# Advanced features

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Beyond the core audio controls, the Video SDK for macOS offers several advanced audio features.

## Select an audio device

Desktop setups often have several microphones and speakers attached. Enumerate them with `getMicList` and `getSpeakerList`, then activate one with `selectMic` or `selectSpeaker`.

```swift
let audioHelper = ZMVideoSDK.shared()?.getAudioHelper()

// Enumerate devices.
let micList = audioHelper?.getMicList()
let speakerList = audioHelper?.getSpeakerList()

// Activate a specific device by ID and name.
audioHelper?.selectMic("micDeviceID", deviceName: "micDeviceName")
audioHelper?.selectSpeaker("speakerDeviceID", deviceName: "speakerDeviceName")
```

```objectivec
ZMVideoSDKAudioHelper *audioHelper = [[ZMVideoSDK sharedVideoSDK] getAudioHelper];

// Enumerate devices.
NSArray<ZMVideoSDKMicDevice *> *micList = [audioHelper getMicList];
NSArray<ZMVideoSDKSpeakerDevice *> *speakerList = [audioHelper getSpeakerList];

// Activate a specific device by ID and name.
[audioHelper selectMic:@"micDeviceID" deviceName:@"micDeviceName"];
[audioHelper selectSpeaker:@"speakerDeviceID" deviceName:@"speakerDeviceName"];
```

## Subscribe to raw audio data

To access raw audio frames, subscribe through the `ZMVideoSDKAudioHelper`. After subscribing, the SDK delivers audio frames to your delegate's raw-data callbacks.

```swift
let audioHelper = ZMVideoSDK.shared()?.getAudioHelper()
audioHelper?.subscribe()
// When you no longer need raw audio:
audioHelper?.unSubscribe()
```

```objectivec
ZMVideoSDKAudioHelper *audioHelper = [[ZMVideoSDK sharedVideoSDK] getAudioHelper];
[audioHelper subscribe];
// When you no longer need raw audio:
[audioHelper unSubscribe];
```

For the raw audio callbacks and how to process mixed, per-user, and shared audio, see [Receive raw data](/docs/video-sdk/macos/raw-data/receive-raw-data/#receive-raw-audio-data).