Static kVTCompressionPropertyKey_EnableLTR 

pub unsafe static kVTCompressionPropertyKey_EnableLTR: &'static CFString

Available on crate feature VTCompressionProperties only.

Enable Long Term Reference (LTR) frames during encoding

When an LTR frame is encoded, encoder will signal a unique token of the LTR frame in the encoder callback through: kVTSampleAttachmentKey_RequireLTRAcknowledgementToken Clients are responsible for reporting acknowledged LTR frames to the encoder through: kVTEncodeFrameOptionKey_AcknowledgedLTRTokens Client can request a refresh frame at any time through: kVTEncodeFrameOptionKey_ForceLTRRefresh Encoder will encode a P frame by using one of acknowledged LTR frames as the reference. Encoder will encode a new reference frame using an acknowledged LTR, or an IDR if no LTR frames have been acknowledged.

Also see: kVTEncodeFrameOptionKey_AcknowledgedLTRTokens kVTEncodeFrameOptionKey_ForceLTRRefresh kVTSampleAttachmentKey_RequireLTRAcknowledgementToken

See also Apple’s documentation