---
title: "CMMetadataFormatDescriptionCopyAsBigEndianMetadataDescriptionBlockBuffer(allocator:metadataFormatDescription:flavor:blockBufferOut:)"
framework: coremedia
role: symbol
role_heading: Function
path: "coremedia/cmmetadataformatdescriptioncopyasbigendianmetadatadescriptionblockbuffer(allocator:metadataformatdescription:flavor:blockbufferout:)"
---

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

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

## Declaration

```swift
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

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.

## See Also

### Working with Metadata Descriptions

- [CMMetadataDescriptionFlavor](coremedia/cmmetadatadescriptionflavor.md)
- [CMMetadataFormatDescriptionCreateWithKeys(allocator:metadataType:keys:formatDescriptionOut:)](coremedia/cmmetadataformatdescriptioncreatewithkeys(allocator:metadatatype:keys:formatdescriptionout:).md)
- [CMMetadataFormatDescriptionGetKeyWithLocalID(_:localKeyID:)](coremedia/cmmetadataformatdescriptiongetkeywithlocalid(_:localkeyid:).md)
- [CMMetadataFormatDescriptionCreateByMergingMetadataFormatDescriptions(allocator:sourceDescription:otherSourceDescription:formatDescriptionOut:)](coremedia/cmmetadataformatdescriptioncreatebymergingmetadataformatdescriptions(allocator:sourcedescription:othersourcedescription:formatdescriptionout:).md)
- [CMMetadataFormatDescriptionCreateFromBigEndianMetadataDescriptionBlockBuffer(allocator:bigEndianMetadataDescriptionBlockBuffer:flavor:formatDescriptionOut:)](coremedia/cmmetadataformatdescriptioncreatefrombigendianmetadatadescriptionblockbuffer(allocator:bigendianmetadatadescriptionblockbuffer:flavor:formatdescriptionout:).md)
- [CMMetadataFormatDescriptionCreateFromBigEndianMetadataDescriptionData(allocator:bigEndianMetadataDescriptionData:size:flavor:formatDescriptionOut:)](coremedia/cmmetadataformatdescriptioncreatefrombigendianmetadatadescriptiondata(allocator:bigendianmetadatadescriptiondata:size:flavor:formatdescriptionout:).md)
- [CMMetadataFormatDescriptionCreateWithMetadataFormatDescriptionAndMetadataSpecifications(allocator:sourceDescription:metadataSpecifications:formatDescriptionOut:)](coremedia/cmmetadataformatdescriptioncreatewithmetadataformatdescriptionandmetadataspecifications(allocator:sourcedescription:metadataspecifications:formatdescriptionout:).md)
- [CMMetadataFormatDescriptionCreateWithMetadataSpecifications(allocator:metadataType:metadataSpecifications:formatDescriptionOut:)](coremedia/cmmetadataformatdescriptioncreatewithmetadataspecifications(allocator:metadatatype:metadataspecifications:formatdescriptionout:).md)
- [CMSwapBigEndianMetadataDescriptionToHost(_:_:)](coremedia/cmswapbigendianmetadatadescriptiontohost(_:_:).md)
- [CMSwapHostEndianMetadataDescriptionToBig(_:_:)](coremedia/cmswaphostendianmetadatadescriptiontobig(_:_:).md)
- [CMMetadataFormatDescriptionGetIdentifiers(_:)](coremedia/cmmetadataformatdescriptiongetidentifiers(_:).md)