pub unsafe static kVTCompressionPropertyKey_ExpectedFrameRate: &'static CFStringVTCompressionProperties only.Expand description
Indicates the expected frame rate of the video to be encoded.
The frame rate is measured in frames per second. This property is used to inform the encoder of the expected cadence of the presentation time stamp values of frames that will be submitted to the encoder. The actual frame rate may vary, and will depend on the frame durations calculated by the difference between subsequent presentation time stamps. If kVTCompressionPropertyKey_RealTime has been set to true, the ExpectedFrameRate may be used to optimize energy usage as well as perform internal encoder configuration before compression begins. If kVTCompressionPropertyKey_RealTime is not set, or has been set to false, the ExpectedFrameRate is still helpful and allows the encoder to optimize internal encoder configuration before compression begins. By default, the property has a value of zero indicating “unknown”.
See also Apple’s documentation