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# CMVideoFormatDescriptionCopyAsBigEndianImageDescriptionBlockBuffer(allocator:videoFormatDescription:stringEncoding:flavor:blockBufferOut:)

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

```
func CMVideoFormatDescriptionCopyAsBigEndianImageDescriptionBlockBuffer(allocator: CFAllocator?, videoFormatDescription: CMVideoFormatDescription, stringEncoding: CFStringEncoding, flavor: CMImageDescriptionFlavor?, blockBufferOut: UnsafeMutablePointer<CMBlockBuffer?>) -> OSStatus
```

## Parameters

`allocator`

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

`videoFormatDescription`

The `CMVideoFormatDescription` to be copied.

`stringEncoding`

Pass <doc://com.apple.documentation/documentation/CoreFoundation/CFStringGetSystemEncoding()> or `GetApplicationTextEncoding`.

`flavor`

`kCMImageDescriptionFlavor` constant or `NULL` for QuickTimeMovie flavor.

`blockBufferOut`

Receives a new `CMBlockBuffer` containing ImageDescription 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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