Static kVTCompressionPropertyKey_RecommendedParallelizationLimit 

pub unsafe static kVTCompressionPropertyKey_RecommendedParallelizationLimit: &'static CFString

Available on crate feature VTCompressionProperties only.

If supported by the underlying video encoder, returns the recommended number of VTCompressionSessions to instantiate in a parallel encoding configuration.

Parallel encoding VTCompressionSessions require the use of the properties kVTCompressionPropertyKey_MoreFramesBeforeStart, kVTCompressionPropertyKey_MoreFramesAfterEnd, and kVTCompressionPropertyKey_SourceFrameCount. e.g. If the property returns 4, a setup for 4 VTCompressionSessions on a 400 frame movie might look like: compressionSession1 kVTCompressionPropertyKey_MoreFramesBeforeStart = false kVTCompressionPropertyKey_MoreFramesAfterEnd = true kVTCompressionPropertyKey_SourceFrameCount = 100 compressionSession2 kVTCompressionPropertyKey_MoreFramesBeforeStart = true kVTCompressionPropertyKey_MoreFramesAfterEnd = true kVTCompressionPropertyKey_SourceFrameCount = 100 compressionSession3 kVTCompressionPropertyKey_MoreFramesBeforeStart = true kVTCompressionPropertyKey_MoreFramesAfterEnd = true kVTCompressionPropertyKey_SourceFrameCount = 100 compressionSession4 kVTCompressionPropertyKey_MoreFramesBeforeStart = true kVTCompressionPropertyKey_MoreFramesAfterEnd = false kVTCompressionPropertyKey_SourceFrameCount = 100

See also Apple’s documentation