D-Link DCS-6511 User Manual page 42

Section 3: Configuration
Constant Bit If the Rate Control is set to CBR, you can set the bit rate to use for this video
Rate: profile.
Max Bit Rate: If the Rate Control is set to CVBR, you can set the maximum bit rate this
video profile can use.
Fixed Quality: Select the image quality level for the camera to try to maintain. High quality
levels will result in increased bit rates and use more bandwidth.
D-Link DCS-6511 User Manual 42