CMFormatDescription

A media format descriptor that describes the samples in a sample buffer.

Overview

CMFormatDescriptions are immutable Core Foundation objects that describe media data of various types, including audio, video, and muxed media data. There are two types of API: media-type-agnostic APIs (supported by all CMFormatDescriptions) and media-type-specific APIs. The media-type-agnostic APIs are prefixed with CMFormatDescription, and the media-type-specific APIs are prefixed with CMAudioFormatDescription, CMVideoFormatDescription, and so on.

Topics

Common Functions

func CMFormatDescriptionCreate(allocator: CFAllocator?, mediaType: CMMediaType, mediaSubType: FourCharCode, extensions: CFDictionary?, formatDescriptionOut: UnsafeMutablePointer<CMFormatDescription?>) -> OSStatus

Creates a generic CMFormatDescription object. You should not call this method for the media types that has specific create functions such as audio, video, text, muxed, metaData and timeCode.

func CMFormatDescriptionEqual(CMFormatDescription?, otherFormatDescription: CMFormatDescription?) -> Bool

Compares two CMFormatDescription objects for equality.

func CMFormatDescriptionEqualIgnoringExtensionKeys(CMFormatDescription?, otherFormatDescription: CMFormatDescription?, extensionKeysToIgnore: CFTypeRef?, sampleDescriptionExtensionAtomKeysToIgnore: CFTypeRef?) -> Bool

Compares two CMFormatDescription objects for equality, ignoring differences in the specified lists of format description extension keys and sample description extension keys.

func CMFormatDescriptionGetExtension(CMFormatDescription, extensionKey: CFString) -> CFPropertyList?

Returns the specified extension of a CMFormatDescription.

func CMFormatDescriptionGetExtensions(CMFormatDescription) -> CFDictionary?

Returns an immutable dictionary containing all the extensions of a CMFormatDescription.

func CMFormatDescriptionGetMediaSubType(CMFormatDescription) -> FourCharCode

Returns the media subtype of a CMFormatDescription.

func CMFormatDescriptionGetMediaType(CMFormatDescription) -> CMMediaType

Returns the media type of a CMFormatDescription.

func CMFormatDescriptionGetTypeID() -> CFTypeID

Returns the CFTypeID of CMFormatDescription objects.

Audio-Specific Functions

func CMAudioFormatDescriptionCreateSummary(allocator: CFAllocator?, formatDescriptionArray: CFArray, flags: UInt32, formatDescriptionOut: UnsafeMutablePointer<CMAudioFormatDescription?>) -> OSStatus

Creates a summary audio format description from an array of audio format descriptions.

func CMAudioFormatDescriptionCreate(allocator: CFAllocator?, asbd: UnsafePointer<AudioStreamBasicDescription>, layoutSize: Int, layout: UnsafePointer<AudioChannelLayout>?, magicCookieSize: Int, magicCookie: UnsafeRawPointer?, extensions: CFDictionary?, formatDescriptionOut: UnsafeMutablePointer<CMAudioFormatDescription?>) -> OSStatus

Creates a format description for an audio media stream.

func CMAudioFormatDescriptionEqual(CMAudioFormatDescription, otherFormatDescription: CMAudioFormatDescription, equalityMask: CMAudioFormatDescriptionMask, equalityMaskOut: UnsafeMutablePointer<CMAudioFormatDescriptionMask>?) -> Bool

Evaluates equality for the specified parts of two audio format descriptions.

func CMAudioFormatDescriptionGetChannelLayout(CMAudioFormatDescription, sizeOut: UnsafeMutablePointer<Int>?) -> UnsafePointer<AudioChannelLayout>?

Returns a read-only pointer to (and size of) the AudioChannelLayout inside an audio CMFormatDescription.

func CMAudioFormatDescriptionGetFormatList(CMAudioFormatDescription, sizeOut: UnsafeMutablePointer<Int>?) -> UnsafePointer<AudioFormatListItem>?

Returns a read-only pointer to (and size of) the array of AudioFormatListItem structs inside an audio CMFormatDescription.

func CMAudioFormatDescriptionGetMagicCookie(CMAudioFormatDescription, sizeOut: UnsafeMutablePointer<Int>?) -> UnsafeRawPointer?

Returns a read-only pointer to (and size of) the magic cookie inside an audio CMFormatDescription.

func CMAudioFormatDescriptionGetMostCompatibleFormat(CMAudioFormatDescription) -> UnsafePointer<AudioFormatListItem>?

