hyp = modified_beam_search(
-                model=model, encoder_out=encoder_out_i, beam=params.beam_size
-            )
-        else:
-            raise ValueError(f"Unsupported method: {params.method}")
 
-        hyps.append(sp.decode(hyp).split())
+        for hyp in sp.decode(hyp_tokens):
+            hyps.append(hyp.split())
+    elif params.method == "greedy_search" and params.max_sym_per_frame == 1:
+        hyp_tokens = greedy_search_batch(
+            model=model,
+            encoder_out=encoder_out,
+        )
+        for hyp in sp.decode(hyp_tokens):
+            hyps.append(hyp.split())
+    else:
+        for i in range(num_waves):
+            # fmt: off
+            encoder_out_i = encoder_out[i:i+1, :encoder_out_lens[i]]
+            # fmt: on
+            if params.method == "greedy_search":
+                hyp = greedy_search(
+                    model=model,
+                    encoder_out=encoder_out_i,
+                    max_sym_per_frame=params.max_sym_per_frame,
+                )
+            elif params.method == "beam_search":
+                hyp = beam_search(
+                    model=model,
+                    encoder_out=encoder_out_i,
+                    beam=params.beam_size,
+                )
+            else:
+                raise ValueError(f"Unsupported method: {params.method}")
+
+            hyps.append(sp.decode(hyp).split())
 
     s = "\n"
     for filename, hyp in zip(params.sound_files, hyps):

egs/librispeech/ASR/pruned_transducer_stateless/train.py

@@ -33,6 +33,7 @@ export CUDA_VISIBLE_DEVICES="0,1,2,3"
 
 import argparse
 import logging
+import warnings
 from pathlib import Path
 from shutil import copyfile
 from typing import Any, Dict, Optional, Tuple
@@ -392,12 +393,16 @@ def load_checkpoint_if_available(
         "batch_idx_train",
         "best_train_loss",
         "best_valid_loss",
-        "cur_batch_idx",
     ]
     for k in keys:
         params[k] = saved_params[k]
 
-    params["start_epoch"] = saved_params["cur_epoch"]
+    if params.start_batch > 0:
+        if "cur_epoch" in saved_params:
+            params["start_epoch"] = saved_params["cur_epoch"]
+
+        if "cur_batch_idx" in saved_params:
+            params["cur_batch_idx"] = saved_params["cur_batch_idx"]
 
     return saved_params
 
@@ -492,7 +497,11 @@ def compute_loss(
     assert loss.requires_grad == is_training
 
     info = MetricsTracker()
-    info["frames"] = (feature_lens // params.subsampling_factor).sum().item()
+    with warnings.catch_warnings():
+        warnings.simplefilter("ignore")
+        info["frames"] = (
+            (feature_lens // params.subsampling_factor).sum().item()
+        )
 
     # Note: We use reduction=sum while computing the loss.
     info["loss"] = loss.detach().cpu().item()
@@ -783,6 +792,13 @@ def run(rank, world_size, args):
 
     def remove_short_and_long_utt(c: Cut):
         # Keep only utterances with duration between 1 second and 20 seconds
+        #
+        # Caution: There is a reason to select 20.0 here. Please see
+        # ../local/display_manifest_statistics.py
+        #
+        # You should use ../local/display_manifest_statistics.py to get
+        # an utterance duration distribution for your dataset to select
+        # the threshold
         return 1.0 <= c.duration <= 20.0
 
     num_in_total = len(train_cuts)
@@ -797,7 +813,9 @@ def run(rank, world_size, args):
     logging.info(f"After removing short and long utterances: {num_left}")
     logging.info(f"Removed {num_removed} utterances ({removed_percent:.5f}%)")
 
-    if checkpoints and "sampler" in checkpoints:
+    if params.start_batch > 0 and checkpoints and "sampler" in checkpoints:
+        # We only load the sampler's state dict when it loads a checkpoint
+        # saved in the middle of an epoch
         sampler_state_dict = checkpoints["sampler"]
     else:
         sampler_state_dict = None

egs/librispeech/ASR/tdnn_lstm_ctc/asr_datamodule.py

@@ -23,6 +23,7 @@ from functools import lru_cache
 from pathlib import Path
 from typing import Any, Dict, Optional
 
+import torch
 from lhotse import CutSet, Fbank, FbankConfig, load_manifest
 from lhotse.dataset import (
     BucketingSampler,
@@ -34,11 +35,20 @@ from lhotse.dataset import (
     SpecAugment,
 )
 from lhotse.dataset.input_strategies import OnTheFlyFeatures
+from lhotse.utils import fix_random_seed
 from torch.utils.data import DataLoader
 
 from icefall.utils import str2bool
 
 
+class _SeedWorkers:
+    def __init__(self, seed: int):
+        self.seed = seed
+
+    def __call__(self, worker_id: int):
+        fix_random_seed(self.seed + worker_id)
+
+
 class LibriSpeechAsrDataModule:
     """
     DataModule for k2 ASR experiments.
@@ -301,12 +311,18 @@ class LibriSpeechAsrDataModule:
             logging.info("Loading sampler state dict")
             train_sampler.load_state_dict(sampler_state_dict)
 
+        # 'seed' is derived from the current random state, which will have
+        # previously been set in the main process.
+        seed = torch.randint(0, 100000, ()).item()
+        worker_init_fn = _SeedWorkers(seed)
+
         train_dl = DataLoader(
             train,
             sampler=train_sampler,
             batch_size=None,
             num_workers=self.args.num_workers,
             persistent_workers=False,
+            worker_init_fn=worker_init_fn,
         )
 
         return train_dl

egs/librispeech/ASR/transducer/train.py

@@ -34,6 +34,7 @@ export CUDA_VISIBLE_DEVICES="0,1,2,3"
 
 import argparse
 import logging
+import warnings
 from pathlib import Path
 from shutil import copyfile
 from typing import Optional, Tuple
@@ -393,7 +394,11 @@ def compute_loss(
     assert loss.requires_grad == is_training
 
     info = MetricsTracker()
-    info["frames"] = (feature_lens // params.subsampling_factor).sum().item()
+    with warnings.catch_warnings():
+        warnings.simplefilter("ignore")
+        info["frames"] = (
+            (feature_lens // params.subsampling_factor).sum().item()
+        )
 
