diff --git a/egs/librispeech/ASR/conformer_ctc/gigaspeech_datamodule.py b/egs/librispeech/ASR/conformer_ctc/gigaspeech_datamodule.py
new file mode 100644
index 000000000..0698154ea
--- /dev/null
+++ b/egs/librispeech/ASR/conformer_ctc/gigaspeech_datamodule.py
@@ -0,0 +1,449 @@
+# Copyright (c)  2021  Johns Hopkins University (Piotr Żelasko)
+# Apache 2.0
+import argparse
+import logging
+import warnings
+from functools import lru_cache
+from pathlib import Path
+from typing import List, Union
+
+from torch.utils.data import DataLoader
+
+from lhotse import CutSet, KaldifeatFbank, KaldifeatFbankConfig, load_manifest
+from lhotse.dataset import (
+    BucketingSampler,
+    CutConcatenate,
+    CutMix,
+    K2SpeechRecognitionDataset,
+    PrecomputedFeatures,
+    SingleCutSampler,
+    SpecAugment,
+)
+from lhotse.dataset.dataloading import LhotseDataLoader
+from lhotse.dataset.input_strategies import OnTheFlyFeatures
+from icefall.utils import str2bool
+from icefall.dataset.datamodule import DataModule
+
+
+def get_context_suffix(args, subparser=True):
+    if subparser:
+        if args.giga_context_window is None or args.giga_context_window <= 0.0:
+            ctx_suffix = ""
+        else:
+                ctx_suffix = f"_{args.giga_context_direction}{args.giga_context_window}"
+    else:
+        if args.context_window is None or args.context_window <= 0.0:
+            ctx_suffix = ""
+        else:
+            ctx_suffix = f"_{args.context_direction}{args.context_window}"
+    return ctx_suffix
+
+
+class GigaSpeechAsrDataModule(DataModule):
+    """
+    DataModule for K2 ASR experiments.
+    It assumes there is always one train and valid dataloader,
+
+    It contains all the common data pipeline modules used in ASR experiments, e.g.:
+    - dynamic batch size,
+    - bucketing samplers,
+    - cut concatenation,
+    - augmentation,
+    - on-the-fly feature extraction
+
+    This class should be derived for specific corpora used in ASR tasks.
+    """
+
+    def __init__(self, args):
+        self.total_train_cuts = 0
+        self.consumed_cuts = 0
+        self.args = args
+
+    @classmethod
+    def add_arguments(cls, parser: argparse.ArgumentParser):
+        subparsers = parser.add_subparsers(help='seperate gigaspeech arguments from librispeech arguments')
+        parser = subparsers.add_parser(name='giga')
+        super().add_arguments(parser)
+        group = parser.add_argument_group(
+            title="ASR data related options",
+            description="These options are used for the preparation of PyTorch DataLoaders "
+                        "from Lhotse CutSet's -- they control the effective batch sizes, "
+                        "sampling strategies, applied data augmentations, etc.",
+        )
+        group.add_argument(
+            "--feature-dir",
+            dest="giga_feature_dir",
+            type=Path,
+            default=Path('exp/giga_data'),
+            help="Path to directory with train/valid/test cuts.",
+        )
+        group.add_argument(
+            "--max-duration",
+            dest="giga_max_duration",
+            type=int,
+            default=500.0,
+            help="Maximum pooled recordings duration (seconds) in a single batch.",
+        )
+        group.add_argument(
+            "--bucketing-sampler",
+            dest="giga_bucketing_sampler",
+            type=str2bool,
+            default=False,
+            help="When enabled, the batches will come from buckets of "
+                 "similar duration (saves padding frames).",
+        )
+        group.add_argument(
+            "--num-buckets",
+            dest="giga_num_buckets",
+            type=int,
+            default=30,
+            help="The number of buckets for the BucketingSampler"
+                 "(you might want to increase it for larger datasets).",
+        )
+        group.add_argument(
+            "--concatenate-cuts",
+            dest="giga_concatenate_cuts",
+            type=str2bool,
+            default=True,
+            help="When enabled, utterances (cuts) will be concatenated "
+                 "to minimize the amount of padding.",
+        )
+        group.add_argument(
+            "--duration-factor",
