Blanking level
In video technology, blanking level is the level of the composite video signal during the front and back porches of the video signal.
The composite video signal is actually the video information superimposed on blanking. The total level of the composite video signal is 1000 mV. This level can also be given in IRE units such that the level difference reserved for video information is 100 IRE units. So white corresponds to 100 IRE units and blanking level corresponds to 0 IRE units. The level of black is 0 IRE units in the case of CCIR System B and CCIR System G and 7.5 IRE units in the case of CCIR System M. So, while there is no difference between the black and the blanking levels in most systems they differ by 50 mV. in system M.
