MPEG-4 Research Articles

Digital Video Watermarking in the Discrete Cosine Transform Domain

Problem statement: Nowadays, digital watermarks have recently become recognized as a solution for protecting copyright of the digital multimedia. For a watermark to be useful, it must be perceptually invisible and robust against any possible attack and image processing by those who seek to corsair the material, researchers have considered various approaches like JPEG compression, geometric distortions and noising. Approach: We proposed a framework based on the Hartung technique which depended on spread spectrum communication in discrete cosine transform (DCT). Results: For the experimental results, researchers had considered various approaches: JPEG compression, geometric distortions and noising. Results showed a good performance in the proposed method. Conclusion: The presented technique was applicable not only to MPEG-2 video, but also to other DCT coding videos like MPEG-1,H261 and H263. Future study could be on improving DCT and comparing it with existing methods. It could be on discrete wavelet transform that is relatively new and has useful properties for the image processing applications.

Soft Error-Aware Voltage Scaling Technique for Power Minimization in Application-Specific Multiprocessor System-on-Chip

There is growing interest in evaluating the impact of soft errors on multiprocessor system-on-chip (MPSoC) at application-level rather than architectural-level, particularly in multimedia applications to optimize system design. This has recently led to the concept of application-level correctness. In this paper, we consider the relationship between application-level correctness and system-level power management using voltage scaling technique with the aim to generate designs that are optimized in terms of power consumption, while providing acceptable application-level correctness and meeting real-time performance deadlines. We propose a novel voltage scaling technique based on linear programming capable of identifying the appropriate supply voltage and frequency values of the processing cores in an MPSoC such that the power consumption is minimized for a given soft error rate (SER) and a specified performance deadline. We evaluate the effectiveness of our technique using an MPEG-2 video decoder as a case study and with peak signal-to-noise ratio (PSNR) as the application-level correctness metric. We show that the proposed voltage scaling technique can achieve up to 85% power reduction for SER of 3.98E?8, while maintaining acceptable levels of real-time performance (29 frames/s) and application-level correctness (30dB PSNR). The above case study is based on an MPSoC architecture with four processing cores. We have also investigated the effect of varying the number of processing cores (architecture allocation) and application task mapping (distribution of tasks among cores of the MPSoC architecture) on the trade-offs between application-level correctness and power consumption minimization using the proposed voltage scaling technique.

An adaptive cross-layer mapping algorithm for MPEG-4 video transmission over IEEE 802.11e WLAN

This paper proposes an adaptive cross-layer mapping algorithm to improve the transmission quality of MPEG-4 video stream over an IEEE 802.11e wireless network. Instead of classifying video data to a specific access category in an 802.11e network, we propose an algorithm that dynamically maps MPEG-4 video packets to appropriate access categories according to both the significance of the video data and the network traffic load. Our proposed cross-layer architecture passes information about the significance of video packets from the application layer to the media access control layer. The queue length of a specific access category is used to deduce the network traffic load. We conducted a performance evaluation of our proposed cross-layer approach under both light and heavily loaded network conditions. Our simulation results demonstrate: (a) superior performance of our proposed approach (under both light and heavy loads) over 802.11e (Enhanced Distributed Channel Access (EDCA) and static mapping schemes, (b) not only guarantees prioritized transmission of essential video data but also provides efficient queue length utilization.

A framework for end-to-end video quality prediction of MPEG video

This paper proposes, describes and evaluates a novel framework for video quality prediction of MPEG-based video services, considering the perceptual degradation that is introduced by the encoding process and the provision of the encoded signal over an error-prone wireless or wire-line network. The concept of video quality prediction is considered in this work, according to which the encoding parameters of the video service and the network QoS conditions are used for performing an estimation/prediction of the video quality level at the user side, without further processing of the actual encoded and transmitted video content. The proposed prediction framework consists of two discrete models: (i) a model for predicting the video quality of an encoded signal at a pre-encoding stage by correlating the spatiotemporal content dynamics to the bit rate that satisfies a specific level of user satisfaction; and (ii) a model that predicts primarily the undecodable frames (and subsequently the perceived quality degradation caused by them) based on the monitored averaged packet loss ratio of the network. The proposed framework is experimentally tested and validated with video signals encoded according to MPEG-4 standard.

