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# parameterChanged(_:at:)

Executes when the host detects that a parameter has changed.

```
optional func parameterChanged(_ paramID: UInt32, at time: CMTime) throws
```

## Parameters

`paramID`

The ID of the parameter that changed.

`time`

The rational time at which the parameter changed.

## Discussion

Use this method to change, enable, disable, hide, or show other parameters. This method is called each time the user changes a parameter. You can use this method to update other parameters (such as hiding or showing them). You have full access to the [`FxParameterCreationAPI_v5`](/documentation/professional_video_applications/FxParameterCreationAPI_v5) or later, [`FxParameterRetrievalAPI_v6`](/documentation/professional_video_applications/FxParameterRetrievalAPI_v6) or later, and [`FxParameterSettingAPI_v5`](/documentation/professional_video_applications/FxParameterSettingAPI_v5) or later, within this method.

---

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