     # Note: We use reduction=sum while computing the loss.
     info["loss"] = loss.detach().cpu().item()

egs/librispeech/ASR/transducer_lstm/train.py

@@ -35,6 +35,7 @@ export CUDA_VISIBLE_DEVICES="0,1,2"
 
 import argparse
 import logging
+import warnings
 from pathlib import Path
 from shutil import copyfile
 from typing import Optional, Tuple
@@ -397,7 +398,11 @@ def compute_loss(
     assert loss.requires_grad == is_training
 
     info = MetricsTracker()
-    info["frames"] = (feature_lens // params.subsampling_factor).sum().item()
+    with warnings.catch_warnings():
+        warnings.simplefilter("ignore")
+        info["frames"] = (
+            (feature_lens // params.subsampling_factor).sum().item()
+        )
 
     # Note: We use reduction=sum while computing the loss.
     info["loss"] = loss.detach().cpu().item()

egs/librispeech/ASR/transducer_stateless/beam_search.py

@@ -17,6 +17,7 @@
 from dataclasses import dataclass
 from typing import Dict, List, Optional
 
+import k2
 import torch
 from model import Transducer
 
@@ -24,7 +25,7 @@ from model import Transducer
 def greedy_search(
     model: Transducer, encoder_out: torch.Tensor, max_sym_per_frame: int
 ) -> List[int]:
-    """
+    """Greedy search for a single utterance.
     Args:
       model:
         An instance of `Transducer`.
@@ -80,7 +81,7 @@ def greedy_search(
         logits = model.joiner(
             current_encoder_out, decoder_out, encoder_out_len, decoder_out_len
         )
-        # logits is (1, 1, 1, vocab_size)
+        # logits is (1, vocab_size)
 
         y = logits.argmax().item()
         if y != blank_id:
@@ -101,6 +102,75 @@ def greedy_search(
     return hyp
 
 
+def greedy_search_batch(
+    model: Transducer, encoder_out: torch.Tensor
+) -> List[List[int]]:
+    """Greedy search in batch mode. It hardcodes --max-sym-per-frame=1.
+    Args:
+      model:
+        The transducer model.
+      encoder_out:
+        Output from the encoder. Its shape is (N, T, C), where N >= 1.
+    Returns:
+      Return a list-of-list of token IDs containing the decoded results.
+      len(ans) equals to encoder_out.size(0).
+    """
+    assert encoder_out.ndim == 3
+    assert encoder_out.size(0) >= 1, encoder_out.size(0)
+
+    device = model.device
+
+    batch_size = encoder_out.size(0)
+    T = encoder_out.size(1)
+
+    blank_id = model.decoder.blank_id
+    context_size = model.decoder.context_size
+
+    hyps = [[blank_id] * context_size for _ in range(batch_size)]
+
+    decoder_input = torch.tensor(
+        hyps,
+        device=device,
+        dtype=torch.int64,
+    )  # (batch_size, context_size)
+    decoder_out = model.decoder(decoder_input, need_pad=False)
+    # decoder_out: (batch_size, 1, decoder_out_dim)
+
+    encoder_out_len = torch.ones(batch_size, dtype=torch.int32)
+    decoder_out_len = torch.ones(batch_size, dtype=torch.int32)
+
+    for t in range(T):
+        current_encoder_out = encoder_out[:, t : t + 1, :]  # noqa
+        # current_encoder_out's shape: (batch_size, 1, encoder_out_dim)
+        logits = model.joiner(
+            current_encoder_out, decoder_out, encoder_out_len, decoder_out_len
+        )  # (batch_size, vocab_size)
+
+        assert logits.ndim == 2, logits.shape
+        y = logits.argmax(dim=1).tolist()
+        emitted = False
+        for i, v in enumerate(y):
+            if v != blank_id:
+                hyps[i].append(v)
+                emitted = True
+
+        if emitted:
+            # update decoder output
+            decoder_input = [h[-context_size:] for h in hyps]
+            decoder_input = torch.tensor(
+                decoder_input,
+                device=device,
+                dtype=torch.int64,
+            )  # (batch_size, context_size)
+            decoder_out = model.decoder(
+                decoder_input,
+                need_pad=False,
+            )  # (batch_size, 1, decoder_out_dim)
+
+    ans = [h[context_size:] for h in hyps]
+    return ans
+
+
 @dataclass
 class Hypothesis:
     # The predicted tokens so far.
@@ -252,9 +322,11 @@ def run_decoder(
 
     device = model.device
 
-    decoder_input = torch.tensor([ys[-context_size:]], device=device).reshape(
+    decoder_input = torch.tensor(
-        1, context_size
+        [ys[-context_size:]],
-    )
+        device=device,
+        dtype=torch.int64,
+    ).reshape(1, context_size)
 
     decoder_out = model.decoder(decoder_input, need_pad=False)
     decoder_cache[key] = decoder_out
@@ -314,13 +386,158 @@ def run_joiner(
     return log_prob
 
