Optimal video placement scheme for batching VOD services

Advances in broadband technology are generating an increasing demand for video-on-demand (VOD) applications. In this paper, an optimal video placement scheme is proposed for a batching VOD system with multiple servers. Given a specified requirement of the blocking probability, an optimal batching interval is derived and the corresponding file placement is obtained by hybrid genetic algorithm. It is demonstrated that the specified requirement on blocking probability is satisfied, while both batching interval and server capacity usage are minimized simultaneously.     

Fast optimal video placement algorithms for hierarchicalvideo-on-demand systems

The multilevel hierarchical network architecture has been shown to be a scalable and cost efficient solution for large video-on-demand (VOD) systems. The predominant operation cost of a hierarchical VOD system consists of network transmission cost and video storage cost. How to minimize the operation cost under several operating constraints is an important issue. Many operating constraints, such as the storage capacity limitation at each level of servers, have made the problem intractable. We proposed several efficient heuristic video placement algorithms that can achieve near optimal operating cost. We have also proposed a time-variant arrival traffic model with arrival rate matching the statistics gathered from commercial systems     

Wavelength division multiplexing-based video-on-demand systems

Serving video-on-demand (VOD) traffic via isochronous transmission service is highly desirable because of the characteristics of VOD traffic. This paper proposes a mechanism to transfer VOD traffic over wavelength division multiplexing (WDM) networks by employing isochronous transmission service. Based on the proposed mechanism, the problem of scheduling isochronous and asynchronous traffic for single-star WDM networks with multiple receivers and transmitters is investigated. The lower bounds on the total switching duration and the number of switching modes for the isochronous and asynchronous traffic scheduling problem are derived. An optimal scheduling algorithm is presented for the cases where only asynchronous traffic exists; and a heuristic algorithm is also proposed for the cases where both the isochronous and asynchronous traffic coexist in the WDM networks. Simulation results indicate that the average switching duration and the average number of switching modes obtained by the proposed algorithm are close to the lower bounds, which implies that the proposed scheduling algorithm is effective     

Adaptive batching scheme for multicast video-on-demand systems

In this paper, an adaptive algorithm is developed for providing true video on demand (VoD) services in a multicast environment. In conventional batching schemes, the batching time of the system is fixed and the performance of such static schemes is highly dependent on the selection of the batching time. If the batching time is wrongly estimated, the performance of the system will be greatly degraded. Our algorithm tries to dynamically find the optimal batching time by the newly updated arrival rate so as to minimize the bandwidth requirement. The results show that the system performance of the adaptive approach is always better than the static scheme in terms of total bandwidth requirement and customer reneging probability, especially in using long batching time for the high arrival rate     

Performance model of interactive video-on-demand systems

An interactive video-on-demand (VoD) system allows users to access video services, such as movies, electronic encyclopedia, interactive games, and educational videos from video servers on a broadband network. This paper develops a performance evaluation tool for the system design. In particular, a user activity model is developed to describe the usage of system resources, i.e., network bandwidth and video server usage, by a user as it interacts with the service. In addition, we allow batching of user requests, and the effect of such batching is captured in a batching model. Our proposed queueing model integrates both the user activity and the batching model. This model can be used to determine the requirements of network bandwidth and video server and, hence, the trade-off in communication and storage costs for different system resource configurations     

Two-layer hierarchical coding for MPEG-2 video

A two-layer scheme for MPEG-2 video that uses adaptive data-partitioning (ADP) is presented. The slice structure of the upper layer and a new synchronisation procedure between the layers are defined. The experimental results prove the effectiveness of the two-layer model. Particularly for increasing values of cell loss probability     

Design of multicast delivery for providing VCR functionality ininteractive video-on-demand systems

Multicast delivery is one of the solutions to reduce the cost in a large video-on-demand (VoD) system. However, multicast transmission makes much more difficult the implementation of interactive functions for individual users and introduces start-up delays for the users, which contradicts the idea of on-demand services. In this paper, we first try to explore and evaluate the performance of different multicast VoD systems. A new scheme called single-rate multicast double-rate unicast (SRMDRU) is then developed to minimize the system resources for supporting full VCR functionality in a multicast VoD system. This scheme also allows multicast systems to support true VoD services so customers can be served as soon as the system receives the requests. Computer simulations show that the multicast systems using the SRMDRU scheme perform much better than other multicast systems in terms of system blocking probabilities     

A low cost optical storage server for near video-on-demand systems

A near video-on-demand system is one of the most economic and practical applications to provide high quality digital video services through a network in terms of cost, storage and network capacity requirements. In this paper, an optical storage server with a novel data placement and retrieval schemes is proposed for a near video-on-demand system. The proposed data placement scheme on the optical discs fully exploits the periodical broadcast characteristic of an NVOD service to optimize the disc bandwidth utilization. By further applying our retrieval schedule strategy, the buffer requirement of a system can be significantly reduced. In that way, the maximal number of supported streams with the minimal buffer requirement can be easily achieved, The storage system can be applied not only to CD-ROMs storing MPEG-1, but also to Digital Video Disks (DVDs) storing MPEG-2 in the near future     

Algorithm for hierarchical vector quantisation of video data

A recursive algorithm is presented that is designed to construct quantisation tables and codebooks for the hierarchical vector quantisation of images. The algorithm is computationally inexpensive and yields high quality codebooks     

Optimal transmission of high definition video transmission in WiMedia systems

WiMedia systems are developed for indoor high-data-rate wireless systems. The H.264/AVC, a high-efficiency video coding technique, is considered for high definition (HD) video application. Considering the transmission of H.264/AVC based HD video over WiMedia, in this paper, we will propose a cross-layer architecture and an analytical model to calculate the optimal payload length with the constraints in error criteria, retransmission mechanism, and the delay budget. Besides, the required minimum reservation slots in WiMedia are also investigated to optimize the transmission performance of HD video.     

