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CAVLC (Context-Adaptive Variable Length Coding) is a high-performance entropy method for video and image compression. It is the most commonly used entropy method in the video standard H.264. In recent years, several hardware accelerators for CAVLC have been designed. In contrast, high-performance software implementations of CAVLC (e.g., GPU-based) are scarce. A high-performance GPU-based implementation of CAVLC is desirable in several scenarios. On the one hand, it can be exploited as the entropy component in GPU-based H.264 encoders, which are a very suitable solution when GPU built-in H.264 hardware encoders lack certain necessary functionality, such as data encryption and information hiding. On the other hand, a GPU-based implementation of CAVLC can be reused in a wide variety of GPU-based compression systems for encoding images and videos in formats other than H.264, such as medical images. This is not possible with hardware implementations of CAVLC, as they are non-separable components of hardware H.264 encoders. In this paper, we present CAVLCU, an efficient implementation of CAVLC on GPU, which is based on four key ideas. First, we use only one kernel to avoid the long latency global memory accesses required to transmit intermediate results among different kernels, and the costly launches and terminations of additional kernels. Second, we apply an efficient synchronization mechanism for thread-blocks (In this paper, to prevent confusion, a block of pixels of a frame will be referred to as simply block and a GPU thread block as thread-block.) that process adjacent frame regions (in horizontal and vertical dimensions) to share results in global memory space. Third, we exploit fully the available global memory bandwidth by using vectorized loads to move directly the quantized transform coefficients to registers. Fourth, we use register tiling to implement the zigzag sorting, thus obtaining high instruction-level parallelism. An exhaustive experimental evaluation showed that our approach is between 2.5x and 5.4x faster than the only state-of-the-art GPUbased implementation of CAVLC., The Journal of Supercomputing, 78 (6), ISSN:0920-8542, ISSN:1573-0484

In the technological era, the primary source of information is in the form of digital data, which has to be secured while storing or transmitting during communication over an unsecured network. Different approaches are used to provide security to digital data, viz. text, audio, image, and video. This paper initially explains the security system such as cryptography, watermarking, and steganography and their comparative analysis based on different characteristics, viz. satisfaction level of objective, type of carrier object and secret information to be used, dependency of security level, and quality assessment parameters. This review article focuses more on steganography methods applied over video. The various methods implemented for video steganography in compressed domain, viz. inter-frame and intra-frame prediction, motion vector estimation, entropy coding (CAVLC and CABAC), and transformed and quantized coefficients of DCT, DST, and DWT, etc. and the methods based on spatial and transform domain for uncompressed video are briefly described. It is followed by the detailed analysis of related work done by various researchers in video steganography and the obtained experimental results. Furthermore, the confidential data hiding in compressed videos are explained using Moving Picture Expert Group (MPEG—1, MPEG—2, MPEG—4), Advanced Video Coding (AVC)/H.264, and High-Efficiency Video Coding (HEVC)/H.265 that includes both spatial and transform domain. This paper summarizes and explains the detailed investigations of numerous techniques of video steganography based on the comprehensive literature survey. The methods used to assess the performance of video steganography are analyzed based on the quality assessment parameters such as imperceptibility; measured by peak signal to noise ratio (PSNR), mean square error (MSE), and structural similarity (SSIM), robustness; measured by bit error rate (BER) and similarity (Sim), and embedding capacity; measured by hiding ratio. The overall review of past literature facilitates to have in-depth knowledge for upgrading the video steganography.

This article investigates the relative performance of multiple data embedding into H.264 compressed video under two schemes of closed-loop and open-loop methods. In closed-loop, a part of an encoder is modified to embed data within the encoding loop during re-compression, while in the open-loop scenario, a part of decoder is modified to embed data out of decoding loop. It is shown, while for the first instance of embedding, both methods behave almost similarly for all picture types, for later instances of embedding, open-loop outperforms the closed-loop method. Moreover, the required time for embedding and extracting processes of open-loop method is only 1-1.5% of that of the closed-loop counterpart. In both methods, the quality of watermarked video and the data hiding capacity are controlled by the position of last non-zero (LNZ) coefficient in the H.264 zigzag scanning order. However, for B-pictures, the side-effect of embedding distortion is very limited (in the order of 0.002 in terms of SSIM), but for I- and P-pictures it can be significant. Picture degradations in I- and P-frames are alleviated by confining data embedding only into the last block of macroblocks of I-frames and the last P-frame in the GOP, respectively. Finally, it is shown that while with CAVLC type entropy coder, the number of increased bits due to data embedding can vary from 5%-65% of the metadata volume (depending on quality degradation) this value with CABAC coder is only less than 20% of that under CAVLC.

Video coding in the YCbCr color space has been widely used, since it is efficient for compression, but it can result in color distortion due to conversion error. Meanwhile, coding in the RGB color space maintains high color fidelity, having the drawback of a substantial bitrate increase with respect to YCbCr coding. Cross-component prediction (CCP) efficiently compresses video content by decorrelating color components while keeping high color fidelity. In this scheme, the chroma residual signal is predicted from the luma residual signal inside the coding loop. This paper gives a description of the CCP scheme from several points of view, from theoretical background to practical implementation. The proposed CCP scheme has been evaluated in standardization communities and adopted into H.265/High Efficiency Video Coding (HEVC) Range Extensions. The experimental results show significant coding performance improvements for both natural and screen content video, while the quality of all color components is maintained. The average coding gains for natural video are 17% and 5% bitrate reduction in the case of intra coding and 11% and 4% in the case of inter coding for RGB and YCbCr coding, respectively, while the average increment of encoding and decoding times in the HEVC reference software implementation are 10% and 4%, respectively.

