---
title: opticalFlow
framework: videotoolbox
role: symbol
role_heading: Instance Property
path: videotoolbox/vtframerateconversionparameters/opticalflow
---

# opticalFlow

A property that defines the optical flow for an object.

## Declaration

```swift
var opticalFlow: VTFrameProcessorOpticalFlow? { get }
```

## Discussion

Discussion An optional VTFrameProcessorReadOnlyOpticalFlow contains the forward and backward optical flow of the next frame. This value is only needed if the optical flow is pre-computed. For the first frame it will always be nil.

## See Also

### Inspecting the parameters

- [sourceFrame](videotoolbox/vtframerateconversionparameters/sourceframe.md)
- [nextFrame](videotoolbox/vtframerateconversionparameters/nextframe.md)
- [interpolationPhase](videotoolbox/vtframerateconversionparameters/interpolationphase-2jky5.md)
- [submissionMode](videotoolbox/vtframerateconversionparameters/submissionmode-swift.property.md)
- [VTFrameRateConversionParameters.SubmissionMode](videotoolbox/vtframerateconversionparameters/submissionmode-swift.enum.md)