npm package: @picovoice/rhino-angular
Description: Angular service for Rhino Web SDK
Author: Picovoice Inc
Latest version: 3.0.4
Deprecated: Package no longer supported. Contact Support at https://www.npmjs.com/support for more info.

# Rhino Binding for Angular

## Rhino Speech-to-Intent engine

Made in Vancouver, Canada by [Picovoice](https://picovoice.ai)

Rhino is Picovoice's Speech-to-Intent engine. It directly infers intent from spoken commands within a given context of
interest, in real-time. For example, given a spoken command:

> Can I have a small double-shot espresso?
Rhino infers that the user would like to order a drink and emits the following inference result:
```json
{
  "isUnderstood": "true",
  "intent": "orderBeverage",
  "slots": {
    "beverage": "espresso",
    "size": "small",
    "numberOfShots": "2"
  }
}
```

Rhino is:

* using deep neural networks trained in real-world environments.
* compact and computationally-efficient, making it perfect for IoT.
* self-service. Developers and designers can train custom models using [Picovoice Console](https://console.picovoice.ai/).

## Compatibility

- Chrome / Edge
- Firefox
- Safari

### Restrictions

IndexedDB and WebWorkers are required to use `Rhino Angular`. Browsers without support (i.e. Firefox Incognito Mode) 
should use the [`RhinoWeb binding`](https://github.com/Picovoice/rhino/tree/master/binding/web) main thread method.

## AccessKey

Rhino requires a valid Picovoice `AccessKey` at initialization. `AccessKey` acts as your credentials when using Rhino SDKs.
You can get your `AccessKey` for free. Make sure to keep your `AccessKey` secret.
Signup or Login to [Picovoice Console](https://console.picovoice.ai/) to get your `AccessKey`.

## Installation

Using `yarn`:

```console
yarn add @picovoice/rhino-angular @picovoice/web-voice-processor
```

or using `npm`:

```console
npm install --save @picovoice/rhino-angular @picovoice/web-voice-processor
```

## Usage

There are two methods to initialize Rhino:

### Public Directory

**NOTE**: Due to modern browser limitations of using a file URL, this method does __not__ work if used without hosting a server.

This method fetches [the model file](https://github.com/Picovoice/rhino/blob/master/lib/common/rhino_params.pv) from the public directory and feeds it to Rhino. Copy the model file into the public directory:

```console
cp ${RHINO_MODEL_FILE} ${PATH_TO_PUBLIC_DIRECTORY}
```

The same procedure can be used for the [Rhino context](https://github.com/Picovoice/rhino/tree/master/resources/contexts) (`.rhn`) files.

### Base64

**NOTE**: This method works without hosting a server, but increases the size of the model file roughly by 33%.

This method uses a base64 string of the model file and feeds it to Rhino. Use the built-in script `pvbase64` to base64 your model file:

```console
npx pvbase64 -i ${RHINO_MODEL_FILE} -o ${OUTPUT_DIRECTORY}/${MODEL_NAME}.js
```

The output will be a js file which you can import into any file of your project. For detailed information about `pvbase64`,
run:

```console
npx pvbase64 -h
```

The same procedure can be used for the [Rhino context](https://github.com/Picovoice/rhino/tree/master/resources/contexts) (`.rhn`) files.

### Rhino Model

Rhino saves and caches your model (`.pv`) and context (`.rhn`) files in the IndexedDB to be used by Web Assembly.
Use a different `customWritePath` variable to hold multiple model values and set the `forceWrite` value to true to force an overwrite of the model file.
If the model (`.pv`) or context (`.rhn`) files change, `version` should be incremented to force the cached model to be updated. Either `base64` or `publicPath` must be set to instantiate Rhino. If both are set, Rhino will use the `base64` parameter.

```typescript
// Context (.rhn)
const rhinoContext = {
  publicPath: ${CONTEXT_RELATIVE_PATH},
  // or
  base64: ${CONTEXT_BASE64_STRING},
  // Optionals
  customWritePath: 'custom_context',
  forceWrite: true,
  version: 1,
  sensitivity: 0.5,
}
// Model (.pv)
const rhinoModel = {
  publicPath: ${MODEL_RELATIVE_PATH},
  // or
  base64: ${MODEL_BASE64_STRING},
  // Optionals
  customWritePath: 'custom_model',
  forceWrite: true,
  version: 1,
}
```

