CMSampleBufferCreate(allocator:dataBuffer:dataReady:makeDataReadyCallback:refcon:formatDescription:sampleCount:sampleTimingEntryCount:sampleTimingArray:sampleSizeEntryCount:sampleSizeArray:sampleBufferOut:)

Declaration

func CMSampleBufferCreate(allocator: CFAllocator?, dataBuffer: CMBlockBuffer?, dataReady: Bool, makeDataReadyCallback: CMSampleBufferMakeDataReadyCallback?, refcon makeDataReadyRefcon: UnsafeMutableRawPointer?, formatDescription: CMFormatDescription?, sampleCount numSamples: CMItemCount, sampleTimingEntryCount numSampleTimingEntries: CMItemCount, sampleTimingArray: UnsafePointer<CMSampleTimingInfo>?, sampleSizeEntryCount numSampleSizeEntries: CMItemCount, sampleSizeArray: UnsafePointer<Int>?, sampleBufferOut: UnsafeMutablePointer<CMSampleBuffer?>) -> OSStatus

Parameters

• allocator:

  The allocator to use for allocating the CMSampleBuffer object. Pass kCFAllocatorDefault to use the default allocator.

• dataBuffer:

  CMBlockBuffer for the media data. This can be NULL, a CMBlockBuffer with no backing memory, a CMBlockBuffer with backing memory but no data yet, or a CMBlockBuffer that already contains the media data. If CMBlockBuffer contains the media data, dataReady should be true. The Boolean dataReady should also be true if the dataBuffer is Null and numSamples is 0.

• dataReady:

  Indicates whether or not the block buffer already contains the media data.

• makeDataReadyCallback:

  Callback that CMSampleBufferMakeDataReady should call to make the data ready. Can be NULL.

• makeDataReadyRefcon:

  Refcon CMSampleBufferMakeDataReady should pass to the callback.

• formatDescription:

  A description of the media data’s format. Can be NULL.

• numSamples:

  Number of samples in the CMSampleBuffer. Can be zero.

• numSampleTimingEntries:

  Number of entries in sampleTimingArray. Must be 0, 1, or numSamples.

• sampleTimingArray:

  Array of CMSampleTimingInfo structs, one struct per sample. If all samples have the same duration and are in presentation order, you can pass a single CMSampleTimingInfo struct with duration set to the duration of one sample, presentationTimeStamp set to the presentation time of the numerically earliest sample, and decodeTimeStamp set to kCMTimeInvalid. Behavior is undefined if samples in a CMSampleBuffer (or even in multiple buffers in the same stream) have the same presentationTimeStamp. Can be NULL.

• numSampleSizeEntries:

  Number of entries in sampleSizeArray. Must be 0, 1, or numSamples.

• sampleSizeArray:

  Array of size entries, one entry per sample. If all samples have the same size, you can pass a single size entry containing the size of one sample. Can be NULL. Must be NULL if the samples are non-contiguous in the buffer (for example, non-interleaved audio, where the channel values for a single sample are scattered through the buffer).

• sampleBufferOut:

  On output, points to the newly created CMSampleBuffer.

Return Value

A result code. See Sample Buffer Error Codes.

Discussion

Array parameters (sampleSizeArray, sampleTimingArray) should have only one element if that same element applies to all samples. All parameters are copied. On return, the caller can release them, free them or reuse them. On return, the caller owns the returned CMSampleBuffer, and must release it when done with it.

Example of usage for in-display-order video frames:

• dataBuffer: contains 7 Motion JPEG frames

• dataFormatDescription: describes Motion JPEG video

• dataFormatDescription: describes Motion JPEG video

• numSamples: 7

• numSampleTimingEntries: 1

• sampleTimingArray: one entry = {duration = 1001/30000, presentationTimeStamp = 0/30000, decodeTimeStamp = invalid }

• numSampleSizeEntries: 7

• sampleSizeArray: [105840, 104456, 103464, 116460, 100412, 94808, 120400]

Example of usage for video frames in out-of-display-order :

• dataBuffer: contains 6 H.264 frames in decode order (P2,B0,B1,I5,B3,B4)

