As the next 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. To improve the coding efficiency of intra frame coding, up to 34 intra prediction modes are defined in HEVC. The best mode among these pre-defined intra prediction modes is selected by rate-distortion optimization (RDO) for each block. If all directions are tested in the RDO process, it will be very time-consuming. To alleviate the encoder computation load, this paper proposes a new method to reduce the candidates in RDO process. In addition, the direction information of the neighboring blocks is made full use of to speed up intra mode decision. Experimental results show that the proposed scheme provides 20% and 28% time savings in intra high efficiency and low complexity cases on average compared to the default encoding scheme in HM 1.0 with almost the same coding efficiency. This algorithm has been proposed to HEVC standard and partially adopted into the HEVC test model.

Fast mode decision algorithm for intra prediction in HEVC

In high efficiency video coding (HEVC), the tree structured coding unit (CU) is adopted to allow recursive splitting into four equally sized blocks. At each depth level (or CU size), it enables up to 35 intraprediction modes, including a planar mode, a dc mode, and 33 directional modes. The intraprediction via exhaustive mode search exploited in the test model of HEVC (HM) effectively improves coding efficiency, but results in a very high computational complexity. In this paper, a fast CU size decision algorithm for HEVC intracoding is proposed to speed up the process by reducing the number of candidate CU sizes required to be checked for each treeblock. The novelty of the proposed algorithm lies in the following two aspects: 1) an early determination of CU size decision with adaptive thresholds is developed based on the texture homogeneity and 2) a novel bypass strategy for intraprediction on large CU size is proposed based on the combination of texture property and coding information from neighboring coded CUs. Experimental results show that the proposed effective CU size decision algorithm achieves a computational complexity reduction up to 67%, while incurring only 0.06-dB loss on peak signal-to-noise ratio or 1.08% increase on bit rate compared with that of the original coding in HM.

Effective CU Size Decision for HEVC Intracoding

High efficiency video coding (HEVC) is the latest video coding standard that has been developed by JCT-VC. It employs plenty of efficient coding algorithms (e.g., highly flexible quad-tree coding block partitioning), and outperforms H.264/AVC by 35–43% bitrate reduction. However, it imposes enormous computational complexity on encoder due to the optimization processing in the efficient coding tools, especially the rate distortion optimization on coding unit (CU), prediction unit, and transform unit. In this article, we propose a CU splitting early termination algorithm to reduce the heavy computational burden on encoder. CU splitting is modeled as a binary classification problem, on which a support vector machine (SVM) is applied. In order to reduce the impact of outliers as well as to maintain the RD performance while a misclassification occurs, RD loss due to misclassification is introduced as weights in SVM training. Efficient and representative features are extracted and optimized by a wrapper approach to eliminate dependency on video content as well as on encoding configurations. Experimental results show that the proposed algorithm can achieve about 44.7% complexity reduction on average with only 1.35% BD-rate increase under the “random access” configuration, and 41.9% time saving with 1.66% BD-rate increase under the “low delay” setting, compared with the HEVC reference software.

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CU splitting early termination based on weighted SVM

Video steganography: A review

Up to 35 intra prediction modes are available for each Luma prediction unit in the coming HEVC standard. This can provide more accurate predictions and thereby improve the compression efficiency of intra coding. However, the encoding complexity is thus increased dramatically due to a large number of modes involved in the intra mode decision process. In addition, more overhead bits should be assigned to signal the mode index. Intuitively, it is not necessary for all modes to be checked and signaled all the time. Therefore, a novel adaptive modes skipping algorithm for mode decision and signaling processing is presented in this paper. More specifically, three optimized candidate sets with 1, 19, and 35 intra prediction modes are initiated for each prediction unit in the proposed algorithm. Based on the statistical properties of the neighboring reference samples used for intra prediction, the proposed algorithm is able to adaptively select the optimal set from the three candidates for each prediction unit preceding the mode decision and signaling processing. As a result, the mode decision process can be speeded up due to some modes skipping in the first two sets, and importantly less bits are required to signal the mode index. Experimental results show that, compared to the test model HM7.0 of HEVC, BD-Rate savings of 0.18% and as well as 0.18% on average are achieved for AI-Main and AI-HE10 cases for low-bitrate ranges, and the average encoding times can also be reduced by 8%-38% and 8%-34% for AI-Main and AI-HE10 cases in low-bitrate ranges, respectively.

