A more accurate model parameter estimation is achieved by using a Kalman filter for discretely estimating the model parameters between the consecutive frames of the frame sequence and performing the correction of the time-discrete Kalman filter twice per frame, firstly using a measurement value which depends on a complexity measure of the current frame to achieve a primarily corrected state of the time-discrete Kalman filter, and secondly using a measurement value depending on an actual coding rate or distortion of the video encoder in encoding the current frame using a predetermined quantization which may have been determined by an estimation of the actual rate- or distortion-quantization function according to the primarily corrected state. A rate-quantization model function relates the quantization of the video encoder to the coding rate of the video encoder and is piecewise defined to exhibit quadratic and exponential functions in finer and coarser quantization intervals, respectively.