<!--
{
  "availability" : [
    "iOS: 6.0.0 -",
    "iPadOS: 6.0.0 -",
    "macCatalyst: 13.0.0 -",
    "macOS: 10.8.0 -",
    "tvOS: 10.2.0 -",
    "visionOS: 1.0.0 -"
  ],
  "documentType" : "symbol",
  "framework" : "VideoToolbox",
  "identifier" : "/documentation/VideoToolbox/VTMotionEstimationOutputHandler",
  "metadataVersion" : "0.1.0",
  "role" : "Type Alias",
  "symbol" : {
    "kind" : "Type Alias",
    "modules" : [
      "Video Toolbox"
    ],
    "preciseIdentifier" : "c:@T@VTMotionEstimationOutputHandler"
  },
  "title" : "VTMotionEstimationOutputHandler"
}
-->

# VTMotionEstimationOutputHandler

A block invoked by motion-estimation session when frame processing is complete.

```
typealias VTMotionEstimationOutputHandler = (OSStatus, __VTMotionEstimationInfoFlags, CFDictionary?, CVPixelBuffer?) -> Void
```

## Parameters

`status`

`noErr` if processing request was successful; an error code if motion-estimation was not successful.

`infoFlags`

A bit field that contains information about the processing operation.

`additionalInfo`

Additional processing information about the operation that cannot fit in `infoFlags`.
Currently, the system expects this to be NULL.

`motionVectorPixelBuffer`

A `CVPixelBuffer` that contains the motion vector information, if processing request
was successful; otherwise, NULL.

## Discussion

When the client requests a motion-estimation, the client passes in a callback block that the system invokes for the
result of that request. If the `VTMotionEstimationSessionCreateMotionEstimation` call returns an error, the system
does not invoke this block.

---

Copyright &copy; 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)