 
+def _get_hyps_shape(hyps: List[HypothesisList]) -> k2.RaggedShape:
+    """Return a ragged shape with axes [utt][num_hyps].
+
+    Args:
+      hyps:
+        len(hyps) == batch_size. It contains the current hypothesis for
+        each utterance in the batch.
+    Returns:
+      Return a ragged shape with 2 axes [utt][num_hyps]. Note that
+      the shape is on CPU.
+    """
+    num_hyps = [len(h) for h in hyps]
+
+    # torch.cumsum() is inclusive sum, so we put a 0 at the beginning
+    # to get exclusive sum later.
+    num_hyps.insert(0, 0)
+
+    num_hyps = torch.tensor(num_hyps)
+    row_splits = torch.cumsum(num_hyps, dim=0, dtype=torch.int32)
+    ans = k2.ragged.create_ragged_shape2(
+        row_splits=row_splits, cached_tot_size=row_splits[-1].item()
+    )
+    return ans
+
+
 def modified_beam_search(
     model: Transducer,
     encoder_out: torch.Tensor,
     beam: int = 4,
+) -> List[List[int]]:
+    """Beam search in batch mode with --max-sym-per-frame=1 being hardcodded.
+
+    Args:
+      model:
+        The transducer model.
+      encoder_out:
+        Output from the encoder. Its shape is (N, T, C).
+      beam:
+        Number of active paths during the beam search.
+    Returns:
+      Return a list-of-list of token IDs. ans[i] is the decoding results
+      for the i-th utterance.
+    """
+    assert encoder_out.ndim == 3, encoder_out.shape
+
+    batch_size = encoder_out.size(0)
+    T = encoder_out.size(1)
+
+    blank_id = model.decoder.blank_id
+    context_size = model.decoder.context_size
+    device = model.device
+    B = [HypothesisList() for _ in range(batch_size)]
+    for i in range(batch_size):
+        B[i].add(
+            Hypothesis(
+                ys=[blank_id] * context_size,
+                log_prob=torch.zeros(1, dtype=torch.float32, device=device),
+            )
+        )
+
+    encoder_out_len = torch.tensor([1])
+    decoder_out_len = torch.tensor([1])
+    for t in range(T):
+        current_encoder_out = encoder_out[:, t : t + 1, :]  # noqa
+        # current_encoder_out's shape is: (batch_size, 1, encoder_out_dim)
+
+        hyps_shape = _get_hyps_shape(B).to(device)
+
+        A = [list(b) for b in B]
+        B = [HypothesisList() for _ in range(batch_size)]
+
+        ys_log_probs = torch.cat(
+            [hyp.log_prob.reshape(1, 1) for hyps in A for hyp in hyps]
+        )  # (num_hyps, 1)
+
+        decoder_input = torch.tensor(
+            [hyp.ys[-context_size:] for hyps in A for hyp in hyps],
+            device=device,
+            dtype=torch.int64,
+        )  # (num_hyps, context_size)
+
+        decoder_out = model.decoder(decoder_input, need_pad=False)
+        # decoder_output is of shape (num_hyps, 1, decoder_output_dim)
+
+        # Note: For torch 1.7.1 and below, it requires a torch.int64 tensor
+        # as index, so we use `to(torch.int64)` below.
+        current_encoder_out = torch.index_select(
+            current_encoder_out,
+            dim=0,
+            index=hyps_shape.row_ids(1).to(torch.int64),
+        )  # (num_hyps, 1, encoder_out_dim)
+
+        logits = model.joiner(
+            current_encoder_out,
+            decoder_out,
+            encoder_out_len.expand(decoder_out.size(0)),
+            decoder_out_len.expand(decoder_out.size(0)),
+        )
+        # logits is of shape (num_hyps, vocab_size)
+
+        log_probs = logits.log_softmax(dim=-1)  # (num_hyps, vocab_size)
+
+        log_probs.add_(ys_log_probs)
+
+        vocab_size = log_probs.size(-1)
+
+        log_probs = log_probs.reshape(-1)
+
+        row_splits = hyps_shape.row_splits(1) * vocab_size
+        log_probs_shape = k2.ragged.create_ragged_shape2(
+            row_splits=row_splits, cached_tot_size=log_probs.numel()
+        )
+        ragged_log_probs = k2.RaggedTensor(
+            shape=log_probs_shape, value=log_probs
+        )
+
+        for i in range(batch_size):
+            topk_log_probs, topk_indexes = ragged_log_probs[i].topk(beam)
+
+            topk_hyp_indexes = (topk_indexes // vocab_size).tolist()
+            topk_token_indexes = (topk_indexes % vocab_size).tolist()
+
+            for k in range(len(topk_hyp_indexes)):
+                hyp_idx = topk_hyp_indexes[k]
+                hyp = A[i][hyp_idx]
+
+                new_ys = hyp.ys[:]
+                new_token = topk_token_indexes[k]
+                if new_token != blank_id:
+                    new_ys.append(new_token)
+
+                new_log_prob = topk_log_probs[k]
+                new_hyp = Hypothesis(ys=new_ys, log_prob=new_log_prob)
+                B[i].add(new_hyp)
+
+    best_hyps = [b.get_most_probable(length_norm=True) for b in B]
+    ans = [h.ys[context_size:] for h in best_hyps]
+
+    return ans
+
+
+def _deprecated_modified_beam_search(
+    model: Transducer,
+    encoder_out: torch.Tensor,
+    beam: int = 4,
 ) -> List[int]:
     """It limits the maximum number of symbols per frame to 1.
 
+    It decodes only one utterance at a time. We keep it only for reference.
+    The function :func:`modified_beam_search` should be preferred as it
+    supports batch decoding.
+
     Args:
       model:
         An instance of `Transducer`.
@@ -341,12 +558,6 @@ def modified_beam_search(
 
     device = model.device
 
-    decoder_input = torch.tensor(
-        [blank_id] * context_size, device=device
-    ).reshape(1, context_size)
-
-    decoder_out = model.decoder(decoder_input, need_pad=False)
-
     T = encoder_out.size(1)
 
     B = HypothesisList()

egs/librispeech/ASR/transducer_stateless/conformer.py

@@ -109,8 +109,11 @@ class Conformer(Transformer):
         x, pos_emb = self.encoder_pos(x)
         x = x.permute(1, 0, 2)  # (N, T, C) -> (T, N, C)
 
-        # Caution: We assume the subsampling factor is 4!
+        with warnings.catch_warnings():
-        lengths = ((x_lens - 1) // 2 - 1) // 2
+            warnings.simplefilter("ignore")
+            # Caution: We assume the subsampling factor is 4!
+            lengths = ((x_lens - 1) // 2 - 1) // 2
+
         assert x.size(0) == lengths.max().item()
         mask = make_pad_mask(lengths)
 

egs/librispeech/ASR/transducer_stateless/decode.py

@@ -55,14 +55,15 @@ import sentencepiece as spm
 import torch
 import torch.nn as nn
 from asr_datamodule import LibriSpeechAsrDataModule
-from beam_search import beam_search, greedy_search, modified_beam_search
+from beam_search import (
-from conformer import Conformer
+    beam_search,
-from decoder import Decoder
+    greedy_search,
-from joiner import Joiner
+    greedy_search_batch,
-from model import Transducer
+    modified_beam_search,
+)
+from train import get_params, get_transducer_model
 
 from icefall.checkpoint import average_checkpoints, load_checkpoint
-from icefall.env import get_env_info
 from icefall.utils import (
     AttributeDict,
     setup_logger,
@@ -135,7 +136,7 @@ def get_parser():
     parser.add_argument(
         "--max-sym-per-frame",
         type=int,
-        default=3,
+        default=1,
         help="""Maximum number of symbols per frame.
         Used only when --decoding_method is greedy_search""",
     )
@@ -143,70 +144,6 @@ def get_parser():
     return parser
 
