Field programmable gate array implementation of variable‐bins high efficiency video coding CABAC decoder with path delay optimisation
Wahiba Menasri, Skoudarli Abdellah, Belhadj Aichouche, Mohamed Salah Azzaz · IET Image Processing · 2019
Context‐based adaptive binary arithmetic coding (CABAC) is a single operation mode for entropy coding in the last video coding standard high‐efficiency video coding. For high‐resolution applications, the throughput of one bin/cycle is not sufficient and it is a very challenging task to implement pipeline and/or parallel CABAC decoding architecture by simply adding more stages. Indeed, the tight data dependencies make it difficult to parallelise and cause it to be a throughput bottleneck for video decoding. Consequently, in order to improve the CABAC decoder throughput, parallel and pipeline architectures are used in authors’ design. In this work, an algorithm‐architecture adequation is proposed to implement a CABAC decoder on a field programmable gate array. Mainly, a new classification of 32 syntax elements is given to speed up the authors’ solution. Furthermore, the context selection and modelling of regular syntax elements are studied, designed and implemented. Finally, a novel technique of memories rearrangement to reduce the critical path delay required to process each binary symbol is proposed. As a result, the implementation can process 2.2 bins/cycle when operated at 123.49 MHz and exhibits an improved high‐throughput of 271.678 Mbins/s. The hardware architecture is coded using hardware description language and synthesised using ISE Xilinx tools targeting the Virtex4 platform.