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# kVTEncodeFrameOptionKey_ForceKeyFrame

Boolean value indicating whether the current frame is forced to be a key frame.

```
let kVTEncodeFrameOptionKey_ForceKeyFrame: CFString
```

## Discussion

This value is set in the `frameProperties` dictionary passed to [`VTCompressionSessionEncodeFrame(_:imageBuffer:presentationTimeStamp:duration:frameProperties:sourceFrameRefcon:infoFlagsOut:)`](/documentation/VideoToolbox/VTCompressionSessionEncodeFrame(_:imageBuffer:presentationTimeStamp:duration:frameProperties:sourceFrameRefcon:infoFlagsOut:)); it determines whether the current frame is forced to be a keyframe or not. Note that it may not be possible for the encoder to accommodate all requests.

---

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