VoskJs

VoskJs is a NodeJs developers toolkit to use Vosk offline speech recognition engine. It give you:

• simple sentence-based transcript APIs
• command line utility voskjs
• demo HTTP transcript server voskjshttp.

VoskJs can be used for speech recognition processing in different scenarios:

• Single-user/standalone programs (e.g. perfect for single-user embedded systems)
• Multi-user/multi-core server architectures

What's Vosk?

Vosk is an open source embedded (offline, on-premise) speech-to-text engine which can run in real time also on small devices. It's based on Kaldi, but Nikolay V. Shmyrev's Vosk offers a smarti, simplified and performant interface!

Documentation:

• https://alphacephei.com/vosk/
• https://github.com/alphacep/vosk-api

What's VoskJs?

The goal of the project is to:

1. Create an simple function API layer on top of already existing Vosk nodejs binding, supplying main sentence-based speech-to-text functionalities:

   • const model = loadModel(modelDirectory)

     Loads once in RAM memory a specific Vosk engine model from a model directory.

   • transcriptFromFile(fileName, model, options)

   • transcriptFromBuffer(buffer, model, options)

     At run-rime, transcripts a speech file or buffer (in WAV/PCM format), through the Vosk engine Recognizer. It supply speech-to-text transcript detailed info.

   • freeModel(mode)

   Using the simple transcript interface you can build your standalone custom application, accessing async functions suitable to run on a usual single thread nodejs program.

2. voskjs

   command line program to test Vosk transcript with specific models (some tests and command line usage here).

3. voskjshttp

   a simple demo HTTP server to transcript speech files.

4. Build your own server. Some usage examples here.

🛍 Install

1. Install Vosk engine and this nodejs module

• Install vosk-api engine

  pip3 install vosk 

  See also: https://alphacephei.com/vosk/install

• Install this module, as global package if you want to use CLI command voskjs

  npm install -g @solyarisoftware/voskjs

2. Install/Download Vosk models

mkdir your/path/models && cd models

# English large model
wget https://alphacephei.com/vosk/models/vosk-model-en-us-aspire-0.2.zip
unzip vosk-model-en-us-aspire-0.2.zip

# English small model
wget http://alphacephei.com/vosk/models/vosk-model-small-en-us-0.15.zip
unzip vosk-model-small-en-us-0.15.zip

# Italian model model
wget https://alphacephei.com/vosk/models/vosk-model-small-it-0.4.zip
unzip vosk-model-small-it-0.4.zip

More about available Vosk models here: https://alphacephei.com/vosk/models

3. Demo audio files

Directory audio contains some English language speech audio files, coming from a Mozilla DeepSpeech repo. Source: Mozilla DeepSpeech audio samples These files are used for some tests and comparisons.

Usage

Some transcript usage examples here

• voskjs Command line utility

• Simple transcript program

• Transcript with grammar

• Transcript HTTP server

• SocketIO server pseudocode

🛠 Tests

Some tests / notes here:

• Transcript using English language, large model
• Transcript using English language, small model
• Comparison between Vosk and Mozilla DeepSpeech (latencies)
• Multithread stress test (10 requests in parallel)
• HTTP Server benchmark test
• Latency tests

To do

• 💣 Important open issue to be solved: solyarisoftware#3 with a temporrary workaround: alphacep/vosk-api#516 (comment)

• Implement a simplified interface for all Vosk-api functions

• Deepen grammar usage with examples

• Review stress and performances tests (especially for the HTTP server)

• To speedup latencies, rethink transcript interface, maybe with an initialization phases, including Model creation an the Recognizer(s) creation

✋ How to contribute

Any contribute is welcome.

• Discussions. Please open a new discussion (a publich chat on github) for any specific open topic, for a clarification, change request proposals, etc.
• Issues Please submit issues for bugs, etc
• e-mail You can contact me privately, via email

🙏 Credits

Thanks to Nicolay V. Shmyrev, author of Vosk project, for the help about nodeJs API bindings for multi-threading management

See also:

• What's the Vosk CPU usage at run-time?
• How to set-up a Vosk multi-threads server architecture in NodeJs

License

MIT (c) Giorgio Robino

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