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

摘要

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.