Nonstationary parametric models of a VBR coder for packet video on ATM networks

In this paper a class of parametric models is proposed to describe the output bit-rate from a motion-compensated two-layer video coder. No frame buffering is considered and the amounts of bits generated are regarded slice by slice (1 slice = 16 consecutive frame lines), thus resulting in a repetitive behavior of the bit rate time series. After removing the nonstationary mean component of each frame, traditionally modeled as Auto Regressive (AR), the resulting cycle-stationary process is spectrally analyzed and the periodical mean is estimated and subtracted. tl. simplified seasonal AR model is tailored to the residuals, still affected by little periodicity. Correlation between the low resolution channel and the detail channel, together making up the full resolution channel, is accounted by the overall model, whose fitness is assessed from true bit rate data from a two-layer subband+discrete cosine transform (SB+DCT) video coder. Simple procedures to derive likely values of the parameters ruling the model are proposed as well. Synthetic realizations of bit rate time series are produced and discussed.