---
title: "CMFormatDescriptionEqualIgnoringExtensionKeys(_:otherFormatDescription:extensionKeysToIgnore:sampleDescriptionExtensionAtomKeysToIgnore:)"
framework: coremedia
role: symbol
role_heading: Function
path: "coremedia/cmformatdescriptionequalignoringextensionkeys(_:otherformatdescription:extensionkeystoignore:sampledescriptionextensionatomkeystoignore:)"
---

# CMFormatDescriptionEqualIgnoringExtensionKeys(_:otherFormatDescription:extensionKeysToIgnore:sampleDescriptionExtensionAtomKeysToIgnore:)

Returns a Boolean value that indicates whether two format descriptions are equal, ignoring differences in the extension keys you specify.

## Declaration

```swift
func CMFormatDescriptionEqualIgnoringExtensionKeys(_ formatDescription: CMFormatDescription?, otherFormatDescription: CMFormatDescription?, extensionKeysToIgnore formatDescriptionExtensionKeysToIgnore: CFTypeRef?, sampleDescriptionExtensionAtomKeysToIgnore: CFTypeRef?) -> Bool
```

## Parameters

- `formatDescription`: The first description to compare.
- `otherFormatDescription`: The second description to compare.
- `formatDescriptionExtensionKeysToIgnore`: A single format description extension key (CFString) or an array (CFArray) of keys.
- `sampleDescriptionExtensionAtomKeysToIgnore`: A single sample description extension atom key (four-character CFString) or an array (CFArray) of such keys.

## Return Value

Return Value true if the two descriptions are equal; otherwise, false.

## Discussion

Discussion When you specify any keys, the function ignores kCMFormatDescriptionExtension_VerbatimSampleDescription and kCMFormatDescriptionExtension_VerbatimISOSampleEntry for the purpose of comparison. note: This function is NULL safe. For extension atom keys, see kCMFormatDescriptionExtension_SampleDescriptionExtensionAtoms.

## See Also

### Comparing Format Descriptions

- [CMFormatDescriptionEqual(_:otherFormatDescription:)](coremedia/cmformatdescriptionequal(_:otherformatdescription:).md)