This paper presents an H.264/AVC decoder realization on a dual-core SoC (System-on-Chip) platform by the well-designed macroblock level software partitioning. Furthermore, optimizations of the procedures executed on each core, and data movement between two cores are captured from software and hardware techniques. The evaluation results show that a video with D1 (720×480 pixels) resolution can reach realtime decoding by the implementation, which provides a valuable experience for similar designs.