MPEG Coding Research Articles

Fast depth map intra-mode selection for 3D-HEVC intra-coding

As the last effort of ISO/IEC MPEG and ITU-T Video Coding Experts Group for 3D video coding, high-efficiency video coding (HEVC)-based 3D video coding (3D-HEVC) is the new international emerging standard to compress multi-view texture videos plus depth maps data. In the test model of 3D-HEVC, the conventional HEVC intra-prediction modes and new additional intra-coding tools called depth modeling modes (DMMs) are exploited for depth map intra-coding. These intra-modes provide important coding improvement. However, the improvement of the coding efficiency is obtained at the expense of a computational complexity increase, which obstructs 3D-HEVC from practical real-world applications. Previously, we propose a depth map intra-model decision using tensor features as homogeneity determination. In this paper, we propose an amelioration of the previously proposed depth map intra-model decision using an efficient homogeneity determination. In most cases, the angular intra-coding and DMM could be skipped if some specific conditions are satisfied. The experimental results show that the proposed intra-model decision can reduce the encoding time significantly, with negligible loss of rate distortion performance.

Fast 3D-HEVC PU size decision algorithm for depth map intra-video coding

High-Efficiency Video Coding (HEVC)-based 3D video coding (3D-HEVC) is the most recent standard and last exertion of ISO/IEC MPEG and ITU-T Video Coding Experts Group (VCEG) for 3D video coding using a new data video format called Multi-View Video plus Depth map (MVD). This new standard achieves a high coding improvement. In any case, one of the most critical difficulties in 3D-HEVC is time computational complexity. The depth map intra-prediction is a critical factor in 3D-HEVC intra-coding, in which, the 3D-HEVC uses a highly adaptable Coding Unit (CU) structure with a specific end goal to expand the coding efficiency of all depth map characteristics. However, it results in an enormous Rate Distortion Optimization Cost (RDO-Cost) because of the broad recursive search for the best CU size from $$64\times 64$$ down to $$4\times 4$$ . This computational complexity excludes the 3D-HEVC from true and real-time application. Hence, it is imperative to build up an algorithm to diminish the complexity of the size decision in depth map intra-coding. To determine the previously mentioned issue, this paper proposes an effective 3D-HEVC PU size decision algorithm for depth map intra-video coding based on tensor features and statistical data analyses. The experimental results demonstrate that the proposed model diminishes the complexity of depth map size decision significantly with low rate distortion increase.

Fast Depth Map Intra Coding for 3D Video Compression Based Tensor Feature Extraction and Data Analysis

3D high-efficiency video coding (3D-HEVC) is the latest standard for 3D video compression created by the ISO/IEC MPEG and ITU-T Video Coding Experts Group (VCEG) based on a new video format called multiview texture videos plus depth maps (MVDs). In 3D-HEVC depth map intra prediction, the test model uses the conventional HEVC intra modes and new supplementary coding tools called depth modeling modes (DMMs) to better preserve the sharp edges of depth maps. These intra prediction modes fundamentally enhance the depth map intra coding efficiency. Although this process enables high coding efficiency, it also results in a very high encoding complexity, which limits the use of the 3D-HEVC encoder in practical and real-world applications. For most cases, the conventional intra coding and DMMs can be skipped if the current region is classified as a homogenous region. Bringing this intuitive approach to practice, this paper proposes fast depth map intra coding based on tensor feature extraction and data analysis. The experimental results show that the proposed intra model decision brings a good complexity reduction with negligible loss of rate distortion performance.

Design and Implementation of TS over IP Gateway System

This paper presents the design and implementation of TS over IP gateway system with FPGA based on MPEG-2 coding format. The system is a bridge between digital terrestrial television and internet protocol television networks. It is implemented on Xilinx Zynq-7020, MARVELL 88E1111 PHY chip is chosen as network interface, supporting 10M/100M1000M. In this system, there are multiple real-time Transport Stream (TS) from 256 sources need to be processed. To prevent PID conflict, self-defining the head structure of TS packet is proposed. Due to stream modifications performed during TS processing, Program Clock Reference (PCR) correction is implemented to guarantee receiver synchronization. The system works well and playout is quite satisfactory.

