Hassan Kibeya

TZSearch pattern search improvement for HEVC motion estimation modules

Motion estimation (ME) is a key operation for video compression. In fact, it contributes heavily to the compression efficiency by removing temporal redundancies. This process is the most critical part in a video encoder and can consume itself more than 50% of coding complexity or computational coding time. To reduce the computational time, many fast ME algorithms were proposed and implemented. The present paper proposes a fast ME algorithm that improves the basic Test Zone Search (TZS) ME algorithm which is considered to be one of the fastest ME algorithms and was implemented in HEVC reference software HM8.0. Experimental results show an improvement that can reach 8% up to 49% compared to the basic TZSearch.

Fast coding unit selection and motion estimation algorithm based on early detection of zero block quantified transform coefficients for high-efficiency video coding standard

High-efficiency video coding (HEVC) is the newest video coding standard developed by the joint video team, consisting of ITU-T video coding experts group and ISO/IEC Moving Picture Experts Group. The HEVC standard has aggregated an exhaustive algorithm for mode decision based on a recursive quad-tree structured coding tree block. Moreover, several specific features have been incorporated into the motion estimation (ME) process to improve its coding efficiency. However, they resulted in very high computational complexity. To accelerate the encoding process, fast mode decision algorithms for the partitioning module and also for the ME module were proposed in this study. These algorithms are based on early zero block detection technique. To improve the efficiency of these algorithms, an overall algorithm which combines the two techniques has been implemented. The performance of the proposed algorithm was checked through a comparative analysis in terms of encoding time and compression rate. Compared to HEVC test model 10.0, the authors’ proposed algorithms bring a great reduction of the HEVC complexity encoder with a saving time, which can reach 25% in average for different tested videos and a slight coding loss in terms of image quality and compression rate.

A fast coding algorithm based on fast mode decision for HEVC standard

As the new generation standard of video coding, the High Efficiency Video Coding (HEVC) is intended to provide significantly better coding efficiency than all existing video coding standards. One of his improvements is the encoding process of the structure block. It was established that this process requires high computing power because it is performed using all the possible depth levels and prediction modes to find the one with the least rate distortion (RD) cost using Lagrange multiplier. To reduce the computational complexity, fast coding unit size decision algorithms were proposed and implemented in HM. These algorithms can significantly reduce computational complexity while maintaining almost the same performance as the original HEVC encoder.

Fast intra-prediction algorithms for high efficiency video coding standard

Abstract. High efficiency video coding (HEVC) is the latest video compression standard that provides significant performance improvement on the compression ratio compared to all existing video coding standards. The intra-prediction procedure plays an important role in the HEVC encoder, and it is being achieved by providing up to 35 intra-modes with a larger coding unit requiring a high computational complexity that needs to be alleviated. Toward this end, the paper proposes two fast intra-mode decision algorithms that exploit the features of video sequences. First, an early detection of zero transform and quantified coefficients method is applied to generate threshold values employed for early termination of the intra-decision process and hence accelerates the encoding procedure. Another fast intra-mode decision algorithm is elaborated that relies on a refinement technique. Based on statistical analyses of frequently chosen modes, only a small part of the candidate modes is chosen for intra-prediction process, which reduces the complexity of the intra-encoding procedure. The performance of the proposed algorithms is verified through comparative analysis of encoding time, visual image quality, and compression ratio. Compared to HM 10.0, the encoding time reduction can reach 69% with only a slight degradation of image quality and compression ratio.

Optimisation of HEVC motion estimation exploiting SAD and SSD GPU-based implementation

The new High-Efficiency Video Coding (HEVC) standard doubles the video compression ratio compared to the previous H.264/AVC at the same video quality and without any degradation. However, this important performance is achieved by increasing the encoder computational complexity. Thats why HEVC complexity is a crucial subject. The most time consuming and the most intensive computing part of HEVC is the motion estimation based principally on the sum of absolute differences (SAD) or the sum of square differences (SSD) algorithms. For these reasons, the authors proposed an implementation of these algorithms on a low cost NVIDIA GPU (graphics processing unit) using the Fermi architecture developed with Compute Unified Device Architecture language. The proposed algorithm is based on the parallel-difference and the parallel-reduction process. The investigational results show a significant speed-up in terms of execution time for most 64 × 64 pixel blocks. In fact, the proposed parallel algorithm permits a significant reduction in the execution time that reaches up to 56.17 and 30.4%, compared to the CPU, for SAD and SSD algorithms, respectively. This improvement proves that parallelising the algorithm with the new proposed reduction process for the Fermi-GPU generation leads to better results. These findings are based on a static study that determines the PU percentage utilisation for each dimension in the HEVC. This study shows that the larger PUs are the most utilised in temporal levels 3 and 4, which attain 84.56% for class E. This improvement is accompanied by an average peak signal-to-noise ratio loss of 0.095 dB and a decrease of 0.64% in terms of BitRate.