In actual application scenarios of the real-time video confidential communication, encrypted videos must meet three performance indicators: security, real-time, and format compatibility. To satisfy these requirements, an improved bitstream-oriented encryption (BOE) method based chaotic encryption for H.264/AVC video is proposed. Meanwhile, an ARM-embedded remote real-time video confidential communication system is built for experimental verification in this paper. Firstly, a 4-D self-synchronous chaotic stream cipher algorithm with cosine anti-controllers (4-D SCSCA-CAC) is designed to enhance the security. The algorithm solves the security loopholes of existing self-synchronous chaotic stream cipher algorithms applied to the actual video confidential communication, which can effectively resist the combinational effect of the chosen-ciphertext attack and the divide-and-conquer attack. Secondly, syntax elements of the H.264 bitstream are analyzed in real-time. Motion vector difference (MVD) coefficients and direct-current (DC) components in Residual syntax element are extracted through the Exponential-Golomb decoding operation and entropy decoding operation based on the context-based adaptive variable length coding (CAVLC) mode, respectively. Thirdly, the DC components and MVD coefficients are encrypted by the 4-D SCSCA-CAC, and the encrypted syntax elements are re-encoded to replace the syntax elements of the original H.264 bitstream, keeping the format compatibility. Besides, hardware codecs and multi-core multi-threading technology are employed to improve the real-time performance of the hardware system. Finally, experimental results show that the proposed scheme, with the advantage of high efficiency and flexibility, can fulfill the requirement of security, real-time, and format compatibility simultaneously.

Context-based adaptive arithmetic coding (CAAC) has high coding efficiency and is adopted by the majority of advanced compression algorithms. In this paper, five new techniques are proposed to further improve the performance of CAAC. They make the frequency table (the table used to estimate the probability distribution of data according to the past input) of CAAC converge to the true probability distribution rapidly and hence improve the coding efficiency. Instead of varying only one entry of the frequency table, the proposed range-adjusting scheme adjusts the entries near to the current input value together. With the proposed mutual-learning scheme, the frequency tables of the contexts highly correlated to the current context are also adjusted. The proposed increasingly adjusting step scheme applies a greater adjusting step for recent data. The proposed adaptive initialization scheme uses a proper model to initialize the frequency table. Moreover, a local frequency table is generated according to local information. We perform several simulations on edge-directed prediction-based lossless image compression, coefficient encoding in JPEG, bit plane coding in JPEG 2000, and motion vector residue coding in video compression. All simulations confirm that the proposed techniques can reduce the bit rate and are beneficial for data compression.

This paper describes a low-complexity, high-efficiency, lossy-to-lossless 3D image coding system. The proposed system is based on a novel probability model for the symbols that are emitted by bitplane coding engines. This probability model uses partially reconstructed coefficients from previous components together with a mathematical framework that captures the statistical behavior of the image. An important aspect of this mathematical framework is its generality, which makes the proposed scheme suitable for different types of 3D images. The main advantages of the proposed scheme are competitive coding performance, low computational load, very low memory requirements, straightforward implementation, and simple adaptation to most sensors.

Nowday, UAV is new technologie among the next generation monitoring system which has the following properties: efficient, real time, secure and reliable. UAV occupied a great importance in many fileds especially national defense in order to protect the human. In fact, the size of transferred data is a basic demand for realtime video communication, partically for military service since the bandwidth limitation in UAV networks.Exprimental results show that the H264 standard outperforms MPEG 4 (Motion Picture Expert Group) encoder in termes of PSNR (Peak signal to noise ratio). The H264’PSNR gain is 6.88% better than MPEG 4. In addition, the H264 standard did not exceed 20 Mbit\s for wireless video transmission.

The authors propose efficient hybrid error resilience and error concealment (ER-EC) algorithms for H.264 3D video-plus-depth (3DV + D) transmission over error-prone channels. At the encoder, content-adaptive pre-processing ER mechanisms are implemented by applying the context adaptive variable length coding (CAVLC), the slice structured coding, and the explicit flexible macro-block ordering. At the decoder, a post-processing EC algorithm with multi-proposition schemes is implemented to recover the lost 3DV colour frames. The convenient EC hypothesis is adopted based on the lost macro-blocks size mode, the faulty view, and the frame types. For the recovery of the lost 3DV depth frames, an encoder-independent decoder-dependent depth-assisted EC algorithm is suggested. It exploits the previously estimated colour disparity vectors (DVs) and motion vectors (MVs) to estimate more additional depth-assisted MVs and DVs. After that, the optimum colour-plus-depth DVs and MVs are accurately selected by employing the directional interpolation EC algorithm and the decoder MV estimation algorithm. Finally, a weighted overlapping block motion and disparity compensation scheme is utilised to reinforce the performance of the proposed hybrid ER-EC algorithms. Experimental results on standard 3DV + D sequences show that the proposed hybrid algorithms have superior objective and subjective performance indices.

While H.264 is a well-established standard for video surveillance, its high-profile implementation, in particular, has the unique capabilities that pack more visual detail into a given bitrate. Several algorithms exist that detect moving objects from the H.264 bitstream, most of which end up incorrectly classifying the nonstationary or dynamic components (e.g., jitter camera, waving trees, ripples, etc.) of the background as foreground. Moreover, the coarse quantization schemes adopted at constrained bitrates pose new challenges for direct identification of moving objects/targets from the bitstream. This paper focuses on dynamic background modeling for the H.264 video encoded at very low bitrates. To this end, enhanced features of the fundamental coding unit, i.e., the macroblock (MB) are proposed. Based on the temporal statistics of the MB features gathered from initial frames, MBs that potentially contain parts of moving objects are selected in subsequent frames. The selected MBs constitute a coarse segmentation map of the foreground at the MB level. Finally, pixel-level segmentation of the foreground is obtained by comparing pixels constituting the selected MBs with the colocated counterparts of a background frame. Experimental results showing the comparison of bitstreams encoded at strikingly low bitrates are obtained over a diverse set of standardized surveillance sequences.

