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# CMBufferQueueSetValidationCallback(_:callback:refcon:)

A validation callback for the queue to call before enqueuing buffers.

```
func CMBufferQueueSetValidationCallback(_ queue: CMBufferQueue, callback: CMBufferValidationCallback, refcon: UnsafeMutableRawPointer?) -> OSStatus
```

## Parameters

`queue`

`CMBufferQueue` that will use the validation callback.

`callback`

Callback that will validate each buffer enqueued.

`refcon`

Context refcon for validation callback.

## Return Value

A result code. See `Result Codes`.

## Discussion

---

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