Abstract: This paper presents a general procedure for determiningthe optimal MPEG coding strategy in terms of theselection of macroblock coding modes and quantizerscales. The two processes of coding mode decision andrate control are intimately related to each other andshould be determined jointly in order to achieveoptimal coding performance. We formulate theconstrained optimization problem and present solutionsbased upon rate- distortion characteristics, or R(D)curves, for all the macroblocks that compose thepicture being coded. Distortion of the entire pictureis assumed to be decomposable and expressible as afunction of individual macroblock distortions, withthis being the objective function to minimize. Thedetermination of the optimal solution is complicated bythe MPEG differential encoding of motion vectors and dccoefficients, which introduces dependencies that carryover from macroblock to macroblock for a duration equalto the slice length. Once the upper bound inperformance is calculated, it can be used to assess howwell practical sub-optimum methods perform.!1
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