P3-CABAC: A Nonstandard Tri-Thread Parallel Evolution of CABAC in the Manycore Era

Due to its high-computational complexity and poor parallelism, the context-based adaptive binary arithmetic coder (CABAC) increasingly poses a bottleneck in the large-scale parallel video encoder like H.264 on a manycore platform. Motivated by the organization of the contexts models in CABAC, this letter presents a tri-thread parallel evolution of CABAC. The evolutional coder, which is named P3-CABAC, statically divides syntax elements into three predefined groups, each of which forms a parallel thread. Since the P3-CABAC is thread-level parallelizable and implementation-friendly for manycore processors, it presents a rational consideration for entropy coding in block-based video encoders in the manycore era.