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# AVExternalSyncDevice

An external sync device connected to a host device that can be used to drive the timing of an internal component, such as a camera sensor.

```
class AVExternalSyncDevice
```

## Overview

Each instance of [`AVExternalSyncDevice`](/documentation/AVFoundation/AVExternalSyncDevice) corresponds to a physical external device that can drive an internal component, like a camera readout. You cannot create instances of [`AVExternalSyncDevice`](/documentation/AVFoundation/AVExternalSyncDevice). Instead, you obtain an array of all currently available external sync devices using [`AVExternalSyncDevice.DiscoverySession`](/documentation/AVFoundation/AVExternalSyncDevice/DiscoverySession).

## Topics

### Finding and monitoring devices

[`AVExternalSyncDevice.DiscoverySession`](/documentation/AVFoundation/AVExternalSyncDevice/DiscoverySession)

A means of discovering and monitoring connection / disconnection of external sync devices to the host.

### Inspecting a device

[`clock`](/documentation/AVFoundation/AVExternalSyncDevice/clock)

A clock representing the source of time from the external sync device.

[`productID`](/documentation/AVFoundation/AVExternalSyncDevice/productID)

The USB product identifier associated with the external sync device.

[`signalCompensationDelay`](/documentation/AVFoundation/AVExternalSyncDevice/signalCompensationDelay)

Delay to wait before starting the frame capture.

[`status`](/documentation/AVFoundation/AVExternalSyncDevice/status)

The status of the externally connected device.

[`uuid`](/documentation/AVFoundation/AVExternalSyncDevice/uuid)

A unique identifier for an external sync device.

[`vendorID`](/documentation/AVFoundation/AVExternalSyncDevice/vendorID)

The USB vendor identifier associated with the external sync device.


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