Support batch-wise forced-alignment (#970)

* support batch-wise forced-alignment based on beam search

* add length_norm to HypothesisList.topk()

* Use Hypothesis and HypothesisList instead

egs/librispeech/ASR/pruned_transducer_stateless2/beam_search.py

@@ -829,11 +829,22 @@ class HypothesisList(object):
                 ans.add(hyp)  # shallow copy
         return ans
 
-    def topk(self, k: int) -> "HypothesisList":
+    def topk(self, k: int, length_norm: bool = False) -> "HypothesisList":
-        """Return the top-k hypothesis."""
+        """Return the top-k hypothesis.
+
+        Args:
+          length_norm:
+            If True, the `log_prob` of a hypothesis is normalized by the
+            number of tokens in it.
+        """
         hyps = list(self._data.items())
 
-        hyps = sorted(hyps, key=lambda h: h[1].log_prob, reverse=True)[:k]
+        if length_norm:
+            hyps = sorted(
+                hyps, key=lambda h: h[1].log_prob / len(h[1].ys), reverse=True
+            )[:k]
+        else:
+            hyps = sorted(hyps, key=lambda h: h[1].log_prob, reverse=True)[:k]
 
         ans = HypothesisList(dict(hyps))
         return ans

egs/librispeech/ASR/pruned_transducer_stateless7/alignment.py

@@ -0,0 +1,206 @@
+# Copyright    2022-2023  Xiaomi Corp.        (authors: Fangjun Kuang,
+#                                                       Zengwei Yao)
+#
+# See ../../../../LICENSE for clarification regarding multiple authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+from typing import List
+
+import k2
+import torch
+
+from beam_search import Hypothesis, HypothesisList, get_hyps_shape
+
+# The force alignment problem can be formulated as finding
+# a path in a rectangular lattice, where the path starts
+# from the lower left corner and ends at the upper right
+# corner. The horizontal axis of the lattice is `t` (representing
+# acoustic frame indexes) and the vertical axis is `u` (representing
+# BPE tokens of the transcript).
+#
+# The notations `t` and `u` are from the paper
+# https://arxiv.org/pdf/1211.3711.pdf
+#
+# Beam search is used to find the path with the highest log probabilities.
+#
+# It assumes the maximum number of symbols that can be
+# emitted per frame is 1.
+
+
+def batch_force_alignment(
+    model: torch.nn.Module,
+    encoder_out: torch.Tensor,
+    encoder_out_lens: torch.Tensor,
+    ys_list: List[List[int]],
+    beam_size: int = 4,
+) -> List[int]:
+    """Compute the force alignment of a batch of utterances given their transcripts
+    in BPE tokens and the corresponding acoustic output from the encoder.
+
+    Caution:
+      This function is modified from `modified_beam_search` in beam_search.py.
+      We assume that the maximum number of sybmols per frame is 1.
+
+    Args:
+      model:
+        The transducer model.
+      encoder_out:
+        A tensor of shape (N, T, C).
+      encoder_out_lens:
+        A 1-D tensor of shape (N,), containing number of valid frames in
+        encoder_out before padding.
+      ys_list:
+        A list of BPE token IDs list. We require that for each utterance i,
+        len(ys_list[i]) <= encoder_out_lens[i].
+      beam_size:
+        Size of the beam used in beam search.
+
+    Returns:
+      Return a list of frame indexes list for each utterance i,
+      where len(ans[i]) == len(ys_list[i]).
+    """
+    assert encoder_out.ndim == 3, encoder_out.ndim
+    assert encoder_out.size(0) == len(ys_list), (encoder_out.size(0), len(ys_list))
+    assert encoder_out.size(0) > 0, encoder_out.size(0)
+
+    blank_id = model.decoder.blank_id
+    context_size = model.decoder.context_size
+    device = next(model.parameters()).device
