k2-sherpa 0.0.1

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Introduction

An ASR server framework in Python, aiming to support both streaming and non-streaming recognition.

Note: Only non-streaming recognition is implemented at present. We will add streaming recognition later.

CPU-bound tasks, such as neural network computation, are implemented in C++; while IO-bound tasks, such as socket communication, are implemented in Python.

Caution: We assume the model is trained using pruned stateless RNN-T from icefa and it is from a directory like pruned_transducer_statelessX where X >=2.

Installation

First, you have to install PyTorch and torchaudio. PyTorch 1.10 is known to work. Other versions may also work.

Second, clone this repository

git clone https://github.com/k2-fsa/sherpa
cd sherpa
pip install -r ./requirements.txt

Third, install C++ extension. You can use one of the following methods.

Option 1: Use pip

pip install k2-sherpa

Option 2: Build from source with setup.py

python3 setup.py install

Option 3: Build from source with cmake

mkdir build
cd build
cmake ..
make -j
export PYTHONPATH=$PWD/../sherpa/python:$PWD/lib:$PYTHONPATH

Usage

First, check that sherpa has been installed successfully:

python3 -c "import sherpa; print(sherpa.__version__)"

It should print the version of sherpa.

Start the server

To start the server, you need to first generate two files:

• (1) The torch script model file. You can use export.py in pruned_transducer_statelessX from icefall

• (2) The BPE model file. You can find it in data/lang_bpe_XXX/bpe.model in icefall, where XXX the number of BPE tokens used in the training.

With the above two files ready, you can start the server with the following command:

sherpa/bin/offline_server.py \
  --port 6006 \
  --num-device 0 \
  --max-batch-size 10 \
  --max-wait-ms 5 \
  --feature-extractor-pool-size 5 \
  --nn-pool-size 1 \
  --nn-model-filename ./path/to/exp/cpu_jit.pt \
  --bpe-model-filename ./path/to/data/lang_bpe_500/bpe.model &

You can use ./sherpa/bin/offline_server.py --help to view the help message.

We provide a pretrained model using the LibriSpeech dataset at https://huggingface.co/csukuangfj/icefall-asr-librispeech-pruned-transducer-stateless3-2022-05-13

The following shows how to use the above pretrained model to start the server.

git lfs install
git clone https://huggingface.co/csukuangfj/icefall-asr-librispeech-pruned-transducer-stateless3-2022-05-13

sherpa/bin/offline_server.py \
  --port 6006 \
  --num-device 0 \
  --max-batch-size 10 \
  --max-wait-ms 5 \
  --feature-extractor-pool-size 5 \
  --nn-pool-size 1 \
  --nn-model-filename ./icefall-asr-librispeech-pruned-transducer-stateless3-2022-05-13/exp/cpu_jit.pt \
  --bpe-model-filename ./icefall-asr-librispeech-pruned-transducer-stateless3-2022-05-13/data/lang_bpe_500/bpe.model

Start the client

After starting the server, you can use the following command to start the client:

./sherpa/bin/offline_client.py \
    --server-addr localhost \
    --server-port 6006 \
    /path/to/foo.wav \
    /path/to/bar.wav

You can use ./sherpa/bin/offline_client.py --help to view the usage message.

The following show how to use the client send some test waves to the server for recognition.

sherpa/bin/offline_client.py \
  --server-addr localhost \
  --server-port 6006 \
  icefall-asr-librispeech-pruned-transducer-stateless3-2022-05-13//test_wavs/1089-134686-0001.wav \
  icefall-asr-librispeech-pruned-transducer-stateless3-2022-05-13//test_wavs/1221-135766-0001.wav \
  icefall-asr-librispeech-pruned-transducer-stateless3-2022-05-13//test_wavs/1221-135766-0002.wav

RTF test

We provide a demo ./sherpa/bin/decode_mainifest.py to decode the test-clean dataset from the LibriSpeech corpus. It creates 50 connections to the server using websockets and sends audio files to the server for recognition. At the end, it will show you the RTF and WER.