Returns a read-only pointer to the appropriate AudioFormatListItem inside an audio CMFormatDescription.

func CMAudioFormatDescriptionGetRichestDecodableFormat(CMAudioFormatDescription) -> UnsafePointer<AudioFormatListItem>?

Returns a read-only pointer to the appropriate AudioFormatListItem inside an audio CMFormatDescription.

func CMAudioFormatDescriptionGetStreamBasicDescription(CMAudioFormatDescription) -> UnsafePointer<AudioStreamBasicDescription>?

Returns a read-only pointer to the AudioStreamBasicDescription inside an audio CMFormatDescription.

func CMDoesBigEndianSoundDescriptionRequireLegacyCBRSampleTableLayout(CMBlockBuffer, flavor: CMSoundDescriptionFlavor?) -> Bool

Examine a big-endian SoundDescription data structure in a CMBlockBuffer, and report whether the sample tables will need to use the legacy CBR layout.

func CMSwapBigEndianSoundDescriptionToHost(UnsafeMutablePointer<UInt8>, Int) -> OSStatus

Converts a SoundDescription data structure from big-endian to host-endian in place.

func CMSwapHostEndianSoundDescriptionToBig(UnsafeMutablePointer<UInt8>, Int) -> OSStatus

Converts a SoundDescription data structure from host-endian to big-endian in place.

func CMAudioFormatDescriptionCreateFromBigEndianSoundDescriptionData(allocator: CFAllocator?, bigEndianSoundDescriptionData: UnsafePointer<UInt8>, size: Int, flavor: CMSoundDescriptionFlavor?, formatDescriptionOut: UnsafeMutablePointer<CMAudioFormatDescription?>) -> OSStatus

Creates a CMAudioFormatDescription from a big-endian SoundDescription data structure.

func CMAudioFormatDescriptionCreateFromBigEndianSoundDescriptionBlockBuffer(allocator: CFAllocator?, bigEndianSoundDescriptionBlockBuffer: CMBlockBuffer, flavor: CMSoundDescriptionFlavor?, formatDescriptionOut: UnsafeMutablePointer<CMAudioFormatDescription?>) -> OSStatus

Creates a CMAudioFormatDescription from a big-endian SoundDescription data structure in a CMBlockBuffer.

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

Copies the contents of a CMAudioFormatDescription to a CMBlockBuffer in big-endian byte ordering.

Video-Specific Functions

func CMVideoFormatDescriptionCreate(allocator: CFAllocator?, codecType: CMVideoCodecType, width: Int32, height: Int32, extensions: CFDictionary?, formatDescriptionOut: UnsafeMutablePointer<CMVideoFormatDescription?>) -> OSStatus

Creates a format description for a video media stream.

func CMVideoFormatDescriptionCreateForImageBuffer(allocator: CFAllocator?, imageBuffer: CVImageBuffer, formatDescriptionOut: UnsafeMutablePointer<CMVideoFormatDescription?>) -> OSStatus

Creates a format description for a video media stream contained in CVImageBuffers of the type provided.

func CMVideoFormatDescriptionGetCleanAperture(CMVideoFormatDescription, originIsAtTopLeft: Bool) -> CGRect

Returns the clean aperture.

func CMVideoFormatDescriptionGetDimensions(CMVideoFormatDescription) -> CMVideoDimensions

Returns the video dimensions (in encoded pixels).

func CMVideoFormatDescriptionGetExtensionKeysCommonWithImageBuffers() -> CFArray

Returns an array of the keys that are used both as CMVideoFormatDescription extensions and CVImageBuffer attachments and attributes.

func CMVideoFormatDescriptionGetPresentationDimensions(CMVideoFormatDescription, usePixelAspectRatio: Bool, useCleanAperture: Bool) -> CGSize

Returns the dimensions, adjusted to take pixel aspect ratio and/or clean aperture into account.

func CMVideoFormatDescriptionMatchesImageBuffer(CMVideoFormatDescription, imageBuffer: CVImageBuffer) -> Bool

Checks to see if a given format description matches an image buffer.

func CMVideoFormatDescriptionCreateFromH264ParameterSets(allocator: CFAllocator?, parameterSetCount: Int, parameterSetPointers: UnsafePointer<UnsafePointer<UInt8>>, parameterSetSizes: UnsafePointer<Int>, nalUnitHeaderLength: Int32, formatDescriptionOut: UnsafeMutablePointer<CMFormatDescription?>) -> OSStatus

Creates a format description for a video media stream described by H.264 parameter set NAL units.

func CMVideoFormatDescriptionGetH264ParameterSetAtIndex(CMFormatDescription, parameterSetIndex: Int, parameterSetPointerOut: UnsafeMutablePointer<UnsafePointer<UInt8>?>?, parameterSetSizeOut: UnsafeMutablePointer<Int>?, parameterSetCountOut: UnsafeMutablePointer<Int>?, nalUnitHeaderLengthOut: UnsafeMutablePointer<Int32>?) -> OSStatus

Returns a parameter set contained in a H.264 format description.

