Openspeech provides reference implementations of various ASR modeling papers and three languages recipe to perform tasks on automatic speech recognition. We aim to make ASR technology easier to use for everyone.

Openspeech is backed by the two powerful libraries — PyTorch-Lightning and Hydra.
Various features are available in the above two libraries, including Multi-GPU and TPU training, Mixed-precision, and hierarchical configuration management.

Get Started

We use Hydra to control all the training configurations.
If you are not familiar with Hydra we recommend visiting the Hydra website.
Generally, Hydra is an open-source framework that simplifies the development of research applications by providing the ability to create a hierarchical configuration dynamically.
If you want to know how we used Hydra, we recommend you to read here.

Supported Datasets

We support LibriSpeech, KsponSpeech, and AISHELL-1.

LibriSpeech is a corpus of approximately 1,000 hours of 16kHz read English speech, prepared by Vassil Panayotov with the assistance of Daniel Povey. The data was derived from reading audiobooks from the LibriVox project, and has been carefully segmented and aligned.

Aishell is an open-source Chinese Mandarin speech corpus published by Beijing Shell Shell Technology Co.,Ltd. 400 people from different accent areas in China were invited to participate in the recording, which was conducted in a quiet indoor environment using high fidelity microphone and downsampled to 16kHz.

KsponSpeech is a large-scale spontaneous speech corpus of Korean. This corpus contains 969 hours of general open-domain dialog utterances, spoken by about 2,000 native Korean speakers in a clean environment. All data were constructed by recording the dialogue of two people freely conversing on a variety of topics and manually transcribing the utterances. To start training, the KsponSpeech dataset must be prepared in advance. To download KsponSpeech, you need permission from AI Hub.

Pre-processed Manifest Files

Dataset Unit Manifest Vocab SP-Model
LibriSpeech character [Link] [Link] -
LibriSpeech subword [Link] [Link] [Link]
AISHELL-1 character [Link] [Link] -
KsponSpeech character [Link] [Link] -
KsponSpeech subword [Link] [Link] [Link]
KsponSpeech grapheme [Link] [Link] -

KsponSpeech needs permission from AI Hub.
Please send e-mail including the approved screenshot to [email protected].

Manifest File

  • Manifest file format:
LibriSpeech/test-other/8188/269288/8188-269288-0052.flac        ▁ANNIE ' S ▁MANNER ▁WAS ▁VERY ▁MYSTERIOUS       4039 20 5 531 17 84 2352
LibriSpeech/test-other/8188/269288/8188-269288-0053.flac        ▁ANNIE ▁DID ▁NOT ▁MEAN ▁TO ▁CONFIDE ▁IN ▁ANYONE ▁THAT ▁NIGHT ▁AND ▁THE ▁KIND EST ▁THING ▁WAS ▁TO ▁LEAVE ▁HER ▁A LONE    4039 99 35 251 9 4758 11 2454 16 199 6 4 323 200 255 17 9 370 30 10 492
LibriSpeech/test-other/8188/269288/8188-269288-0054.flac        ▁TIRED ▁OUT ▁LESLIE ▁HER SELF ▁DROPP ED ▁A SLEEP        1493 70 4708 30 115 1231 7 10 1706
LibriSpeech/test-other/8188/269288/8188-269288-0055.flac        ▁ANNIE ▁IS ▁THAT ▁YOU ▁SHE ▁CALL ED ▁OUT        4039 34 16 25 37 208 7 70
LibriSpeech/test-other/8188/269288/8188-269288-0056.flac        ▁THERE ▁WAS ▁NO ▁REPLY ▁BUT ▁THE ▁SOUND ▁OF ▁HURRY ING ▁STEPS ▁CAME ▁QUICK ER ▁AND ▁QUICK ER ▁NOW ▁AND ▁THEN ▁THEY ▁WERE ▁INTERRUPTED ▁BY ▁A ▁GROAN     57 17 56 1368 33 4 489 8 1783 14 1381 133 571 49 6 571 49 82 6 76 45 54 2351 44 10 3154
LibriSpeech/test-other/8188/269288/8188-269288-0057.flac        ▁OH ▁THIS ▁WILL ▁KILL ▁ME ▁MY ▁HEART ▁WILL ▁BREAK ▁THIS ▁WILL ▁KILL ▁ME 299 46 71 669 50 41 235 71 977 46 71 669 50