+            dest="giga_duration_factor",
+            type=float,
+            default=1.0,
+            help="Determines the maximum duration of a concatenated cut "
+                 "relative to the duration of the longest cut in a batch.",
+        )
+        group.add_argument(
+            "--gap",
+            dest="giga_gap",
+            type=float,
+            default=1.0,
+            help="The amount of padding (in seconds) inserted between concatenated cuts. "
+                 "This padding is filled with noise when noise augmentation is used.",
+        )
+        group.add_argument(
+            "--on-the-fly-feats",
+            dest="giga_on_the_fly_feats",
+            type=str2bool,
+            default=False,
+            help="When enabled, use on-the-fly cut mixing and feature extraction. "
+                 "Will drop existing precomputed feature manifests if available.",
+        )
+        group.add_argument(
+            "--shuffle",
+            dest="giga_shuffle",
+            type=str2bool,
+            default=True,
+            help="When enabled (=default), the examples will be shuffled for each epoch.",
+        )
+        group.add_argument(
+            "--return-cuts",
+            dest="giga_return_cuts",
+            type=str2bool,
+            default=True,
+            help="When enabled, each batch will have the field: batch['supervisions']['cut']"
+                 " with the cuts that were used to construct it.",
+        )
+        group.add_argument(
+            "--num-workers",
+            dest="giga_num_workers",
+            type=int,
+            default=4,
+            help="The number of training dataloader workers that collect the batches.",
+        )
+        group.add_argument(
+            "--num-workers-inner",
+            dest="giga_num_workers_inner",
+            type=int,
+            default=16,
+            help="The number of sub-workers (replicated for each of training dataloader"
+                 " workers) that parallelize the I/O to collect each batch.",
+        )
+
+        # GigaSpeech specific arguments
+        group.add_argument(
+            "--subset",
+            dest="giga_subset",
+            type=str,
+            default="XS",
+            help="Select the GigaSpeech subset (XS|S|M|L|XL)",
+        )
+        group.add_argument(
+            "--context-window",
+            dest="giga_context_window",
+            type=float,
+            default=0.0,
+            help="Training cut duration in seconds. "
+                 "Use 0 to train on supervision segments without acoustic context, with variable cut lengths; "
+                 "number larger than zero will create multi-supervisions cuts with actual acoustic context. ",
+        )
+        group.add_argument(
+            "--context-direction",
+            dest="giga_context_direction",
+            type=str,
+            default="center",
+            help="If context-window is 0, does nothing. "
+                 "If it's larger than 0, determines in which direction (relative to the supervision) "
+                 "to seek for extra acoustic context. Available values: (left|right|center|random).",
+        )
+        group.add_argument(
+            "--use-context-for-test",
+            dest="giga_use_context_for_text",
+            type=str2bool,
+            default=False,
+            help="Should we read cuts with acoustic context or without it. "
+                 "(note: for now, they may contain duplicated segments)",
+        )
+        group.add_argument(
+            "--small-dev",
+            dest="giga_small_dev",
+            type=str2bool,
+            default=False,
+            help="Should we use only 1000 utterances for dev (speeds up training)",
+        )
+
+    def validate_args(self):
+        if self.args.giga_subset in ["L", "XL"]:
+            assert (
+                    self.args.giga_shuffle == False
+            ), "For GigaSpeech L/XL, you must use --shuffle 0 to avoid eagerly reading pyarrow manifests."
+            assert (
+                    self.args.giga_bucketing_sampler == False
+            ), "For GigaSpeech L/XL, you must use --bucketing-sampler 0 to avoid eagerly reading pyarrow manifests."
