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In this paper, we propose a new R/D estimation method for intra-predictive coding with deep block partitioning structures. In our proposed R/D prediction, we adopt a particle filtering based prediction (PFP) to precisely predict intermediate R/D estimates for the next frame in a stochastic manner, which helps increasing the prediction accuracy of fast changing R/D values. Then, based on the intermediate R/D estimates by PFP, we infer an optimal model parameter of the TC’s probability density function (pdf) via convex optimization. We found that the proposed method brings about more stable R/D estimation performance thanks to both the improved prediction accuracy using the PFP for abrupt changes in true R/D values and the precise estimation of the optimal model parameter. Experimental results show that our method significantly reduces the normalized root mean square error from average 3.17 to 0.79 (74.90% reduction) for rate and from average 2.32 to 0.82 (64.61% reduction) for distortion, compared to the state-of-the art method. [ABSTRACT FROM AUTHOR]

Joint exploration model (JEM) reference codecs of ISO/IEC and ITU-T utilize multiple types of integer transforms based on DCT and DST of various transform sizes for intra- and inter-predictive coding, which has brought a significant improvement in coding efficiency. JEM adopts three types of integer DCTs (DCT-II, DCT-V, and DCT-VIII), and two types of integer DSTs (DST-I and DST-VII). The fast computations of Integer DCT-II and DST-I are well known, but few studies have been performed for the other types such as DCT-V, DCT-VIII, and DST-VII for all transform sizes. In this paper, we present fast computation methods of N-point DCT-V and DCT-VIII. For this, we first decompose the DCT-VIII into a preprocessing matrix, the DST-VII and a post-processing matrix to quickly compute it by using the linear relation between DCT-VIII and DST-VII. Then, we approximate integer kernels of N = 4, 8, 16, and 32 for DCT-V, DCT-VIII, and DST-VII with norm scaling and bit-shift to be compatible with quantization in each stage of multiplications between decomposed matrices for video coding. In various experiments, the proposed fast computation methods have shown to effectively reduce the total complexity of the matrix operations with little loss in BDBR performance. In particular, our methods reduce the number of addition and multiplication operations by 38% and 80.3%, respectively, in average, compared to the original JEM. [ABSTRACT FROM AUTHOR]

In this paper, an all-zero block detection scheme is proposed prior to DCT to reduce the encoding complexity for high efficiency video coding (HEVC). Since many coding blocks tend to have all zero coefficients after DCT and quantization, it is worthwhile to detect all-zero-quantized blocks for input residual blocks before DCT so that subsequent transform and quantization can be skipped. Unlike previous coding standards, HEVC adopts large transform sizes such as $16 \times 16$ and $32 \times 32$ in addition to $4 \times 4$ and $8 \times 8$. It becomes more difficult to accurately detect all-zero blocks in HEVC because the large transform blocks contains more variety of content characteristics than smaller ones, thus making it ineffective the existing all-zero block (AZB) detection schemes for large transform blocks in HEVC. In this paper, a novel AZB detection scheme is proposed for the case that Hadamard transform is used as a distortion metric for RDO in HEVC. Statistical upper bounds to be all-zero blocks are derived using the relationship between Walsh Hadamard and DCT transform kernels. Then, a small number of quantized coefficients in a upper left corner of a transform block, which are obtained using the relations between Hadamard transform and DCT, are examined for AZB detection. For $32 \times 32$ blocks, DC coefficients of $8 \times 8$ sub-blocks are further examined for AZB detection. The experimental results demonstrate that the proposed scheme detects 87.79% of actual AZBs with 2.87% false alarm rate in average, outperforming the state-of-the-art method. Computational complexity to detect AZB is almost negligible compared to the conventional method. [ABSTRACT FROM PUBLISHER]