H.264 standard, known as an efficient video codec, is still sensitive to transmission errors. This issue is achieved by several error resilience/concealment techniques, to deal with packet losses. Whereas, these typical techniques are not suited for streaming video transmission which requires high quality. In fact, since the H.264 standard provides different type of frame, these techniques don’t give high priority to I frames. Moreover, video transmission over error prone channel has increased greatly. These facts provided the necessary to propose a new technique to deal with errors in video streaming over noisy channels. In this paper, we propose a novel technique, named novel robust decoding algorithm-aware channel conditions for video streaming (denoted as RDVS). The main idea of RDVS is to estimate CAVLC sequence by exploiting the bitstream structure and the semantic property. Obtained results confirm the effectiveness of the proposed strategy which outperforms the existing state-of-the-art Robust Decoding strategies.

This paper considers the problem of lossy source coding with a specific distortion measure: logarithmic loss. The focus of this paper is on the single-shot approach, which exposes crisply the connection between lossless source coding with list decoding and lossy source coding with log-loss. Fixed-length and variable-length bounds are presented. Fixed-length bounds include the single-shot fundamental limit for average as well as excess distortion. Variable-length bounds include the single-shot fundamental limit for average as well as excess length. Two multi-terminal problems are addressed: coding with side information (Wyner–Ziv) and multiple descriptions coding. In both the cases, the application of the Shannon–McMillan theorem to the single-shot bounds yields the rate-distortion function and the rate distortion-region for stationary ergodic sources.

The joint collaborative team on video coding has been developing an emerging standard for screen content coding (SCC) as an extension of HEVC known as HEVC-SCC. Intrablock copy (IBC) and palette coding are the two powerful coding tools adopted into HEVC-SCC. In this paper, a novel coding tool named inter-palette coding is proposed, which takes the advantages of both IBC and palette coding. With the inter-palette method, a new palette copy mode COPY_INTER can be applied, which enables the index samples to copy the pixels in the prediction block fetched by IBC or motion compensation. Experimental results show that the proposed scheme can achieve 3.15% BD-rate savings under all intra conditions on typical sequences containing “text and graphics with motion” averagely, with almost no complexity penalty.

The second generation of the audio video coding standard (AVS2), which has been issued as IEEE 1857.4, doubles the coding efficiency of AVS1 and H.264/AVC. However, the advanced techniques in AVS2 also dramatically increase the computational complexity. The research on a commercial encoder for AVS2 is still at an early stage. In this paper, we propose the first fast intra-encoding platform for AVS2, which we term iAVS2. The platform uses numerous speedup methods, including code optimization, single-instruction multiple-data acceleration, and fast algorithms for almost all the time-consuming modules. To meet different application scenarios, five different speed levels are designed in iAVS2 to provide flexible tradeoffs between compression efficiency and encoding speed. The experimental results show that the fastest speed level of iAVS2 can accelerate the AVS2 reference software (RD12.0) by $144\times $ on average. Compared with the well-known HEVC encoder platform $\times 265$ , iAVS2 can provide over 10% bit rate saving at a similar coding speed. For the UHD and 1080 sequences, iAVS2 outperforms $\times 265$ at all speed levels.

The paper presents an efficient implementation of Context-Adaptive Variable Length Coding (CAVLC) entropy encoder in H.264/AVC standard. The architecture is designed with a parallel structure targeting real-time video compression. The intensive memory access demand in the syntax element coding stage is lowered by using the proposed arithmetic table elimination technique. The packing stage implementation is interleaved with syntax element generation stage and includes fast methods for syntax elements concatenation. The register update method performs concatenation of the bitstream of previously processed sub-blocks and the syntax codewords of the currently processed sub-block. The CAVLC encoder processes 4 × 4 sub-block coefficients in parallel, introducing the initial latency of 12 clock cycles, after which the full pipeline of the data encoding on the sub-block level is performed, and 16 residuals are processed at each clock cycle. The achieved high throughput allows the encoding core to perform real-time processing of 8 K UHD (4320 p) video sequences with a frame rate of 30 frames/s.

Lossless compression is desired, especially for professional applications like medical imaging. However, scalability may be necessary to transmit a fast preview of pictures when the channel capacity is limited. Furthermore, there may be the need for random access to single frames of a losslessly reconstructed video. We present and evaluate a lossy-to-lossless scalable video coding system in which the scalability is achieved by using a lossy base layer (BL) in conjunction with lossless compression of the reconstruction error in the enhancement layer (EL). High Efficiency Video Coding (HEVC) is employed for encoding the BL. For compression of the EL, we propose a low-complexity scheme called sample-based weighted prediction for EL coding (SELC). Furthermore, EL compression using JPEG-LS and the scalable extension of HEVC (SHVC) are evaluated. The performance of scalable coding using each of these three methods is compared with lossless single-layer (SL) coding using the intra-main RExt configuration. Experimental results show that the scalable coding with SELC achieves average bitrate savings of 7.3% compared with the lossless SL coding, while average bitrate reductions of only 6.3% and 3.9% are obtained using JPEG-LS and SHVC, respectively. Concerning runtime, the additional encoder runtimes of SELC and JPEG-LS compared with the BL coding are negligible. In contrast to that, the runtime of the SHVC EL encoder is much higher and similar to the runtime of the BL encoder.

The Consultative Committee for Space Data Systems (CCSDS) has issued several data compression standards devised to reduce the amount of data transmitted from satellites to ground stations. This paper introduces a contextual arithmetic encoder for on-board data compression. The proposed arithmetic encoder checks the causal adjacent neighbors, at most, to form the context and uses only bitwise operations to estimate the related probabilities. As a result, the encoder consumes few computational resources, making it suitable for on-board operation. Our coding approach is based on the prediction and mapping stages of CCSDS-123 lossless compression standard, an optional quantizer stage to yield lossless or near-lossless compression and our proposed arithmetic encoder. For both lossless and near-lossless compression, the achieved coding performance is superior to that of CCSDS-123, M-CALIC, and JPEG-LS. Taking into account only the entropy encoders, fixed-length codeword is slightly better than MQ and interleaved entropy coding.