+            # compute_and_store_features_batch is efficient for L/XL subsets.
+            # if not self.args.giga_on_the_fly_feats:
+            #     warnings.warn(
+            #         "For GigaSpeech L/XL, we advise to set --on-the-fly-feats 1,"
+            #         " as we do not pre-compute them by default. If you pre-computed them,"
+            #         " ignore this warning."
+            #     )
+
+    def train_dataloaders(self) -> DataLoader:
+        self.validate_args()
+        logging.info("About to get train cuts")
+        cuts_train = self.train_cuts()
+        self.total_train_cuts = len(cuts_train)
+        self.consumed_cuts = 0
+
+        logging.info("About to get Musan cuts")
+        cuts_musan = load_manifest(self.args.giga_feature_dir / "cuts_musan.json.gz")
+
+        logging.info("About to create train dataset")
+        transforms = [CutMix(cuts=cuts_musan, prob=0.5, snr=(10, 20))]
+        if self.args.giga_concatenate_cuts:
+            logging.info(
+                f"Using cut concatenation with duration factor "
+                f"{self.args.giga_duration_factor} and gap {self.args.giga_gap}."
+            )
+            # Cut concatenation should be the first transform in the list,
+            # so that if we e.g. mix noise in, it will fill the gaps between different utterances.
+            transforms = [
+                             CutConcatenate(
+                                 duration_factor=self.args.giga_duration_factor, gap=self.args.giga_gap
+                             )
+                         ] + transforms
+
+        train = K2SpeechRecognitionDataset(
+            cut_transforms=transforms,
+            return_cuts=self.args.giga_return_cuts,
+        )
+
+        if self.args.giga_on_the_fly_feats:
+            # NOTE: the PerturbSpeed transform should be added only if we remove it from data prep stage.
+            # # Add on-the-fly speed perturbation; since originally it would have increased epoch
+            # # size by 3, we will apply prob 2/3 and use 3x more epochs.
+            # # Speed perturbation probably should come first before concatenation,
+            # # but in principle the transforms order doesn't have to be strict (e.g. could be randomized)
+            # transforms = [PerturbSpeed(factors=[0.9, 1.1], p=2 / 3)] + transforms
+            train = K2SpeechRecognitionDataset(
+                cut_transforms=transforms,
+                input_strategy=OnTheFlyFeatures(
+                    # To avoid unexpected GPU OOM issue during training,
+                    # I think using the cpu version is safer
+                    # KaldifeatFbank(KaldifeatFbankConfig(device='cuda')),
+                    KaldifeatFbank(KaldifeatFbankConfig()),
+                    num_workers=self.args.giga_num_workers_inner,
+                ),
+                return_cuts=self.args.giga_return_cuts,
+            )
+
+        if self.args.giga_bucketing_sampler:
+            logging.info("Using BucketingSampler.")
+            train_sampler = BucketingSampler(
+                cuts_train,
+                max_duration=self.args.giga_max_duration,
+                shuffle=self.args.giga_shuffle,
+                num_buckets=self.args.giga_num_buckets,
+            )
+        else:
+            logging.info("Using SingleCutSampler.")
