Continuous Media Applications Research Articles

A Reference-Based Multiobjective Bacteria Foraging Optimization Technique for QoS Multicast Routing

Nowadays multicast services are gaining high popularity in supporting various and continuous media applications over wired and wireless networks. But the desired quality of service for these applications makes multicast routing optimization a NP Hard problem. In this manuscript, we propose a reference-based multiple objective bacteria foraging algorithm that solves multicasting routing problem, based on user’s preference. Instead of searching for a preferred solution from the obtained Pareto front, we would rather search for a set of solutions in the desired objective space simultaneously. The algorithm starts with a single-step tree construction method to generate multicast trees as initial bacteria population. The Pareto optimal front generated will comprise of solutions, each of which best suits the user’s choice. The multiobjective bacteria foraging optimization algorithm used here is based on the reference-based method, where the user inputs a reference point in the possible region of the problem search space. Hence the Pareto optimal front generated is in the proximity of the given reference point which would help the user in making more feasible and reliable decisions. Simulations have been carried upon various benchmark as well as some random networks to study and analyze the performance of the proposed algorithm with the existing algorithms. The simulation results reveal that our proposed algorithm (RBMOBFO) yields better results in terms of solution quality and convergence speed.

An IEEE 802.11 energy efficient mechanism for continuous media applications

The widespread deployment of wireless mobile communications enables an almost permanent usage of portable devices, which imposes high demands on the battery of these devices. Indeed, battery lifetime is becoming one the most critical factors on the end-users satisfaction when using wireless communications. In this work, the optimized power save algorithm for continuous media applications (OPAMA) is proposed, aiming at enhancing the energy efficiency on end-users devices. By combining the application specific requirements with data aggregation techniques, OPAMA improves the standard IEEE 802.11 legacy Power Save Mode (PSM) performance. The algorithm uses the feedback on the end-user expected quality to establish a proper tradeoff between energy consumption and application performance. OPAMA was assessed in the OMNeT++ simulator, using real traces of variable bitrate video streaming applications, and in a real testbed employing a novel methodology intended to perform an accurate evaluation concerning video Quality of Experience (QoE) perceived by the end-users. The results revealed the OPAMA capability to enhance energy efficiency without degrading the end-user observed QoE, achieving savings up to 44% when compared with the IEEE 802.11 legacy PSM.

Theoretical and Experimental Study of Strain Localization and Energy Dissipation at Fatigue Crack Tip

This work includes both experimental and theoretical studies of crack propagation under cyclic loading. The theoretical part is devoted to the description of energy balance under plastic deformation based on the results of statistical model of mesodefect ensemble proposed in the Institute of continuous media mechanics UB RAS and application of this model to the calculation of strain energy distribution at crack tip. The experimental part of the work is devoted to the study of the temperature evolution at crack tip with high spatial and time resolution. The thermodynamic measurement was combined with study of strain field at crack tip based on the digital image correlation technique. The analysis of experimental data allows us to determine the evolution of plastic deformation zone and dissipation energy at the crack tip.

On the impact of user mobility on peer-to-peer video streaming

Wireless mesh networks are emerging as a promising solution for ubiquitous Internet access with mobility support. In such networks, user mobility may lead to Internet gateway changes and consequently, impact the performance of continuous media applications. In this article, we investigate the impact of user mobility on the performance of peer-to-peer video applications over wireless mesh networks. Peer-to-peer video streaming applications rely on the collaborative behavior of peers to assist the source in delivering multimedia content, reduce costs, and increase the scalability of video distribution. We identify practical issues related to mobility for P2P video streaming implementation in WMNs, such as addressing and forwarding strategies. Furthermore, we evaluate the performance of different P2P streaming applications as the user walks in our WMN testbed. Results indicate mobile users benefit from the frequent shortlived connections established in modern P2P video sessions.

A QoS multicast routing protocol for clustering mobile ad hoc networks

The provision of Quality-of-service (QoS) guarantees is of utmost importance for the development of the multicast services. These multicast services have been used by various continuous media applications. For example, the multicast backbone (Mbone) of the Internet has been used to transport real time audio/video for news, video conferencing and distance learning. This paper presents a QoS multicast routing protocol for clustering mobile ad hoc networks (QMRPCAH). It can provide QoS-sensitive routes in a scalable and flexible way, in the network environment with mobility. In the proposed QMRPCAH scheme, each local node only needs to maintain local multicast routing information and/or summary information of other clusters (or domains) but does not require any global ad hoc network states to be maintained. The QMRPCAH also allows any ad hoc group member can join/leave the multicast group dynamically, and supports multiple QoS constraints. This paper presents formal description and main procedures for realizing routing decision process of the QMRPCAH, and the proof of correctness and complexity analysis of the protocol. It also presents a theoretical analysis of the mobility in the mobile ad hoc network environment. The performance measures of QMRPCAH are evaluated using simulation. The studies show that QMRPCAH can provide an available approach to QoS multicast routing for mobile ad hoc networks.

