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# AVVideoH264EntropyModeKey

The entropy encoding mode for H.264 compression.

```
let AVVideoH264EntropyModeKey: String
```

## Discussion

This property controls whether an H.264 encoder uses [`AVVideoH264EntropyModeCAVLC`](/documentation/AVFoundation/AVVideoH264EntropyModeCAVLC) or [`AVVideoH264EntropyModeCABAC`](/documentation/AVFoundation/AVVideoH264EntropyModeCABAC). CABAC generally gives better compression at the expense of higher computational overhead.

> Important:
> The default value is encoder-specific and may change depending on other encoder settings. Set a value for this property only if the requested profile and level support it. Setting an incompatible value may result in encoding errors or a noncompliant output stream.

---

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