Rhino Speech-to-Intent
Flutter Quick Start

Platforms

• Flutter (2.8.1+)
• Android (5.0+, API 21+)
• iOS (11.0+)

Requirements

• Flutter SDK
• Android SDK (21+)
• JDK (8+)
• Xcode (11+)

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.

Alternatively, if the context file is deployed to the device with a different method, the absolute path to the file on device can be used.

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
}

Alternatively, if the model file is deployed to the device with a different method, the absolute path to the file on device can be used.

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