---
title: audioOutputDeviceUniqueID
framework: avfoundation
role: symbol
role_heading: Instance Property
path: avfoundation/avsamplebufferaudiorenderer/audiooutputdeviceuniqueid
---

# audioOutputDeviceUniqueID

The unique identifier of the output device used to play audio.

## Declaration

```swift
var audioOutputDeviceUniqueID: String? { get set }
```

## Discussion

Discussion The default value of this property is nil, which indicates the use of the default audio device. Otherwise, set the value to an NSString containing the unique identifier of the Core Audio output device to use for audio output. kAudioDevicePropertyDeviceUID is a suitable source of audio output device unique IDs. Modifying this property while the timebase’s rate isn’t 0.0 may cause the rate to briefly change to 0.0. On macOS, you can use the audio device clock as the AVSampleBufferRenderSynchronizer and all attached AVQueuedSampleBufferRendering timebase clocks. If you modify the audioOutputDeviceUniqueID, the clocks of all these timebases may also change. If you attach multiple renderers with different values for audioOutputDeviceUniqueID to the same buffer renderer synchronizer, audio may not stay in sync during playback. To avoid this, ensure that all synchronized sample buffer renderers are using the same audio output device.

## See Also

### Managing audio output

- [volume](avfoundation/avsamplebufferaudiorenderer/volume.md)
- [isMuted](avfoundation/avsamplebufferaudiorenderer/ismuted.md)