Layered media multicast control (LMMC): rate allocation and partitioning

The objective of layering techniques of distributing multimedia traffic over multicast IP networks is to effectively cope with the challenges in continuous media applications. The challenges include heterogeneity, fairness, real-time constraints, and quality of service. We study the problem of rate allocation and receiver partitioning in layered and replicated media systems. We formulate an optimization problem aimed at maximizing a close approximation of the so-called max-min fairness metric subject to loss and bandwidth constraints. Our optimal layered media multicast control (LMMC) solution to the problem analytically determines the layer rates and the corresponding partitioning of the receivers. Our simulation results show the effectiveness of our proposed solution in realistic scenarios.

Picture-perfect streaming over the Internet: is there hope?

Quality of service in streaming of continuous media over the Internet is poor, which is partly due to variations in delays, bandwidth limitations, and packet losses. Although continuous media applications can tolerate some missing data, non-recoverable information loss degrades these applications' QoS. Consequently, a number of application areas (e.g., those related to the entertainment industry) have backed away from streaming of their content over the Internet. Inability to control the resulting visual and auditory quality of the resulting streamed presentation is an important reason for such a trend. We believe that this trend can be reversed. To this end, our work focuses on providing high-quality streaming through the exploitation of multiple paths existing in the network. By high quality, we mean with significant bandwidth requirements, of relatively long duration, and without information loss or hiccups in data delivery. In this article we present evidence that multi-path streaming is a promising approach.

Optimal Cache Memory Exploitation for Continuous Media: To Cache or to Prefetch?

Network continuous-media applications are emerging with a great pace. Cache memories have long been recognized as a key resource (along with network bandwidth) whose intelligent exploitation can ensure high performance for such applications. Cache memories exist at the continuous-media servers and their proxy servers in the network. Within a server, cache memories exist in a hierarchy (at the host, the storage-devices, and at intermediate multi-device controllers). Our research is concerned with how to best exploit these resources in the context of continuous media servers and in particular, how to best exploit the available cache memories at the drive, the disk array controller, and the host levels. Our results determine under which circumstances and system configurations it is preferable to devote the available memory to traditional caching (a.k.a. “data sharing”) techniques as opposed to prefetching techniques. In addition, we show how to configure the available memory for optimal performance and optimal cost. Our results show that prefetching techniques are preferable for small-size caches (such as those expected at the drive level). For very large caches (such as those employed at the host level) caching techniques are preferable. For intermediate cache sizes (such as those at multi-device controllers) a combination of both strategies should be employed.

Storage system support for continuous media applications. 2. Multiple disks, memory, and integration

To meet multimedia servers' increasing performance and scalability requirements, researchers must design multimedia storage system components that adapt to various workloads and requirements. They must also develop strategies for combining components into a single high-performance system.

Storage system support for continuous-media applications. 1. Requirements and single-disk issues

A multimedia storage system plays a vital role for the performance and scalability of multimedia servers. To handle the server load imposed by increased user access to on-demand multimedia streaming applications, new storage system solutions are needed. Multimedia storage systems store and retrieve data from storage devices and manage related issues including data placement, scheduling, file management, continuous data delivery, memory buffering, and prefetching. For high-data-rate multimedia systems, storage systems have long been viewed as a primary bottleneck for two reasons. First, multimedia applications have a much higher storage system load than previous applications. Second, storage devices have become only marginally faster compared to increased processor and network performance. This increasing speed mismatch has fueled a search for new storage structures and file system storage and retrieval mechanisms

BANDWIDTH ALLOCATION IN MULTICAST TREES WITH QoS CONSTRAINTS

Growth in continuous media applications and group communications highlight the need for efficient multicast support. In multicast tree construction and resource reservation a central problem is ensuring that the determined multicast tree can support specified QoS requirements economically. In this paper, we focus on this specific problem under a typical QoS requirement that end-to-end delays must not exceed a specified limit. For the resulting optimization problem, we develop a fast and efficient algorithm that is suitable for implementing a router to perform real time provisioning for multicast sessions.