Scalable Audio Coding Using Trellis-Based Optimized Joint Entropy Coding and Quantization

There is a considerable performance gap between the current scalable audio coding schemes and a nonscalable coder operating at the same bitrate. This suboptimality results from the independent coding of the layers in these systems. One of the aspects that plays a role in this suboptimality is the entropy coding. In practical audio coding systems including MPEG advanced audio coding (AAC), the transform domain coefficients are quantized using an entropy-constrained quantizer. In MPEG-4 scalable AAC (S-AAC), the quantization and coding are performed separately at each layer. In case of Huffman coding, the redundancy introduced by the entropy coding at each layer is larger at lower quantization resolutions. Also, the redundancy for the overall coder becomes larger as the number of layers increases. In fact, there is a tradeoff between the overall redundancy and the fine-grain scalability in which the bitrate per layer is smaller and more layers are required. In this paper, a fine-grain scalable coder for audio signals is proposed where the entropy coding of a quantizer is made scalable via joint design of entropy coding and quantization. By constructing a Huffman-like coding tree where the internal nodes can be mapped to the reconstruction points, the tree can be pruned at any internal node to control the rate-distortion (RD) performance of the encoder in a fine-grain manner. A set of metrics and a trellis-based approach is proposed to create a coding tree so that an appropriate path is generated on the RD plane. The results show the proposed method outperforms the scalable audio coding performed based on reconstruction error quantization as used in practical systems, e.g., in S-AAC.

Multimedia digital rights management based on selective encryption for flexible business model

This paper proposes an advanced encryption of MP3 and MPEG-4 coder with a quality degradation-based security model. For the MP3 audio, the magnitude and phase information of modified discrete cosine transform (MDCT) coefficients is encrypted. DCT coefficients and motion vectors (MVs) are used for the scrambling of the MPEG-4 video. This encryption scheme has a level of security, secures in perception, keeps format compliance, and obtains better time efficiency by reducing the encrypted volumes of multimedia contents. These properties make it practical to incorporate encryption and decryption process into compression and decompression process, and thus suitable for secure A/V transmission or sharing. Experimental results indicate that the proposed technique provides levels of security for a flexible business model and achieves a simple and coding-efficient architecture with no adverse impact on error resilience.

Exploring Contextual Redundancy in Improving Object-Based Video Coding for Video Sensor Networks Surveillance

In recent years, intelligent video surveillance attempts to provide content analysis tools to understand and predict the actions via video sensor networks (VSN) for automated wide-area surveillance. In this emerging network, visual object data is transmitted through different devices to adapt to the needs of the specific content analysis task. Therefore, they raise a new challenge for video delivery: how to efficiently transmit visual object data to various devices such as storage device, content analysis server, and remote client server through the network. Object-based video encoder can be used to reduce transmission bandwidth with minor quality loss. However, the involved motion-compensated technique often leads to high computational complexity and consequently increases the cost of VSN. In this paper, contextual redundancy associated with background and foreground objects in a scene is explored. A scene analysis method is proposed to classify macroblocks (MBs) by type of contextual redundancy. The motion search is only performed on the specific type of context of MB which really involves salient motion. To facilitate the encoding by context of MB, an improved object-based coding architecture, namely dual-closed-loop encoder, is derived. It encodes the classified context of MB in an operational rate-distortion-optimized sense. The experimental results show that the proposed coding framework can achieve higher coding efficiency than MPEG-4 coding and related object-based coding approaches, while significantly reducing coding complexity.

Audio watermarking based on quantization index modulation using combined perceptual masking

In this paper, a robust audio watermarking scheme for MPEG-1/ Audio Layer II compressed domain is proposed. The scheme is implemented by modifying the subband coefficients using adaptive quantization index modulation. The watermarking procedure exploits perceptual frequency and temporal masking of the human auditory system (HAS) of MPEG coder to satisfy the requirements of robustness, security and transparency. This reduces the computational complexity of proposed scheme. The paper investigates the use of elevated masking threshold to improve detection and achieve higher robustness against re-encoding and awgn attacks. Experimental results show that high capacity of 6,840 bps with ODG ?0.5 without altering the MPEG/audio bitrate.

Video Watermarking Scheme Based on MPEG-2 for Copyright Protection

Abstract An innovative practical video watermarking scheme based on MPEG-2 is proposed in this paper. By operating the compressed video data-stream directly, we embed watermarking information in DC coefficients of block image which is in the IDR picture, in DPCM process of MPEG-2 coder. Watermark can be extracted blindly without original images and complete decoding is unnecessary. The algorithm designs one kind of synchronization code in order to resolve the synchronization problem. Watermark information is embedded periodically for random testing. The experimental results show the proposed scheme can achieve good excellent robustness to common video processing methods such as low bit rate MPEG-2 compression and synchronization attacks.

Development of Digital Watermark Inserting and Detecting System for MPEG-2 Codec

This paper describes a study on developing an insert and detect system of digital watermark to the MPEG-2 coder and decoder. Digital watermark inserting system substitutes a coefficient among the DCT coefficients for new one. This replacement performs in MPEG-2 PS format. Watermark detecting system analyzes the input data stream of MPEG-2 and detect the probability of occurrence of a specific code or watermarking code. Our inserting system had very high invisibility and the PSNR of the results was 130 dB around. And our detection rate of watermark was over 99% in digital format and over 85% in analog captured format according to the quality of contents.

