1. A quantizer estimator, comprising: a linear regression unit to generate a quantizer estimate from input values of prior quantizer selections and coding rates, first memory to store predetermined values of quantizer selections and coding rates, the table indexed by a complexity indicator signal, second memory to store quantizer selections and coding rates of previously coded P pictures, and a selector selectively coupling an input to the linear regression unit to the first memory when a picture type signal indicates an I picture and to the second memory when the picture type signal indicates a P picture.