diff --git a/egs/librispeech/ASR/tdnn_lstm_ctc/asr_datamodule.py b/egs/librispeech/ASR/tdnn_lstm_ctc/asr_datamodule.py
index e075a2d03..2af2f5e8a 100644
--- a/egs/librispeech/ASR/tdnn_lstm_ctc/asr_datamodule.py
+++ b/egs/librispeech/ASR/tdnn_lstm_ctc/asr_datamodule.py
@@ -180,14 +180,14 @@ class LibriSpeechAsrDataModule:
         )
 
     def train_dataloaders(self, cuts_train: CutSet) -> DataLoader:
-        logging.info("About to get Musan cuts")
-        cuts_musan = load_manifest(
-            self.args.manifest_dir / "cuts_musan.json.gz"
-        )
 
         transforms = []
         if self.args.enable_musan:
             logging.info("Enable MUSAN")
+            logging.info("About to get Musan cuts")
+            cuts_musan = load_manifest(
+                self.args.manifest_dir / "cuts_musan.json.gz"
+            )
             transforms.append(
                 CutMix(
                     cuts=cuts_musan, prob=0.5, snr=(10, 20), preserve_id=True
diff --git a/egs/librispeech/ASR/transducer_stateless/alignment.py b/egs/librispeech/ASR/transducer_stateless/alignment.py
new file mode 100644
index 000000000..60c737163
--- /dev/null
+++ b/egs/librispeech/ASR/transducer_stateless/alignment.py
@@ -0,0 +1,187 @@
+# Copyright    2022  Xiaomi Corp.        (authors: Fangjun Kuang)
+#
+# 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 dataclasses import dataclass
+from typing import List, Optional
+
+import torch
+from model import Transducer
+
+# TODO(fangjun): Add more documentation
+
+# The force alignment problem can be formulated as find
+# 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`
+# and the vertical axis is `u`.
+#
+# AlignItem is a node in the lattice, where its
+# len(ys) equals to `t` and pos_u is the u coordinate
+# in the lattice.
+@dataclass
+class AlignItem:
+    log_prob: float
+    ys: List[int]
+    pos_u: int
+
+
+class AlignItemList:
+    def __init__(self, items: Optional[List[AlignItem]] = None):
+        if items is None:
+            items = []
+        self.data = items
+
+    def __iter__(self):
+        return iter(self.data)
+
+    def __len__(self):
+        return len(self.data)
+
+    def __getitem__(self, i: int) -> AlignItem:
+        return self.data[i]
+
+    def append(self, item: AlignItem) -> None:
+        self.data.append(item)
+
+    def get_active_items(self, T: int, U: int) -> "AlignItemList":
+        ans = []
+        for item in self:
+            t = len(item.ys)
+            if U - item.pos_u > T - t:
+                continue
+            ans.append(item)
+
+        return AlignItemList(ans)
+
+    def get_decoder_input(
+        self,
+        ys: List[int],
+        context_size: int,
+        blank_id: int,
+    ) -> List[List[int]]:
+        ans: List[List[int]] = []
+        buf = [blank_id] * context_size + ys
+        for item in self:
+            # fmt: off
+            ans.append(buf[item.pos_u:(item.pos_u + context_size)])
+            # fmt: on
+        return ans
+
+    def topk(self, k: int) -> "AlignItemList":
+        items = list(self)
+        items = sorted(items, key=lambda i: i.log_prob, reverse=True)
+        return AlignItemList(items[:k])
+
+
+def force_alignment(
+    model: Transducer,
+    encoder_out: torch.Tensor,
+    ys: List[int],
+    beam_size: int = 4,
+) -> List[int]:
+    """
+    Args:
+      model:
+        The transducer model.
+      encoder_out:
+        A tensor of shape (N, T, C). Support only for N==1 now.
+      ys:
+        A list of token IDs. We require that len(ys) <= T.
+      beam:
+        Size of the beam used in beam search.
+    Returns:
+      Return a list of int such that
+        - len(ans) == T
+        - After removing blanks from ans, we have ans == ys.