+
+    packed_encoder_out = torch.nn.utils.rnn.pack_padded_sequence(
+        input=encoder_out,
+        lengths=encoder_out_lens.cpu(),
+        batch_first=True,
+        enforce_sorted=False,
+    )
+    batch_size_list = packed_encoder_out.batch_sizes.tolist()
+    N = encoder_out.size(0)
+    assert torch.all(encoder_out_lens > 0), encoder_out_lens
+    assert N == batch_size_list[0], (N, batch_size_list)
+
+    sorted_indices = packed_encoder_out.sorted_indices.tolist()
+    encoder_out_lens = encoder_out_lens.tolist()
+    ys_lens = [len(ys) for ys in ys_list]
+    sorted_encoder_out_lens = [encoder_out_lens[i] for i in sorted_indices]
+    sorted_ys_lens = [ys_lens[i] for i in sorted_indices]
+    sorted_ys_list = [ys_list[i] for i in sorted_indices]
+
+    B = [HypothesisList() for _ in range(N)]
+    for i in range(N):
+        B[i].add(
+            Hypothesis(
+                ys=[blank_id] * context_size,
+                log_prob=torch.zeros(1, dtype=torch.float32, device=device),
+                timestamp=[],
+            )
+        )
+
+    encoder_out = model.joiner.encoder_proj(packed_encoder_out.data)
+
+    offset = 0
+    finalized_B = []
+    for (t, batch_size) in enumerate(batch_size_list):
+        start = offset
+        end = offset + batch_size
+        current_encoder_out = encoder_out.data[start:end]
+        current_encoder_out = current_encoder_out.unsqueeze(1).unsqueeze(1)
+        # current_encoder_out's shape is (batch_size, 1, 1, encoder_out_dim)
+        offset = end
+
+        finalized_B = B[batch_size:] + finalized_B
+        B = B[:batch_size]
+        sorted_encoder_out_lens = sorted_encoder_out_lens[:batch_size]
+        sorted_ys_lens = sorted_ys_lens[:batch_size]
+
+        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_out = model.joiner.decoder_proj(decoder_out)
+        # decoder_out is of shape (num_hyps, 1, 1, joiner_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, project_input=False
+        )  # (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)
+
+        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.reshape(-1)
+        )  # [batch][num_hyps*vocab_size]
+
+        for i in range(batch_size):
+            for h, hyp in enumerate(A[i]):
+                pos_u = len(hyp.timestamp)
+                idx_offset = h * vocab_size
+                if (sorted_encoder_out_lens[i] - 1 - t) >= (sorted_ys_lens[i] - pos_u):
+                    # emit blank token
+                    new_hyp = Hypothesis(
+                        log_prob=ragged_log_probs[i][idx_offset + blank_id],
+                        ys=hyp.ys[:],
+                        timestamp=hyp.timestamp[:],
+                    )
+                    B[i].add(new_hyp)
+                if pos_u < sorted_ys_lens[i]:
+                    # emit non-blank token
+                    new_token = sorted_ys_list[i][pos_u]
+                    new_hyp = Hypothesis(
+                        log_prob=ragged_log_probs[i][idx_offset + new_token],
+                        ys=hyp.ys + [new_token],
+                        timestamp=hyp.timestamp + [t],
+                    )
+                    B[i].add(new_hyp)
+
+            if len(B[i]) > beam_size:
+                B[i] = B[i].topk(beam_size, length_norm=True)
+
+    B = B + finalized_B
+    sorted_hyps = [b.get_most_probable() for b in B]
+    unsorted_indices = packed_encoder_out.unsorted_indices.tolist()
+    hyps = [sorted_hyps[i] for i in unsorted_indices]
+    ans = []
+    for i, hyp in enumerate(hyps):
+        assert hyp.ys[context_size:] == ys_list[i], (hyp.ys[context_size:], ys_list[i])
+        ans.append(hyp.timestamp)
+
+    return ans

