Design and Implementation of Parallel Bypass Bin Processing for CABAC Encoder

The ever-increasing demand for high-quality digital video requires efficient compression techniques and fast video codecs. It necessitates increased complexity of the video codec algorithms. So, there is a need for hardware accelerators to implement such complex algorithms. The latest video compression algorithms such as High-Efficiency Video Coding (HEVC) and Versatile Video Coding (VVC) have been adopted Context-based Adaptive Binary Arithmetic Coding (CABAC) as the entropy coding method. The CABAC has two main data processing paths: regular and bypass bin path, which can achieve good compression when used with Syntax Elements (SEs) statistics. However, it is highly intrinsic data dependence and has sequential coding characteristics. Thus, it is challenging to parallelize. In this work, a 6-core bypass bin path having high-throughput and low hardware area has been proposed. It is a parallel architecture capable of processing up to 6 bypass bins per clock cycle to improve throughput. Further, the resource-sharing techniques within the binarization and a common controller block have reduced the hardware area. The proposed architecture has been simulated, synthesized, and prototyped on 28 nm Artix 7 Field Programmable Gate Array (FPGA). The implementation of Application Specific Integrated Circuit (ASIC) has been done using 65 nm CMOS technology. The proposed design achieved a throughput of 1.26 Gbin/s at 210 MHz operating frequency with a low hardware area compared to existing architectures. This architecture also supports multi-standard (HEVC/VVC) encoders for Ultra High Definition (UHD) applications.