With the popularity of high-efficiency video coding (HEVC) standard, a video server usually transcodes a video stream to HEVC for its higher compression ratio. In this paper, a fast H.264/advanced video coding (AVC) to HEVC transcoding method is proposed. In the HEVC encoding procedure, a coding unit (CU), which is a motion-homogeneous block, is first checked based on the analysis of the decoded information from H.264/AVC bit stream. Then, for motion-homogeneous blocks, CU depth and the corresponding prediction unit (PU) mode's early termination strategies are proposed based on the CU size and corresponding prior statistical knowledge. For non-motion-homogeneous blocks, a corresponding PU mode's early termination strategy is also proposed. Experimental results demonstrate the effectiveness of the proposed method.

In this paper, we propose a selective encryption scheme with a chaotic encryption system for the High Efficiency Video Coding (HEVC) standard in which Context Adaptive Binary Arithmetic Coding (CABAC) is the only entropy coder for transform coefficient coding. Our method focuses on the binstrings of truncated rice with a context “p” (TRp) code suffix and kth order Exp-Golomb (k = p + 1) code suffix before Binary Arithmetic Coding (BAC) for the remaining absolute level coding, which is coded by the bypass mode in the entropy coding stage. The probability of symbols does not change and CABAC decoding has no effect after encryption. Several different YUV sequences are used for experimental evaluation of the proposed algorithm. Compared to previous researches, our approach has good protection for video information, which keeps a constant bitrate and format compatibility, and meantime it has a negligible impact on encoding performance.

CONTEXT ADAPTIVE VARIABLE LENGTH CODING (CAVLC) is a method designed for coding residual pixel data after transform and quantization, in which different codes with variable length are chosen based on recently coded coefficients. Coded bitstream can be stored or transmitted. This method is optional in widely adopted H.264 video coding standard. The entire algorithm is a complex one, and also difficult to implement efficiently in Field-Programmable Gate Array (FPGA), due to data dependency. When the complexity of the Register Transfer Logic (RTL) implementation rises, it impacts the duration and costs of development. Therefore, usage of High Level Synthesis (HLS) may be beneficial with these types of projects. In this paper first known to authors implementation of CAVLC and Exp-Golomb decoders for H.264 intra decoder in Impulse C language will be presented and compared with other implementations. Proposed solution is able to decode more then 720p@40fps with FPGA module clock at 166MHz.

The recently issued second generation IEEE 1857 video coding standard (AVS2) provides a doubling in coding efficiency relative to previous standards such as H.264/AVC and AVS1. The coding performance improvement is mainly due to the adoption of advanced coding tools. However, these coding tools also cause a dramatic increase in computational complexity. A fast encoder design for AVS2 is strongly demanded to promote it being widely used in video compression practice. In this paper, we propose a fast encoder design for AVS2. In our design, we propose a new quantization step (QStep) dependent fast CU depth decision algorithm for inter frames, and a combination strategy to integrate fast algorithms in different coding Presets to get a good trade-off between coding speed and coding efficiency. In addition, instruction optimization, parallel coding and some coding flow optimizations are also used in our design. According to the proposed design, we developed the first fast AVS2 encoder, and named it as uAVS2. Experimental results show that uAVS2 is 56.58 times faster than the AVS2 reference software, and 19.32 times faster than the HEVC reference software, with negligible performance loss. uAVS2 is 2.76.6 times faster than the well-known fast HEVC encoder x265 under similar coding performance configurations. Under similar coding speed, the coding performance of uAVS2 is superior to x265 by 1030% in BD-rate. uAVS2 with the highest speed Preset can encode 1080P video in real-time on PC platform. A new quantization step dependent fast CU depth decision algorithm is proposed.A combination strategy to integrate fast algorithms is proposed.The first fast AVS2 encoder is designed and developed.Our encoder is 2.76.6 times faster than x265 under similar BDRate.

This paper presents a fault-tolerance technique for H.264's Context-Adaptive Variable Length Coding (CAVLC) on unreliable computing hardware. The application-specific knowledge is leveraged at both algorithm and architecture levels to protect the CAVLC process (especially context adaptation and coding tables) in a reliable yet power-efficient manner. Specifically, the statistical analysis of coding syntax and video content properties are exploited for: (1) selective redundancy of coefficient/header data of video bitstreams; (2) partitioning the coding tables into various sub-tables to reduce the power overhead of fault tolerance; and (3) run-time power management of memory parts storing the sub-tables and their parity computations. Experimental results demonstrate that leveraging application-specific knowledge reduces area and performance overhead by 2x compared to a double-parity table protection technique. For functional verification and area comparison, the complete H.264 CAVLC architecture is prototyped on a Xilinx Virtex-5 FPGA (though not limited to it).

This paper proposes an extended selective encryption (SE) method for both H.264/advanced video coding (AVC) (CABAC) and High Efficiency Video Coding (HEVC) streams, addressing the main security issue that SE is facing: content protection, related to the amount of information leakage through a protected video. Our contribution is the improvement in the visual distortion induced by SE approaches. Previous works on both H.264/AVC (CABAC) and HEVC limit encryption to bins treated by one specific mode of CABAC—its bypass mode—which has the advantage of preserving the overall bitrate, we propose here to also rely on the encryption of the more widely used mode of CABAC—its regular mode. This allows encryption of a major codeword for video reconstruction, the prediction modes for intra blocks/units. Disturbing their statistics may cause bitrate overhead, which is the tradeoff for improving the content security level of the SE approach. A comprehensive study of this compromise between the improvement in the scrambling efficiency and the undesirable aftereffects is presented in this paper, and a specific security analysis of the proposed CABAC regular mode encryption is conducted.