egs/librispeech/ASR/pruned_transducer_stateless7/compute_ali.py

@@ -0,0 +1,345 @@
+#!/usr/bin/env python3
+#
+# Copyright 2021-2023 Xiaomi Corporation (Author: Fangjun Kuang,
+#                                                 Zengwei Yao,
+#                                                 Xiaoyu Yang)
+#
+# See ../../../../LICENSE for clarification regarding multiple authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""
+The script gets forced-alignments based on the modified_beam_search decoding method.
+Both token-level alignments and word-level alignments are saved to the new cuts manifests.
+
+It loads a checkpoint and uses it to get the forced-alignments.
+You can generate the checkpoint with the following command:
+
+./pruned_transducer_stateless7/export.py \
+  --exp-dir ./pruned_transducer_stateless7/exp \
+  --bpe-model data/lang_bpe_500/bpe.model \
+  --epoch 30 \
+  --avg 9
+
+Usage of this script:
+
+./pruned_transducer_stateless7/compute_ali.py \
+    --checkpoint ./pruned_transducer_stateless7/exp/pretrained.pt \
+    --bpe-model data/lang_bpe_500/bpe.model \
+    --dataset test-clean \
+    --max-duration 300 \
+    --beam-size 4 \
+    --cuts-out-dir data/fbank_ali_beam_search
+"""
+
+
+import argparse
+import logging
+from pathlib import Path
+from typing import List, Tuple
+
+import sentencepiece as spm
+import torch
+import torch.nn as nn
+from alignment import batch_force_alignment
+from asr_datamodule import LibriSpeechAsrDataModule
+from train import add_model_arguments, get_params, get_transducer_model
+
+from icefall.utils import AttributeDict, convert_timestamp, parse_timestamp
+from lhotse import CutSet
+from lhotse.serialization import SequentialJsonlWriter
+from lhotse.supervision import AlignmentItem
+
+
+def get_parser():
+    parser = argparse.ArgumentParser(
+        formatter_class=argparse.ArgumentDefaultsHelpFormatter
+    )
+
+    parser.add_argument(
+        "--checkpoint",
+        type=str,
+        required=True,
+        help="Path to the checkpoint. "
+        "The checkpoint is assumed to be saved by "
+        "icefall.checkpoint.save_checkpoint().",
+    )
+
+    parser.add_argument(
+        "--bpe-model",
+        type=str,
+        default="data/lang_bpe_500/bpe.model",
+        help="Path to the BPE model",
+    )
+
+    parser.add_argument(
+        "--dataset",
+        type=str,
+        required=True,
+        help="""The name of the dataset to compute alignments for.
+        Possible values are:
+        - test-clean
+        - test-other
+        - train-clean-100
+        - train-clean-360
+        - train-other-500
+        - dev-clean
+        - dev-other
+        """,
+    )
+
+    parser.add_argument(
+        "--beam-size",
+        type=int,
+        default=4,
+        help="""An integer 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(
+        "--context-size",
+        type=int,
+        default=2,
+        help="The context size in the decoder. 1 means bigram; 2 means tri-gram",
+    )
+
+    parser.add_argument(
+        "--cuts-out-dir",
+        type=str,
+        default="data/fbank_ali_beam_search",
+        help="The dir to save the new cuts manifests with alignments",
+    )
+
+    add_model_arguments(parser)
+
+    return parser
+
+
+def align_one_batch(
+    params: AttributeDict,
+    model: nn.Module,
+    sp: spm.SentencePieceProcessor,
+    batch: dict,
+) -> Tuple[List[List[str]], List[List[str]], List[List[float]], List[List[float]]]:
+    """Get forced-alignments for one batch.
+
+    Args:
+      params:
