Gradient-based pre-processing for intra prediction in High Efficiency Video Coding

Abstract

In order to reach higher coding efficiency compared to its predecessor, a state-of-the-art video compression standard, the High Efficiency Video Coding (HEVC), has been designed to rely on many improved coding tools and sophisticated techniques. The new features are achieving significant coding efficiency but at the cost of huge implementation complexity. This complexity has increased the HEVC encoders' need for fast algorithms and hardware friendly implementations. In fact, encoders have to perform the different encoding decisions, overcoming the real-time encoding constraint while taking care of coding efficiency. In this sense, in order to reduce the encoding complexity, HEVC encoders rely on look-ahead mechanisms and pre-processing solutions. In this context, we propose a gradient-based pre-processing stage. We investigate particularly the Prewitt operator used to generate the gradient and we propose necessary approaches that enhance the gradient performance of detecting the HEVC intra modes. We also set different probability scenarios, based on the gradient information, in order to speed up the mode search process. Moreover, we propose a gradient-based estimation of the texture complexity that we use for coding unit decision. Results show that the proposed algorithm achieves a reduction of 42.8% in encoding time with an increase in BD rate of only 1.1%.

Enhanced Intra Prediction Based on Adaptive Coding Order and Multiple Reference Sets in HEVC

“…Unfortunately, the complexity of the HEVC encoder is already high because of the high performance coding tools [24], so it is not desirable to add high computational tools in HEVC. In order to reduce the encoding complexity of the proposed method, it is possible to apply some fast intra prediction methods, such as traditional fast intra prediction methods [25,26] and fast algorithms using deep learning [27,28]. Table 5.…”

H.265 Intra-Picture Prediction Acceleration using Low Complexity Model

“…Anis BenHajyoussef et al (2017) [4] calculates the gradient direction and gradient magnitude for the picture and for all 33 angular modes. It supports the rough mode decision process with the gradient values to calculate the cost.…”

Fast inter-prediction algorithm based on motion vector information for high efficiency video coding

“…In recent years, numerous fast algorithms are also proposed to further accelerate and improve the encoding process of HEVC. BenHajyoussef et al [8] detect the gradient information and speed up the intra modes searching. Zhang et al [9] shrink unnecessary intra modes in Rate-distortion Optimization (RDO) process and early terminate CU partition according to the coding bits of the current CU.…”

“…With EV in (7), we hope to extend the MV range obtained by (8), namely by adjusting the value obtained in (6) to make it similar to the MV distribution of the Merge 2N×2N in Section 3.2.1. We also define the length of the component in positive (posV D ) or negative (negV D ) direction, respectively, as shown in (8) without considering forward and backward predictions.…”