The H.264/Advanced Video Coding (AVC) standard has been widely used in the last 10 years, and this has led to a large amount of legacy video being currently encoded in this format. However, the new High Efficiency Video Coding (HEVC) standard has recently been developed and it is thought that it will dominate the market in the next few years. These two facts make an efficient transcoding system between H.264/AVC and HEVC necessary. Moreover, it should be taken into account that intra sequences are commonly used in certain scenarios, such as video editing and post-production, making a migration of these intra contents from H.264/AVC to HEVC necessary. This paper proposes a fast intra H.264/AVC to HEVC transcoding system that is based on Bayesian classifiers and which outperforms other state-of-the-art algorithms, achieving a good complexity reduction with a negligible bit rate increase.

In this paper, a novel dynamic voltagefrequency scaling-aware (DVFS-aware) bandwidth- efficient motion estimation (ME) scheme is presented for mobile application processor (AP) systems. Under volatile operating performance conditions due to the power management mechanism, we model the coding bandwidth (BW) and coding performance for the video processor as a convex function of the working frequency. In this paper, we present a bandwidthratedistortion (BRD) optimized framework that will guarantee the smallest possible ratedistortion cost among coding BW constraints applied in video coding design. By formulating the coding bandwidth-constrained ME problem as an optimization problem, known convex optimization theory can be applied to yield optimal resource-constrained compression. Using varied CIF (352288)- and HP (1280720)-sized video sequences with different motion activities over our proposed DVFS-aware video coding approach, the excellent results in terms of coding performance and coding bandwidth savings are obtained. With negligible quality loss, the proposed scheme under coding BW constraints achieves 4565% coding BW usage reduction over HD-sized 30 frame/s video coding.

Coding complexity and error-resilience are the two key factors for video streaming in Wireless Multimedia Sensor Networks (WMSNs). Towards this objective, this paper proposes a Robust Distributed Video Coding (RDVC) framework to optimize the quality of video transmission for WMSNs. A new error-resilient Key frame coding scheme is proposed based on the protection of Wyner-Ziv Coding (WZC), in which additional Wyner-Ziv bits play a significant role for better error resilience and better Rate/Distortion (RD) performance. In addition, following the theoretical background of Distributed Joint Source Channel Coding (DJSCC), a novel distributed source channel codec based on Group Puncture Rate Adaptive IRA code (GPRA-IRA) is proposed, upon which the error-resilient Wyner-Ziv codec is designed. These experimental results show that the proposed RDVC scheme outperforms the relevant coding in terms of RD performance, notably by up to 1-3 dB, while achieving a lower encoding complexity.

The quad-tree based picture partition scheme in High Efficiency Video Coding (HEVC) results in a more substantial increase in computational complexity than those incurred by its predecessor video coding standards because of the need in this scheme to determine the best coding unit (CU) partitions. In this paper, we propose a method to effectively reduce the computational complexity of inter-prediction coding in the HEVC standard. The relative displacement of the largest coding unit (LCU) at the corresponding position between adjacent frames is tested through optical flow (motion estimation). The texture intensity of the LCU at the given time is tested if the condition that determines the coding depth in advance cannot be satisfied. The depth of the coding unit (CU) can be determined in advance beyond the xCompressCU function by using our proposed method, which does not require the calculation of the rate-distortion (RD) cost for each level of depth, and thus reduces the circular traversal times of the xCompressCU function. Experimental results proved that our proposed method is effective, as it reduced the computational complexity of an encoder by 53.2% on average, and had a slight influence on coding performance.

Context-based Adaptive Binary Arithmetic Coding (CABAC) is the entropy coding module in the HEVC/H.265 video coding standard. As in its predecessor, H.264/AVC, CABAC is a well-known throughput bottleneck due to its strong data dependencies. Besides other optimizations, the replacement of the context model memory by a smaller cache has been proposed for hardware decoders, resulting in an improved clock frequency. However, the effect of potential cache misses has not been properly evaluated. This work fills the gap by performing an extensive evaluation of different cache configurations. Furthermore, it demonstrates that application-specific context model prefetching can effectively reduce the miss rate and increase the overall performance. The best results are achieved with two cache lines consisting of four or eight context models. The 2 × 8 cache allows a performance improvement of 13.2 percent to 16.7 percent compared to a non-cached decoder due to a 17 percent higher clock frequency and highly effective prefetching. The proposed HEVC/H.265 CABAC decoder allows the decoding of high-quality Full HD videos in real-time using few hardware resources on a low-power FPGA.

We present an in-depth analysis of the problem of lossy compression of binary sources in the presence of correlated side information, where the correlation is given by a generic binary asymmetric channel and the Hamming distance is the distortion metric. Our analysis is motivated by systematic rate-distortion gains observed when applying asymmetric correlation models in Wyner-Ziv video coding. Firstly, we derive for the first time the rate-distortion function for conventional predictive coding in the binary-asymmetric-correlation-channel scenario. Secondly, we propose a new bound for the case where the side information is only available at the decoder - Wyner-Ziv coding. We conjecture this bound to be tight. We show that the maximum rate needed to encode as well as the maximum rate-loss of Wyner-Ziv coding relative to predictive coding correspond to uniform sources and symmetric correlations. Importantly, we show that the upper bound on the rate-loss established by Zamir is not tight and that the maximum value is actually significantly lower. Moreover, we prove that the only binary correlation channel that incurs no rate-loss for Wyner-Ziv coding compared to predictive coding is the Z-channel. Finally, we complement our analysis with new compression performance results obtained with our state-of-the-art Wyner-Ziv video coding system.

