Low power as a de facto is one of the most important criteria for many signal-processing system designs, particularly in multimedia cellular applications and multimedia system on chip design. There have been many approaches to achieve this design goal at many different implementation levels ranging from very-large-scale-integration fabrication technology to system design. In this paper, the multirate low-power design technique will be used along with other methods such as look-ahead, pipelining in designing cost-effective low-power architectures of compressed domain video coding co-processor. Our emphasis is on optimizing power consumption by minimizing computational units along the data path. We demonstrate both low-power and high-speed can be accomplished at algorithm/architecture level. Based on the calculation and simulation results, the design can achieve significant power savings in the range of 60%-80% or speedup factor of two at the needs of users.Index Terms-Compressed domain video coding, DCT, low-power architecture, motion estimation.