Real Time All Intra HEVC HD Encoder on FPGA

Higher compression efficiency in HEVC encoders comes with increased computational complexity, making real time encoding of high resolution videos a challenging task. This challenge can be addressed by software, yet hardware solutions are more appealing due to their superior performance and low power consumption. This paper presents an FPGA based hardware implementation of an all intra HEVC encoder, which can encode 8 bits per sample, 1920x1080 resolution, 30 frames per second raw video, that is viable in real time even at low operating frequencies. A major obstacle to real time encoding in available architectures is the dependency created by reference generation. Moreover, each coding unit (CU) has to be processed in multiple configurations to determine the most efficient split and prediction mode representation, based on the bit stream generated. We propose a new three stage architecture to reduce these dependencies and increase parallelism. Feedback needed for CU split and prediction direction decision from binarization is avoided by a Hadamard based early decision method. Feedback constrained coefficient and reconstruction derivation module exploits several optimization techniques. All modules can operate at 200 MHz and the encoder can achieve real time encoding with a minimum operating frequency of 140 MHz. The design consumes 83K LUTs, 28K registers, and 34 DSPs when implemented on Xilinx Zynq ZC706.