+            train_sampler = SingleCutSampler(
+                cuts_train,
+                max_duration=self.args.giga_max_duration,
+                shuffle=self.args.giga_shuffle,
+            )
+        logging.info("About to create train dataloader")
+        # train_dl = DataLoader(
+        #    train,
+        #    sampler=train_sampler,
+        #    batch_size=None,
+        #    num_workers=16,
+        #    persistent_workers=True,
+        # )
+        train_dl = LhotseDataLoader(
+            train,
+            sampler=train_sampler,
+            num_workers=self.args.giga_num_workers,
+            prefetch_factor=5,
+        )
+        return train_dl
+
+    def valid_dataloaders(self) -> DataLoader:
+        self.validate_args()
+        logging.info("About to get dev cuts")
+        cuts_valid = self.valid_cuts()
+
+        transforms = []
+        if self.args.giga_concatenate_cuts:
+            transforms = [
+                             CutConcatenate(
+                                 duration_factor=self.args.giga_duration_factor, gap=self.args.giga_gap
+                             )
+                         ] + transforms
+
+        logging.info("About to create dev dataset")
+        if self.args.giga_on_the_fly_feats:
+            validate = K2SpeechRecognitionDataset(
+                cut_transforms=transforms,
+                input_strategy=OnTheFlyFeatures(
+                    # To avoid unexpected GPU OOM issue during training,
+                    # I think using the cpu version is safer
+                    # KaldifeatFbank(KaldifeatFbankConfig(device='cuda')), num_workers=8
+                    KaldifeatFbank(KaldifeatFbankConfig()), num_workers=8
+                ),
+                return_cuts=self.args.giga_return_cuts,
+            )
+        else:
+            validate = K2SpeechRecognitionDataset(
+                cut_transforms=transforms,
+                return_cuts=self.args.giga_return_cuts,
+            )
+        valid_sampler = SingleCutSampler(
+            cuts_valid,
+            max_duration=self.args.giga_max_duration,
+            shuffle=False,
+        )
+        logging.info("About to create dev dataloader")
+        # valid_dl = DataLoader(
+        #    validate,
+        #    sampler=valid_sampler,
+        #    batch_size=None,
+        #    num_workers=8,
+        #    persistent_workers=True,
+        # )
+        valid_dl = LhotseDataLoader(
+            validate,
+            sampler=valid_sampler,
+            num_workers=2,
+        )
+        return valid_dl
+
+    def test_dataloaders(self) -> Union[DataLoader, List[DataLoader]]:
+        self.validate_args()
+        cuts = self.test_cuts()
+        is_list = isinstance(cuts, list)
+        test_loaders = []
+        if not is_list:
+            cuts = [cuts]
+
+        for cuts_test in cuts:
+            logging.debug("About to create test dataset")
+            test = K2SpeechRecognitionDataset(
+                input_strategy=(
+                    # To avoid unexpected GPU OOM issue during training,
+                    # I think using the cpu version is safer
+                    # OnTheFlyFeatures(KaldifeatFbank(KaldifeatFbankConfig(device='cuda')), num_workers=8)
+                    OnTheFlyFeatures(KaldifeatFbank(KaldifeatFbankConfig()), num_workers=8)
+                    if self.args.giga_on_the_fly_feats
+                    else PrecomputedFeatures()
+                ),
+                return_cuts=self.args.giga_return_cuts,
+            )
+            sampler = SingleCutSampler(cuts_test, max_duration=self.args.giga_max_duration)
+            logging.debug("About to create test dataloader")
+            # test_dl = DataLoader(test, batch_size=None, sampler=sampler, num_workers=1)
+            test_dl = LhotseDataLoader(test, sampler=sampler, num_workers=2)
+            test_loaders.append(test_dl)
+
+        if is_list:
+            return test_loaders
+        else:
+            return test_loaders[0]
+
+    @lru_cache()
+    def train_cuts(self) -> CutSet:
+        logging.info("About to get train cuts")
+        path = (
+                self.args.giga_feature_dir
+                / f"gigaspeech_cuts_{self.args.giga_subset}{get_context_suffix(self.args)}.jsonl.gz"
+        )
+        if self.args.giga_subset in ["L", "XL"]:
+            # "L" and "XL" partitions are large enough that we have to read their manifests lazily;
+            # The "CutSet" holds a file handle and reads the items sequentially on-the-fly to avoid
+            # wasting memory and time pre-reading everything. Some operations on "CutSet" won't work,
+            # e.g. shuffling (or they would have read everything into memory in the process).
+            # We expect that the manifests read lazily are pre-shuffled, otherwise you might experience
+            # issues with convergence.
