kVTCompressionPropertyKey_VariableBitRate

objc2_video_toolbox

Static kVTCompressionPropertyKey_VariableBitRate 

Source 
pub unsafe static kVTCompressionPropertyKey_VariableBitRate: &'static CFString
Available on crate feature VTCompressionProperties only.
Expand description

Requires that the encoder use a variable bitrate (VBR) rate control algorithm and specifies the desired variable bitrate in bits per second.

The actual peak bitrate present in the bitstream may be above or below this value based on other parameters such as kVTCompressionPropertyKey_VBVMaxBitRate. This property key needs to be set to achieve Variable Bitrate (VBR) rate control. This property key is not compatible with:

  1. kVTCompressionPropertyKey_AverageBitRate,
  2. kVTCompressionPropertyKey_ConstantBitRate,
  3. kVTCompressionPropertyKey_DataRateLimits,
  4. VTVideoEncoderSpecification_EnableLowLatencyRateControl = True.

See also Apple’s documentation