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# CMAudioFormatDescriptionCopyAsBigEndianSoundDescriptionBlockBuffer(allocator:audioFormatDescription:flavor:blockBufferOut:)

Copies the contents of an audio format description to a buffer in big-endian byte ordering.

```
func CMAudioFormatDescriptionCopyAsBigEndianSoundDescriptionBlockBuffer(allocator: CFAllocator?, audioFormatDescription: CMAudioFormatDescription, flavor: CMSoundDescriptionFlavor?, blockBufferOut: UnsafeMutablePointer<CMBlockBuffer?>) -> OSStatus
```

## Parameters

`allocator`

Allocator to use for allocating the CMBlockBuffer object. May be NULL.

`audioFormatDescription`

CMAudioFormatDescription to be copied.

`flavor`

kCMSoundDescriptionFlavor constant or NULL for QuickTimeMovie flavor.

`blockBufferOut`

Receives new CMBlockBuffer containing SoundDescription data structure in big-endian byte ordering.

## Discussion

On return, the caller owns the returned `CMBlockBuffer`, and must release it when done with it.

> Note:
> The `dataRefIndex` field of the SampleDescription is intentionally filled with placeholder values (`0xFFFF`). The caller must overwrite these values with a valid `dataRefIndex` if writing the SampleDescription to a QuickTime/ISO file.

---

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