+            cuts_train = CutSet.from_jsonl_lazy(path)
+        else:
+            # For other subsets, just read everything into memory.
+            cuts_train = CutSet.from_file(path)
+        return cuts_train
+
+    @lru_cache()
+    def valid_cuts(self) -> CutSet:
+        if self.args.giga_use_context_for_test:
+            path = (
+                    self.args.giga_feature_dir
+                    / f"gigaspeech_cuts_DEV{get_context_suffix(self.args)}.jsonl.gz"
+            )
+        else:
+            path = self.args.giga_feature_dir / f"gigaspeech_cuts_DEV.jsonl.gz"
+        logging.info(f"About to get valid cuts from {path}")
+        cuts_valid = load_manifest(path)
+        if self.args.giga_small_dev:
+            return cuts_valid.subset(first=1000)
+        else:
+            return cuts_valid
+
+    @lru_cache()
+    def test_cuts(self) -> CutSet:
+        if self.args.giga_use_context_for_test:
+            path = (
+                    self.args.giga_feature_dir
+                    / f"gigaspeech_cuts_TEST{get_context_suffix(self.args)}.jsonl.gz"
+            )
+        else:
+            path = self.args.giga_feature_dir / f"gigaspeech_cuts_TEST.jsonl.gz"
+        logging.info(f"About to get test cuts from {path}")
+        cuts_test = load_manifest(path)
+        return cuts_test
+
+    def inexhaustible_train_dataloaders(self):
+      return self
+
+    def __iter__(self):
+      # work horse for inexhuastible_train_dataloaders
+      while True:
+        # self.total_train_cuts == 0 for the first run
+        # self.consumed_cuts  == self.total_train_cuts for recreating dataloader
+        if self.total_train_cuts == 0 or self.consumed_cuts == self.total_train_cuts:
+          self.train_dl = self.train_dataloaders()
+          self.consumed_cuts = 0
+
+        for batch in self.train_dl:
+          self.consumed_cuts += len(batch["supervisions"]["text"])
+          yield batch
diff --git a/egs/librispeech/ASR/example_giga_dataloader.py b/egs/librispeech/ASR/example_giga_dataloader.py
new file mode 100644
index 000000000..7f8aa20eb
--- /dev/null
+++ b/egs/librispeech/ASR/example_giga_dataloader.py
@@ -0,0 +1,28 @@
+import argparse
+import json
+from pathlib import Path
+
+from gigaspeech_datamodule import GigaSpeechAsrDataModule
+
+def get_parser():
+    parser = argparse.ArgumentParser(
+        formatter_class=argparse.ArgumentDefaultsHelpFormatter
+    )
+    group = parser.add_argument_group(title='libri related options')
+    group.add_argument(
+        '--max-duration',
+        type=int,
+        default=500.0,
+        help="Maximum pooled recordings duration (seconds) in a single batch.")
+    return parser
+
+if __name__ == '__main__':
+    parser = get_parser()
+    GigaSpeechAsrDataModule.add_arguments(parser)
+    args = parser.parse_args()
+    gigaspeech = GigaSpeechAsrDataModule(args)
+    train_dl = gigaspeech.inexhaustible_train_dataloaders()
+    for idx, batch in enumerate(train_dl):
+        print(batch["inputs"].shape)
+        print(len(batch["supervisions"]["text"]))
+        print(batch["supervisions"]["text"][0:2])
diff --git a/egs/librispeech/ASR/prepare_gigaspeech.py b/egs/librispeech/ASR/prepare_gigaspeech.py
new file mode 100755
index 000000000..870909787
--- /dev/null
+++ b/egs/librispeech/ASR/prepare_gigaspeech.py
@@ -0,0 +1,313 @@
+#!/usr/bin/env python3
+
+# Copyright (c)  2021  Johns Hopkins University (Piotr Żelasko)
+# Apache 2.0
+import argparse
+import os
+import re
+import subprocess
+import sys
+from contextlib import contextmanager
+from pathlib import Path
+from functools import partial
+
+import torch
+
+from gigaspeech_datamodule import get_context_suffix
+from lhotse import (
+    CutSet,
+    KaldifeatFbank,
+    KaldifeatFbankConfig,
+    LilcomHdf5Writer,
+    SupervisionSegment,
+    combine,
+)
+from lhotse.recipes import prepare_gigaspeech, prepare_musan
+from icefall.utils import str2bool
+
+# Torch's multithreaded behavior needs to be disabled or it wastes a lot of CPU and
+# slow things down.  Do this outside of main() in case it needs to take effect
+# even when we are not invoking the main (e.g. when spawning subprocesses).