Software Code Generation for the RVC-CAL Language

The MPEG Reconfigurable Video Coding (RVC) framework is a new standard under development by MPEG that aims at providing a unified high-level specification of current and future MPEG video coding technologies using dataflow models. In this framework, a decoder is built as a configuration of video coding modules taken from the standard MPEG toolbox library or proprietary libraries. The elements of the library are specified by a textual description that expresses the I/O behavior of each module and by a reference software written using a subset of the CAL Actor Language named RVC-CAL. A decoder configuration is written in an XML dialect by connecting a set of CAL modules. Code generators are fundamental supports that enable the direct transformation of a high level specification to efficient hardware and software implementations. This paper presents a synthesis tool that from a CAL dataflow program generates C code and an associated SystemC model. The generated code is validated against the original CAL description simulated using the Open Dataflow environment. Experimental results of the translation of two descriptions of an MPEG-4 Simple Profile decoder with different granularities are shown and discussed.

Power-saving scheduling with a QoS guarantee in a mobile WiMAX system

This paper presents a power-saving scheduling scheme to improve energy efficiency and guarantee Quality of Service (QoS) in Mobile Worldwide Interoperability for Microwave Access (WiMAX), i.e. IEEE 802.16e. Due to the popularization of multimedia services such as Voice over IP (VoIP) and MPEG video, different types of QoS coexist in one mobile subscriber station (MSS). Many previous studies have considered the QoS issue. Unfortunately, they only considered the delay in QoS. In this work, we consider that delay and jitter types of QoS should be scheduled at the same time and integrate the sleep duration in one MSS. The packets would be scheduled successively to reduce the number of status transitions under the QoS requirements of delay and jitter. The proposed approach not only minimizes power consumption of the MSS, but also guarantees both the delay and jitter QoS of real-time connections.

Directional diamond motion estimation algorithm based on parallelism and prediction

The motion estimation algorithm in the MPEG-4 video encoding was studied and the potential parallelism in the algorithm was analyzed.Then the multi-core parallel computing concept was used in the directional diamond searching algorithm,and a prediction mechanism was introduced to improve the degree of parallelism.Then the directional diamond Motion estimation algorithm based on parallelism and prediction(PPDDME) was proposed.The experimental results coming from PC and the Omap5910 embedded platform show that the encoding speed is improved efficiently and the compression quality is the same as the serial algorithm.

Simple model for VBR MPEG digital video sources with gamma functions

This article presents a very simple model based on gamma functions for MPEG1 and MPEG2 VBR digital video. This model is a simplification of Frey's et al model.It captures first grade statistics and the cyclicity of the autocorrelation function. Buffer overflow losses with the proposed model are of the same magnitude that buffer overflow losses of the original video clips. We have found three zones in the buffer overflow losses under certain conditions. Zone number two is of special interest because identified losses are produced by extraordinary large frames.

Convex Optimization-Based Bit Allocation for Video Coding

This paper presents a new convex optimization-based bit allocation framework for video coding. Motivated by the statistical analysis of the relationship between the rate and the corresponding distortion in typical video sequences, an improved empirical rate-distortion model with more flexibility in explaining the experimental observations is proposed. The convexity and monotonicity properties of the proposed model allow us to formulate the bit allocation problem as a convex programming problem, which can be solved using interior-point methods. Coupled with the region of interest (ROI) functionality and the technique of MB classification, the proposed bit allocation scheme is then applied to the problem of frame-level bit allocation for various video coding standards employing motion compensated hybrid DCT/DPCM technique. Similar bit allocation scheme is also developed for MPEG-4 video object coding at the object level. The relevant model parameters are determined using previously encoded data by means of linear regression. Simulation results show that the proposed algorithms can achieve considerably better PSNR performance than the conventional approaches for the tested video sequences, at the expenses of slight increase in coding complexity.

Optimization scheduling of MPEG-4 FGS video coding stream under the feasible mandatory constraint

MPEG-4 video coding stream with Fine Granularity Scalability (FGS) can be flexibly dropped by very fine granularity so as to adapt to the available network bandwidth. The MPEG-4 FGS model is similar to the imprecise computation model originally proposed in the real-time scheduling field. In both models, it is required that all the mandatory tasks be completely scheduled before their deadlines even in the worst case, which is called the feasible mandatory constraint. The problem is how to maximize the number of the scheduled tasks based on the importance of tasks and to satisfy the feasible mandatory constraint. We adapt the existing unit-time tasks scheduling algorithm to address the problem by using a weighted assignment scheme that adds constant weights to mandatory tasks. Under the feasible mandatory constraint, we prove that the proposed algorithm maximizes the total weights of the scheduled tasks, and all mandatory tasks are guaranteed to be completely scheduled before their deadlines. The experimental results show the performance of the video quality for our scheduling algorithm by the measurements of Peak Signal to Noise Ratio (PSNR).