In this paper, an accurate rate model is proposed for inter-frame coding of high-efficiency video coding, which is useful for rate control. The proposed model considers the effect of entropy coding where the inter-symbol dependency is exploited in context- adaptive binary arithmetic coding (CABAC) for saving coded bits. The mutual information is first predicted to measure the reduction of uncertain information in CABAC, and then the conditional entropy is calculated to estimate the output bit-rate of inter-frame residues. Since the source characteristic also significantly impacts on the building of rate model, a joint Laplacian distribution source at the transform unit levels is employed in the proposed rate model. The experimental results show that the proposed model achieves a better rate-distortion performance in rate control. The proposed approach can be also extended to other video codecs using CABAC for the design of rate models.

In this paper, an adaptive block coding order for intra prediction is proposed. Modern video coding standards, including the most recent High Efficiency Video Coding (HEVC), utilize fixed scan orders in processing blocks during intra coding. However, the fixed scan orders typically result in residual blocks with noticeable edge patterns. That means the fixed scan orders cannot fully exploit the content-adaptive spatial correlations between adjacent blocks, thus the bitrate after compression tends to be large. To reduce the bitrate induced by inaccurate intra prediction, the proposed approach adaptively chooses both the block and subblock coding orders by minimizing the coding cost. Specifically, determining the block coding order is formulated as a traveling salesman problem that is solved using dynamic programming. Besides the block coding order, we also design the subblock coding order in each block with an adaptive manner. The experimental results demonstrate a Bjontegaard-Delta-rate reduction of up to 4.4% compared with HEVC anchor.

The block transform video coder of H.265/HEVC has been formulated for a more flexible content representation to satisfy various implementation demands. Here three coefficient-scanning methods of diagonal, horizontal and vertical scan are employed for mapping a 2-D array to a 1-D vector for further reducing redundancy in entropy coding. However, the fixation scanning pattern does not fully exploit the correlation among quantized coefficients and the coding redundancy still exists. In this paper, a new adaptive coefficient scanning (ACS) method is proposed for effective H.265/HEVC entropy coding. Here the characteristic of syntax elements of quantized coefficients is first studied and then the related context probability of symbol is estimated through combining local property. Guided by the principle of entropy coding, the scanning approach is established for higher coding performance. Experimental results demonstrate that a reduction of about 3.6%–4.2% in bit-rate can be observed with almost no loss in coding complexity.

High Efficiency Video Coding (HEVC) has brought significant improvement to video compression in terms of coding performance and subjective quality. However, it is computationally more complex than H.264/Advanced Video Coding (AVC) and, hence, adaptation of HEVC to real-time video services has not been promising. In order to reduce the computational cost, we propose a fast mode decision method that is based on the adaptive ordering of modes. Our experimental results show that the proposed method reduces the total encoding time by 47.27%–60.73% and 47.65%–61.31%, with negligible degradation of coding performance, which is a Bjontegaard delta rate increment of 0.35%–1.04% and 0.64%–1.80% under random-access configuration and low-delay configuration, respectively, compared with HEVC test model 12.1 with fast mode off.

In this paper, a residual differential pulse code modulation (RDPCM) coding technique using a weighted linear combination of neighboring residual samples is proposed to provide coding efficiency in the screen content video coding. The RDPCM performs the sample-based prediction of residue to reduce spatial redundancies. The proposed method uses the $l_1$ optimization in the weight derivation by considering the statistical characteristics of graphical components in videos in an intracoding. Specifically we use the least absolute shrinkage and selection operator to derive the weights because the solution is accurate in high variance residue. Furthermore, we enhance parallelism in a line processing by restricting the support to the row-wise prediction to above samples or the column-wise prediction to the left samples. The proposed method uses an explicit RDPCM scheme, so a coding mode determined by rate-distortion optimization is transmitted to a decoder. For coding the overhead, we develop a context design in CABAC based on correlation between an intraprediction direction and an RDPCM prediction mode. It is demonstrated with the experimental results that the proposed method provides a significant coding gain over the state-of-the-art reference codec for screen content video coding.

Modern video coding standards such as High Efficiency Video Coding (HEVC) and H.264/MPEG-4 advanced video coding (AVC) supersede the previous coding standards because of their improved coding efficiency. These standards adopt variable block sizes in frame coding ranging from 4 × 4 to 16 × 16 and 4 × 4 to 64 × 64 for H.264/AVC and HEVC, respectively. The use of variable block sizes for inter prediction provides a significant coding gain compared to coding a macroblock (MB) using regular block size. However, this new feature greatly increases the computational complexity of the encoder when brute-force rate distortion optimization (RDO) algorithm is used for coding parameter selection. This paper proposes an efficient inter prediction mode selection scheme based on motion homogeneity and residual complexity measures of an MB to speed up the encoding process. The motion homogeneity is assessed through the normalized motion vector (MV) field, and residual complexity is evaluated by the sum of absolute difference (SAD). To acquire the MVs and SADs, motion estimation at 8 × 8 block size is performed using a lightweight recursive motion estimator in which the vector field tends toward true object motion. Based on motion homogeneity and residual complexity of an MB, only a small number of inter prediction modes are selected for the RDO process. The experimental results for H.264/AVC show that the proposed scheme reduces the encoding time by 64% on average without any significant degradation of coding efficiency. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

The next-generation video coding standard known as High-Efficiency Video Coding (HEVC) was developed with the aim of doubling the bitrate reduction offered by H.264/Advanced Video Coding (AVC) at the expense of an increase in computational complexity. Mode decision with motion estimation is still one of the most time-consuming computations in HEVC, as it is with H.264/AVC. Several schemes for a fast mode decision have been presented in reference software and in other studies. However, a possible speed-up in conventional schemes is sometimes insignificant for videos that have inhomogeneous spatial and temporal characteristics. This paper proposes a bypass algorithm to skip large-block-size predictions for videos where small block sizes are preferred over large ones. The proposed algorithm does not overlap with those in previous works, and thus, is easily used with other fast algorithms. Consequently, an independent speed-up is possible.