+torch.set_num_threads(1)
+torch.set_num_interop_threads(1)
+
+
+@contextmanager
+def get_executor():
+    # We'll either return a process pool or a distributed worker pool.
+    # Note that this has to be a context manager because we might use multiple
+    # context manager ("with" clauses) inside, and this way everything will
+    # free up the resources at the right time.
+    try:
+        # If this is executed on the CLSP grid, we will try to use the
+        # Grid Engine to distribute the tasks.
+        # Other clusters can also benefit from that, provided a cluster-specific wrapper.
+        # (see https://github.com/pzelasko/plz for reference)
+        #
+        # The following must be installed:
+        # $ pip install dask distributed
+        # $ pip install git+https://github.com/pzelasko/plz
+        name = subprocess.check_output("hostname -f", shell=True, text=True)
+        if name.strip().endswith(".clsp.jhu.edu"):
+            import plz
+            from distributed import Client
+
+            with plz.setup_cluster() as cluster:
+                cluster.scale(80)
+                yield Client(cluster)
+            return
+    except:
+        pass
+    # No need to return anything - compute_and_store_features
+    # will just instantiate the pool itself.
+    yield None
+
+
+def locate_corpus(*corpus_dirs):
+    for d in corpus_dirs:
+        if os.path.exists(d):
+            return d
+    print(
+        "Please create a place on your system to put the downloaded Librispeech data "
+        "and add it to `corpus_dirs`"
+    )
+    sys.exit(1)
+
+
+def get_parser():
+    parser = argparse.ArgumentParser(
+        formatter_class=argparse.ArgumentDefaultsHelpFormatter
+    )
+    parser.add_argument(
+        "--num-jobs",
+        type=int,
+        default=min(15, os.cpu_count()),
+        help="Number of parallel jobs.",
+    )
+    parser.add_argument(
+        "--subset",
+        type=str,
+        default="XS",
+        help="Select the GigaSpeech subset (XS|S|M|L|XL)",
+    )
+    parser.add_argument(
+        "--context-window",
+        type=float,
+        default=0.0,
+        help="Training cut duration in seconds. "
+        "Use 0 to train on supervision segments without acoustic context, with variable cut lengths; "
+        "number larger than zero will create multi-supervisions cuts with actual acoustic context. ",
+    )
+    parser.add_argument(
+        "--context-direction",
+        type=str,
+        default="center",
+        help="If context-window is 0, does nothing. "
+        "If it's larger than 0, determines in which direction (relative to the supervision) "
+        "to seek for extra acoustic context. Available values: (left|right|center|random).",
+    )
+    parser.add_argument(
+        "--precomputed-features",
+        type=str2bool,
+        default=True,
+        help="Should we pre-compute features and store them on disk or not. "
+        "It is recommended to disable it for L and XL splits as the pre-computation "
+        "might currently consume excessive memory and time -- use on-the-fly feature "
+        "extraction in the training script instead.",
+    )
+    parser.add_argument(
+        "--num-workers",
+        type=int,
+        default=4,
+        help="Number of workers for compute_and_store_features_batch.",
+    )
+    parser.add_argument(
+        "--batch-duration",
+        type=float,