Statistical analysis of intra prediction in HEVC video encoder

High Efficiency Video Coding (HEVC) standard represents the newest video coding standard generation for both ITU-T Video Coding Experts Group and the ISO/IEC Moving Picture Experts Group. The new standard reduces bitrates by 50% compared to the existing standards using Advanced Video Coding (AVC) for equal video quality. This paper provides an overview of the technical features and characteristics of the new HEVC standard. A detailed statistical analysis of intra prediction unit showed that the RDO process represent the most time consuming module. Concerning intra prediction mode selection, the frequently chosen modes were 0, 1, 26, and 10. Then, the optimal mode represents on average 87% to belong to the most probable mode list MPM.

A fast CU Partitionning algorithm based on early detection of zero block quantified transform coefficients for HEVC standard

In this paper, a fast Coding Unit (CU) partitioning algorithm is proposed to reduce encoding time of HEVC test model (HM). HEVC is the new generation video codec which improves the coding efficiency significantly and provides more than 50% bit rate reduction while maintaining the same image quality compared to its predecessor H.264/AVC. Different sizes of CUs are adopted during encoding which makes the encoding process time consuming. To reduce this computational complexity, a fast CU partitioning method is proposed based on early zero block detection technique. The performance of the proposed algorithm is verified through comparative analysis of encoding time and rate compression. Comparing to HM 10, our method saves the encoding time from 2% to 56% for different test videos with negligible coding loss.

Adaptive motion estimation search window size for HEVC standard

Recently standardized by the Joint Video Team (JVT) of ITU-T Video Coding Experts Group (VCEG) and ISO/IEC Moving Picture Experts Group (MPEG), the High Efficiency Video Coding (HEVC) was adopted to replace the H264/AVC with better compression performance that facilitates video transmission and storage while maintaining the same reconstructed video quality. This excellent coding efficiency is performed through an exhaustive algorithm for mode decision that requires a huge computational complexity. To accelerate the encoding process, fast motion estimation (ME) algorithms are proposed in this paper. Firstly, according to statistical results of the motion vector difference prediction distribution, an adaptive search range selection algorithm based on a depth level is presented. In addition, several motion estimation search patterns were designed to reduce the calculation redundancy of motion estimation process. Experimental results show that the proposed algorithm schemes can save the ME time up to 88% while upholding almost the same rate-distortion performances.

SAD and SSE implementation for HEVC encoder on DSP TMS320C6678

High Efficiency Video Coding is the latest video standard aiming to replace H264/AVC standard by improving significantly the coding efficiency and the compression performance which allows HEVC to be mostly suitable for high-definition videos for multimedia applications. However, the encoding process requires a high computational complexity that needs to be alleviated. Hence, the paper proposes a software implementation of HEVC encoder and an optimized architecture on single core DSP TMS320C6678 to perform the rate distortion optimization (RDO) for mode decision procedure. The goal is to use single instruction multiple data (SIMD) operations and data level parallelism in order to optimize the Sum of Absolute Differences (SAD) and Sum Square Error (SSE) engines. The performance of the proposed implementation shows more than 88% improvement in terms of cycle cost for the distortion functions computation and the encoding speed of the proposed optimized HEVC encoder is accelerated by approximately 24% compared to the HEVC reference model (HM12.0) software with slight loss of coding efficiency.

A new intra coding approach without planar representation for HEVC standard

The latest High Efficiency Video Coding was aggregated in order to enhance the previous H264.AVC by a rate compression decrease of 50% with the same image quality. The HEVC intra prediction procedure requires a high computational complexity that needs to be alleviated. To this end, the paper proposes a new approach of intra prediction process without the use of the planar mode. The performance of the proposed algorithms is verified through comparative analysis of encoding time and visual image quality. Comparing to HM 10.0, the encoding time reduction achieves 4% with a slight enhancement of image quality.