Static kCMSampleBufferAttachmentKey_SpeedMultiplier 

pub unsafe static kCMSampleBufferAttachmentKey_SpeedMultiplier: &'static CFString

Available on crate feature CMSampleBuffer only.

The factor by which the sample buffer’s presentation should be accelerated (eg, in a scaled edit).

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 OutputPresentationTimeStamp attachments to clarify when each should be output.

See also Apple’s documentation