+        default=600.0,
+        help="The maximum number of audio seconds in a batch"
+              "for compute_and_store_features_batch.",
+    )
+    return parser
+
+
+# Similar text filtering and normalization procedure as in:
+# https://github.com/SpeechColab/GigaSpeech/blob/main/toolkits/kaldi/gigaspeech_data_prep.sh
+
+
+def normalize_text(
+    utt: str,
+    punct_pattern=re.compile(r"<(COMMA|PERIOD|QUESTIONMARK|EXCLAMATIONPOINT)>"),
+    whitespace_pattern=re.compile(r"\s\s+"),
+) -> str:
+    return whitespace_pattern.sub(" ", punct_pattern.sub("", utt))
+
+
+def has_no_oov(
+    sup: SupervisionSegment, oov_pattern=re.compile(r"<(SIL|MUSIC|NOISE|OTHER)>")
+) -> bool:
+    return oov_pattern.search(sup.text) is None
+
+
+def main():
+    args = get_parser().parse_args()
+    dataset_parts = [args.subset, "DEV", "TEST"]
+
+    print("Parts we will prepare: ", dataset_parts)
+
+    corpus_dir = locate_corpus(
+        Path("/export/corpora5/gigaspeech"),
+        Path("/exp/pzelasko/gigaspeech"),
+        Path("/home/storage07/zhangjunbo/data/GigaSpeech")
+    )
+    musan_dir = locate_corpus(
+        Path("/export/corpora5/JHU/musan"),
+        Path("/export/common/data/corpora/MUSAN/musan"),
+        Path("/root/fangjun/data/musan"),
+    )
+
+    output_dir = Path("exp/giga_data")
+    print("GigaSpeech manifest preparation:")
+    gigaspeech_manifests = prepare_gigaspeech(
+        corpus_dir=corpus_dir,
+        dataset_parts=dataset_parts,
+        output_dir=output_dir,
+        num_jobs=args.num_jobs,
+    )
+
+    print("Musan manifest preparation:")
+    musan_cuts_path = output_dir / "cuts_musan.json.gz"
+    musan_manifests = prepare_musan(
+        corpus_dir=musan_dir, output_dir=output_dir, parts=("music", "speech", "noise")
+    )
+
+    ctx_suffix = get_context_suffix(args, subparser=False)
+
+    print("Feature extraction:")
+    # extractor = Fbank(FbankConfig(num_mel_bins=80))
+    extractor = KaldifeatFbank(KaldifeatFbankConfig(device='cuda'))  # default config uses 80 mel bins already
+    with get_executor() as ex:  # Initialize the executor only once.
+        for partition, manifests in gigaspeech_manifests.items():
+            raw_cuts_path = output_dir / f"gigaspeech_cuts_{partition}_raw.jsonl.gz"
+            cuts_path = (
+                    output_dir / f"gigaspeech_cuts_{partition}{ctx_suffix}.jsonl.gz"
+            )
+
+            if raw_cuts_path.is_file():
+                print(f"{partition} already exists - skipping feature extraction.")
+            else:
+                # Note this step makes the recipe different than LibriSpeech:
+                # We must filter out some utterances and remove punctuation to be consistent with Kaldi.
+                print("Filtering OOV utterances from supervisions")
+                manifests["supervisions"] = manifests["supervisions"].filter(has_no_oov)
+                print("Normalizing text in", partition)
+                for sup in manifests["supervisions"]:
+                    sup.text = normalize_text(sup.text)
+
+                # Create long-recording cut manifests.
+                print("Processing", partition)
+                cut_set = CutSet.from_manifests(
+                    recordings=manifests["recordings"],
+                    supervisions=manifests["supervisions"],
+                )
+
+                # Run data augmentation that needs to be done in the time domain.
