Rhino — Flutter Quick Start

Platforms

• Flutter (1.20.0+)
• Android (44+, API 19+)
• iOS (9.0+)

Requirements

• Flutter SDK
• Android SDK (16+)
• JDK (8+)
• Xcode (9+)

Picovoice Account & AccessKey

Signup or Login to Picovoice Console to get your AccessKey. Make sure to keep your AccessKey secret.

Quick Start

Setup

1. Install Flutter SDK.

2. Run flutter doctor to determine any missing requirements.

3. Add the Rhino plugin to your app project by referencing it in pubspec.yaml:

dependencies:  
  rhino_flutter: ^<version>

4. Enable the proper permission for recording with the hardware's microphone on both iOS and Android:

<key>NSMicrophoneUsageDescription</key>
<string>[Permission explanation]</string>

<uses-permission android:name="android.permission.RECORD_AUDIO" />
<uses-permission android:name="android.permission.INTERNET" />

Usage

1. Add the context file (either a pre-built context file (.rhn) from the Rhino GitHub Repository or a custom context created with the Picovoice Console) to the assets folder in the project directory.

2. Add the path to the pubspec.yaml:

flutter:
  assets:
    - assets/${CONTEXT_FILE}

3. Create an instance of RhinoManager using the constructor RhinoManager.create that infers custom commands:

import 'package:rhino/rhino_manager.dart';
import 'package:rhino/rhino_error.dart';

try {
    _rhinoManager = await RhinoManager.create(
            "{ACCESS_KEY}"
            "assets/${CONTEXT_FILE}",
            _inferenceCallback);
} on RhinoException catch (err) {
    // handle rhino init error
}

The _inferenceCallback parameter is a function that is invoked when Rhino made an intent inference.

void _infererenceCallback(RhinoInference inference) {
    if(inference.isUnderstood!){
        String intent = inference.intent!
        Map<String, String> slots = inference.slots!
        // take action based on inferred intent and slot values
    }
    else {
        // handle unsupported commands
    }    
}

Start audio capture and intent inference:

try{
    await _rhinoManager.process();
} on RhinoException catch (ex) {
    // deal with either audio exception     
}

Once an inference has been made, the _inferenceCallback will be invoked and audio capture will stop automatically. Release resources explicitly when done with Rhino:

await _rhinoManager.delete();

Custom Contexts

1. Create custom contexts with the Picovoice Console. Download the custom context file (.rhn).

2. Add the file to the assets folder in the project directory.

3. Add it to the pubspec.yaml:

flutter:
  assets:
    - assets/${CUSTOM_CONTEXT_FILE}

3. Create an instance of RhinoManager using the constructor RhinoManager.create with the custom context.

Non-English Languages

Use the corresponding model file (.pv) to detect non-English wake words. The model files for all supported languages are available on the Rhino GitHub repository.

1. Add the file to the assets folder in the project directory.
2. Add it to the pubspec.yaml:

flutter:
  assets:
    - assets/${CUSTOM_CONTEXT_FILE}
    - assets/${MODEL_FILE}

3. Pass in the model file using the modelPath parameter to change the language:

try{
    _rhinoManager = await RhinoManager.create(
        "{ACCESS_KEY}"
        "assets/${CUSTOM_CONTEXT_FILE}",
        _inferenceCallback,
        modelPath: "assets/${MODEL_FILE}");
} on RhinoException catch (err) {
    // handle rhino init error
}

Demo

For the Rhino Flutter SDK, we offer demo applications that demonstrate how to use the Speech-to-Intent engine on real-time audio streams (i.e. microphone input).

Setup

Clone the Rhino GitHub Repository:

git clone --recurse-submodules https://github.com/Picovoice/rhino.git

Usage

1. Replace {YOUR_ACCESS_KEY_HERE} with a valid AccessKey in the demo/flutter/lib/main.dart file:

2. Copy assets:

cd rhino/demo/flutter
bash copy_assets.sh

NOTE: on Windows, Git Bash or another bash shell is required, or you will have to manually copy

• The android context into ${DEMO_FOLDER}/assets/contexts/android.
• The iOS context into ${DEMO_FOLDER}/assets/contexts/ios.

3. Build and deploy the demo to your device:

flutter run

For more information on our Rhino demos for Flutter, head over to our GitHub repository.

Resources

Packages

• rhino_flutter on pub.dev

API

• rhino_flutter API Docs

GitHub

• Rhino Flutter SDK on GitHub
• Rhino Flutter Demos on GitHub

Benchmark

• Speech-to-Intent Benchmark

Further Reading

• Offline Speech Recognition in Flutter: No Siri, No Google, and No, It’s Not Speech-To-Text

Video

• Offline Speech Recognition with Flutter (iOS/Android)