Adaptive rate control algorithm based on logarithmic R-Q model for MPEG-1 to MPEG-4 transcoding

Abstract

This paper proposes an adaptive rate control algorithm for MPEG-1 to MPEG-4 transcoder for video internetworking where a compressed video is transmitted through networks of different capacities. It is based on an adaptive logarithmic R-Q (rate-quantization) model for controlling the new target bit-rate of a transcoded MPEG-4 bitstream. In R-Q modeling, the R-Q characteristics predicted from a previous picture of the same picture type are used in combination with the R-Q data measured for the current picture. The proposed adaptive model takes into account the effect of picture dependencies arising in motion-compensated video coding. Furthermore, full advantage is taken of the special situation related to transcoding where a priori knowledge of the current R-Q data can be obtained by just counting the number of bits in the input bitstream without re-encoding. It is shown by simulation that the adaptive R-Q model-based rate control can efficiently control the output bit-rate to match the target bit-budget. (C) 2002 Elsevier Science B.V. All rights reserved.