A Low-overhead Scheduling Methodology for Fine-grained Acceleration of Signal Processing Systems

Fine-grained accelerators have the potential to deliver significant benefits in various platforms for embedded signal processing. Due to the moderate complexity of their targeted operations, these accelerators must be managed with minimal run-time overhead. In this paper, we present a methodology for applying flow-shop scheduling techniques to make effective, low-overhead use of fine-grained DSP accelerators. We formulate the underlying scheduling approach in terms of general flow-shop scheduling concepts, and demonstrate our methodology concretely by applying it to MPEG-4 video decoding. We present quantitative experiments on a soft processor that runs on a field-programmable gate array, and provide insight on trends and trade-offs among different flow-shop scheduling approaches when applied to run-time management of fine-grained acceleration.

Video watermarking using wavelet transform and tensor algebra

We present a robust, hybrid non-blind MPEG video watermarking technique based on a high-order tensor singular value decomposition and the discrete wavelet transform (DWT). The core idea behind our proposed technique is to use the scene change analysis to embed the watermark repeatedly into the singular values of high-order tensors computed form the DWT coefficients of selected frames of each scene. Experimental results on video sequences are presented to illustrate the effectiveness of the proposed approach in terms of perceptual invisibility and robustness against attacks.

Power optimization for application-specific networks-on-chips: A topology-based approach

This paper analyzes the main sources of power consumption in Networks-on-Chip (NoC)-based systems. Analytical power models of global interconnection links are studied at different levels of abstraction. Additionally, power measurement experiments are performed for different types of routers. Based on this study, we propose a new topology-based methodology to optimize the power consumption of complex NoC-based systems at early design phases. The efficiency of the proposed methodology is verified through a case study of an MPEG4 video application. Experimental results show a promising improvement in power consumption (8.55%), average number of hops (10.80%), and number of global links (56.25%) compared to the best known related work.

Efficient Traffic Scheduling for Real Time VBR MPEG Video Transmission Over DOCSIS-Based HFC Networks

Data-over-cable service interface specifications (DOCSIS), the de facto standard in the cable industry, defines a scheduling service called real-time polling service (rtPS) to provision quality of service (QoS) transmission of real-time variable bit rate (VBR) videos. However, the rtPS service intrinsically has high latency, which makes it not applicable to real-time traffic transport. In this paper, we present a novel traffic scheduling algorithm for hybrid fiber coax (HFC) networks based on DOCSIS that aims to provide QoS for real-time VBR video transmissions. The novel characteristics of this algorithm, as compared to those described in published literatures, include 1) it predicts the bandwidth requirements for future traffic using a novel traffic predictor designed to provide simple yet accurate online prediction; and 2) it takes the attributes of physical (PHY) layer, media access control (MAC) layer and application layer into consideration. In addition, the proposed traffic scheduling algorithm is completely compatible with the DOCSIS specification and does not require any protocol changes. We analyze the performance of the proposed traffic predictor and traffic scheduling algorithm using real-life MPEG video traces. Simulation results indicate that 1) the proposed traffic predictor significantly outperforms previously published techniques with respect to the prediction error and 2) compared with several existing scheduling algorithms, the proposed traffic scheduling algorithm surpasses other mechanisms in terms of channel utilization, buffer usage, packet delay, and packet loss rate.

MPEG video encryption algorithm based on Lorenz chaotic system

An encryption algorithm which combined the process of MPEG video compressing with video encryption based on Lorenz chaotic system was put forward to deal with the security problem of video information. Three dimensional chaotic sequences of Lorenz system were used to encrypt DC, AC and motion vector coefficients during the compressing of I frame, B frame and P frame. The luminance information of I frame was encrypted among blocks by the chaotic sequence. The algorithm is secure and real-time because the encryption is done during the process of video compressing.

Mapping of nomadic multimedia applications on the ADRES reconfigurable array processor

This paper introduces the mapping of MPEG video decoders on ADRES, IMEC’s new coarse-grain reconfigurable and fully C-programmable array processor that targets nomadic devices. ADRES is a flexible template that allows the instantiation of many different processor versions. An XML-based architecture description language allows a designer to easily generate different processor instances with full compiler support by specifying different values for the communication topology, the number and size of local register files and functional units and supported instruction set. ADRES supports a VLIW-like programming model with a pure VLIW mode for legacy code, and a (coarse-grain reconfigurable) array mode with very high parallelism for the processing of compute intensive loops. We demonstrate the mapping of two video decoders MPEG-2 and AVC, and discuss the performance trade-offs for two critical kernels: IDCT and integer transform. As a result, an ADRES based system can perform AVC decoding in CIF resolution with less then 50 MHz on a 4 × 4 array processor.

