Hardware/software codesign is a rapidly-growing research area branching from hardware synthesis. The purpose of codesign is to facilitate the design of small embedded systems, that is, those consisting of a microprocessor, for which software is required, in addition to one or more semi-custom ASICs or FPGAs. In this paper, a design flow of an H.264 HW/SW digital video encoder is introduced. A design example of a hardware 4times4 DCT-like transform and quantization block integrated with the H.264 software reference model is described