Static kVTSampleAttachmentKey_RequireLTRAcknowledgementToken 

pub unsafe static kVTSampleAttachmentKey_RequireLTRAcknowledgementToken: &'static CFString

Available on crate feature VTCompressionProperties only.

CFNumber containing a unique token for this LTR

This CMSampleBuffer attachment contains a unique token which can be returned to the encoder through kVTEncodeFrameOptionKey_AcknowledgedLTRTokens to indicate that the LTR has been received and may be used as a reference.

Also see: kVTCompressionPropertyKey_EnableLTR kVTEncodeFrameOptionKey_AcknowledgedLTRTokens kVTEncodeFrameOptionKey_ForceLTRRefresh

See also Apple’s documentation