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

Copies the contents of a CMVideoFormatDescription to a CMBlockBuffer in big-endian byte ordering.

func CMVideoFormatDescriptionCreateFromBigEndianImageDescriptionBlockBuffer(allocator: CFAllocator?, bigEndianImageDescriptionBlockBuffer: CMBlockBuffer, stringEncoding: CFStringEncoding, flavor: CMImageDescriptionFlavor?, formatDescriptionOut: UnsafeMutablePointer<CMVideoFormatDescription?>) -> OSStatus

Creates a CMVideoFormatDescription from a big-endian ImageDescription data structure in a CMBlockBuffer.

func CMVideoFormatDescriptionCreateFromBigEndianImageDescriptionData(allocator: CFAllocator?, bigEndianImageDescriptionData: UnsafePointer<UInt8>, size: Int, stringEncoding: CFStringEncoding, flavor: CMImageDescriptionFlavor?, formatDescriptionOut: UnsafeMutablePointer<CMVideoFormatDescription?>) -> OSStatus

Creates a CMVideoFormatDescription from a big-endian ImageDescription data structure.

func CMSwapBigEndianImageDescriptionToHost(UnsafeMutablePointer<UInt8>, Int) -> OSStatus

Converts an ImageDescription data structure from big-endian to host-endian in place.

func CMSwapHostEndianImageDescriptionToBig(UnsafeMutablePointer<UInt8>, Int) -> OSStatus

Converts an ImageDescription data structure from host-endian to big-endian in place.

Muxed-Specific Function

func CMMuxedFormatDescriptionCreate(allocator: CFAllocator?, muxType: CMMuxedStreamType, extensions: CFDictionary?, formatDescriptionOut: UnsafeMutablePointer<CMMuxedFormatDescription?>) -> OSStatus

Creates a format description for a muxed media stream.

Metadata-Specific Functions

func CMMetadataFormatDescriptionCreateWithKeys(allocator: CFAllocator?, metadataType: CMMetadataFormatType, keys: CFArray?, formatDescriptionOut: UnsafeMutablePointer<CMMetadataFormatDescription?>) -> OSStatus

Creates a metadata format description object specified by the key.

func CMMetadataFormatDescriptionGetKeyWithLocalID(CMMetadataFormatDescription, localKeyID: OSType) -> CFDictionary?

Returns the key associated with the metadata for the given local id.

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

Copies the contents of a CMMetadataFormatDescription to a CMBlockBuffer in big-endian byte ordering.

func CMMetadataFormatDescriptionCreateByMergingMetadataFormatDescriptions(allocator: CFAllocator?, sourceDescription: CMMetadataFormatDescription, otherSourceDescription: CMMetadataFormatDescription, formatDescriptionOut: UnsafeMutablePointer<CMMetadataFormatDescription?>) -> OSStatus

func CMMetadataFormatDescriptionCreateFromBigEndianMetadataDescriptionBlockBuffer(allocator: CFAllocator?, bigEndianMetadataDescriptionBlockBuffer: CMBlockBuffer, flavor: CMMetadataDescriptionFlavor?, formatDescriptionOut: UnsafeMutablePointer<CMMetadataFormatDescription?>) -> OSStatus

Creates a CMMetadataFormatDescription from a big-endian MetadataDescription data structure in a CMBlockBuffer.

func CMMetadataFormatDescriptionCreateFromBigEndianMetadataDescriptionData(allocator: CFAllocator?, bigEndianMetadataDescriptionData: UnsafePointer<UInt8>, size: Int, flavor: CMMetadataDescriptionFlavor?, formatDescriptionOut: UnsafeMutablePointer<CMMetadataFormatDescription?>) -> OSStatus

Creates a CMMetadataFormatDescription from a big-endian MetadataDescription data structure.

func CMMetadataFormatDescriptionCreateWithMetadataFormatDescriptionAndMetadataSpecifications(allocator: CFAllocator?, sourceDescription: CMMetadataFormatDescription, metadataSpecifications: CFArray, formatDescriptionOut: UnsafeMutablePointer<CMMetadataFormatDescription?>) -> OSStatus

