---
title: MTAudioProcessingTapInitCallback
framework: mediatoolbox
role: symbol
role_heading: Type Alias
path: mediatoolbox/mtaudioprocessingtapinitcallback
---

# MTAudioProcessingTapInitCallback

An initialization callback function.

## Declaration

```swift
typealias MTAudioProcessingTapInitCallback = (MTAudioProcessingTap, UnsafeMutableRawPointer?, UnsafeMutablePointer<UnsafeMutableRawPointer?>) -> Void
```

## Parameters

- `tap`: The processing tap.
- `clientInfo`: The client data of the processing tap passed in callbacks struct in MTAudioProcessingTapCreate().
- `tapStorageOut`: Additional client data. The intent is for clients to allocate a block of memory for use within their custom MTAudioProcessingTap implementation that will be freed when the finalize callback is invoked. This argument is optional.

## Overview

Overview An init callback that is invoked when MTAudioProcessingTapCreate() is called. The init callback is always balanced by a finalize callback when the MTAudioProcessingTap object is released.

## See Also

### Callback functions

- [MTAudioProcessingTapPrepareCallback](mediatoolbox/mtaudioprocessingtappreparecallback.md)
- [MTAudioProcessingTapProcessCallback](mediatoolbox/mtaudioprocessingtapprocesscallback.md)
- [MTAudioProcessingTapUnprepareCallback](mediatoolbox/mtaudioprocessingtapunpreparecallback.md)
- [MTAudioProcessingTapFinalizeCallback](mediatoolbox/mtaudioprocessingtapfinalizecallback.md)