Additional engine options are provided via the `options` parameter.
Use `endpointDurationSec` and `requireEndpoint` to control the engine's endpointing behavior.
An endpoint is a chunk of silence at the end of an utterance that marks the end of spoken command.

```typescript
// Optional. These are the default values
const options = {
  endpointDurationSec: 1.0,
  requireEndpoint: true,
}
```

### Initialize Rhino

First subscribe to the events from `RhinoService`. There are five subscription events:

- `inference$`: Returns the inference.
- `contextInfo$`: Returns the context info once `Rhino` has loaded successfully.
- `isLoaded$`: Returns true if `Rhino` has loaded successfully.
- `isListening$`: Returns true if `WebVoiceProcessor` has started successfully and Rhino is listening for an utterance.
- `error$`:  Returns any errors occurred.

```typescript
import { Subscription } from "rxjs"
import { RhinoService } from "@picovoice/rhino-angular"
...
  constructor(private rhinoService: RhinoService) {
    this.contextInfoSubscription = rhinoService.contextInfo$.subscribe(
      contextInfo => {
        console.log(contextInfo);
      });
    this.inferenceSubscription = rhinoService.inference$.subscribe(
      inference => {
        console.log(inference);
      });
    this.isLoadedSubscription = rhinoService.isLoaded$.subscribe(
      isLoaded => {
        console.log(isLoaded);
      });
    this.isListeningSubscription = rhinoService.isListening$.subscribe(
      isListening => {
        console.log(isListening);
      });
    this.errorSubscription = rhinoService.error$.subscribe(
      error => {
        console.log(error);
      });
  }
```

After setting up the subscriber events, initialize `Rhino`:

```typescript
async ngOnInit() {
  await this.rhinoService.init(
    ${ACCESS_KEY},
    rhinoContext,
    rhinoModel,
  );
}
````

### Process Audio Frames

The Rhino Angular binding uses [WebVoiceProcessor](https://github.com/Picovoice/web-voice-processor) to record audio.
To start detecting detecting an inference, run the `process` function:
```typescript
await this.rhinoService.process();
```
The `process` function initializes WebVoiceProcessor.
Rhino will then listen and process frames of microphone audio until it reaches a conclusion, then return the result via the `inference$` event.
Once a conclusion is reached Rhino will enter a paused state. From the paused state Rhino call `process` again to detect another inference.

### Cleanup

When you are done with Rhino call `release`. This cleans up all resources used by Rhino and WebVoiceProcessor.

```typescript
ngOnDestroy() {
  this.contextInfoSubscription.unsubscribe();
  this.inferenceSubscription.unsubscribe();
  this.isLoadedSubscription.unsubscribe();
  this.isListeningSubscription.unsubscribe();
  this.errorSubscription.unsubscribe();
  this.rhinoService.release();
}
```

If any arguments require changes, call `release` then `init` again to initialize Rhino with the new settings.

## Contexts

Create custom contexts using the [Picovoice Console](https://console.picovoice.ai/).
Train and download a Rhino context file (`.rhn`) for the target platform `Web (WASM)`.
This model file can be used directly with `publicPath`, but, if `base64` is preferable, convert the `.rhn` file to a
base64 JavaScript variable using the built-in `pvbase64` script:

```console
npx pvbase64 -i ${CONTEXT_FILE}.rhn -o ${CONTEXT_BASE64}.js -n ${CONTEXT_BASE64_VAR_NAME}
```

Similar to the model file (`.pv`), context files (`.rhn`) are saved in IndexedDB to be used by Web Assembly.
Either `base64` or `publicPath` must be set for the context to instantiate Rhino.
If both are set, Rhino will use the `base64` model.

```typescript
const contextModel = {
  publicPath: "${CONTEXT_RELATIVE_PATH}",
  // or
  base64: "${CONTEXT_BASE64_STRING}",
}
```

## Switching Languages

In order to make inferences in different language you need to use the corresponding model file (`.pv`).
The model files for all supported languages are available [here](https://github.com/Picovoice/rhino/tree/master/lib/common).

## Demo

For example usage, refer to our [Angular demo application](https://github.com/Picovoice/rhino/tree/master/demo/angular).