let audioCapturer = await audio.createAudioCapturer(audioCapturerOptions);
var state = audioRenderer.state;
```
## When to Use
You can use the APIs provided by **AudioCapturer** to record raw audio files.
### State Check
During application development, you are advised to use **on('stateChange')** to subscribe to state changes of the **AudioCapturer** instance. This is because some operations can be performed only when the audio capturer is in a given state. If the application performs an operation when the audio capturer is not in the given state, the system may throw an exception or generate other undefined behavior.
For details about the APIs, see [AudioCapturer in Audio Management](../reference/apis/js-apis-audio.md).
**Figure 1** Audio capturer state
## How to Develop
1. Use **createAudioCapturer()** to create an **AudioCapturer** instance.
Set parameters of the **AudioCapturer** instance in **audioCapturerOptions**. This instance is used to capture audio, control and obtain the recording status, and register a callback for notification.
2. (Optional) Subscribe to audio capturer state change events using the **on('stateChange')** API.
If an application wants to take some action based on the state updates in capturer, the application can subscribe to the state change event.
There are more events that applications can subscribe to, such as 'markReach' and 'periodReach'. Refer to [Audio](../reference/apis/js-apis-audio.md) for more details.
2. (Optional) Use **on('stateChange')** to subscribe to audio renderer state changes.
If an application needs to perform some operations when the audio renderer state is updated, the application can subscribe to the state changes. For more events that can be subscribed to, see [Audio Management](../reference/apis/js-apis-audio.md).
```js
audioCapturer.on('stateChange',(state)=>{
console.info('AudioCapturerLog: Changed State to : '+state)
switch(state){
case audio.AudioState.STATE_PREPARED:
console.info('--------CHANGE IN AUDIO STATE----------PREPARED--------------');
console.info('Audio State is : Prepared');
break;
case audio.AudioState.STATE_RUNNING:
console.info('--------CHANGE IN AUDIO STATE----------RUNNING--------------');
console.info('Audio State is : Running');
break;
case audio.AudioState.STATE_STOPPED:
console.info('--------CHANGE IN AUDIO STATE----------STOPPED--------------');
console.info('Audio State is : stopped');
break;
case audio.AudioState.STATE_RELEASED:
console.info('--------CHANGE IN AUDIO STATE----------RELEASED--------------');
console.info('Audio State is : released');
break;
default:
console.info('--------CHANGE IN AUDIO STATE----------INVALID--------------');
console.info('Audio State is : invalid');
break;
}
caseaudio.AudioState.STATE_PREPARED:
console.info('--------CHANGE IN AUDIO STATE----------PREPARED--------------');
console.info('Audio State is : Prepared');
break;
caseaudio.AudioState.STATE_RUNNING:
console.info('--------CHANGE IN AUDIO STATE----------RUNNING--------------');
console.info('Audio State is : Running');
break;
caseaudio.AudioState.STATE_STOPPED:
console.info('--------CHANGE IN AUDIO STATE----------STOPPED--------------');
console.info('Audio State is : stopped');
break;
caseaudio.AudioState.STATE_RELEASED:
console.info('--------CHANGE IN AUDIO STATE----------RELEASED--------------');
console.info('Audio State is : released');
break;
default:
console.info('--------CHANGE IN AUDIO STATE----------INVALID--------------');
console.info('Audio State is : invalid');
break;
}
});
```
3. Call the **start()** function on the AudioCapturer instance to start/resume the recording task.\
The capturer state will be STATE_RUNNING once the start is complete. The application can then begin reading buffers.
```
await audioCapturer.start();
if (audioCapturer.state == audio.AudioState.STATE_RUNNING) {
5. Read the captured audio data and convert it to a byte stream. Call **read()** repeatedly to read the data until the application wants to stop the recording.
The following example shows how to write recorded data into a file.
Application developers should keep in mind that an AudioCapturer is state-based.
That is, the AudioCapturer has an internal state that the application must always check when calling recorder control APIs, because some operations are only acceptable while the capturer is in a given state.\
The system may throw an error/exception or generate other undefined behaviour if the application performs an operation while capturer is in an improper state.
7. After the task is complete, call **release()** to release related resources.
## **Other APIs**
See [AudioCapturer in the Audio API](../reference/apis/js-apis-audio.md) for more useful APIs like **getAudioTime**, **getCapturerInfo** and **getStreamInfo**.