Creates a new CMMetadataFormatDescription.

func CMMetadataFormatDescriptionCreateWithMetadataSpecifications(allocator: CFAllocator?, metadataType: CMMetadataFormatType, metadataSpecifications: CFArray, formatDescriptionOut: UnsafeMutablePointer<CMMetadataFormatDescription?>) -> OSStatus

Creates a new CMMetadataFormatDescription.

func CMSwapBigEndianMetadataDescriptionToHost(UnsafeMutablePointer<UInt8>, Int) -> OSStatus

Converts a MetadataDescription data structure from big-endian to host-endian in place.

func CMSwapHostEndianMetadataDescriptionToBig(UnsafeMutablePointer<UInt8>, Int) -> OSStatus

Converts a MetadataDescription data structure from host-endian to big-endian in place.

func CMMetadataFormatDescriptionGetIdentifiers(CMMetadataFormatDescription) -> CFArray?

Gets an array of metadata identifiers from a metadata format description.

Text-Specific Functions

func CMTextFormatDescriptionGetDefaultStyle(CMFormatDescription, localFontIDOut: UnsafeMutablePointer<UInt16>?, boldOut: UnsafeMutablePointer<DarwinBoolean>?, italicOut: UnsafeMutablePointer<DarwinBoolean>?, underlineOut: UnsafeMutablePointer<DarwinBoolean>?, fontSizeOut: UnsafeMutablePointer<CGFloat>?, colorComponentsOut: UnsafeMutablePointer<CGFloat>?) -> OSStatus

Returns the default style.

func CMTextFormatDescriptionGetDefaultTextBox(CMFormatDescription, originIsAtTopLeft: Bool, heightOfTextTrack: CGFloat, defaultTextBoxOut: UnsafeMutablePointer<CGRect>) -> OSStatus

Returns the default text box.

func CMTextFormatDescriptionGetDisplayFlags(CMFormatDescription, displayFlagsOut: UnsafeMutablePointer<CMTextDisplayFlags>) -> OSStatus

Returns the displayFlags.

func CMTextFormatDescriptionGetFontName(CMFormatDescription, localFontID: UInt16, fontNameOut: AutoreleasingUnsafeMutablePointer<CFString?>) -> OSStatus

Returns the font name for a local font ID.

func CMTextFormatDescriptionGetJustification(CMFormatDescription, horizontalOut: UnsafeMutablePointer<CMTextJustificationValue>?, verticalOut: UnsafeMutablePointer<CMTextJustificationValue>?) -> OSStatus

Returns horizontal and vertical justification.

func CMTextFormatDescriptionCopyAsBigEndianTextDescriptionBlockBuffer(allocator: CFAllocator?, textFormatDescription: CMTextFormatDescription, flavor: CMTextDescriptionFlavor?, blockBufferOut: UnsafeMutablePointer<CMBlockBuffer?>) -> OSStatus

Copies the contents of a CMTextFormatDescription to a CMBlockBuffer in big-endian byte ordering.

func CMTextFormatDescriptionCreateFromBigEndianTextDescriptionBlockBuffer(allocator: CFAllocator?, bigEndianTextDescriptionBlockBuffer: CMBlockBuffer, flavor: CMTextDescriptionFlavor?, mediaType: CMMediaType, formatDescriptionOut: UnsafeMutablePointer<CMTextFormatDescription?>) -> OSStatus

Creates a CMTextFormatDescription from a big-endian TextDescription data structure in a CMBlockBuffer.

func CMTextFormatDescriptionCreateFromBigEndianTextDescriptionData(allocator: CFAllocator?, bigEndianTextDescriptionData: UnsafePointer<UInt8>, size: Int, flavor: CMTextDescriptionFlavor?, mediaType: CMMediaType, formatDescriptionOut: UnsafeMutablePointer<CMTextFormatDescription?>) -> OSStatus

Creates a CMTextFormatDescription from a big-endian TextDescription data structure.

func CMSwapBigEndianTextDescriptionToHost(UnsafeMutablePointer<UInt8>, Int) -> OSStatus

Converts a TextDescription data structure from big-endian to host-endian in place.

func CMSwapHostEndianTextDescriptionToBig(UnsafeMutablePointer<UInt8>, Int) -> OSStatus

Converts a TextDescription data structure from host-endian to big-endian in place.