Over the past years, multimedia usage has changed dramatically, with networks and terminals of diverse bandwidths and capabilities coexisting, making an adaptability of the video stream necessary. By the use of video scalability schemes, video streams would be able to adapt to these heterogeneous networks and a wide range of terminals. Moreover, some devices may be able to decode a subset of all the available video standards, e.g. most devices can decode the well-known H.264/advanced video coding (AVC) standard, which has dominated the market for the past 10 years. However, more recent devices can take the advantage of more modern standards whose compression performance is much higher, such as high-efficiency video coding (HEVC). This problem can be solved by the use of hybrid scalability, which allows the use of H.264/AVC for the base layer and HEVC for the enhancement layers. However, scalable video coding is very computationally expensive, so acceleration techniques are of great help in this kind of encoders. This paper presents a fast inter prediction algorithm which makes use of information from H.264/AVC base layer encoding and uses it to make faster decisions in HEVC. Experimental results show that the proposed algorithm can achieve a good tradeoff between coding efficiency and complexity.

With the advent of 3D displays, an efficient encoder is required to compress the video information needed by them. Moreover, for gradual market acceptance of this new technology, it is advisable to offer backward compatibility with existing devices. Thus, a multiview H.264/Advance Video Coding (AVC) and High Efficiency Video Coding (HEVC) hybrid architecture was proposed in the standardization process of HEVC. However, it requires long encoding times due to the use of HEVC. With the aim of tackling this problem, this paper presents an algorithm that reduces the complexity of this hybrid architecture by reducing the encoding complexity of the HEVC views. By using Na < ve-Bayes classifiers, the proposed technique exploits the information gathered in the encoding of the H.264/AVC view to make decisions on the splitting of coding units in HEVC side views. Given the novelty of the proposal, the only similar work found in the literature is an unoptimized version of the algorithm presented here. Experimental results show that the proposed algorithm can achieve a good tradeoff between coding efficiency and complexity.

A multiview video plus depth format was introduced to support 3D depth perception and arbitrary view generation. To achieve high coding performance in AVC-compatible 3D video coding (3D-AVC), we herein propose an efficient depth map coding method that includes synthesis-based depth residual coding and filtering. The synthesis-based depth residual coding method adaptively encodes a residual by predicting synthesis distortion from spatial complexity of the corresponding texture, in a nonnormative way. In order to compensate for possible error from the proposed coding method, synthesis-based depth filtering is additionally conducted on the reconstructed depth map. Experimental results demonstrate that the proposed method reduces the bit rates by 4.4% and 4.8%, compared with the original method for the decoded and synthesized PSNRs, respectively, while satisfying the compatibility with the current 3D-AVC.

Most rate-distortion (R-D) optimized quantization methods of video coding involve an exhaustive search process to determine the optimal quantized transform coefficients of a coding block and are computationally more expensive than the conventional quantization. In this paper, we present a novel analytical method that directly solves the rate–distortion optimization problem in a closed form by employing a rate model for entropy coding. It has the appealing property of low complexity and is easy to implement. The results show that the proposed method is $4\times $ to $40\times $ faster than the previous methods and 3%–5% more efficient in bitrate than the H.264/AVC reference encoder, which uses the conventional quantization, for video coded with the IBBP structure of group of pictures (GOP) in the normal peak signal-to-noise ratio (PSNR) range (30–40 dB).

3D extension of high efficiency video coding (3D-HEVC) supports the coding of multi-view video and depth map. It adds new coding tools to the high efficiency video coding (HEVC) design, which improve the HEVC compression capabilities for 3D video. These coding tools achieve high coding efficiency, but it brings relatively high computational complexity which limits 3D-HEVC from practical applications. In this paper, we propose an adaptive early termination mode decision algorithm to reduce 3D-HEVC computational complexity. An experimental analysis is performed to study inter-view and spatio-temporal correlations in the coding information. Based on the analysis results, we can determine to skip some specific prediction mode at the early termination stage without a normal 3D-HEVC encoding process. The proposed algorithm uses the correlation between inter-view and spatio-temporal blocks. Experimental results demonstrate that the proposed algorithm can significantly reduce computational complexity of 3D-HEVC encoding while maintaining almost the same rate-distortion (RD) performance.

The embedding is done on encrypted H.264/AVC data without knowing the decryption key.The paired code-word substitution and multiple-base notational system are exploited.Both encryption and data embedding keep the bit-rate intact.Data extraction can be carried out either in encrypted or decrypted domain. Recently, a novel scheme to hide data into encrypted H.264/AVC videos using code-word substitution has been proposed by Xu et al. However, the statistical analysis of CAVLC code-words demonstrate that Xu et al.'s work does not fully exploit redundancy existing in CAVLC code-word for data embedding. In this paper, an improved version of Xu et al.'s data hiding method in encrypted H.264/AVC videos is proposed. Specifically, when suffixLength is equal to 1, data embedding is performed by paired code-word substitution. When suffixLength is greater than 2, not the single code-word substitution but the multiple-based notational system is adopted for data embedding. Experimental results have demonstrated that the improved method is indeed capable of providing a larger embedding capacity in comparison with Xu et al.'s method. Moreover, both encryption and data embedding can be accomplished without affecting the coding efficiency of H.264/AVC by keeping exactly the same bitrate.