 
-def get_params() -> AttributeDict:
-    params = AttributeDict(
-        {
-            # parameters for conformer
-            "feature_dim": 80,
-            "encoder_out_dim": 512,
-            "subsampling_factor": 4,
-            "attention_dim": 512,
-            "nhead": 8,
-            "dim_feedforward": 2048,
-            "num_encoder_layers": 12,
-            "vgg_frontend": False,
-            "env_info": get_env_info(),
-        }
-    )
-    return params
-
-
-def get_encoder_model(params: AttributeDict):
-    # TODO: We can add an option to switch between Conformer and Transformer
-    encoder = Conformer(
-        num_features=params.feature_dim,
-        output_dim=params.encoder_out_dim,
-        subsampling_factor=params.subsampling_factor,
-        d_model=params.attention_dim,
-        nhead=params.nhead,
-        dim_feedforward=params.dim_feedforward,
-        num_encoder_layers=params.num_encoder_layers,
-        vgg_frontend=params.vgg_frontend,
-    )
-    return encoder
-
-
-def get_decoder_model(params: AttributeDict):
-    decoder = Decoder(
-        vocab_size=params.vocab_size,
-        embedding_dim=params.encoder_out_dim,
-        blank_id=params.blank_id,
-        context_size=params.context_size,
-    )
-    return decoder
-
-
-def get_joiner_model(params: AttributeDict):
-    joiner = Joiner(
-        input_dim=params.encoder_out_dim,
-        output_dim=params.vocab_size,
-    )
-    return joiner
-
-
-def get_transducer_model(params: AttributeDict):
-    encoder = get_encoder_model(params)
-    decoder = get_decoder_model(params)
-    joiner = get_joiner_model(params)
-
-    model = Transducer(
-        encoder=encoder,
-        decoder=decoder,
-        joiner=joiner,
-    )
-    return model
-
-
 def decode_one_batch(
     params: AttributeDict,
     model: nn.Module,
@@ -251,32 +188,47 @@ def decode_one_batch(
     encoder_out, encoder_out_lens = model.encoder(
         x=feature, x_lens=feature_lens
     )
-    hyps = []
+    hyp_list: List[List[int]] = []
-    batch_size = encoder_out.size(0)
 
-    for i in range(batch_size):
+    if (
-        # fmt: off
+        params.decoding_method == "greedy_search"
-        encoder_out_i = encoder_out[i:i+1, :encoder_out_lens[i]]
+        and params.max_sym_per_frame == 1
-        # fmt: on
+    ):
-        if params.decoding_method == "greedy_search":
+        hyp_list = greedy_search_batch(
-            hyp = greedy_search(
+            model=model,
-                model=model,
+            encoder_out=encoder_out,
-                encoder_out=encoder_out_i,
+        )
-                max_sym_per_frame=params.max_sym_per_frame,
+    elif params.decoding_method == "modified_beam_search":
-            )
+        hyp_list = modified_beam_search(
-        elif params.decoding_method == "beam_search":
+            model=model,
-            hyp = beam_search(
+            encoder_out=encoder_out,
-                model=model, encoder_out=encoder_out_i, beam=params.beam_size
+            beam=params.beam_size,
-            )
+        )
-        elif params.decoding_method == "modified_beam_search":
+    else:
-            hyp = modified_beam_search(
+        batch_size = encoder_out.size(0)
-                model=model, encoder_out=encoder_out_i, beam=params.beam_size
+        for i in range(batch_size):
-            )
+            # fmt: off
-        else:
+            encoder_out_i = encoder_out[i:i+1, :encoder_out_lens[i]]
-            raise ValueError(
+            # fmt: on
-                f"Unsupported decoding method: {params.decoding_method}"
+            if params.decoding_method == "greedy_search":
-            )
+                hyp = greedy_search(
-        hyps.append(sp.decode(hyp).split())
+                    model=model,
+                    encoder_out=encoder_out_i,
+                    max_sym_per_frame=params.max_sym_per_frame,
+                )
+            elif params.decoding_method == "beam_search":
+                hyp = beam_search(
+                    model=model,
+                    encoder_out=encoder_out_i,
+                    beam=params.beam_size,
+                )
+            else:
+                raise ValueError(
+                    f"Unsupported decoding method: {params.decoding_method}"
+                )
+            hyp_list.append(hyp)
+
+    hyps = [sp.decode(hyp).split() for hyp in hyp_list]
 
     if params.decoding_method == "greedy_search":
         return {"greedy_search": hyps}
@@ -487,8 +439,5 @@ def main():
     logging.info("Done!")
 
 
-torch.set_num_threads(1)
-torch.set_num_interop_threads(1)
-
 if __name__ == "__main__":
     main()

egs/librispeech/ASR/transducer_stateless/pretrained.py

@@ -59,17 +59,15 @@ from typing import List
 import kaldifeat
 import sentencepiece as spm
 import torch
-import torch.nn as nn
 import torchaudio
-from beam_search import beam_search, greedy_search, modified_beam_search
+from beam_search import (
-from conformer import Conformer
+    beam_search,
-from decoder import Decoder
+    greedy_search,
-from joiner import Joiner
+    greedy_search_batch,
-from model import Transducer
+    modified_beam_search,
+)
 from torch.nn.utils.rnn import pad_sequence
-
+from train import get_params, get_transducer_model
-from icefall.env import get_env_info
-from icefall.utils import AttributeDict
 
 
 def get_parser():
@@ -115,6 +113,13 @@ def get_parser():
         "The sample rate has to be 16kHz.",
     )
 