Video transcoding from H.264/AVC to MPEG-2 with reduced computational complexity

This paper addresses video transcoding from H.264/AVC into MPEG-2 with reduced complexity and high rate-distortion efficiency. While the overall concept is based on a cascaded decoder–encoder, the novel adaptation methods developed in this work have the advantage of providing very good performance in H.264/AVC to MPEG-2 transcoding. The proposed approach exploits the similarities between the coding tools used in both standards, with the objective of obtaining a computationally efficient transcoder without penalising the signal quality. Fast and efficient methods are devised for conversion of macroblock coding modes and translation of motion information in order to compute the MPEG-2 coding format with a reduced number of operations, by reusing the corresponding data embedded in the incoming H.264/AVC coded stream. In comparison with a cascaded decoder–encoder, the fast transcoder achieves computational complexity savings up to 60% with slightly better peak signal-to-noise ratio (PSNR) at the same bitrate.

Compression of Patient Monitoring Video Using Motion Segmentation Technique

The volume of patient monitoring video acquired in hospitals is very huge and hence there is a need for better compression of the same for effective storage and transmission. This paper presents a new motion segmentation technique, which improves the compression of patient monitoring video. The proposed motion segmentation technique makes use of a binary mask, which is obtained by thresholding the standard deviation values of the pixels along the temporal axis. Two compression methods, which make use of the proposed motion segmentation technique, are presented. The first method uses MPEG-4 coder and 9/7-biorthogonal wavelet for compressing the moving and stationary portions of the video respectively. The second method uses 5/3-biorthogonal wavelet for compressing both the moving and the stationary portions of the video. The performances of these compression algorithms are evaluated in terms of PSNR and bitrate. From the experimental results, it is found that the proposed motion technique improves the performance of the MPEG-4 coder. Among the two compression methods presented, the MPEG-4 based method performs better for bitrates less than 767 Kbps whereas for bitrates above 767 Kbps the performance of the wavelet based method is found superior.

Adaptive GOP Structure for Joint Scalable Video Coding

This paper introduces an adaptive GOP structure (AGS), which adaptively defines the GOP structure according to the time-varying temporal properties of video sequences, and thus improves the coding efficiency of the MPEG & ITU-T's Joint Scalable Video Coding (JSVC) scheme, the method proposed in this paper, which adaptively modifies the size of GOP based on the image characteristics of video sequence, improves the coding efficiency up to 0.77 dB compared to the JSVC JSVM (Joint Scalable Video Model).

MPEG-2 to WMV Transcoder With Adaptive Error Compensation and Dynamic Switches

In this paper, we study the problem of video transcoding from MPEG-2 to Windows Media Video (WMV) format, together with several desired functionalities such as bit-rate reduction and spatial resolution downscaling. Based on in-depth analysis of error propagation behavior, we propose two architectures (for different typical application scenarios) that are unique in their complexity scalability and adaptive drifting error control, which in return provide a mechanism to achieve a desired tradeoff between complexity and quality. We perform extensive experiments for various design targets such as complexity, scalability, performance tradeoff, and drifting control effect. The proposed transcoding architectures can be straightforwardly applied to the MPEG-2 to MPEG-4 transcoding applications due to the significant overlap between the MPEG-4 and WMV coding technology

Structures for SNR scalable speech coding

SNR scalable speech coding is desirable for a number of network multimedia applications, but relatively few SNR-scalable speech coders exist for operation at rates below 16 kb/s. We investigate several SNR scalable source coding structures and define the new concepts of dependent and independent SNR scalability, where independent SNR scalable coders depend on the core layer coder only through the core layer output. Independent SNR scalable structures offer the possibility of providing bit rate scalable functionality to existing nonscalable coders and standards. We show that the MPEG-4 scalable coders are examples of dependent SNR scalable coders, and we introduce a new independent SNR scalable coder called CELPTree, which has the additional advantage of being low delay. We compare the performance of the MPEG-4 coders and CELPTree for both clean and noisy speech, and we examine the effects of frequency-weighted distortion measures in the enhancement layers of SNR scalable speech coders.

A novel PDE-based rate-distortion model for rate control

This paper presents a novel rate-distortion (R-D) model for rate control of video coding. First, we investigate the well-known heat conduction equation (HCE) in the heat conduction process for a thin bar. HCE describes the dynamic distribution of temperature in a thin bar using a partial differential equation (PDE). Motivated by the heat conduction process in a thin bar, a new rate transmission equation (RTE) is proposed to describe the dynamic behaviors of the bit-rate fluctuation during video coding. Second, a particular solution of RTE is employed as our proposed R-D model, which consists of two variables, i.e., the distortion D and the source statistical character M. Based on our model, a corresponding rate-control scheme is proposed for MPEG coding. Finally, extensive experimental results are reported to show that, compared with the well-known MPEG-4 Q2 rate-control scheme, our proposed work achieves better buffer status, higher control accuracy, and stabler and more consistent picture quality.