In this paper, a High Efficiency Video Coding (HEVC)-compliant perceptual video coding (PVC) scheme is introduced based on just-noticeable difference (JND) models in both transform and pixel domains. We adopt an existing pixel-domain JND model for the transform skip mode of HEVC and propose a transform-domain JND model for the transform nonskip modes of HEVC. The proposed transform-domain JND model is designed by considering the spatial JND characteristics such as contrast sensitivity, luminance adaptation, and contrast masking effects as well as by considering the summation effects of variable block-sized transforms in HEVC. A temporal JND model is additionally incorporated into the proposed transform-domain JND model to further reduce perceptual redundancy. To incorporate the transform- and pixel-domain JND models into the encoding process in an HEVC-compliant manner, the transform coefficients and residues are suppressed in harmonization with the transform/quantization process and the quantization-only process of HEVC, respectively. To make the JND-based suppression effective, a distortion compensation factor is also proposed to reflect the perceptual distortion in the rate-distortion optimization-based encoding process. Based on subjective quality assessments of the encoded bit streams of test sequences, the proposed HEVC-compliant PVC scheme yields remarkable bitrate reductions of a maximum 49.10% and an average 16.10% with negligible subjective quality loss, compared with an HEVC reference software HEVC test model (HM 11.0). In addition, the proposed HEVC-compliant PVC scheme increases the encoding complexity of HM 11.0 only by an average of 11.25%. [ABSTRACT FROM AUTHOR]

HEVC is a next generation video coding standard designed with modern coding techniques to be especially efficient for coding high-resolution video such as 4 K/8 K-ultra high- definition (UHD) video. Among the advanced coding tools of HEVC, tiles and wavefront parallel processing (WPP) have been newly adopted for parallel processing of such high-resolution (4 K/8 K-UHD) video. To realize UHD video services over portable devices with limited battery power, it is essential to implement multi-core-based and dedicated HEVC hardware decoders that support the tile- and wavefront-based parallel processing. By doing so, each frame is divided into a multiple number of picture partitions which can then be processed by multiple hardware decoder cores in parallel. However, in-loop filtering (ILF) at tile boundaries cannot be easily parallelized by a multi-core HEVC hardware decoder because of the data dependency between samples in different tiles. In this paper, an efficient control method for ILF across tile boundaries is proposed for multi-core HEVC hardware decoders. The proposed method does not require additional in-loop filters for ILF across the tile boundaries and it allows a decoder core to continue to process the next coding tree unit (CTU) without waiting for other decoders until they finish their ILF processing for the neighboring CTUs in other tiles. From experiments, we show the effectiveness of our ILF control method via a quad-core HEVC decoder for 4 K-UHD video implemented on a prototyping FPGA board. [ABSTRACT FROM PUBLISHER]

Recently, a new video coding standard, High Efficiency Video Coding (HEVC), has shown greatly improved coding efficiency by adopting hierarchical structures of coding unit (CU), prediction unit (PU), and transform unit (TU). To best achieve the coding efficiency, the best combinations of CU, PU, and TU must be found in the sense of the minimum rate-distortion (R-D) costs. Owing to this, a large computational complexity occurs. Among these CU, PU, and TU, the determination of CU sizes most significantly affects the R-D performance of HEVC encoders, which causes large computational costs in operation with PU and TU size determinations. In spite of recent works in the complexity reduction of HEVC encoders, most of the research has focused on the complexity reduction with fast CU split in intra slice coding and with early TU split in both intra and inter slice. In this paper, we propose a fast and an efficient CU encoding scheme based on the spatiotemporal encoding parameters of HEVC encoders, which consists of an improved early CU SKIP detection method and a fast CU split decision method. For the current CU block under encoding, the proposed scheme utilizes sample-adaptive-offset parameters as the spatial encoding parameter to estimate the texture complexity that affects the CU partition. In addition, the motion vectors, TU size, and coded block flag information are used as the temporal encoding parameters to estimate the temporal complexity that also affects the CU partition. The proposed scheme effectively utilizes the spatiotemporal encoding parameters that are the byproducts during the encoding process of HEVC without additionally required computation. The proposed novel fast CU encoding scheme significantly reduces the total encoding time with negligible RD-performance loss. The experimental results show that the proposed scheme achieves the total encoding time savings of average 49.6% and 42.7% only with average 1.4% and 1.0% bit-rate losses for various test sequences under random access and low delay B conditions, respectively. The proposed scheme has an advantage on the implementation for parallel processing in pipeline structures of HEVC encoders due to its independency with neighboring CU blocks. [ABSTRACT FROM PUBLISHER]