TimeCode-Specific Functions

func CMTimeCodeFormatDescriptionCreate(allocator: CFAllocator?, timeCodeFormatType: CMTimeCodeFormatType, frameDuration: CMTime, frameQuanta: UInt32, flags: UInt32, extensions: CFDictionary?, formatDescriptionOut: UnsafeMutablePointer<CMTimeCodeFormatDescription?>) -> OSStatus

Creates a format description for a timecode media.

func CMTimeCodeFormatDescriptionGetFrameDuration(CMTimeCodeFormatDescription) -> CMTime

Returns the duration of each frame (for example 100/2997).

func CMTimeCodeFormatDescriptionGetFrameQuanta(CMTimeCodeFormatDescription) -> UInt32

Returns the frames/sec for timecode (for example, 30) or frames/tick for counter mode.

func CMTimeCodeFormatDescriptionGetTimeCodeFlags(CMTimeCodeFormatDescription) -> UInt32

Returns the flags for kCMTimeCodeFlag_DropFrame, kCMTimeCodeFlag_24HourMax, kCMTimeCodeFlag_NegTimesOK

func CMTimeCodeFormatDescriptionCopyAsBigEndianTimeCodeDescriptionBlockBuffer(allocator: CFAllocator?, timeCodeFormatDescription: CMTimeCodeFormatDescription, flavor: CMTimeCodeDescriptionFlavor?, blockBufferOut: UnsafeMutablePointer<CMBlockBuffer?>) -> OSStatus

Copies the contents of a CMTimeCodeFormatDescription to a CMBlockBuffer in big-endian byte ordering.

func CMTimeCodeFormatDescriptionCreateFromBigEndianTimeCodeDescriptionBlockBuffer(allocator: CFAllocator?, bigEndianTimeCodeDescriptionBlockBuffer: CMBlockBuffer, flavor: CMTimeCodeDescriptionFlavor?, formatDescriptionOut: UnsafeMutablePointer<CMTimeCodeFormatDescription?>) -> OSStatus

Creates a CMTimeCodeFormatDescription from a big-endian TimeCodeDescription data structure in a CMBlockBuffer.

func CMTimeCodeFormatDescriptionCreateFromBigEndianTimeCodeDescriptionData(allocator: CFAllocator?, bigEndianTimeCodeDescriptionData: UnsafePointer<UInt8>, size: Int, flavor: CMTimeCodeDescriptionFlavor?, formatDescriptionOut: UnsafeMutablePointer<CMTimeCodeFormatDescription?>) -> OSStatus

Creates a CMTimeCodeFormatDescription from a big-endian TimeCodeDescription data structure.

func CMSwapBigEndianTimeCodeDescriptionToHost(UnsafeMutablePointer<UInt8>, Int) -> OSStatus

Converts a TimeCodeDescription data structure from big-endian to host-endian in place.

func CMSwapHostEndianTimeCodeDescriptionToBig(UnsafeMutablePointer<UInt8>, Int) -> OSStatus

Converts a TimeCodeDescription data structure from host-endian to big-endian in place.

Closed Captioning-Functions

func CMClosedCaptionFormatDescriptionCopyAsBigEndianClosedCaptionDescriptionBlockBuffer(allocator: CFAllocator?, closedCaptionFormatDescription: CMClosedCaptionFormatDescription, flavor: CMClosedCaptionDescriptionFlavor?, blockBufferOut: UnsafeMutablePointer<CMBlockBuffer?>) -> OSStatus

Copies the contents of a CMClosedCaptionFormatDescription to a CMBlockBuffer in big-endian byte ordering.

func CMClosedCaptionFormatDescriptionCreateFromBigEndianClosedCaptionDescriptionBlockBuffer(allocator: CFAllocator?, bigEndianClosedCaptionDescriptionBlockBuffer: CMBlockBuffer, flavor: CMClosedCaptionDescriptionFlavor?, formatDescriptionOut: UnsafeMutablePointer<CMClosedCaptionFormatDescription?>) -> OSStatus

Creates a CMClosedCaptionFormatDescription from a big-endian ClosedCaptionDescription data structure in a CMBlockBuffer.

func CMClosedCaptionFormatDescriptionCreateFromBigEndianClosedCaptionDescriptionData(allocator: CFAllocator?, bigEndianClosedCaptionDescriptionData: UnsafePointer<UInt8>, size: Int, flavor: CMClosedCaptionDescriptionFlavor?, formatDescriptionOut: UnsafeMutablePointer<CMClosedCaptionFormatDescription?>) -> OSStatus