+        It's the return value of :func:`get_params`.
+      model:
+        The neural model.
+      sp:
+        The BPE model.
+      batch:
+        It is the return value from iterating
+        `lhotse.dataset.K2SpeechRecognitionDataset`. See its documentation
+        for the format of the `batch`.
+
+    Returns:
+      token_list:
+        A list of token list.
+      word_list:
+        A list of word list.
+      token_time_list:
+        A list of timestamps list for tokens.
+      word_time_list.
+        A list of timestamps list for words.
+
+      where len(token_list) == len(word_list) == len(token_time_list) == len(word_time_list),
+      len(token_list[i]) == len(token_time_list[i]),
+      and len(word_list[i]) == len(word_time_list[i])
+
+    """
+    device = next(model.parameters()).device
+    feature = batch["inputs"]
+    assert feature.ndim == 3
+
+    feature = feature.to(device)
+    # at entry, feature is (N, T, C)
+
+    supervisions = batch["supervisions"]
+    feature_lens = supervisions["num_frames"].to(device)
+
+    encoder_out, encoder_out_lens = model.encoder(x=feature, x_lens=feature_lens)
+
+    texts = supervisions["text"]
+    ys_list: List[List[int]] = sp.encode(texts, out_type=int)
+
+    frame_indexes = batch_force_alignment(
+        model, encoder_out, encoder_out_lens, ys_list, params.beam_size
+    )
+
+    token_list = []
+    word_list = []
+    token_time_list = []
+    word_time_list = []
+    for i in range(encoder_out.size(0)):
+        tokens = sp.id_to_piece(ys_list[i])
+        words = texts[i].split()
+        token_time = convert_timestamp(
+            frame_indexes[i], params.subsampling_factor, params.frame_shift_ms
+        )
+        word_time = parse_timestamp(tokens, token_time)
+        assert len(word_time) == len(words), (len(word_time), len(words))
+
+        token_list.append(tokens)
+        word_list.append(words)
+        token_time_list.append(token_time)
+        word_time_list.append(word_time)
+
+    return token_list, word_list, token_time_list, word_time_list
+
+
+def align_dataset(
+    dl: torch.utils.data.DataLoader,
+    params: AttributeDict,
+    model: nn.Module,
+    sp: spm.SentencePieceProcessor,
+    writer: SequentialJsonlWriter,
+) -> None:
+    """Get forced-alignments for the dataset.
+
+    Args:
+      dl:
+        PyTorch's dataloader containing the dataset to decode.
+      params:
+        It is returned by :func:`get_params`.
+      model:
+        The neural model.
+      sp:
+        The BPE model.
+      writer:
+        Writer to save the cuts with alignments.
+    """
+    log_interval = 20
+    num_cuts = 0
+
+    try:
+        num_batches = len(dl)
+    except TypeError:
+        num_batches = "?"
+
+    for batch_idx, batch in enumerate(dl):
+        token_list, word_list, token_time_list, word_time_list = align_one_batch(
+            params=params, model=model, sp=sp, batch=batch
+        )
+
+        cut_list = batch["supervisions"]["cut"]
+        for cut, token, word, token_time, word_time in zip(
+            cut_list, token_list, word_list, token_time_list, word_time_list
+        ):
+            assert len(cut.supervisions) == 1, f"{len(cut.supervisions)}"
+            token_ali = [
+                AlignmentItem(
+                    symbol=token[i],
+                    start=round(token_time[i], ndigits=3),
+                    duration=None,
+                )
+                for i in range(len(token))
+            ]
+            word_ali = [
+                AlignmentItem(