High-efficiency video coding (HEVC) is a new video coding compression standard. As the successor to H.264/AVC, it provides better performance and supports higher resolution. However, the encoding complexity increases drastically. One of the major reasons is that the coding unit (CU) in HEVC is multi-sized and adjustable rather than fixed as in H.264. In addition, the number of prediction modes used in intra-frame coding is expanded from 9 to 35. The authors analysed the statistical correlations of CU depth to the deviation of pixels in the largest coding unit (LCU) and rate-distortion cost (RDcost). Accordingly, a fast CU decision method is proposed, which contains two steps: first, the depth to begin searching is determined according to the deviation of the LCU and then splitting the current CU further is decided according to RDcost. For intra-prediction, we also propose a fast mode selection method to reduce complexity. This method can quickly determine the modes for rate-distortion optimisation when the combination of most probable modes reveals the pattern direction. Software simulations show that the proposed methods reduce encoding time by more than 50% with an average of 1.4% increase of BD-rate compared to reference software HM12.0.

High Efficiency Video Coding (HEVC) is the latest video coding standard to meet market demands for real-time high quality video codecs. As compared to its predecessor H.264/AVC, HEVC can achieve significant compression gains but with higher encoding complexity. Therefore, for real-time applications, significant encoding time reduction is still necessary. In the HEVC test model, the large number of coding quad-tree decisions to be tested during rate-distortion optimization would result in high encoding time. Hence, we propose a method to reduce the high encoding time by pruning the coding quad-trees using prediction residuals statistics. Experimental results from HM16.3-based implementations show that the proposed residual-based pruning method can reduce encoding time by an average of about 44% with an average of about 1.0% coding loss.

High-Efficiency Video Coding (HEVC) was conceived by the Joint Collaborative Team on Video Coding as the natural successor of the H.264/AVC standard, which has been the most extended digital video standard in all segments of the domestic and professional markets for over 10 years. HEVC roughly doubles the compression performance of H.264/AVC in Rate-Distortion terms at the expense of a high computational cost. Thus, most of the previous-generation devices can decode H.264/AVC streams but they cannot decode HEVC yet, while emerging devices are supposed to be able to decode both standards. Video providers should take advantage of bandwidth reduction using HEVC when possible, but they should also provide compatible streams to older devices, making it necessary to encode the same stream using both H.264/AVC and HEVC standards. This paper presents a coding tree unit splitting algorithm for a heterogeneous simultaneous encoding scenario which makes use of information from H.264/AVC encoder to make faster decisions in HEVC. Experimental results show that the proposed algorithm can achieve a good trade-off between coding efficiency and complexity.

This paper presents a high-performance encoder for H.264/AVC intra prediction. Due to long data dependency loop of intra 4×4 prediction and complex algorithms, improving encoding speed turns into a stumbling block we have to face. To solve this problem, we first propose a pipelined method in and between macro blocks with new block processing order to accelerate the encoding speed. Benefiting from the pipelined method, reconstructed pixels of up-right blocks are available for two blocks in a macro block which could not take advantage of reconstructed pixels of up-right blocks in JM. So diagonal down left mode and vertical left mode are effective for these two blocks, which ultimately achieves a better bit-rate. Secondly, all 4×4 mode formula sharing method is proposed to reduce the redundancy of predicting formulas. Thirdly, streamlined reconstruction method is applied to improve the performance of reconstruction. CAVLC encoder with three parallel units is proposed to improve entropy coding speed significantly. As a result, it takes 268 cycles to encode a macro block. The experimental results indicate that synthesized into a 0.18?m CMOS cell library, the new architecture only requires about 238K gates and it is able to encode 1080pHD video sequences at 30 frames per second (fps), at the operating frequency of 56MHz. Display Omitted The pipelined method in and between macro blocks accelerates the encoding speed.All 4×4 mode formula sharing method allows 16-pixel and 9-mode parallelism.Streamlined reconstruction method optimizes the computational redundancy.CAVLC encoder with three parallel units improves entropy coding speed signi?cantly.

Today, eavesdropping is becoming a common issue in the rapidly growing digital network and has foreseen the need for secret communication channels embedded in digital media. In this paper, a novel steganography technique designed for Standard Definition Digital Television (SDTV) H.264/AVC encoded video sequences is presented. The algorithm introduced here makes use of the compression properties of the Context Adaptive Variable Length Coding (CAVLC) entropy encoder to achieve a low complexity and real-time inserting method. The chosen scheme hides the private message directly in the H.264/AVC bit stream by modifying the AC frequency quantized residual luminance coefficients of intrapredicted I-frames. In order to avoid error propagation in adjacent blocks, an interlaced embedding strategy is applied. Likewise, the steganography technique proposed allows self-detection of the hidden message at the target destination. The code source was implemented by mixing MATLAB 2010 b and Java development environments. Finally, experimental results have been assessed through objective and subjective quality measures and reveal that less visible artifacts are produced with the technique proposed by reaching PSNR values above 40.0 dB and an embedding bit rate average per secret communication channel of 425 bits/sec. This exemplifies that steganography is affordable in digital television. Revisión por pares

High Efficiency Video Coding (HEVC) was developed by the Joint Collaborative Team on Video Coding to replace the current H.264/Advanced Video Coding (AVC) standard, which has dominated digital video services in all segments of the domestic and professional markets for over ten years. Therefore, there is a lot of legacy content encoded with H.264/AVC, and an efficient video transcoding from H.264/AVC to HEVC will be needed to enable gradual migration to HEVC. In terms of rate-distortion (RD) performance, HEVC roughly doubles the RD compression performance of H.264/AVC at the expense of a high computational cost. HEVC 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 due to the necessity of finding the best CU partitions. This paper presents an adaptive fast quadtree level decision algorithm that is designed to exploit the information gathered at the H.264/AVC decoder in order to make faster decisions on CU splitting in HEVC using a Naive-Bayes probabilistic classifier that is determined by a supervised data mining process. The experimental results show that the proposed algorithm can achieve a good tradeoff between coding efficiency and complexity compared with the anchor transcoder; moreover, it outperforms other related works available in the literature.