Performance Tradeoffs in Scheduling Techniques for Mixed Workloads

Many modern multimedia applications require the retrieval of different “classes” of data with drastically different characteristics. For instance, digital libraries type systems must be designed to deliver not only text files and still images, but voice and video as well. These applications can benefit from the sharing of resources such as disk and network bandwidth, instead of the conservative approach of partitioning the resources according to the characteristics of each type of data being retrieved. Continuous and non-continuous media applications, require different performance metrics to be achieved, so that the necessary quality of service (QoS) is satisfied. As a consequence, the proper managing of resources is a major issue in order to provide the complete sharing of resources and yet reaching the QoS goals. This work focuses on multimedia storage systems that are capable of serving a mixture of continuous and non-continuous workloads. Our main objective is to expose and investigate the tradeoffs involved in managing the system resources, in particular, I/O bandwidth. The performance metrics of interest are the mean and variance of response time for non-continuous media requests and the probability of missing an imposed deadline for continuous media workloads. Different scheduling algorithms are considered and tradeoffs to achieve performance goals are studied, including those involving buffer sizing.

Decentralized resource management for a distributed continuous media server

Distributed continuous media server (DCMS) architectures are proposed to minimize the communication-storage cost for those continuous media applications that serve a large number of geographically distributed clients. Typically, a DCMS is designed as a pure hierarchy (tree) of centralized continuous media servers. In an earlier work, we proposed a redundant hierarchical topology for DCMS networks, termed RedHi, which can potentially result in higher utilization and better reliability over pure hierarchy. We focus on the design of a resource management system for RedHi that can exploit the resources of its DCMS network to achieve these performance objectives. Our proposed resource management system is based on a fully decentralized approach to achieve optimal scalability and robustness. In general, the major drawback of a fully decentralized design is the increase in latency time and communication overhead to locate the requested object. However, as compared to the typically long duration and high resource/bandwidth requirements of continuous media objects, the extra latency and overhead of a decentralized resource management approach become negligible. Moreover, our resource management system collapses three management tasks: (1) object location, (2) path selection, and (3) resource reservation, into one fully decentralized object delivery mechanism, reducing the latency even further. In sum, decentralization of the resource management satisfies our scalability and robustness objectives, whereas collapsing the management tasks helps alleviate the latency and overhead constraints.

An efficient deadline-credit-based transport scheme for prerecorded semisoft continuous media applications

In this paper, an efficient scheme is proposed based on the introduced deadline-credit-based (DC) policy. This scheme is appropriate for any prerecorded media, but is particularly relevant for prerecorded semisoft continuous media (CM) applications. Semisoft are applications with very small initial delay tolerance and, thus, for which very small amount of content may be sent in advance. The proposed policy pushes content toward the end user during the session by taking advantage of any bandwidth underutilization periods, exploiting available storage, and building up fairly a deadline credit to be consumed during periods of overutilization. The scheduling policy is studied for the single-hop case (applicable to the server of the content), as well as for the multihop case (applicable to the server and network nodes). The derived results demonstrate the ability of the proposed scheme to decrease the amount of required bandwidth (or equivalently induced losses) with respect to alternative schemes without requiring large initial delay, which is not acceptable for semisoft CM applications.

Decentralized resource management for a distributed continuous media server

Distributed continuous media server (DCMS) architectures are proposed to minimize the communication-storage cost for those continuous media applications that serve a large number of geographically distributed clients. Typically, a DCMS is designed as a pure hierarchy of centralized continuous media servers. RedHi, a Redundant Hierarchical topology for DCMS networks, can result in higher utilization and better reliability over pure hierarchy. We focus on the design of a resource management system (RMS) for RedHi that can exploit the resources of its DCMS network to achieve these performance objectives. Our RMS is based on a fully decentralized approach to achieve optimal scalability and robustness. The major drawback of a fully decentralized design is the increase in latency time and communication overhead to locate the requested object. However, as compared to the typically long duration and high resource/bandwidth requirements of continuous media objects, the extra latency and overhead of a decentralized resource management approach become negligible. Moreover, our RMS collapses three management tasks (object location, path selection and resource reservation) into one fully decentralized object delivery mechanism, reducing the latency even further. Decentralization of the resource management satisfies our scalability and robustness objectives, whereas collapsing the management tasks helps alleviate the latency and overhead constraints. To achieve a high resource utilization, the object delivery scheme uses our proposed cost function, as well as various object location and resource reservation policies to select and allocate the best streaming path to serve each request. The object delivery scheme is designed as an application-layer resource management middleware for the DCMS architecture to be independent of the underlying telecommunication infrastructure. Experiments show that our RMS is successful in realization of the higher resource utilization for the DCMS networks with the RedHi topology.