+                    symbol=word[i], start=round(word_time[i], ndigits=3), duration=None
+                )
+                for i in range(len(word))
+            ]
+            cut.supervisions[0].alignment = {"word": word_ali, "token": token_ali}
+            writer.write(cut, flush=True)
+
+        num_cuts += len(cut_list)
+        if batch_idx % log_interval == 0:
+            batch_str = f"{batch_idx}/{num_batches}"
+            logging.info(f"batch {batch_str}, cuts processed until now is {num_cuts}")
+
+
+@torch.no_grad()
+def main():
+    parser = get_parser()
+    LibriSpeechAsrDataModule.add_arguments(parser)
+    args = parser.parse_args()
+
+    params = get_params()
+    params.update(vars(args))
+
+    device = torch.device("cpu")
+    if torch.cuda.is_available():
+        device = torch.device("cuda", 0)
+
+    logging.info(f"Device: {device}")
+
+    sp = spm.SentencePieceProcessor()
+    sp.load(params.bpe_model)
+
+    # <blk> and <unk> are defined in local/train_bpe_model.py
+    params.blank_id = sp.piece_to_id("<blk>")
+    params.vocab_size = sp.get_piece_size()
+
+    logging.info(params)
+
+    logging.info("About to create model")
+    model = get_transducer_model(params)
+
+    checkpoint = torch.load(args.checkpoint, map_location="cpu")
+    model.load_state_dict(checkpoint["model"], strict=False)
+    model.to(device)
+    model.eval()
+
+    num_param = sum([p.numel() for p in model.parameters()])
+    logging.info(f"Number of model parameters: {num_param}")
+
+    # we need cut ids to display recognition results.
+    args.return_cuts = True
+    librispeech = LibriSpeechAsrDataModule(args)
+
+    if params.dataset == "test-clean":
+        test_clean_cuts = librispeech.test_clean_cuts()
+        dl = librispeech.test_dataloaders(test_clean_cuts)
+    elif params.dataset == "test-other":
+        test_other_cuts = librispeech.test_other_cuts()
+        dl = librispeech.test_dataloaders(test_other_cuts)
+    elif params.dataset == "train-clean-100":
+        train_clean_100_cuts = librispeech.train_clean_100_cuts()
+        dl = librispeech.train_dataloaders(train_clean_100_cuts)
+    elif params.dataset == "train-clean-360":
+        train_clean_360_cuts = librispeech.train_clean_360_cuts()
+        dl = librispeech.train_dataloaders(train_clean_360_cuts)
+    elif params.dataset == "train-other-500":
+        train_other_500_cuts = librispeech.train_other_500_cuts()
+        dl = librispeech.train_dataloaders(train_other_500_cuts)
+    elif params.dataset == "dev-clean":
+        dev_clean_cuts = librispeech.dev_clean_cuts()
+        dl = librispeech.valid_dataloaders(dev_clean_cuts)
+    else:
+        assert params.dataset == "dev-other", f"{params.dataset}"
+        dev_other_cuts = librispeech.dev_other_cuts()
+        dl = librispeech.valid_dataloaders(dev_other_cuts)
+
+    cuts_out_dir = Path(params.cuts_out_dir)
+    cuts_out_dir.mkdir(parents=True, exist_ok=True)
+    cuts_out_path = cuts_out_dir / f"librispeech_cuts_{params.dataset}.jsonl.gz"
+
+    with CutSet.open_writer(cuts_out_path) as writer:
+        align_dataset(dl=dl, params=params, model=model, sp=sp, writer=writer)
+
+    logging.info(
+        f"For dataset {params.dataset}, the cut manifest with framewise token alignments "
+        f"and word alignments are saved to {cuts_out_path}"
+    )
+    logging.info("Done!")
+
+
+if __name__ == "__main__":
+    formatter = "%(asctime)s %(levelname)s [%(filename)s:%(lineno)d] %(message)s"
+
+    logging.basicConfig(format=formatter, level=logging.INFO)
+    main()

