kCMSampleBufferAttachmentKey_SpeedMultiplier
The factor by which the sample buffer’s presentation should be accelerated (type CFNumber, default 1.0).
Declaration
let kCMSampleBufferAttachmentKey_SpeedMultiplier: CFStringDiscussion
For normal playback the speed multiplier would be 1.0 (which is used if this attachment is not present); for double-speed playback the speed multiplier would be 2.0, which would halve the output duration. Speed-multiplication factors take effect after trimming; see CMSampleBufferGetOutputDuration(_:). Note that this attachment principally provides information about the duration-stretching effect: by default, it should be implemented by rate conversion, but other attachments may specify richer stretching operations—for example, scaling without pitch shift, or pitch shift without changing duration. Sequences of speed-multiplied sample buffers should have explicit time stamps to clarify when each should be output (see CMSampleBufferSetOutputPresentationTimeStamp(_:newValue:)).
See Also
Sample Buffer Keys
kCMSampleBufferAttachmentKey_DisplayEmptyMediaImmediatelykCMSampleBufferAttachmentKey_DrainAfterDecodingkCMSampleBufferAttachmentKey_DroppedFrameReasonkCMSampleBufferDroppedFrameReason_FrameWasLatekCMSampleBufferDroppedFrameReason_OutOfBufferskCMSampleBufferDroppedFrameReason_DiscontinuitykCMSampleBufferAttachmentKey_DroppedFrameReasonInfokCMSampleBufferDroppedFrameReasonInfo_CameraModeSwitchkCMSampleBufferAttachmentKey_EmptyMediakCMSampleBufferAttachmentKey_EndsPreviousSampleDurationkCMSampleBufferAttachmentKey_FillDiscontinuitiesWithSilencekCMSampleBufferAttachmentKey_ForceKeyFramekCMSampleBufferAttachmentKey_GradualDecoderRefreshkCMSampleBufferAttachmentKey_PermanentEmptyMediakCMSampleBufferAttachmentKey_PostNotificationWhenConsumed