+    """
+    import pdb
+
+    pdb.set_trace()
+    assert encoder_out.ndim == 3, encoder_out.ndim
+    assert encoder_out.size(0) == 1, encoder_out.size(0)
+    assert 0 < len(ys) <= encoder_out.size(1), (len(ys), encoder_out.size(1))
+
+    blank_id = model.decoder.blank_id
+    context_size = model.decoder.context_size
+
+    device = model.device
+
+    T = encoder_out.size(1)
+    U = len(ys)
+
+    encoder_out_len = torch.tensor([1])
+    decoder_out_len = encoder_out_len
+
+    start = AlignItem(log_prob=0.0, ys=[], pos_u=0)
+    B = AlignItemList([start])
+
+    for t in range(T):
+        # fmt: off
+        current_encoder_out = encoder_out[:, t:t+1, :]
+        # current_encoder_out is of shape (1, 1, encoder_out_dim)
+        # fmt: on
+
+        #  A = B.get_active_items()
+        A = B  # shallow copy
+        B = AlignItemList()
+
+        decoder_input = A.get_decoder_input(
+            ys=ys, context_size=context_size, blank_id=blank_id
+        )
+        decoder_input = torch.tensor(decoder_input, device=device)
+        # decoder_input is of shape (num_active_items, context_size)
+
+        decoder_out = model.decoder(decoder_input, need_pad=False)
+        # decoder_output is of shape (num_active_items, 1, decoder_output_dim)
+
+        current_encoder_out = current_encoder_out.expand(
+            decoder_out.size(0), 1, -1
+        )
+
+        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_active_items, vocab_size)
+        log_probs = logits.log_softmax(dim=-1).tolist()
+
+        for i, item in enumerate(A):
+            if (T - 1 - t) >= (U - item.pos_u):
+                # horizontal transition
+                new_item = AlignItem(
+                    log_prob=item.log_prob + log_probs[i][blank_id],
+                    ys=item.ys + [blank_id],
+                    pos_u=item.pos_u,
+                )
+                B.append(new_item)
+
+            if item.pos_u < U:
+                # diagonal transition
+                u = ys[item.pos_u]
+                new_item = AlignItem(
+                    log_prob=item.log_prob + log_probs[i][u],
+                    ys=item.ys + [u],
+                    pos_u=item.pos_u + 1,
+                )
+                B.append(new_item)
+        if len(B) > beam_size:
+            B = B.topk(beam_size)
+
+    return B.topk(1)[0].ys
diff --git a/egs/librispeech/ASR/transducer_stateless/compute_ali.py b/egs/librispeech/ASR/transducer_stateless/compute_ali.py
new file mode 100755
index 000000000..4813154b2
--- /dev/null
+++ b/egs/librispeech/ASR/transducer_stateless/compute_ali.py
@@ -0,0 +1,322 @@
+#!/usr/bin/env python3
+# Copyright    2022  Xiaomi Corp.        (authors: Fangjun Kuang)
+#
+# 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.
+
+"""
+Usage:
+    ./transducer_stateless/compute_ali.py \
+            --exp-dir ./transducer_stateless/exp \
+            --bpe-model ./data/lang_bpe_500/bpe.model \
+            --epoch 20 \
+            --avg 10 \
+            --max-duration 300 \
+            --dataset train-clean-100 \
+            --out-dir data/ali
+"""
+
+import argparse
+import logging
+from pathlib import Path
+from typing import List
+
+import k2
+import numpy as np
+import sentencepiece as spm
+import torch
+from alignment import force_alignment
+from asr_datamodule import LibriSpeechAsrDataModule
+from lhotse import CutSet
+from lhotse.features.io import FeaturesWriter, NumpyHdf5Writer
+from train import get_params, get_transducer_model
+
+from icefall.checkpoint import average_checkpoints, load_checkpoint
+from icefall.utils import AttributeDict, setup_logger
+
+
+def get_parser():
+    parser = argparse.ArgumentParser(
+        formatter_class=argparse.ArgumentDefaultsHelpFormatter
+    )
+
+    parser.add_argument(
+        "--epoch",
+        type=int,
+        default=34,
+        help="It specifies the checkpoint to use for decoding."
+        "Note: Epoch counts from 0.",
+    )
+    parser.add_argument(
+        "--avg",
+        type=int,
+        default=20,
+        help="Number of checkpoints to average. Automatically select "
+        "consecutive checkpoints before the checkpoint specified by "
+        "'--epoch'. ",
+    )
+
+    parser.add_argument(
+        "--bpe-model",
+        type=str,
+        default="data/lang_bpe_500/bpe.model",
+        help="Path to the BPE model",
+    )
+
+    parser.add_argument(
+        "--exp-dir",
+        type=str,
+        default="transducer_stateless/exp",
+        help="The experiment dir",
+    )
+
+    parser.add_argument(
+        "--out-dir",
+        type=str,
+        required=True,
+        help="""Output directory.
+        It contains 3 generated files:
+
+        - labels_xxx.h5
+        - aux_labels_xxx.h5
+        - cuts_xxx.json.gz
+
+        where xxx is the value of `--dataset`. For instance, if
+        `--dataset` is `train-clean-100`, it will contain 3 files:
+
+        - `labels_train-clean-100.h5`
+        - `aux_labels_train-clean-100.h5`
+        - `cuts_train-clean-100.json.gz`
+
+        Note: Both labels_xxx.h5 and aux_labels_xxx.h5 contain framewise
+        alignment. The difference is that labels_xxx.h5 contains repeats.