• dataFormatDescription: describes H.264 video

• numSamples: 6

• numSampleTimingEntries: 6

• sampleTimingArray: 6 entries = {

• {duration = 1001/30000, presentationTimeStamp = 12012/30000, decodeTimeStamp = 10010/30000},

• {duration = 1001/30000, presentationTimeStamp = 10010/30000, decodeTimeStamp = 11011/30000},

• {duration = 1001/30000, presentationTimeStamp = 11011/30000, decodeTimeStamp = 12012/30000},

• {duration = 1001/30000, presentationTimeStamp = 15015/30000, decodeTimeStamp = 13013/30000},

• {duration = 1001/30000, presentationTimeStamp = 13013/30000, decodeTimeStamp = 14014/30000},

• {duration = 1001/30000, presentationTimeStamp = 13013/30000, decodeTimeStamp = 14014/30000}}

• numSampleSizeEntries: 6

• sampleSizeArray: [10580, 1234, 1364, 75660, 1012, 988]

Example of usage for compressed audio:

• dataBuffer: contains 24 compressed AAC packets

• dataFormatDescription: describes 44.1kHz AAC audio

• numSamples: 24

• numSampleTimingEntries: 1

• sampleTimingArray: one entry = {{duration = 1024/44100, presentationTimeStamp = 0/44100, decodeTimeStamp = invalid }}

• numSampleSizeEntries: 24

• sampleSizeArray:[191, 183, 208, 213, 202, 206, 209, 206, 204, 192, 202, 277, 282, 240, 209, 194, 193, 197, 196, 198, 168, 199, 171, 194]

Example of usage for uncompressed interleaved audio:

• dataBuffer: contains 24000 uncompressed interleaved stereo frames, each containing 2 Float32s =

• {{L,R},

• {L,R},

• {L,R}, …}

• dataFormatDescription: describes 48kHz Float32 interleaved audio

• numSamples: 24000

• numSampleTimingEntries: 1

• sampleTimingArray: one entry = {{duration = 1/48000, presentationTimeStamp = 0/48000, decodeTimeStamp = invalid }}

• numSampleSizeEntries: 1

• sampleSizeArray: {8}

Example of usage for uncompressed non-interleaved audio:

• dataBuffer: contains 24000 uncompressed non-interleaved stereo frames, each containing 2 (non-contiguous) Float32s =

• {{L,L,L,L,L,…},

• {R,R,R,R,R,…}}

• dataFormatDescription: describes 48kHz Float32 non-interleaved audio

• numSamples: 24000

• numSampleTimingEntries: 1

• sampleTimingArray: one entry = {duration = 1/48000, presentationTimeStamp = 0/48000, decodeTimeStamp = invalid }

• numSampleSizeEntries: 0

• sampleSizeArray: NULL (because the samples aren’t contiguous)

Topics

Callbacks

• CMSampleBufferMakeDataReadyCallback

See Also

Creating Sample Buffers

• CMSampleBufferCreateReady(allocator:dataBuffer:formatDescription:sampleCount:sampleTimingEntryCount:sampleTimingArray:sampleSizeEntryCount:sampleSizeArray:sampleBufferOut:)
• CMSampleBufferCreateReadyWithImageBuffer(allocator:imageBuffer:formatDescription:sampleTiming:sampleBufferOut:)
• CMAudioSampleBufferCreateReadyWithPacketDescriptions(allocator:dataBuffer:formatDescription:sampleCount:presentationTimeStamp:packetDescriptions:sampleBufferOut:)
• CMSampleBufferCreateWithMakeDataReadyHandler(_:_:_:_:_:_:_:_:_:_:_:)
• CMSampleBufferCreateForImageBufferWithMakeDataReadyHandler(_:_:_:_:_:_:_:)
• CMAudioSampleBufferCreateWithPacketDescriptionsAndMakeDataReadyHandler(_:_:_:_:_:_:_:_:_:)
• CMSampleBufferCreateForImageBuffer(allocator:imageBuffer:dataReady:makeDataReadyCallback:refcon:formatDescription:sampleTiming:sampleBufferOut:)
• CMAudioSampleBufferCreateWithPacketDescriptions(allocator:dataBuffer:dataReady:makeDataReadyCallback:refcon:formatDescription:sampleCount:presentationTimeStamp:packetDescriptions:sampleBufferOut:)