Function

CMVideoFormatDescriptionGetExtensionKeysCommonWithImageBuffers

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

Declaration

CFArrayRef CMVideoFormatDescriptionGetExtensionKeysCommonWithImageBuffers(void);

Discussion

When specifying a CMFormatDescription for a CMSampleBuffer, the format description must be consistent with formatting information attached to the CVImageBuffer. The width, height, and codecType must match (for CVPixelBuffers the codec type is given by CVPixelBufferGetPixelFormatType(pixelBuffer); for other CVImageBuffers, the codecType must be 0). The format description extensions must match the image buffer attachments for all the keys in the list returned by this function (if absent in either they must be absent in both). Currently, the list is:

  • kCMFormatDescriptionExtension_CleanAperture

  • kCMFormatDescriptionExtension_FieldCount

  • kCMFormatDescriptionExtension_FieldDetail

  • kCMFormatDescriptionExtension_PixelAspectRatio

  • kCMFormatDescriptionExtension_ColorPrimaries

  • kCMFormatDescriptionExtension_TransferFunction

  • kCMFormatDescriptionExtension_GammaLevel

  • kCMFormatDescriptionExtension_YCbCrMatrix

  • kCMFormatDescriptionExtension_ICCProfile

  • kCMFormatDescriptionExtension_ChromaLocationTopField

  • kCMFormatDescriptionExtension_ChromaLocationBottomField

See Also

Video-Specific Functions

CMVideoFormatDescriptionCreate

Creates a format description for a video media stream.

CMVideoFormatDescriptionCreateForImageBuffer

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

CMVideoFormatDescriptionGetCleanAperture

Returns the clean aperture.

CMVideoFormatDescriptionGetDimensions

Returns the video dimensions (in encoded pixels).

CMVideoFormatDescriptionGetPresentationDimensions

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

CMVideoFormatDescriptionMatchesImageBuffer

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

CMVideoFormatDescriptionCreateFromH264ParameterSets

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

CMVideoFormatDescriptionGetH264ParameterSetAtIndex

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

CMVideoFormatDescriptionCopyAsBigEndianImageDescriptionBlockBuffer

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

CMVideoFormatDescriptionCreateFromBigEndianImageDescriptionBlockBuffer

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

CMVideoFormatDescriptionCreateFromBigEndianImageDescriptionData

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

CMSwapBigEndianImageDescriptionToHost

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

CMSwapHostEndianImageDescriptionToBig

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