Hi, there's something I find strange: H263 dequantization is the same for intra or non-intra coeffs: ( C' = C*2q + (q&1?q:q-1) ) But there's a different bias used during *quantization*. For intra, it's 0, and for inter, it's -q/2. I've checked MoMuSys, and it's the same. Does someone has an explanation/pointer? Something to do with the AC-values distribution function? bye, Skal