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A rate control algorithm based on adaptive R-Q model for MPEG-1 to MPEG-4 transcoding in DCT domain

This paper proposes an adaptive rate control algorithm for MPEG-1 to MPEG-4 transcoder for video transmission over networks of different capacities and characteristics. It is based on an adaptive R-Q model to follow the new target bit-rate of a transcoded 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. To overcome the quantizer mismatch between MPEG-1 and MPEG-4 syntax, a gradual adaptation function is applied. It is shown that the adaptive R-Q model-based rate control can efficiently control the output bit-rate to match the target bit budget.