Optical flow approximation based motion object extraction for MPEG-2 video stream

This paper presents a compressed-domain motion object extraction algorithm based on optical flow approximation for MPEG-2 video stream. The discrete cosine transform (DCT) coefficients of P and B frames are estimated to reconstruct DC + 2AC image using their motion vectors and the DCT coefficients in I frames, which can be directly extracted from MPEG-2 compressed domain. Initial optical flow is estimated with Black’s optical flow estimation framework, in which DC image is substituted by DC + 2AC image to provide more intensity information. A high confidence measure is exploited to generate dense and accurate motion vector field by removing noisy and false motion vectors. Global motion estimation and iterative rejection are further utilized to separate foreground and background motion vectors. Region growing with automatic seed selection is performed to extract accurate object boundary by motion consistency model. The object boundary is further refined by partially decoding the boundary blocks to improve the accuracy. Experimental results on several test sequences demonstrate that the proposed approach can achieve compressed-domain video object extraction for MPEG-2 video stream in CIF format with real-time performance.

Quasi-commutative watermarking and encryption for secure media content distribution

Commutative Watermarking and Encryption (CWE) provides a solution for interoperation between watermarking and encryption. It realizes the challenging operation that embeds a watermark into the encrypted multimedia data directly, which avoids the decryption---watermarking---encryption triples. Till now, few CWE schemes have been reported. They often obtain the commutative property by partitioning multimedia data into independent parts (i.e., the encryption part and the watermarking part). Since the two parts are isolated, it can not keep secure enough against replacement attacks. To avoid the disadvantage, a novel quasi-commutative watermarking and encryption (QCWE) scheme based on quasi-commutative operations is proposed in this paper. In the proposed scheme, the encryption operation and watermarking operation are applied to the same data part. Since the two operations are homogenous with commutative properties, their orders can be commutated. As an example, the scheme for MPEG2 video encryption and watermarking is presented. In this example, the DCs in intra macroblocks are encrypted or watermarked based on random module addition, while the DCs in other macroblocks and all the ACs' signs are encrypted with a stream cipher or block cipher. Analysis and experiments show that the scheme obtains high perceptual security and time efficiency, and the watermarking and encryption operations can be commutated. These properties make the scheme a suitable choice for efficient media content distribution. Additionally, the paper shows the availability of constructing the commutative watermarking and encryption scheme with homogenous operations, which is expected to activate the new research topic.

A Cross-Layer Model for Video Multicast Based TCP-Adaptive FEC over Heterogeneous Networks

In this article, we present a simple cross-layer model that leads to the optimal throughput of multiple users for multicasting MPEG-4 video over a heterogeneous network. For heterogeneous wired-to-wireless network, at the last wireless hop there are bit errors associated with the link-layer packets that are arising in the wireless channel, in addition of overflow packet dropping over wired links. We employ a heuristic TCP function to optimize the cross-layer model of data link and physical (radio-link) layer. An adaptive Forward-Error-Correction (FEC) scheme is applied at the byte-level as well as at the packet-level. The corresponding optimal video quality can be evaluated at each client end. The results show that a server can significantly adapt to the bandwidth and FEC codes to maximize the video quality of service (QoS) in terms of temporal scaling when a maximum network throughput for each client is reached.

Improved Error Control for Real-Time Video Broadcasting Over CDMA2000 Networks

The broadcast and multicast services (BCMCS) protocol is designed for real-time applications such as MPEG-4 video streaming, which requires successive frames to arrive within a specific time interval. We analyze the execution time of Reed-Solomon (RS) decoding, which is the medium access control (MAC)-layer forward error-correction (FEC) scheme used in CDMA2000 1xEV-DO BCMCS, under various air channel conditions. The results show that the timing constraints of MPEG-4 cannot always be met by RS decoding when the packet loss rate (PLR) is high, due to the limited processing power of current hardware. We therefore propose three error control schemes: First, we have our static scheme, which bypasses RS decoding at the mobile node to satisfy the MPEG-4 timing constraint when the PLR exceeds a given level. Second, we have the dynamic scheme, which corrects as many errors as possible within the timing constraint, instead of giving up altogether when the PLR is high; this improves quality. Third, we have the video-aware dynamic scheme, which fixes errors in a similar way to the dynamic scheme but in a priority-driven manner, yielding a further increment in video quality at mobile terminals. Extensive simulation results show the effectiveness of our schemes compared with the original FEC scheme.