+    parser.add_argument(
+        "--sample-rate",
+        type=int,
+        default=16000,
+        help="The sample rate of the input sound file",
+    )
+
     parser.add_argument(
         "--beam-size",
         type=int,
@@ -132,7 +137,7 @@ def get_parser():
     parser.add_argument(
         "--max-sym-per-frame",
         type=int,
-        default=3,
+        default=1,
         help="""Maximum number of symbols per frame. Used only when
         --method is greedy_search.
         """,
@@ -141,70 +146,6 @@ def get_parser():
     return parser
 
 
-def get_params() -> AttributeDict:
-    params = AttributeDict(
-        {
-            "sample_rate": 16000,
-            # parameters for conformer
-            "feature_dim": 80,
-            "encoder_out_dim": 512,
-            "subsampling_factor": 4,
-            "attention_dim": 512,
-            "nhead": 8,
-            "dim_feedforward": 2048,
-            "num_encoder_layers": 12,
-            "vgg_frontend": False,
-            "env_info": get_env_info(),
-        }
-    )
-    return params
-
-
-def get_encoder_model(params: AttributeDict) -> nn.Module:
-    encoder = Conformer(
-        num_features=params.feature_dim,
-        output_dim=params.encoder_out_dim,
-        subsampling_factor=params.subsampling_factor,
-        d_model=params.attention_dim,
-        nhead=params.nhead,
-        dim_feedforward=params.dim_feedforward,
-        num_encoder_layers=params.num_encoder_layers,
-        vgg_frontend=params.vgg_frontend,
-    )
-    return encoder
-
-
-def get_decoder_model(params: AttributeDict) -> nn.Module:
-    decoder = Decoder(
-        vocab_size=params.vocab_size,
-        embedding_dim=params.encoder_out_dim,
-        blank_id=params.blank_id,
-        context_size=params.context_size,
-    )
-    return decoder
-
-
-def get_joiner_model(params: AttributeDict) -> nn.Module:
-    joiner = Joiner(
-        input_dim=params.encoder_out_dim,
-        output_dim=params.vocab_size,
-    )
-    return joiner
-
-
-def get_transducer_model(params: AttributeDict) -> nn.Module:
-    encoder = get_encoder_model(params)
-    decoder = get_decoder_model(params)
-    joiner = get_joiner_model(params)
-
-    model = Transducer(
-        encoder=encoder,
-        decoder=decoder,
-        joiner=joiner,
-    )
-    return model
-
-
 def read_sound_files(
     filenames: List[str], expected_sample_rate: float
 ) -> List[torch.Tensor]:
@@ -294,33 +235,45 @@ def main():
         )
 
     num_waves = encoder_out.size(0)
-    hyps = []
+    hyp_list = []
     msg = f"Using {params.method}"
     if params.method == "beam_search":
         msg += f" with beam size {params.beam_size}"
     logging.info(msg)
-    for i in range(num_waves):
-        # fmt: off
-        encoder_out_i = encoder_out[i:i+1, :encoder_out_lens[i]]
-        # fmt: on
-        if params.method == "greedy_search":
-            hyp = greedy_search(
-                model=model,
-                encoder_out=encoder_out_i,
-                max_sym_per_frame=params.max_sym_per_frame,
-            )
-        elif params.method == "beam_search":
-            hyp = beam_search(
-                model=model, encoder_out=encoder_out_i, beam=params.beam_size
-            )
-        elif params.method == "modified_beam_search":
-            hyp = modified_beam_search(
-                model=model, encoder_out=encoder_out_i, beam=params.beam_size
-            )
-        else:
-            raise ValueError(f"Unsupported method: {params.method}")
 
-        hyps.append(sp.decode(hyp).split())
+    if params.method == "greedy_search" and params.max_sym_per_frame == 1:
+        hyp_list = greedy_search_batch(
+            model=model,
+            encoder_out=encoder_out,
+        )
+    elif params.method == "modified_beam_search":
+        hyp_list = modified_beam_search(
+            model=model,
+            encoder_out=encoder_out,
+            beam=params.beam_size,
+        )
+    else:
+        for i in range(num_waves):
+            # fmt: off
+            encoder_out_i = encoder_out[i:i+1, :encoder_out_lens[i]]
+            # fmt: on
+            if params.method == "greedy_search":
+                hyp = greedy_search(
+                    model=model,
+                    encoder_out=encoder_out_i,
+                    max_sym_per_frame=params.max_sym_per_frame,
+                )
+            elif params.method == "beam_search":
+                hyp = beam_search(
+                    model=model,
+                    encoder_out=encoder_out_i,
+                    beam=params.beam_size,
+                )
+            else:
+                raise ValueError(f"Unsupported method: {params.method}")
+            hyp_list.append(hyp)
+
+    hyps = [sp.decode(hyp).split() for hyp in hyp_list]
 
     s = "\n"
     for filename, hyp in zip(params.sound_files, hyps):

egs/librispeech/ASR/transducer_stateless/train.py

@@ -34,6 +34,7 @@ export CUDA_VISIBLE_DEVICES="0,1,2,3"
 
 import argparse
 import logging
+import warnings
 from pathlib import Path
 from shutil import copyfile
 from typing import Optional, Tuple
@@ -419,7 +420,11 @@ def compute_loss(
     assert loss.requires_grad == is_training
 
     info = MetricsTracker()
-    info["frames"] = (feature_lens // params.subsampling_factor).sum().item()
+    with warnings.catch_warnings():
+        warnings.simplefilter("ignore")
+        info["frames"] = (
+            (feature_lens // params.subsampling_factor).sum().item()
+        )
 
     # Note: We use reduction=sum while computing the loss.
     info["loss"] = loss.detach().cpu().item()

egs/librispeech/ASR/transducer_stateless_multi_datasets/asr_datamodule.py

@@ -22,6 +22,7 @@ import logging
 from pathlib import Path
 from typing import Optional
 