Motion analysis in 3D DCT domain and its application to video coding

Global, constant-velocity, translational motion in an image sequence induces a characteristic energy footprint in the Fourier-transform (FT) domain; spectrum is limited to a plane with orientation defined by the direction of motion. By detecting these spectral occupancy planes, methods have been proposed to estimate such global motion. Since the discrete cosine transform (DCT) is a ubiquitous tool of all video compression standards to date, we investigate in this paper properties of motion in the DCT domain. We show that global, constant-velocity, translational motion in an image sequence induces in the DCT domain spectral occupancy planes, similarly to the FT domain. Unlike in the FT case, however, these planes are subject to spectral folding. Based on this analysis, we propose a motion estimation method in the DCT domain, and we show that results comparable to standard block matching can be obtained. Moreover, by realizing that significant energy in the DCT domain concentrates around a folded plane, we propose a new approach to video compression. The approach is based on 3D DCT applied to a group of frames, followed by motion-adaptive scanning of DCT coefficients (akin to “zig-zag” scanning in MPEG coders), their adaptive quantization, and final entropy coding. We discuss the design of the complete 3D DCT coder and we carry out a performance comparison of the new coder with ubiquitous hybrid coders.

New adaptive partial distortion search using clustered pixel matching error Characteristic

In order to reduce the computation load, many conventional fast block-matching algorithms have been developed to reduce the set of possible searching points in the search window. All of these algorithms produce some quality degradation of a predicted image. Alternatively, another kind of fast block-matching algorithms which do not introduce any prediction error as compared with the full-search algorithm is to reduce the number of necessary matching evaluations for every searching point in the search window. The partial distortion search (PDS) is a well-known technique of the second kind of algorithms. In the literature, many researches tried to improve both lossy and lossless block-matching algorithms by making use of an assumption that pixels with larger gradient magnitudes have larger matching errors on average. Based on a simple analysis, it is found that, on average, pixel matching errors with similar magnitudes tend to appear in clusters for natural video sequences. By using this clustering characteristic, we propose an adaptive PDS algorithm which significantly improves the computation efficiency of the original PDS. This approach is much better than other algorithms which make use of the pixel gradients. Furthermore, the proposed algorithm is most suitable for motion estimation of both opaque and boundary macroblocks of an arbitrary-shaped object in MPEG-4 coding.

Low Complexity Scalable Perceptual Audio Coder using an Optimum Wavelet Packet basis Representation and Vector Quantization

In this paper, we describe a high quality low complexity scalable audio coding scheme, using an optimum wavelet packet (WP) basis signal representation based on the time varying characteristics of the audio signal. In ISO/MPEG audio coding standards [1–3], resolution of decomposition filterbank (uniform) does not match with the resolution of psychoacoustic model (which requires more resolution and needs to be matched with the critical bands (non uniform) of cochlea). Hence MPEG coder uses a separate high resolution decomposition filterbank for psychoacoustic model implementation, which increases the computational load of the coder. Here, we use a wavelet packet decomposition structure closely matching to the critical bands [4,5] of human auditory system, to transform the data into wavelet domain and then these wavelet packet coefficients are used to drive the psychoacoustic model directly. Hence, psychoacoustic model design is integrated with the design of decomposition filterbank. Other features of the proposed coder are scalability (can support three standard industrial sampling frequencies 11.025 kHz, 22.050 kHz and 44.1 kHz) and optimum wavelet basis selection from a predefined library of wavelet bases, by extracting seven statistical features of the audio signal to be encoded. A new Vector Quantization (VQ) scheme is also proposed here, in which the length of the code book can be varied in accordance with the psychoacoustic model requirement. Experimental results show that the proposed coder yields almost transparent quality with compression ratios in the range of e to 10.

A Secure and Robust Object-Based Video Authentication System

An object-based video authentication system, which combines watermarking, error correction coding (ECC), and digital signature techniques, is presented for protecting the authenticity between video objects and their associated backgrounds. In this system, a set of angular radial transformation (ART) coefficients is selected as the feature to represent the video object and the background, respectively. ECC and cryptographic hashing are applied to those selected coefficients to generate the robust authentication watermark. This content-based, semifragile watermark is then embedded into the objects frame by frame before MPEG4 coding. In watermark embedding and extraction, groups of discrete Fourier transform (DFT) coefficients are randomly selected, and their energy relationships are employed to hide and extract the watermark. The experimental results demonstrate that our system is robust to MPEG4 compression, object segmentation errors, and some common object-based video processing such as object translation, rotation, and scaling while securely preventing malicious object modifications. The proposed solution can be further incorporated into public key infrastructure (PKI).