In this paper, a frame-level rate control scheme is proposed based on texture and nontexture rate models for High Efficiency Video Coding (HEVC). Due to more complicated coding structures and the adoption of new coding tools, the statistical characteristics of transform residues are significantly different depending on the depth levels of coding units (CUs) from which the residues are obtained. A new texture rate model is constructed for the transform residues, which are categorized into three types of CUs: low-, medium- and high-textured CUs. One single Laplacian probability PDF model is used for each residue category to derive a rate-quantization model. Based on the Laplacian PDF, a simplified rate model for texture bits is derived using entropy. In addition, an analytic rate model for nontexture bits is proposed, which also takes into account the different characteristics of nontexture bits occurring in various depths of CUs in HEVC. The nontexture bitrates are modeled based on the linear relation between the total nontexture data and the dominant nontexture data in each CU category. Based on the proposed rate models for the texture and nontexture bits, accurate rate control can be achieved owing to more precise rate estimation. The experimental results show that the proposed rate control scheme achieves the average PSNR with 0.44 dB higher and the average PSNR standard deviation of 0.32 point lower with the buffer status levels maintained very close to target buffer levels, compared to the conventional methods. Finally, the proposed rate control scheme remarkably outperforms the conventional schemes especially for the sequences of complex texture and large motion. [ABSTRACT FROM PUBLISHER]

High Efficiency Video Coding (HEVC), a new video coding standard currently being established, adopts a quadtree-based Coding Unit (CU) block partitioning structure that is flexible in adapting various texture characteristics of images. However, this causes a dramatic increase in computational complexity compared to previous video coding standards due to the necessity of finding the best CU partitions. In this paper, a fast CU splitting and pruning method is presented for HEVC intra coding, which allows for significant reduction in computational complexity with small degradations in rate-distortion (RD) performance. The proposed fast splitting and pruning method is performed in two complementary steps: 1) early CU split decision and 2) early CU pruning decision. For CU blocks, the early CU splitting and pruning tests are performed at each CU depth level according to a Bayes decision rule method based on low-complexity RD costs and full RD costs, respectively. The statistical parameters for the early CU split and pruning tests are periodically updated on the fly for each CU depth level to cope with varying signal characteristics. Experimental results show that our proposed fast CU splitting and pruning method reduces the computational complexity of the current HM to about 50% in encoding time with only 0.6% increases in BD rate. [ABSTRACT FROM PUBLISHER]

Recently, 3DTV has drawn much attention as a new broadcasting service. In spite of technical advances in 3DTV broadcasting services, there are two barriers that hinder the new services from being launched for terrestrial broadcasting: the lack of available bandwidth for transmission of additional-view video via terrestrial channel and backward compatibility with the legacy 2-D HDTV services. As an alternative, a hybrid stereoscopic video coding scheme is proposed for a stereoscopic 3DTV service, where one-view video is transmitted through the legacy broadcasting systems and the other one is delivered via broadband networks to which TV terminals are connected. In this paper, the proposed hybrid stereoscopic video coding scheme incorporates an MPEG-2 codec for backward compatibility with a legacy 2-D HDTV service and an HEVC codec with inter-view prediction coding as an extension to encode additional-view video sequences with high coding efficiency. The proposed inter-view prediction coding scheme in the extended HEVC incorporates an advanced motion and disparity vector prediction (AMDVP) method for enhanced motion- and disparity-compensated coding. The experimental results demonstrate that the proposed hybrid stereoscopic video coding scheme achieves an average coding efficiency of 38.22% (32.86%) in BD-rate or 1.394 dB (1.235 dB) in BD-PSNR for the out-band (in-band) scenario. [ABSTRACT FROM PUBLISHER]

