Design of a high-throughput CABAC encoder of HEVC standard for 8K video coding

Abstract

High Efficiency Video Coding (HEVC), as known as H.265, is a recently standardized video coding format. It has been known that HEVC performs twice the data compression ratio compared to that of its predecessor, H.264. Since the improvement in the compression capability, HEVC can provide ultra-high definition video with a resolution of up to 8K (8192x4320). In order to process the high-definition video in real-time applications, high-throughput encoder and decoder architectures are required. Most of all, Context-Adaptive Binary Arithmetic Coding (CABAC), which is used for entropy coding in HEVC, is actively discussed in the previous studies because it causes a bottleneck effect in the HEVC coder due to its serial property. In this paper, we propose a high-performance hazard-free CABAC encoder which satisfies the speed requirement for 8K video coding of HEVC standard by adopting advanced techniques for high-performance and resolving the aforementioned serial property. In more detail, we find a proper form of a parallel binarizer and its groups of binarization by simulation. Furthermore, we consider all possible dependency in the consecutive inputs to a parallel BAE and propose a state lookahead scheme which forwards an updated state to the remaining parallel pipelines. On top of that, we retime the proposed pipeline architecture of the CABAC encoder in order to maximize its performance. Synthesis results claimed that the proposed architecture enhances the bin-rate by 18% compared to the state-of-the-art CABAC encoder.