+                if partition not in ["DEV", "TEST"]:
+                    cut_set = (
+                        cut_set
+                        + cut_set.perturb_speed(0.9)
+                        + cut_set.perturb_speed(1.1)
+                    )
+
+                cut_set.to_file(raw_cuts_path)
+
+            if cuts_path.is_file():
+                print(
+                    f"{partition} already exists - skipping cutting into sub-segments."
+                )
+            else:
+                try:
+                    # If we skipped initializing `cut_set` because it exists on disk, we'll load it.
+                    # This helps us avoid re-computing the features for different variants of
+                    # context windows.
+                    cut_set
+                except NameError:
+                    print(f"Reading {partition} raw cuts from disk.")
+                    cut_set = CutSet.from_file(raw_cuts_path)
+                # Note this step makes the recipe different than LibriSpeech:
+                # Since recordings are long, the initial CutSet has very long cuts with a plenty of supervisions.
+                # We cut these into smaller chunks centered around each supervision, possibly adding acoustic
+                # context.
+                print(f"About to split {partition} raw cuts into smaller chunks.")
+                cut_set = cut_set.trim_to_supervisions(
+                    keep_overlapping=False,
+                    min_duration=None
+                    if args.context_window <= 0.0
+                    else args.context_window,
+                    context_direction=args.context_direction,
+                )
+                if partition in ["L", "XL"]:
+                    # Before storing manifests in, we want to pre-shuffle them,
+                    # as the sampler won't be able to do it later in an efficient manner.
+                    cut_set = cut_set.shuffle()
+
+                if args.precomputed_features:
+                    # Extract the features after cutting large recordings into smaller cuts.
+                    # Note: we support very efficient "chunked" feature reads with the argument
+                    #       `storage_type=ChunkedLilcomHdf5Writer`, but we don't support efficient
+                    #       data augmentation and feature computation for long recordings yet.
+                    #       Therefore, we sacrifice some storage for the ability to precompute
+                    #       features on shorter chunks, without memory blow-ups.
+                    # cut_set = cut_set.compute_and_store_features(
+                    #     extractor=extractor,
+                    #     storage_path=f"{output_dir}/feats_gigaspeech_{partition}",
+                    #     # when an executor is specified, make more partitions
+                    #     num_jobs=args.num_jobs if ex is None else 80,
+                    #     executor=ex,
+                    # )
+                    cut_set = cut_set.compute_and_store_features_batch(
+                        extractor=extractor,
+                        storage_path=f"{output_dir}/feats_gigaspeech_{partition}",
+                        batch_duration=args.batch_duration,
+                        num_workers=args.num_workers,
+                        storage_type=partial(LilcomHdf5Writer, tick_power=-3),
+                    )
+
+
+                cut_set.to_file(cuts_path)
+
+                # Remove cut_set so the next iteration can correctly infer whether it needs to
+                # load the raw cuts from disk or not.
+                del cut_set
+
+        # Now onto Musan
+        if not musan_cuts_path.is_file():
+            print("Extracting features for Musan")
+            # create chunks of Musan with duration 5 - 10 seconds
+            musan_cuts = (
+                CutSet.from_manifests(
+                    recordings=combine(
+                        part["recordings"] for part in musan_manifests.values()
+                    )
+                )
+                .cut_into_windows(10.0)
+                .filter(lambda c: c.duration > 5)
+                .compute_and_store_features_batch(
+                    extractor=extractor,
+                    storage_path=f"{output_dir}/feats_musan",
+                    batch_duration=args.batch_duration,
+                    num_workers=args.num_workers,
+                )
+                # .compute_and_store_features(
+                #     extractor=extractor,
+                #     storage_path=f"{output_dir}/feats_musan",
+                #     num_jobs=args.num_jobs if ex is None else 80,
+                #     executor=ex,
+                #     storage_type=LilcomHdf5Writer,
+                # )
+            )
+            musan_cuts.to_file(musan_cuts_path)
+
+
+if __name__ == "__main__":
+    main()