+import torch
 from lhotse import CutSet, Fbank, FbankConfig
 from lhotse.dataset import (
     BucketingSampler,
@@ -34,11 +35,20 @@ from lhotse.dataset.input_strategies import (
     OnTheFlyFeatures,
     PrecomputedFeatures,
 )
+from lhotse.utils import fix_random_seed
 from torch.utils.data import DataLoader
 
 from icefall.utils import str2bool
 
 
+class _SeedWorkers:
+    def __init__(self, seed: int):
+        self.seed = seed
+
+    def __call__(self, worker_id: int):
+        fix_random_seed(self.seed + worker_id)
+
+
 class AsrDataModule:
     def __init__(self, args: argparse.Namespace):
         self.args = args
@@ -253,12 +263,19 @@ class AsrDataModule:
             )
 
         logging.info("About to create train dataloader")
+
+        # 'seed' is derived from the current random state, which will have
+        # previously been set in the main process.
+        seed = torch.randint(0, 100000, ()).item()
+        worker_init_fn = _SeedWorkers(seed)
+
         train_dl = DataLoader(
             train,
             sampler=train_sampler,
             batch_size=None,
             num_workers=self.args.num_workers,
             persistent_workers=False,
+            worker_init_fn=worker_init_fn,
         )
         return train_dl
 

egs/librispeech/ASR/transducer_stateless_multi_datasets/decode.py

@@ -46,15 +46,16 @@ import sentencepiece as spm
 import torch
 import torch.nn as nn
 from asr_datamodule import AsrDataModule
-from beam_search import beam_search, greedy_search, modified_beam_search
+from beam_search import (
-from conformer import Conformer
+    beam_search,
-from decoder import Decoder
+    greedy_search,
-from joiner import Joiner
+    greedy_search_batch,
+    modified_beam_search,
+)
 from librispeech import LibriSpeech
-from model import Transducer
+from train import get_params, get_transducer_model
 
 from icefall.checkpoint import average_checkpoints, load_checkpoint
-from icefall.env import get_env_info
 from icefall.utils import (
     AttributeDict,
     setup_logger,
@@ -127,7 +128,7 @@ def get_parser():
     parser.add_argument(
         "--max-sym-per-frame",
         type=int,
-        default=3,
+        default=1,
         help="""Maximum number of symbols per frame.
         Used only when --decoding_method is greedy_search""",
     )
@@ -135,71 +136,6 @@ def get_parser():
     return parser
 
 
-def get_params() -> AttributeDict:
-    params = AttributeDict(
-        {
-            # parameters for conformer
-            "feature_dim": 80,
-            "encoder_out_dim": 512,
-            "subsampling_factor": 4,
-            "attention_dim": 512,
-            "nhead": 8,
-            "dim_feedforward": 2048,
-            "num_encoder_layers": 12,
-            "vgg_frontend": False,
-            "env_info": get_env_info(),
-        }
-    )
-    return params
-
-
-def get_encoder_model(params: AttributeDict):
-    # TODO: We can add an option to switch between Conformer and Transformer
-    encoder = Conformer(
-        num_features=params.feature_dim,
-        output_dim=params.encoder_out_dim,
-        subsampling_factor=params.subsampling_factor,
-        d_model=params.attention_dim,
-        nhead=params.nhead,
-        dim_feedforward=params.dim_feedforward,
-        num_encoder_layers=params.num_encoder_layers,
-        vgg_frontend=params.vgg_frontend,
-    )
-    return encoder
-
-
-def get_decoder_model(params: AttributeDict):
-    decoder = Decoder(
-        vocab_size=params.vocab_size,
-        embedding_dim=params.encoder_out_dim,
-        blank_id=params.blank_id,
-        context_size=params.context_size,
-    )
-    return decoder
-
-
-def get_joiner_model(params: AttributeDict):
-    joiner = Joiner(
-        input_dim=params.encoder_out_dim,
-        output_dim=params.vocab_size,
-    )
-    return joiner
-
-
-def get_transducer_model(params: AttributeDict):
-    encoder = get_encoder_model(params)
-    decoder = get_decoder_model(params)
-    joiner = get_joiner_model(params)
-
-    model = Transducer(
-        encoder=encoder,
-        decoder=decoder,
-        joiner=joiner,
-    )
-
-    return model
-
-
 def decode_one_batch(
     params: AttributeDict,
     model: nn.Module,
@@ -244,32 +180,47 @@ def decode_one_batch(
     encoder_out, encoder_out_lens = model.encoder(
         x=feature, x_lens=feature_lens
     )
-    hyps = []
+    hyp_list = []
     batch_size = encoder_out.size(0)
 
-    for i in range(batch_size):
+    if (
-        # fmt: off
+        params.decoding_method == "greedy_search"
-        encoder_out_i = encoder_out[i:i+1, :encoder_out_lens[i]]
+        and params.max_sym_per_frame == 1
-        # fmt: on
+    ):
-        if params.decoding_method == "greedy_search":
+        hyp_list = greedy_search_batch(
-            hyp = greedy_search(
+            model=model,
-                model=model,
+            encoder_out=encoder_out,
-                encoder_out=encoder_out_i,
+        )
-                max_sym_per_frame=params.max_sym_per_frame,
+    elif params.decoding_method == "modified_beam_search":
-            )
+        hyp_list = modified_beam_search(
-        elif params.decoding_method == "beam_search":
+            model=model,
-            hyp = beam_search(
+            encoder_out=encoder_out,
-                model=model, encoder_out=encoder_out_i, beam=params.beam_size
+            beam=params.beam_size,
-            )
+        )
-        elif params.decoding_method == "modified_beam_search":
+    else:
-            hyp = modified_beam_search(
+        for i in range(batch_size):
-                model=model, encoder_out=encoder_out_i, beam=params.beam_size
+            # fmt: off
-            )
+            encoder_out_i = encoder_out[i:i+1, :encoder_out_lens[i]]
-        else:
+            # fmt: on
-            raise ValueError(
+            if params.decoding_method == "greedy_search":
-                f"Unsupported decoding method: {params.decoding_method}"
+                hyp = greedy_search(
-            )
+                    model=model,
-        hyps.append(sp.decode(hyp).split())
+                    encoder_out=encoder_out_i,
+                    max_sym_per_frame=params.max_sym_per_frame,
+                )
+            elif params.decoding_method == "beam_search":
+                hyp = beam_search(
+                    model=model,
+                    encoder_out=encoder_out_i,
+                    beam=params.beam_size,
+                )
+            else:
+                raise ValueError(
+                    f"Unsupported decoding method: {params.decoding_method}"
+                )
+            hyp_list.append(sp.decode(hyp).split())
+
+    hyps = [sp.decode(hyp).split() for hyp in hyp_list]
 
     if params.decoding_method == "greedy_search":
         return {"greedy_search": hyps}
@@ -483,8 +434,5 @@ def main():
     logging.info("Done!")
 
