A video encoder that allows for the selection of a distortion level, comprising: a selection system for selecting a target distortion level; and a system for determining a quantization parameter q that will ensure compliance with the selected target distortion level, wherein the system includes an algorithm for calculating distortion that utilizes a Gaussian distribution having a variance that is a function of the quantization parameter q. The algorithm is based on a distortion model D(q)=N(a1q2+a2q+a3, b1q2+b2q+b3), wherein N is a Gaussian distribution and a1, a2, a3, b1, b2 and b3 are distortion model parameters.