H.264/AVC is the latest video coding standard. It significantly outperforms the previous video coding standards, but the extraordinary huge computation complexity and memory access requirement make the hardwired codec solution a tough job. This paper describes the design methodology for H.264/AVC video codec. The system architecture and scheduling are addressed. The design consideration and optimization for its significant modules including bandwidth optimized motion compensation engine, reconfigurable intra predictor generator, low bandwidth parallel integer motion estimation are mentioned. Due to the complex, sequential, and highly data-depended characteristics of all essential algorithms in H.264/AVC, not only the pipeline structure but also efficient memory hierarchy is required. The design case with a hybrid task pipelining scheme, a balanced schedule with block-level, MB-level, and frame-level pipelining, are presented. By combining with many bandwidth reduction techniques and data reused schemes, very efficient architecture and implementation for plate-form based system is proved by the prototype chips.