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# VTSessionSetProperty(_:key:value:)

Sets a property on a VideoToolbox session.

```
func VTSessionSetProperty(_ session: VTSession, key propertyKey: CFString, value propertyValue: CFTypeRef?) -> OSStatus
```

## Discussion

Setting a property value to `NULL` restores the default value.

## Topics

### Related Documentation

[Compression Properties](/documentation/VideoToolbox/compression-properties)

Properties that you use to configure a compression session.

[Decompression Properties](/documentation/VideoToolbox/decompression-properties)

Properties used to configure a VideoToolbox decompression session.

[Pixel Transfer Properties](/documentation/VideoToolbox/pixel-transfer-properties)

Properties used to configure a VideoToolbox pixel transfer session.


---

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