Dynamic QoS mapping control for streaming video in relative service differentiation networks

AbstractA dynamic quality of service (QoS) mapping control scheme, which includes feedforward and feedback QoS control, is proposed for the differentiated services (DiffServ) networks in this work. To achieve reliable and consistent end—to—end video streaming with relative service differentiation, the proposed solution consists of two parts: (1) relative priority—based indexing and categorization of streaming video content at the sending end—system and (2) dynamic and aggregate QoS mapping control with packet, session, and class—based granularity level for categorized packets at the edge of the DiffServ domain, called the video gateway (VG), based upon the load variation of the network. In particular, we focus on dynamic solutions to handle QoS demand variations of continuous media applications (e. g. varying priorities from aggregated/categorized packets) and QoS supply variations of the DiffServ network (e. g. varying loss/delay due to fluctuating network loads). Thus, with the proposed dynamic QoS mapping control, video streaming with enhanced quality is demonstrated under a pricing model.

MIDDLEWARE FOR BUILDING ADAPTIVE MIGRATORY CONTINUOUS MEDIA APPLICATIONS

In this paper, we propose a middleware system for building adaptive migratory continuous media applications. In future computing environments, a variety of objects at home and in offices will embed computers, and various applications will be moved among these computers according to the user's locations. For example, a computer that executes an application may be changed to another computer according to the location of the application's user for monitoring his behavior. However, since the computers may have dramatically different hardware and software configurations, the application cannot be moved without taking into account the configurations of the computers that the application is migrated. Therefore, migratory applications should be aware of environments where they are executed. The paper focuses on middleware for building adaptive migratory continuous media applications that are one of the most important classes of migratory applications. Our middleware consists of three components. The first component is an environment server that monitors computing environments that applications run, and it notifies the changes of the environments to the applications. The second component is a continuous media toolkit that enables us to build adaptive migratory continuous media applications easily. The toolkit enables us to build continuous media applications in a highly configurable way. This makes applications to be adapted to every computing environment by changing their configurations. The third component is a migration manager that makes applications migratory. We also show an example of a migratory application, and describe some experiences with building the application.

Performance evaluation of a Java-based networking Application Programming Interface (API)

Over the last few years, we have witnessed the emergence of many network-based multimedia applications, particularly those rich in audio, video, and images. Access to network services has become an integral component of these applications. In this paper, we present a Java-based networking Application Programming Interface (API), and compare the performance of our Java-based API with Microsoft Winsock 2 API over different protocols namely, TCP/IP, UDP/IP and native Asynchronous Transfer Mode (ATM). From the results obtained, we observe that the Java layer increases the overall user-to-user latency by about 120 microseconds compared to native Winsock 2 over ATM local area networks. We also found that jitter performance for continuous media applications, such as those involving digital video is highly non-deterministic. We obtained large variations in video jitter over Java, with maximum jitter in the range 6 to 12 milliseconds.

Multicast routing and its QoS extension: problems, algorithms, and protocols

Multicast services have been increasingly used by various continuous media applications. The QoS requirements of these continuous media applications prompt the necessity for QoS-driven, constraint-based multicast routing. This article provides a comprehensive overview of existing multicast routing algorithms, protocols, and their QoS extension. In particular, we classify multicast routing problems according to their optimization functions and performance constraints, present basic routing algorithms in each problem class, and discuss their strengths and weaknesses. We also categorize existing multicast routing protocols, outline the issues and challenges in providing QoS in multicast routing, and point out possible future research directions.

MobiWeb: enabling adaptive continuous media applications over 3G wireless links

MobiWeb is a proxy-based network architecture designed to enhance the performance of adaptive real-time streams over 3G wireless links. MobiWeb includes a priority scheme that preserves media smoothness despite short-term fluctuations of the link, as well as an adaptation mechanism applied to streams responding to long-term link changes and handoffs. A set of timers permits the rapid exploration of the link, increasing the utilization of resources when they are abundant, while forcing enhanced streams to back off to more moderate resource usage when resources are scarce. MobiWeb uses admission control for real-time traffic in order to provide a base level of quality, while remaining transparent to unaware best-effort traffic. This article validates the enhanced performance of adaptive real-time streams when MobiWeb is used through the evaluation of several scenarios simulated on NS-the Network Simulator tool.