Dynamic MB-level Scheduling for parallel video coding

MB-level parallelism is widely used in parallel video coding thanks to its merits of low latency, no performance loss and high degree of parallelism. Most of video encoders with MB-level parallelism employ MB Row Scheduling (MRS) scheme. In software video encoder, early terminate algorithms tend to cause significant difference in coding time of different MBs. Consequently, the running speeds of multiple threads are unbalanced. When the number of threads is more than that of physical cores, the running speed unbalance is further worsened by computation resources competition among multiple threads. The computation resources of multiple cores can´t be fully utilized without careful handling of the above running speed unbalance. Additionally, synchronization of multiple threads can also penalize the running speed of the whole video encoder. In this paper, we analyze the running speed unbalance of multiple threads in MRS scheme, and propose a new Dynamic MB-level Scheduling (DMS) scheme for parallel video coding. DMS alleviates both the running speed unbalance and synchronization delay among multiple threads on multi-core platform. Experiment results verified that video encoder with MRS can be accelerated in average 9% by our proposed DMS, when processors are fully utilized.