---
title: minSupportedExternalSyncFrameDuration
framework: avfoundation
role: symbol
role_heading: Instance Property
path: avfoundation/avcapturedevice/minsupportedexternalsyncframeduration
---

# minSupportedExternalSyncFrameDuration

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

## Declaration

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

## Discussion

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.

## See Also

### Synchronizing with external devices

- [isFollowingExternalSyncDevice](avfoundation/avcapturedevice/isfollowingexternalsyncdevice.md)
- [isVideoFrameDurationLocked](avfoundation/avcapturedevice/isvideoframedurationlocked.md)
- [minSupportedLockedVideoFrameDuration](avfoundation/avcapturedevice/minsupportedlockedvideoframeduration.md)