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Natural Language Understanding - C++

VDK features only one Natural Language Understanding library: VNLU (Vivoka).

VNLU is the name of the Natural Language Understanding engine created by Vivoka. It is integrated in the VSDK framework under the designation VSDK-VNLU. It is designed to work with an ASR engine.

Supported Languages

Currently 5 languages are supported:

  • 🇫🇷 fra-FR → French of France

  • 🇺🇸 eng-US → Enlish of United States

  • 🇮🇹 ita-IT → Italian from Italy

  • 🇪🇸 spa-ES → Spanish from Spain

  • 🇩🇪 deu-DE → German from Germany

Supported Features

Here is a list of all supported features by this engine:

Feature name


Intent extraction

Ability to extract the intention of a sentence

Entities extraction

Ability to extract zero or more entities from a sentence

Specialized to a custom domain

Fine-tuned on customer domain

Engine Configuration

Like any other engine in VSDK, this one also have its own configuration that needs to be provided as a JSON file when instantiating the engine.

Here is a sample of the configuration:

  "version": "2.0",
  "vnlu": {
    "paths": {
      "data_root": "../data"
    "nlu": {
      "parsers": {
        "p1": {
          "model": "my-custom-model.vum"

This configuration represents the minimum required in order to operate the engine.

Required Resources

As seen in the configuration file above, only 1 resource file is required in order to run the engine and it is the .vum (Vivoka Understanding Model) file.

Sample Code

#include <vsdk/Exception.hpp>
#include <vsdk-nlu/nlu/vnlu/Engine.hpp>
#include <vsdk-nlu/nlu/vnlu/Parser.hpp>
std::string getMoreText();
int main(int argc, char * argv) try
    auto engine = Vsdk::Nlu::Engine::make<Vsdk::Nlu::Vnlu::Engine>("vsdk.json");
    auto parser = engine->parser("p1");
    parser->subscribe([](Vsdk::Nlu::Vnlu::Parser::Result const & result)
        fmt::print("Result: {}\n", result.json.dump(4));
    return EXIT_SUCCESS;
catch (std::exception & const e)
    fmt::print(stderr, "A fatal error occured:\n");
    return EXIT_FAILURE;

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