Patent ID: 7257159

Claim:
A device for coding video pictures, the device comprising: first dividing means for dividing a video picture into one or more picture blocks; a picture transformer for obtaining a series of coefficients from a picture block of the video picture; a quantizer for quantizing the series of coefficients with a step size (s); an encoder for coding the series of coefficients; second dividing means for dividing the series of coefficients into one or more sub-series of coefficients and for determining a sub-target value (R t (k,n)) for a number of bits per sub-series of coefficients; and control means for controlling the step size (s) based on a target value (R t (k)) for a number of bits per series of coefficients, the control means being adapted to control a step size for each sub-series of coefficients in accordance with a corresponding sub-target value (R t (k,n)) for the sub-series of coefficients.