This paper studied an H. 264 HDTV decoder on two multiprocessor system-on-chip architectures. Two types of networks-on-chip, the RAW network and the application specific networks-on-chip, were used. Regular-topology networks-on-chip (mesh, torus, and fat tree) have been proposed. However, we showed in this paper that the application-specific networks-on-chip provided substantial improvements in power, performance, and cost compared to regular-topology networks-on-chip. We measured the power, performance, area, total switch and link capacity, and switch and link utilization based on floorplans and circuit designs. Measurement results showed th at the application-specific networks-on-chip was both faster in absolute terms and more efficient. The application-specific networks-on-chip used 39% less power, 59% less silicon area, 74% less metal area, 63% less switch capacity, and 69% less link capacity to achieve 2X performance compared to the RAW network.