 
-torch.set_num_threads(1)
-torch.set_num_interop_threads(1)
-
 if __name__ == "__main__":
     main()

egs/librispeech/ASR/transducer_stateless_multi_datasets/pretrained.py

@@ -59,17 +59,15 @@ from typing import List
 import kaldifeat
 import sentencepiece as spm
 import torch
-import torch.nn as nn
 import torchaudio
-from beam_search import beam_search, greedy_search, modified_beam_search
+from beam_search import (
-from conformer import Conformer
+    beam_search,
-from decoder import Decoder
+    greedy_search,
-from joiner import Joiner
+    greedy_search_batch,
-from model import Transducer
+    modified_beam_search,
+)
 from torch.nn.utils.rnn import pad_sequence
-
+from train import get_params, get_transducer_model
-from icefall.env import get_env_info
-from icefall.utils import AttributeDict
 
 
 def get_parser():
@@ -115,6 +113,13 @@ def get_parser():
         "The sample rate has to be 16kHz.",
     )
 
+    parser.add_argument(
+        "--sample-rate",
+        type=int,
+        default=16000,
+        help="The sample rate of the input sound file",
+    )
+
     parser.add_argument(
         "--beam-size",
         type=int,
@@ -132,7 +137,7 @@ def get_parser():
     parser.add_argument(
         "--max-sym-per-frame",
         type=int,
-        default=3,
+        default=1,
         help="""Maximum number of symbols per frame. Used only when
         --method is greedy_search.
         """,
@@ -141,70 +146,6 @@ def get_parser():
     return parser
 
 
-def get_params() -> AttributeDict:
-    params = AttributeDict(
-        {
-            "sample_rate": 16000,
-            # parameters for conformer
-            "feature_dim": 80,
-            "encoder_out_dim": 512,
-            "subsampling_factor": 4,
-            "attention_dim": 512,
-            "nhead": 8,
-            "dim_feedforward": 2048,
-            "num_encoder_layers": 12,
-            "vgg_frontend": False,
-            "env_info": get_env_info(),
-        }
-    )
-    return params
-
-
-def get_encoder_model(params: AttributeDict) -> nn.Module:
-    encoder = Conformer(
-        num_features=params.feature_dim,
-        output_dim=params.encoder_out_dim,
-        subsampling_factor=params.subsampling_factor,
-        d_model=params.attention_dim,
-        nhead=params.nhead,
-        dim_feedforward=params.dim_feedforward,
-        num_encoder_layers=params.num_encoder_layers,
-        vgg_frontend=params.vgg_frontend,
-    )
-    return encoder
-
-
-def get_decoder_model(params: AttributeDict) -> nn.Module:
-    decoder = Decoder(
-        vocab_size=params.vocab_size,
-        embedding_dim=params.encoder_out_dim,
-        blank_id=params.blank_id,
-        context_size=params.context_size,
-    )
-    return decoder
-
-
-def get_joiner_model(params: AttributeDict) -> nn.Module:
-    joiner = Joiner(
-        input_dim=params.encoder_out_dim,
-        output_dim=params.vocab_size,
-    )
-    return joiner
-
-
-def get_transducer_model(params: AttributeDict) -> nn.Module:
-    encoder = get_encoder_model(params)
-    decoder = get_decoder_model(params)
-    joiner = get_joiner_model(params)
-
-    model = Transducer(
-        encoder=encoder,
-        decoder=decoder,
-        joiner=joiner,
-    )
-    return model
-
-
 def read_sound_files(
     filenames: List[str], expected_sample_rate: float
 ) -> List[torch.Tensor]:
@@ -294,33 +235,46 @@ def main():
         )
 
     num_waves = encoder_out.size(0)
-    hyps = []
+    hyp_list = []
     msg = f"Using {params.method}"
     if params.method == "beam_search":
         msg += f" with beam size {params.beam_size}"
     logging.info(msg)
-    for i in range(num_waves):
-        # fmt: off
-        encoder_out_i = encoder_out[i:i+1, :encoder_out_lens[i]]
-        # fmt: on
-        if params.method == "greedy_search":
-            hyp = greedy_search(
-                model=model,
-                encoder_out=encoder_out_i,
-                max_sym_per_frame=params.max_sym_per_frame,
-            )
-        elif params.method == "beam_search":
-            hyp = beam_search(
-                model=model, encoder_out=encoder_out_i, beam=params.beam_size
-            )
-        elif params.method == "modified_beam_search":
-            hyp = modified_beam_search(
-                model=model, encoder_out=encoder_out_i, beam=params.beam_size
-            )
-        else:
-            raise ValueError(f"Unsupported method: {params.method}")
 
-        hyps.append(sp.decode(hyp).split())
+    if params.method == "greedy_search" and params.max_sym_per_frame == 1:
+        hyp_list = greedy_search_batch(
+            model=model,
+            encoder_out=encoder_out,
+        )
+    elif params.method == "modified_beam_search":
+        hyp_list = modified_beam_search(
+            model=model,
+            encoder_out=encoder_out,
+            beam=params.beam_size,
+        )
+
+    else:
+        for i in range(num_waves):
+            # fmt: off
+            encoder_out_i = encoder_out[i:i+1, :encoder_out_lens[i]]
+            # fmt: on
+            if params.method == "greedy_search":
+                hyp = greedy_search(
+                    model=model,
+                    encoder_out=encoder_out_i,
+                    max_sym_per_frame=params.max_sym_per_frame,
+                )
+            elif params.method == "beam_search":
+                hyp = beam_search(
+                    model=model,
+                    encoder_out=encoder_out_i,
+                    beam=params.beam_size,
+                )
+            else:
+                raise ValueError(f"Unsupported method: {params.method}")
+            hyp_list.append(hyp)
+
+    hyps = [sp.decode(hyp).split() for hyp in hyp_list]
 
     s = "\n"
     for filename, hyp in zip(params.sound_files, hyps):

egs/librispeech/ASR/transducer_stateless_multi_datasets/train.py

@@ -58,6 +58,7 @@ export CUDA_VISIBLE_DEVICES="0,1,2,3"
 import argparse
 import logging
 import random
+import warnings
 from pathlib import Path
 from shutil import copyfile
 from typing import Optional, Tuple
@@ -466,7 +467,11 @@ def compute_loss(
     assert loss.requires_grad == is_training
 
     info = MetricsTracker()
-    info["frames"] = (feature_lens // params.subsampling_factor).sum().item()
+    with warnings.catch_warnings():
+        warnings.simplefilter("ignore")
+        info["frames"] = (
+            (feature_lens // params.subsampling_factor).sum().item()
+        )
 
