Android build

For Android make sure you use mavenCentral repository and just add aar to dependencies.

repositories {
    mavenCentral()
}

dependencies {
    implementation group: 'com.alphacephei', name: 'vosk-android', version: '0.3.32+'
}

In case you still want to build android library, do the following:

export ANDROID_SDK_HOME=...
cd vosk-api/android/lib
./build-vosk.sh
gradle build

Please note that medium blog post about 64-bit is not relevant anymore, the script builds x86, arm64 and armv7 libraries automatically without any modifications.

For an example Android application using the Vosk-API check the https://github.com/alphacep/vosk-android-demo project.

iOS build

Available on request. Drop us an e-mail at contact@alphacephei.com. Describe the organization you are working at if any. Describe the purpose of the project.

Python installation from Pypi

The easiest way to install vosk api is with pip. You do not have to compile anything.

We currently support the following platforms:

  • Linux on x86_64
  • Raspbian on Raspberry Pi 3/4
  • Linux on arm64
  • OSX (both x86 and M1)
  • Windows x86 and 64

We do not support:

  • ARMv6 (Rpi Zero is too slow)
  • Windows ARM64

Make sure you have up-to-date pip and python3 versions:

  • Python version: 3.5-3.9
  • pip version: 20.3 and newer.

Upgrade python and pip if needed. Then install vosk on Linux/Mac from pip:

pip3 install vosk

Please note that some platforms are not fully supported by pip, for example on riscv64 you have install from released wheels:

pip3 install https://github.com/alphacep/vosk-api/releases/download/v0.3.42/vosk-0.3.42-py3-none-linux_riscv64.whl

If you have trouble installing, check the output of the following commands and provide it for reference:

python3 --version
pip3 --version
pip3 -v install vosk

Websocket Server and GRPC server

We also provide a websocket server and grpc server which can be used in telephony and other applications. With bigger models adapted for 8khz audio it provides more accuracy.

The server is installable from docker and can be run with a single command:

docker run -d -p 2700:2700 alphacep/kaldi-en:latest

For details see https://github.com/alphacep/vosk-server

Compilation from source

If you still want to build from scratch, you can compile Kaldi and Vosk yourself. Please note that compilation is not straightforward and includes several nuances. We recommend to follow our build process we document in Docker files:

https://github.com/alphacep/vosk-api/tree/master/travis

https://github.com/alphacep/vosk-server/blob/master/docker/Dockerfile.kaldi-vosk-server

https://github.com/alphacep/vosk-server/blob/master/docker/Dockerfile.kaldi-vosk-server-gpu

You might need to build yourself if you want to try CUDA decoder since we do not provide CUDA binaries.

For Windows and Raspberry Pi we recommend cross-build with mingw and corresponding ARM toolchain. See docker files for details.

The outline of the build is here.

Building the library libvosk.so

Take a note that you need special Kaldi from our repo and also you need special compilation mode (openblas+clapack or mkl, shared, optionally cuda). For more details on build see our dockerfiles.

cd <KALDI_ROOT>
git clone -b vosk --single-branch https://github.com/alphacep/kaldi /opt/kaldi
cd kaldi/tools
make openfst
./extras/install_openblas_clapack.sh
cd ../src
./configure --mathlib=OPENBLAS_CLAPACK --shared
make -j 10 online2 lm rnnlm
cd ../..
git clone https://github.com/alphacep/vosk-api
cd vosk-api/src
KALDI_ROOT=<KALDI_ROOT> make

Python module build

To build Python module you need to build a library libvosk.so in vosk-api/src folder first. You also can download prebuilt library from github releases. Put it inside vosk-api/src. Now lets build python module

cd ../vosk-api/python
python3 setup.py install

Usage examples

Python

You can transcribe a file with a simple vosk-transcriber command line tool:

vosk-transcriber -i test.mp4 -o test.txt
vosk-transcriber -i test.mp4 -t srt -o test.srt
vosk-transcriber -l fr -i test.m4a -t srt -o test.srt
vosk-transcriber --list-languages

To run python samples, clone the vosk-api and run the following commands:

git clone https://github.com/alphacep/vosk-api
cd vosk-api/python/example
python3 ./test_simple.py test.wav

When using your own audio file make sure it has the correct format - PCM 16khz 16bit mono. Otherwise, if you have ffmpeg installed, you can use test_ffmpeg.py, which does the conversion for you.

Find more examples such as using a microphone, decoding with a fixed small vocabulary or speaker identification setup in the python/example subfolder

For more info see this video:

Java

We distribute Vosk library on MavenCentral. To plug the library simply add MavenCentral repo and add the dependency:

repositories {
    mavenCentral()
}

dependencies {
    implementation group: 'net.java.dev.jna', name: 'jna', version: '5.7.0'
    implementation group: 'com.alphacephei', name: 'vosk', version: '0.3.31+'
}

For example of a full demo project built with gradle see:

https://github.com/alphacep/vosk-api/tree/master/java/demo

The code samples are here:

https://github.com/alphacep/vosk-api/blob/master/java/demo/src/main/java/org/vosk/demo/DecoderDemo.java

We support Java 8+ on Linux, OSX and Windows.

C#

We recommend install with nuget. See https://www.nuget.org/packages/Vosk/

To try the system

git clone https://github.com/alphacep/vosk-api
cd vosk-api/csharp/demo
dotnet run

To integrate library in your software simply execute

dotnet add package Vosk

and then follow the example in our code.

For details of the wrapper see the nuget folder.

Nuget should work on Windows and Linux. We might add OSX later.

Javascript/Nodejs

We implement node bindings with node-ffi-napi library and thus should support more or less recent node versions

To install node module simply run

npm install vosk

For example of the API see the code on github.