+        """,
+    )
+
+    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,
+    )
+
+    parser.add_argument(
+        "--context-size",
+        type=int,
+        default=2,
+        help="The context size in the decoder. 1 means bigram; "
+        "2 means tri-gram",
+    )
+
+    return parser
+
+
+def get_word_begin_time(ali: List[int], sp: spm.SentencePieceProcessor):
+    underscore = b"\xe2\x96\x81".decode()  # '_'
+    ans = []
+    for i in range(len(ali)):
+        print(sp.id_to_piece(ali[i]))
+        if sp.id_to_piece(ali[i]).startswith(underscore):
+            print("yes")
+            ans.append(i * 0.04)
+    return ans
+
+
+def compute_alignments(
+    model: torch.nn.Module,
+    dl: torch.utils.data,
+    params: AttributeDict,
+    sp: spm.SentencePieceProcessor,
+):
+    try:
+        num_batches = len(dl)
+    except TypeError:
+        num_batches = "?"
+    num_cuts = 0
+
+    device = model.device
+    cuts = []
+
+    for batch_idx, batch in enumerate(dl):
+        feature = batch["inputs"]
+
+        # at entry, feature is [N, T, C]
+        assert feature.ndim == 3
+        feature = feature.to(device)
+
+        supervisions = batch["supervisions"]
+
+        cut_list = supervisions["cut"]
+        for cut in cut_list:
+            assert len(cut.supervisions) == 1, f"{len(cut.supervisions)}"
+
+        feature_lens = supervisions["num_frames"].to(device)
+
+        encoder_out, encoder_out_lens = model.encoder(
+            x=feature, x_lens=feature_lens
+        )
+
+        batch_size = encoder_out.size(0)
+
+        texts = supervisions["text"]
+
+        ys_list: List[List[int]] = sp.encode(texts, out_type=int)
+
+        ali_list = []
+        word_begin_time_list = []
+        for i in range(batch_size):
+            # fmt: off
+            encoder_out_i = encoder_out[i:i+1, :encoder_out_lens[i]]
+            # fmt: on
+
+            ali = force_alignment(
+                model=model,
+                encoder_out=encoder_out_i,
+                ys=ys_list[i],
+                beam_size=params.beam_size,
+            )
+            ali_list.append(ali)
+            word_begin_time_list.append(get_word_begin_time(ali, sp))
+            import pdb
+
+            pdb.set_trace()
+
+
+@torch.no_grad()
+def main():
+    parser = get_parser()
+    LibriSpeechAsrDataModule.add_arguments(parser)
+    args = parser.parse_args()
+
+    args.enable_spec_aug = False
+    args.enable_musan = False
+    args.return_cuts = True
+    args.concatenate_cuts = False
+
+    params = get_params()
+    params.update(vars(args))
+
+    setup_logger(f"{params.exp_dir}/log-ali")
+
+    sp = spm.SentencePieceProcessor()
+    sp.load(params.bpe_model)
+
+    # <blk> is defined in local/train_bpe_model.py
+    params.blank_id = sp.piece_to_id("<blk>")
+    params.vocab_size = sp.get_piece_size()
+
+    logging.info(f"Computing alignments for {params.dataset} - started")
+    logging.info(params)
+
+    device = torch.device("cpu")
+    if torch.cuda.is_available():
+        device = torch.device("cuda", 0)
+    logging.info(f"Device: {device}")
+
+    out_dir = Path(params.out_dir)
+    out_dir.mkdir(exist_ok=True)
+
+    out_labels_ali_filename = out_dir / f"labels_{params.dataset}.h5"
+    out_aux_labels_ali_filename = out_dir / f"aux_labels_{params.dataset}.h5"
+    out_manifest_filename = out_dir / f"cuts_{params.dataset}.json.gz"
+
+    for f in (
+        out_labels_ali_filename,
+        out_aux_labels_ali_filename,
+        out_manifest_filename,
+    ):
+        if f.exists():
+            logging.info(f"{f} exists - skipping")
+            return
+
+    logging.info("About to create model")
+    model = get_transducer_model(params)
+
+    if params.avg == 1:
+        load_checkpoint(f"{params.exp_dir}/epoch-{params.epoch}.pt", model)
+    else:
+        start = params.epoch - params.avg + 1
+        filenames = []
+        for i in range(start, params.epoch + 1):
+            if start >= 0:
+                filenames.append(f"{params.exp_dir}/epoch-{i}.pt")
+        logging.info(f"averaging {filenames}")
+        model.to(device)
+        model.load_state_dict(
+            average_checkpoints(filenames, device=device), strict=False
+        )
+
+    model.to(device)
+    model.eval()
+    model.device = device
+
+    num_param = sum([p.numel() for p in model.parameters()])
+    logging.info(f"Number of model parameters: {num_param}")
+
+    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)
+
+    logging.info(f"Processing {params.dataset}")
+
+    cut_set = compute_alignments(
+        model=model,
+        dl=dl,
+        #  labels_writer=labels_writer,
+        #  aux_labels_writer=aux_labels_writer,
+        params=params,
+        sp=sp,
+    )
+
+
+#  torch.set_num_interop_threads(1)
+#  torch.set_num_threads(1)
+
+if __name__ == "__main__":
+    main()