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# CMMetadataFormatDescriptionCopyAsBigEndianMetadataDescriptionBlockBuffer(allocator:metadataFormatDescription:flavor:blockBufferOut:)

Copies the contents of a metadata format description to a buffer in big-endian byte order.

```
func CMMetadataFormatDescriptionCopyAsBigEndianMetadataDescriptionBlockBuffer(allocator: CFAllocator?, metadataFormatDescription: CMMetadataFormatDescription, flavor: CMMetadataDescriptionFlavor?, blockBufferOut: UnsafeMutablePointer<CMBlockBuffer?>) -> OSStatus
```

## Parameters

`allocator`

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

`metadataFormatDescription`

CMMetadataFormatDescriptionRef to be copied.

`flavor`

Reserved for future use. Pass NULL for QuickTime Movie or ISO flavor.

`blockBufferOut`

Receives new CMBlockBuffer containing MetadataDescription 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 garbage 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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