egs/librispeech/ASR/pruned_transducer_stateless7/test_compute_ali.py

@@ -0,0 +1,130 @@
+#!/usr/bin/env python3
+#
+# Copyright 2021-2023 Xiaomi Corporation (Author: Fangjun Kuang,
+#                                                 Zengwei Yao)
+#
+# See ../../../../LICENSE for clarification regarding multiple authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+"""
+This script compares the word-level alignments generated based on modified_beam_search decoding
+(in ./pruned_transducer_stateless7/compute_ali.py) to the reference alignments generated
+by torchaudio framework (in ./add_alignments.sh).
+
+Usage:
+
+./pruned_transducer_stateless7/compute_ali.py \
+    --checkpoint ./pruned_transducer_stateless7/exp/pretrained.pt \
+    --bpe-model data/lang_bpe_500/bpe.model \
+    --dataset test-clean \
+    --max-duration 300 \
+    --beam-size 4 \
+    --cuts-out-dir data/fbank_ali_beam_search
+
+And the you can run:
+
+./pruned_transducer_stateless7/test_compute_ali.py \
+  --cuts-out-dir ./data/fbank_ali_test \
+  --cuts-ref-dir ./data/fbank_ali_torch \
+  --dataset train-clean-100
+"""
+import argparse
+import logging
+from pathlib import Path
+
+import torch
+from lhotse import load_manifest
+
+
+def get_parser():
+    parser = argparse.ArgumentParser(
+        formatter_class=argparse.ArgumentDefaultsHelpFormatter
+    )
+
+    parser.add_argument(
+        "--cuts-out-dir",
+        type=Path,
+        default="./data/fbank_ali",
+        help="The dir that saves the generated cuts manifests with alignments",
+    )
+
+    parser.add_argument(
+        "--cuts-ref-dir",
+        type=Path,
+        default="./data/fbank_ali_torch",
+        help="The dir that saves the reference cuts manifests with alignments",
+    )
+
+    parser.add_argument(
+        "--dataset",
+        type=str,
+        required=True,
+        help="""The name of the dataset:
+        Possible values are:
+            - test-clean
+            - test-other
+            - train-clean-100
+            - train-clean-360
+            - train-other-500
+            - dev-clean
+            - dev-other
+        """,
+    )
+
+    return parser
+
+
+def main():
+    args = get_parser().parse_args()
+
+    cuts_out_jsonl = args.cuts_out_dir / f"librispeech_cuts_{args.dataset}.jsonl.gz"
+    cuts_ref_jsonl = args.cuts_ref_dir / f"librispeech_cuts_{args.dataset}.jsonl.gz"
+
+    logging.info(f"Loading {cuts_out_jsonl} and {cuts_ref_jsonl}")
+    cuts_out = load_manifest(cuts_out_jsonl)
+    cuts_ref = load_manifest(cuts_ref_jsonl)
+    cuts_ref = cuts_ref.sort_like(cuts_out)
+
+    all_time_diffs = []
+    for cut_out, cut_ref in zip(cuts_out, cuts_ref):
+        time_out = [
+            ali.start
+            for ali in cut_out.supervisions[0].alignment["word"]
+            if ali.symbol != ""
+        ]
+        time_ref = [
+            ali.start
+            for ali in cut_ref.supervisions[0].alignment["word"]
+            if ali.symbol != ""
+        ]
+        assert len(time_out) == len(time_ref), (len(time_out), len(time_ref))
+        diff = [
+            round(abs(out - ref), ndigits=3) for out, ref in zip(time_out, time_ref)
+        ]
+        all_time_diffs += diff
+
+    all_time_diffs = torch.tensor(all_time_diffs)
+    logging.info(
+        f"For the word-level alignments abs difference on dataset {args.dataset}, "
+        f"mean: {'%.2f' % all_time_diffs.mean()}s, std: {'%.2f' % all_time_diffs.std()}s"
+    )
+    logging.info("Done!")
+
+
+if __name__ == "__main__":
+    formatter = "%(asctime)s %(levelname)s [%(filename)s:%(lineno)d] %(message)s"
+
+    logging.basicConfig(format=formatter, level=logging.INFO)
+    main()

icefall/utils.py

@@ -1378,7 +1378,7 @@ def parse_timestamp(tokens: List[str], timestamp: List[float]) -> List[float]:
       List of timestamp of each word.
     """
     start_token = b"\xe2\x96\x81".decode()  # '_'
-    assert len(tokens) == len(timestamp)
+    assert len(tokens) == len(timestamp), (len(tokens), len(timestamp))
     ans = []
     for i in range(len(tokens)):
         flag = False