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# AVVideoCompressionPropertiesKey

A key to access the dictionary of compression properties for a video asset.

```
let AVVideoCompressionPropertiesKey: String
```

## Discussion

The value for this key is an instance of <doc://com.apple.documentation/documentation/Foundation/NSDictionary>. Add entries to this dictionary to manually change bit rate, B-frame delivery, I-frame interval, and codec quality. Querying the [`supportedOutputSettingsKeys(for:)`](/documentation/AVFoundation/AVCaptureMovieFileOutput/supportedOutputSettingsKeys(for:)) method reveals the keys supported for the current release and configuration.

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