Novel Adaptive Algorithm for Intra Prediction With Compromised Modes Skipping and Signaling Processes in HEVC

To reduce the intra encoding complexity of HEVC, a fast intra prediction mode decision algorithm is proposed in this paper. According to different size of prediction unit, based on statistical data, the algorithm uses threshold method to exclude the intra prediction modes of small possibility, then reduce the number of intra prediction modes for the rate distortion cost (RD Cost) calculation and cut down the encoding complexity. Experimental results show that compared with the HEVC reference software HM12.0, the proposed algorithm can achieve a reduction of 24.27% in average in intra prediction coding time, with a negligible average PSNR loss and average bit rate increment.

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A Fast Mode Decision Algorithm for Intra Prediction in HEVC

An information hiding algorithm for HEVC is proposed. For 33 kinds of directional prediction modes in the encoding process of 4×4 luminance blocks, intra prediction modes are mapped to the angle values. We are establishing a mapping relationship table between the angle differences and secret information. Modifying the intra prediction modes to embed secret information is based on the mapping. The extraction of information merely requires decoding the prediction mode from the bit stream. Experimental results show that the proposed hiding algorithm can embed information with little influence on the bit-rate and effectively guarantee the quality of the cover video.

An Information Hiding Algorithm for HEVC Based on Angle Differences of Intra Prediction Mode.

A large-capacity information hiding algorithm for HEVC is proposed. We modify the intra prediction modes in 4x4 luminance blocks to embed secret information. According to the probability distribution of the statistical optimal prediction mode and suboptimal prediction mode, we are establishing a mapping relationship between prediction modes and secret information. Modifying the intra prediction modes to embed secret information is based on the mapping. The extraction of information merely requires decoding the prediction mode from the bit stream. Experimental results show that the proposed hiding algorithm can embed information with large capacity and effectively guarantee the subjective and objective quality of video. Keywords-information hiding; HEVC; intra prediction; mapping

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A Large-capacity Information Hiding Method for HEVC Video

The invention discloses a quick HEVC (High Efficiency Video Coding) inter-frame prediction mode selection method. After coarse selection of inter-frame prediction modes, the statistical property of Hadamard transform-based cost values corresponding to the coarsely selected inter-frame prediction modes is fully utilized, and the correlation of the video texture direction and an inter-frame prediction mode angle are fully considered; for prediction unit types of different sizes, the inter-frame prediction modes after the coarse selection are quickly screened through a threshold value method or the continuity of the coarsely selected inter-frame prediction modes is calculated to reflect the texture direction of the prediction unit, so that the unnecessary coarsely selected inter-frame prediction mode is screened without introducing more extra calculation; in a verification process of the most possible prediction mode, the correlation of the coarsely selected inter-frame prediction modes and the most possible prediction mode and the space correlation of a video image per se are fully considered, the final optimal inter-frame prediction mode is quickly obtained, and the inter-frame coding complexity is reduced on the premise that the video coding quality is guaranteed.

Quick HEVC (High Efficiency Video Coding) inter-frame prediction mode selection method

The invention provides a method for hiding HEVC (High Efficiency Video Coding) video information. The method comprises two steps of secret information embedding and secret information extracting; during secret information embedding, a prediction model is modulated in an intra-frame prediction coding process aiming at 4*4 prediction units by analyzing an HEVC coding and decoding structure, an intra-frame coding mode is selected in a self-adapting manner by using a Lagrangian rate-distortion model to decide whether to embed secret information; a corresponding relation between two bits of information to be embedded and angle difference intervals of the prediction model, completed information embedding of the prediction model is corrected according to the two bits of information to be embedded, a prediction model of only one prediction unit in the two continuous 4*4 prediction units in most cases is required to be corrected, so that correction bits is reduced under the same hiding capacity, and influence on the video quality, which is caused by the embedded secret information is reduced; objective and subjective video quality can be well ensured, and influence on a video bitstream, which is caused by the embedded secret information is greatly reduced.

Li Wei

Papers

A Fast Mode Decision Algorithm for Intra Prediction in HEVC

An Information Hiding Algorithm for HEVC Based on Angle Differences of Intra Prediction Mode.

A Large-capacity Information Hiding Method for HEVC Video

Quick HEVC (High Efficiency Video Coding) inter-frame prediction mode selection method

Method for hiding HEVC video information