A 2014 Mbin/s deeply pipelined CABAC decoder for HEVC

Abstract

High Efficiency Video Coding (HEVC) is the latest video standard that specifies video resolutions up to 8K Ultra-HD (UHD) at 120 fps to support the next decade of video applications. This results in high throughput requirements for the Context Adaptive Binary Arithmetic Coding (CABAC) entropy decoder, which was already a well-known bottleneck in H.264/AVC. Several modifications were made to the HEVC CABAC to address the throughput challenges. This work leverages these improvements in the design of a high throughput HEVC CABAC decoder. The proposed design uses a deeply pipelined architecture to achieve a high clock rate. Additional techniques such as state prefetch logic, latched-based context memory, and separate finite state machines are applied to minimize stall cycles, while multi-bypass bins decoding is used to further increase the throughput. The design is synthesized in a IBM 45nm SOI process, and achieves throughputs up to 2014 and 2748 Mbin/s under common and worst-case test conditions, respectively, at 1.9 GHz operating frequency. The results show that the design is sufficient to decode video bitstreams in real-time at Level 6.2, or at Level 6.0 for applications requiring sub-frame latency.