Scalability of Macroblock-level Parallelism for H.264 Decoding

This paper investigates the scalability of macroblock (MB) level parallelization of the H.264 decoder for high definition (HD) applications. The study includes three parts. First, a formal model for predicting the maximum performance that can be obtained taking into account variable processing time of tasks and thread synchronization overhead. Second, an implementation on a real multiprocessor architecture including a comparison of different scheduling strategies and a profiling analysis for identifying the performance bottlenecks. Finally, a trace-driven simulation methodology has been used for identifying the opportunities of acceleration for removing the main bottlenecks. It includes the acceleration potential for the entropy decoding stage and thread synchronization and scheduling. Our study presents a quantitative analysis of the main bottlenecks of the application and estimates the acceleration levels that are required to make the MB-level parallel decoder scalable.