Video quality estimation is considered a means of monitoring quality of service in broadcasting or IPTV services. In this paper, a no-reference peak signal-to-noise ratio (PSNR) estimation method is first presented for a quadtree-based motion estimation or compensation and transform coding scheme such as HEVC test model (HM), which is expected to be popularly used due to its highly enhanced coding efficiency, in 2-D and 3-D high resolution videos. The proposed no-reference PSNR estimation method is based on a Laplacian mixture distribution, which takes into account the distribution characteristics of residual transform coefficients in different quadtree depths and coding types of coding units (CUs). In order to predict the model parameters of the Laplacian mixture distribution for all zero quantized coefficients case, an exponential regression scheme is employed over quadtree depth levels of CUs. The proposed no-reference PSNR estimation method yields fairly accurate results from 0.970 to 0.983 in correlation and from 0.530 to 0.890 in RMSE between the actual and the estimated PSNR values for HM encoded bitstreams, outperforming single PDF based models. [ABSTRACT FROM PUBLISHER]

Although the temporal scalability coding supported by both H.264/AVC and H.264/SVC provides a good means of adapting bitstream scalability in temporal dimension, it entails heavy computational complexity due to bidirectional motion estimation and compensation for B-pictures in temporal scalability levels. To make it more applicable, this paper introduces a fast inter-prediction mode decision method which is efficiently performed using statistical hypothesis testing. The hypothesis testing is performed on mean and variance of pixels in 16 \times 16 and 8 \times 8 blocks to decide early termination against further processing for their sub-blocks. Fallback check is employed to compromise the tradeoff between the compression efficiency and encoding time saving. The proposed method exhibits effective performance for early termination in the inter-prediction mode decision, thus leading to a significant reduction of the total encoding time up to average 64.8% with small increments in bit amounts and small degradation in visual quality. [ABSTRACT FROM PUBLISHER]

Selective protection can exploit dependency coding properties to effectively perform partial protection on scalable video coding (SVC) bitstreams since protecting frames in lower scalability layers affects visual quality of the reconstructed frames in higher scalability layers. In this paper, we propose a selective protection scheme that maximizes protection effects by the minimum number of encoded frames to be protected in the SVC bitstream domain. We first model the SVC dependency coding structure as a directed acyclic graph which is characterized with an estimated visual quality value as the attribute at each node. In addition, a visual quality estimation model is proposed based on the proportions of intra-predicted and inter-predicted MBs, amounts of residues, and estimated visual quality of reference frames. The proposed selective protection scheme traverses the dependency graph to find optimal protection paths that can give the maximum visual quality degradation. Experimental results show that, compared to the existing protection schemes, the proposed selective protection scheme reduces computation complexity in the number of protected frames, the amount of protected data, and the protection time saving. The SVC file format specification supports the carriage of selectively protected bitstreams based on the concept of our selective protection in dependency coding structure of SVC. [ABSTRACT FROM AUTHOR]

An intra-frame joint rate control scheme is first proposed for a hybrid coder to encode stereoscopic video, which is based on an optimization framework with a gradient-based quadratic rate-quantization model and a gradient-based linear distortion-quantization model. The proposed rate control scheme jointly works on the left and right encoders for stereoscopic video input by controlling the output bit rates of both encoders in the sense that the sum of the two decoded video qualities is maximized and the quality difference is maintained around a desired level for a given target bit budget at the same time. In experiments, the proposed intra-frame joint rate control scheme for the hybrid coder produces the average 0.62 dB gain in PSNR, 64.93% reduction in the mean PSNR differences and 72.04% reduction in the MSE of PSNR difference, compared with the independent rate control schemes of the MPEG-2 TM5 and H.264 JM 16. [ABSTRACT FROM AUTHOR]

In this paper, a fast mode decision method for the spatial higher layers (SHLs) in scalable video coding (SVC) is proposed based on coding dependency between two adjacent spatial lower and higher layers. The proposed fast mode decision method detects zero motion and zero transform coefficient blocks in the current spatial layer using the already encoded information of the corresponding blocks from the lower layer. The information for zero motion vectors and zero transform coefficients is used to induce a reduced set of candidate modes in SHLs of SVC, which reduces the computation complexity up to about 75% of the total encoding time while maintaining the coding performance with negligible amounts of degradation in peak signal-to-noise ratio values and bitrates. [ABSTRACT FROM PUBLISHER]