---
title: VTRAWProcessingSessionSetParameterChangedHander
framework: Video Toolbox
role: symbol
role_heading: Function
platforms: [macOS 15.0+]
path: videotoolbox/vtrawprocessingsessionsetparameterchangedhander
---

# VTRAWProcessingSessionSetParameterChangedHander

Provides a block which will be called when the session changes the set of processing parameters.

## Declaration

```occ
extern OSStatus VTRAWProcessingSessionSetParameterChangedHander(VTRAWProcessingSessionRef session, VTRAWProcessingParameterChangeHandler parameterChangeHandler);
```

## Parameters

- `session`: The RAW processing session.
- `parameterChangeHandler`: A doc://com.apple.videotoolbox/documentation/VideoToolbox/VTRAWProcessingParameterChangeHandler block which will be called when the set of processing parameters changes, or the value of a parameter changes without the client explicitly requesting it. Setting this to NULL removes the current handler.

## See Also

### Data types

- [VTRAWProcessingSession](videotoolbox/vtrawprocessingsession.md)
- [VTRAWProcessingParameterChangeHandler](videotoolbox/vtrawprocessingparameterchangehandler.md)
- [VTRAWProcessingOutputHandler](videotoolbox/vtrawprocessingoutputhandler.md)