A Computation and Energy Reduction Technique for HEVC Discrete Cosine Transform
Abstract : In this paper, a novel computation and energy reduction technique for High Efficiency Video Coding (HEVC) Discrete Cosine Transform (DCT) for all Transform Unit (TU) sizes is proposed. The proposed technique reduces the computational complexity of HEVC DCT significantly at the expense of slight decrease in PSNR and slight increase in bit rate by only calculating several pre-determined low frequency coefficients of TUs and assuming that the remaining coefficients are zero. It reduced the execution time of HEVC HM software encoder up to 12.74%, and it reduced the execution time of DCT operations in HEVC HM software encoder up to 37.27%. In this paper, a low energy HEVC 2D DCT hardware for all TU sizes is also designed and implemented using Verilog HDL. The proposed hardware, in the worst case, can process 53 Ultra HD (7680x4320) video frames per second. The proposed technique reduced the energy consumption of this hardware up to 18.9%. Therefore, it can be used in portable consumer electronics products that require a real-time HEVC encoder.
? The existing system reduces the computational complexity of HEVC DCT significantly at the expense of slight decrease in PSNR and slight increase in bit rate by only calculating several pre-determined low frequency coefficients of TUs and assuming that the remaining coefficients are zero.
? In this paper, a novel computation and energy reduction technique for High Efficiency Video Coding (HEVC) Discrete Cosine Transform (DCT) for all Transform Unit (TU) sizes is proposed.
? In this paper, another low energy HEVC 2D DCT hardware for all TU sizes with higher hardware utilization is also designed and implemented using Verilog HDL.
? If the values of non-zero forward transformed and quantized low frequency coefficients in a TU are small, they have small impact on the inverse quantized and inverse transformed TU.
? However, the technique proposed in this paper avoids most of the DCT operations that have no impact or low impact on the transformed and quantized TUs in both mode decision and coding stages of an HEVC encoder.
? The impact of the proposed technique on the computational complexity and rate-distortion performance is determined for three different DCT coefficient sets.
? These DCT coefficient percentages are experimentally determined to reduce the computational complexity of HEVC DCT significantly with slight impact on distortion and bit rate.
• In multiplierless DCT, the resulting error is kept under a predefined threshold when the approximate adders and subtractors are proposed in addition to common optimization.
• There are more radical approximations proposed with the development of the approximate computing paradigm.
• The new method for optimization and approximation of the DCT block were successfully proposed, which were employed in the HEVC standard.
• The developed and proposed approximation methods will be applied to other blocks of HEVC in the future works in order to find much more power trade-off/better quality.
? A new international video compression standard called High Efficiency Video Coding (HEVC) is recently developed.
? After forward transform and quantization, most of the forward transformed and quantized high frequency coefficients in a TU become zero.
? The proposed technique only calculates several predetermined low frequency coefficients of TUs, and it assumes that the remaining coefficients are zero.
? These techniques try to predict the blocks with zero forward transformed and quantized coefficients before DCT and quantization operations in the coding stage of an H.264 or HEVC encoder in order to avoid DCT and quantization operations.
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