Optimal pilot placement for frequency offset estimation and data detection in burst transmission systems

In this letter, we address the problem of pilot design for carrier frequency offset (CFO) and data detection in digital burst transmission systems. We consider a quasistatic flat-fading channel. We find that placing half of the pilot symbols at the beginning of the burst and the other half at the end of the burst is optimal for both CFO estimation and data detection. Our findings are based on the Cramer-Rao bound and on empirical evaluations of the bit error rate for different pilot designs. The equal-preamble-postamble pilot design is shown to provide a significant gain in performance over the conventional preamble-only pilot design.     

A novel optimization algorithm for video placement and routing

In this paper, we propose a novel optimization algorithm for the solution of the video placement and routing problem based on Lagrangean relaxation,and decomposition. The main contribution can be stated as the use of integer programming models to obtain feasible solutions to the problem within the algorithm. Computational experimentation reveals that the use of such integer models help greatly in obtaining good quality solutions in a small amount of solution time.     

Optimisation-based placement of resynchronisation markers for errorrobust video transmission

A novel method for placement of resynchronisation markers for error robust video transmission is proposed. Given the number of markers assigned to the current frame, marker positions are decided in a rate-distortion optimal sense. The Viterbi algorithm is employed to solve the rate-distortion problem     

Optimal quality adaptation for scalable encoded video

The dynamic behavior of the Internet's transmission resources makes it difficult to provide perceptually good quality streaming video. Scalable video encoding techniques have been proposed to deal with this problem. However, an encoded video generally exhibits significant data rate variability to provide consistent visual quality. We are, therefore, faced with the problem of accommodating the mismatch between the available bandwidth variability and the encoded video variability. We investigate quality adaptation algorithms for scalable encoded variable bit-rate video over the Internet. Our goal is to develop a quality adaptation scheme that maximizes perceptual video quality by minimizing quality variation, while at the same time increasing the usage of available bandwidth. We propose an optimal adaptation algorithm and a real-time adaptation algorithm based on whether the network conditions are known a priori. Experimental results show that the real-time adaptation as well as the optimal adaptation algorithm provide consistent video quality when used over both TCP-friendly rate control (TFRC) and transmission control protocol (TCP).     

基于多观察层次动态贝叶斯网络的视频行为分析

为了分析视频监控中行人和车辆的行为,本文提出了一种多观察层次动态贝叶斯网络模型。首先,行人和车辆的行为用静态、动态及相互关系特征来表示。然后将其作为模型的输入,通过网络提取和分析目标的行为及其相互关系。同时,本文设计了一个简单的模型选择准则,从候选模型池中选择适合当前场景的模型来减小计算复杂度。实验结果表明本文提出的方法能有效的分析视频监控场景中行人和车辆的行为。     

Harmonic broadcasting for video-on-demand service

Using conventional broadcasting, if we want to support a 120-minute popular movie every 10 minutes, we need 12 video channels. Assuming the set-top box at the client end can buffer portions of the playing video on a disk, pyramid broadcasting schemes can reduce the bandwidth requirements to 5.7 channels. We present a new scheme which only needs 3.2 channels. For a movie with length D minutes, if we want to reduce the viewer waiting time to D/N minutes, we only need to allocate H(N) video channels to broadcast the movie periodically, where H(N) is the harmonic number of N, H(N)=1+1/2+…+1/N. In order to support video-on-demand service for a popular movie, the new scheme greatly reduces the bandwidth requirements     

Computer-aided placement for high-density chip-interconnection systems

A placement algorithm is presented for high-density chip-interconnection systems. The algorithm is novel in that the irregular nature of the pad positions and geometries of integrated-circuit chips are accommodated and used. The placement technique is based on the solution of a set of zeroth-order simultaneous equations, and is demonstrated by a simple example.     

Optimal placement of training for frequency-selective block-fading channels

The problem of placing training symbols optimally for orthogonal frequency-division multiplexing (OFDM) and single-carrier systems is considered. The channel is assumed to be quasi-static with a finite impulse response of length (L + 1) samples. Under the assumptions that neither the transmitter nor the receiver knows the channel, and that the receiver forms a minimum mean square error (MMSE) channel estimate based on training symbols only, training is optimized by maximizing a tight lower bound on the ergodic training-based independent and identically distributed (i.i.d.) capacity. For OFDM systems, it is shown that the lower bound is maximized by placing the known symbols periodically in frequency. For single-carrier systems, under the assumption that the training symbols are placed in clusters of length /spl alpha/ /spl ges/ (2L + 1), it is shown that the lower bound is maximized by a family of placement schemes called QPP-/spl alpha/, where QPP stands for quasi-periodic placement. These placement schemes are formed by grouping the known symbols into as many clusters as possible and then placing these clusters periodically in the packet. For both OFDM and single-carrier systems, the optimum energy tradeoff between training and data is also obtained.     

Optimal server bandwidth for mobile video on demand

Multimedia services such as video-on-demand or Internet protocol television in mobile environments have established themselves in our daily lives, yet the obtained quality of service still leads to many open issues. One of them consists in minimizing the server bandwidth, and we recently proposed a novel patching scheme for transporting true video-on-demand called Hierarchical Patching, which minimizes the server bandwidth. In this paper, we present a new concept called Low Start, consisting of encoding the first part of a movie with a lower bitrate than the rest. In Hierarchical Patching, video parts at the beginning have a much higher probability to be transmitted than parts at the end. By using Low Start, we show that the overall server bandwidth can be drastically reduced. We furthermore investigate the impact of Low Start on the subjective quality of service as perceived by human observers, and show that, for mobile video, the optimal strategy is to encode a very short start time with a bandwidth as low as possible.