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# minSupportedExternalSyncFrameDuration

The minimum frame duration that can be passed as the `videoFrameDuration` when directing your device input to follow an external sync device.

```
var minSupportedExternalSyncFrameDuration: CMTime { get }
```

## Discussion

Use this property as the minimum allowable frame duration to pass to `AVCaptureDeviceInput/follow:externalSyncDevice:videoFrameDuration:delegate:` when you want to follow an external sync device. This property returns `kCMTimeInvalid` when the device’s’ current configuration does not support external sync device following.

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