     # Note: We use reduction=sum while computing the loss.
     info["loss"] = loss.detach().cpu().item()

icefall/__init__.py

@@ -0,0 +1,55 @@
+from .checkpoint import (
+    average_checkpoints,
+    find_checkpoints,
+    load_checkpoint,
+    remove_checkpoints,
+    save_checkpoint,
+    save_checkpoint_with_global_batch_idx,
+)
+
+from .decode import (
+    get_lattice,
+    nbest_decoding,
+    nbest_oracle,
+    one_best_decoding,
+    rescore_with_attention_decoder,
+    rescore_with_n_best_list,
+    rescore_with_whole_lattice,
+)
+
+from .dist import (
+    cleanup_dist,
+    setup_dist,
+)
+
+from .env import (
+    get_env_info,
+    get_git_branch_name,
+    get_git_date,
+    get_git_sha1,
+)
+
+from .utils import (
+    AttributeDict,
+    MetricsTracker,
+    add_eos,
+    add_sos,
+    concat,
+    encode_supervisions,
+    get_alignments,
+    get_executor,
+    get_texts,
+    l1_norm,
+    l2_norm,
+    linf_norm,
+    load_alignments,
+    make_pad_mask,
+    measure_gradient_norms,
+    measure_weight_norms,
+    optim_step_and_measure_param_change,
+    save_alignments,
+    setup_logger,
+    store_transcripts,
+    str2bool,
+    write_error_stats,
+)

icefall/checkpoint.py

@@ -216,27 +216,62 @@ def save_checkpoint_with_global_batch_idx(
     )
 
 
-def find_checkpoints(out_dir: Path) -> List[str]:
+def find_checkpoints(out_dir: Path, iteration: int = 0) -> List[str]:
     """Find all available checkpoints in a directory.
 
     The checkpoint filenames have the form: `checkpoint-xxx.pt`
     where xxx is a numerical value.
 
+    Assume you have the following checkpoints in the folder `foo`:
+
+        - checkpoint-1.pt
+        - checkpoint-20.pt
+        - checkpoint-300.pt
+        - checkpoint-4000.pt
+
+    Case 1 (Return all checkpoints)::
+
+      find_checkpoints(out_dir='foo')
+
+    Case 2 (Return checkpoints newer than checkpoint-20.pt, i.e.,
+    checkpoint-4000.pt, checkpoint-300.pt, and checkpoint-20.pt)
+
+        find_checkpoints(out_dir='foo', iteration=20)
+
+    Case 3 (Return checkpoints older than checkpoint-20.pt, i.e.,
+    checkpoint-20.pt, checkpoint-1.pt)::
+
+        find_checkpoints(out_dir='foo', iteration=-20)
+
     Args:
       out_dir:
         The directory where to search for checkpoints.
+      iteration:
+        If it is 0, return all available checkpoints.
+        If it is positive, return the checkpoints whose iteration number is
+        greater than or equal to `iteration`.
+        If it is negative, return the checkpoints whose iteration number is
+        less than or equal to `-iteration`.
     Returns:
       Return a list of checkpoint filenames, sorted in descending
       order by the numerical value in the filename.
     """
     checkpoints = list(glob.glob(f"{out_dir}/checkpoint-[0-9]*.pt"))
     pattern = re.compile(r"checkpoint-([0-9]+).pt")
-    idx_checkpoints = [
+    iter_checkpoints = [
         (int(pattern.search(c).group(1)), c) for c in checkpoints
     ]
+    # iter_checkpoints is a list of tuples. Each tuple contains
+    # two elements: (iteration_number, checkpoint-iteration_number.pt)
+
+    iter_checkpoints = sorted(
+        iter_checkpoints, reverse=True, key=lambda x: x[0]
+    )
+    if iteration >= 0:
+        ans = [ic[1] for ic in iter_checkpoints if ic[0] >= iteration]
+    else:
+        ans = [ic[1] for ic in iter_checkpoints if ic[0] <= -iteration]
 
-    idx_checkpoints = sorted(idx_checkpoints, reverse=True, key=lambda x: x[0])
-    ans = [ic[1] for ic in idx_checkpoints]
     return ans
 
 

icefall/diagnostics.py

@@ -135,8 +135,13 @@ def get_diagnostics_for_dim(
             return ""
         count = sum(counts)
         stats = stats / count
-        stats, _ = torch.symeig(stats)
+        try:
-        stats = stats.abs().sqrt()
+            eigs, _ = torch.symeig(stats)
+            stats = eigs.abs().sqrt()
+        except:  # noqa
+            print("Error getting eigenvalues, trying another method.")
+            eigs = torch.linalg.eigvals(stats)
+            stats = eigs.abs().sqrt()
         # sqrt so it reflects data magnitude, like stddev- not variance
     elif sizes_same:
         stats = torch.stack(stats).sum(dim=0)

pyproject.toml

@@ -1,5 +1,6 @@
 [tool.isort]
 profile = "black"
+skip = ["icefall/__init__.py"]
 
 [tool.black]
 line-length = 80

requirements-ci.txt

@@ -11,7 +11,7 @@ graphviz==0.19.1
 -f https://download.pytorch.org/whl/cpu/torch_stable.html torch==1.10.0+cpu
 -f https://download.pytorch.org/whl/cpu/torch_stable.html torchaudio==0.10.0+cpu
 
--f https://k2-fsa.org/nightly/ k2==1.9.dev20211101+cpu.torch1.10.0
+-f https://k2-fsa.org/nightly/ k2==1.14.dev20220316+cpu.torch1.10.0
 
 git+https://github.com/lhotse-speech/lhotse
 kaldilm==1.11