Training examples

You can simply train with LibriSpeech dataset like below:

  • Example1: Train the conformer-lstm model with filter-bank features on GPU.
$ python ./openspeech_cli/ \
    dataset=librispeech \
    dataset.dataset_download=True \
    dataset.dataset_path=$DATASET_PATH \
    dataset.manifest_file_path=$MANIFEST_FILE_PATH \  
    vocab=libri_subword \
    model=conformer_lstm \
    audio=fbank \
    lr_scheduler=warmup_reduce_lr_on_plateau \
    trainer=gpu \

You can simply train with KsponSpeech dataset like below:

  • Example2: Train the listen-attend-spell model with mel-spectrogram features On TPU:
$ python ./openspeech_cli/ \
    dataset=ksponspeech \
    dataset.dataset_path=$DATASET_PATH \
    dataset.manifest_file_path=$MANIFEST_FILE_PATH \  
    dataset.test_dataset_path=$TEST_DATASET_PATH \
    dataset.test_manifest_dir=$TEST_MANIFEST_DIR \
    vocab=kspon_character \
    model=listen_attend_spell \
    audio=melspectrogram \
    lr_scheduler=warmup_reduce_lr_on_plateau \
    trainer=tpu \

You can simply train with AISHELL-1 dataset like below:

  • Example2: Train the quartznet model with mfcc features On GPU with FP16:
$ python ./openspeech_cli/ \
    dataset=aishell \
    dataset.dataset_path=$DATASET_PATH \
    dataset.dataset_download=True \
    dataset.manifest_file_path=$MANIFEST_FILE_PATH \  
    vocab=aishell_character \
    model=quartznet15x5 \
    audio=mfcc \
    lr_scheduler=warmup_reduce_lr_on_plateau \
    trainer=gpu-fp16 \

Evaluation examples

  • Example1: Evaluation the listen_attend_spell model:
$ python ./openspeech_cli/ \
    audio=melspectrogram \
    eval.model_name=listen_attend_spell \
    eval.dataset_path=$DATASET_PATH \
    eval.checkpoint_path=$CHECKPOINT_PATH \
  • Example2: Evaluation the listen_attend_spell, conformer_lstm models with ensemble:
$ python ./openspeech_cli/ \
    audio=melspectrogram \
    eval.model_names=(listen_attend_spell, conformer_lstm) \
    eval.dataset_path=$DATASET_PATH \
    eval.checkpoint_paths=($CHECKPOINT_PATH1, $CHECKPOINT_PATH2) \
    eval.ensemble_weights=(0.3, 0.7) \
    eval.ensemble_method=weighted \


This project recommends Python 3.7 or higher.
We recommend creating a new virtual environment for this project (using virtual env or conda).


  • numpy: pip install numpy (Refer here for problem installing Numpy).
  • pytorch: Refer to PyTorch website to install the version w.r.t. your environment.
  • librosa: conda install -c conda-forge librosa (Refer here for problem installing librosa)
  • torchaudio: pip install torchaudio==0.6.0 (Refer here for problem installing torchaudio)
  • sentencepiece: pip install sentencepiece (Refer here for problem installing sentencepiece)
  • pytorch-lightning: pip install pytorch-lightning (Refer here for problem installing pytorch-lightning)
  • hydra: pip install hydra-core --upgrade (Refer here for problem installing hydra)
  • warp-rnnt: Refer to warp-rnnt page to install the library.
  • ctcdecode: Refer to ctcdecode page to install the library.

Install from pypi

You can install openspeech with pypi.

pip install openspeech-core

Install from source

Currently we only support installation from source code using setuptools. Checkout the source code and run the
following commands:

$ ./

Install Apex (for 16-bit training)

For faster training install NVIDIA's apex library:

$ git clone
$ cd apex

# ------------------------
# OPTIONAL: on your cluster you might need to load CUDA 10 or 9
# depending on how you installed PyTorch

# see available modules
module avail

# load correct CUDA before install
module load cuda-10.0
# ------------------------

# make sure you've loaded a cuda version > 4.0 and < 7.0
module load gcc-6.1.0

$ pip install -v --no-cache-dir --global-option="--cpp_ext" --global-option="--cuda_ext" ./