Continuous Media Streams Research Articles

Stressogenicity of Media Noise in the Conditions of Background Media Consumption

The authors of the paper present for the first time the concept of media noise in the living space of modern children; they also introduce the concept of media noise as forced media consumption in a background (backdrop) format, and consumption in parallel with the main activity (foreground). The stressful effect of the operation of screens and players in the background on people in this space, and the impact of the inclusion of children in a continuous media stream are assessed. It is noted that pervasive media increase the potential of psycho-emotional impact through trance methods of exposure affecting the cognitive, affective and behavioural sphere of individuals, and this forces them to consume information, burden the information space of children, and qualitatively change the social situation of their development. The paper presents the findings concerning pilot studies of the media noise phenomenon and the state of media noise. The existence of a relationship between various parameters of forced background media consumption is shown; the main situations of background media consumption, as well as the reasons for the independent media noise initiation and its duration, are given. The aggravated negative impact of background media consumption in connection with the new life realities of mankind during the period of total immersion in the media space is noted; the last is caused by the need for social distance.

Buffer management for streaming media transmission in hierarchical data of opportunistic networks

An opportunistic network is a kind of novel and self-organizing mobility network with DTN (Delay Tolerant Networks) features, which has no fixed topological structure and transfers messages using the opportunity of nodes encountering. Transmitting steaming media in such a network faces significant challenge, since the topology between source node and destination node is variable. In order to increase the delivery ratio, an opportunistic network employs the message redundancy mechanism, which leads to the existing of multiple copies of messages in different routes at the same moment. These duplicates tend to jam the network, block later messages and jeopardize network performance due to the limited buffer resource of nodes. In this context, we propose a novel buffer management algorithm for streaming media (BMSM) in an opportunistic network by combining the characters of opportunistic networks with the feature of hierarchical data encoding of H.264 streaming media. The BMSM algorithm fully utilizes the real-time dynamic parameters of the network, i.e., remaining living time and the estimation of message copies, and it automatically assigns a priority parameter to a message to determine its transitivity and priority in the node׳s buffer sequence based on the hierarchical property of the messages. By combining the mobility of nodes, a new queuing strategy for managing the buffer is also proposed in BMSM, in which a message is forwarded preferentially to the interacting closely truck nodes when it is at the head of the sequence. Simulation results show that the proposed BMSM algorithm effectively improves the delivery rate and limited the network overhead ratio and thereby ensures the continuous media streams.

Analytical Study of Disk Performance for Continuous Media Streaming

The Study of disk performance is of prime importance as it helps in determining the number of streams that can be serviced by the system. There are two main parameters for disk performance - disk bandwidth and disk cache. Disk bandwidth refers to data transfer rate that is consumed in accessing data from disk. There are three different overheads that incur while accessing data from disk: seek time, rotational time, and transfer time. Because of large seek and rotational times, no data can be provided to users directly from disk on time. In that case, the data is first prefetched into disk cache from the disk that contributes only transfer time; no seek or rotational time. Disk cache is a very small area on disk and because of small size, its seek and rotational times are negligible. Thus the only overhead is transfer time. In this paper, we propose an analytical study to evaluate the performance of disk as regard to these parameters and show how both parameters can be utilized efficiently and effectively. This study is primarily useful in deciding the number of concurrent continuous media streams, especially video streams supported by a disk without hiccups and glitches.

Popularity Aware Limited Caching for Reliable On Demand P2P Video Streaming

In nowadays network group, the Peer-To-Peer (P2P) network is exploring as a good environment for resource sharing over the Internet. Compared with traditional file sharing workloads, continuous streaming of multimedia content provokes a significant amount of today’s internet traffic. Streaming media has various real-time constraints such as insufficient memory, high bandwidth utilization for largescale media objects, and lack of cooperation between proxies and their clients. Under these circumstances, it is a challenging task to achieve efficient content delivery under the increased availability of continuous-media streaming. In this paper, PALC (Popularity Aware Limited caching) is proposed to achieve efficient, reliable and scalable P2P-VoD system. It is an attractive approach to minimize the network traffic incurred in video streaming through cooperative caching. In this approach, P2P network is constructed in the form of a two-tier architecture, where the upper tier is composed of proxy overlay with high connectivity super peers. It serves as a structured DHT node to maintenance the detached hash table for prominent information retrieval. On the contrary, in lower tier, less connectivity peers are loosely coupled to the corresponding super peers in the form of unstructured network. We proposed an efficient hybrid proxy caching system in order to reduce the network/ server load while improving the end user perceived video quality. It also proposes an efficient Popularity Aware Limited Caching (PALC) algorithm that cooperatively utilizes the memory space of the proxy servers and clients to achieve efficient and cost effective P2P video streaming. The effectiveness of the proposed approach is evaluated under various network and end system configurations. The experimental results demonstrate that the proposed approach incurs minimum Internet traffic and low cost of transmission as compared to the proxy-based caching approach with limited storage space.

A Trust-Based Framework for Fault-Tolerant Data Aggregation in Wireless Multimedia Sensor Networks

For wireless multimedia sensor networks (WMSNs) deployed in noisy and unattended environments, it is necessary to establish a comprehensive framework that protects the accuracy of the gathered multimedia information. In this paper, we jointly consider data aggregation, information trust, and fault tolerance to enhance the correctness and trustworthiness of collected information. Based on the multilayer aggregation architecture of WMSNs, we design a trust-based framework for data aggregation with fault tolerance with a goal to reduce the impact of erroneous data and provide measurable trustworthiness for aggregated results. By extracting statistical characteristics from different sources and extending Josang's trust model, we propose how to compute self-data trust opinion, peer node trust opinion, and peer data trust opinion. According to the trust transfer and trust combination rules designed in our framework, we derive the trust opinion of the sink node on the final aggregated result. In particular, this framework can evaluate both discrete data and continuous media streams in WMSNs through a uniform mechanism. Results obtained from both simulation study and experiments on a real WMSN testbed demonstrate the validity and efficiency of our framework, which can significantly improve the quality of multimedia information as well as more precisely evaluate the trustworthiness of collected information.

Streaming Media Caching Model Based on Knapsack Problem

The dominant traffic on the Internet has changed from text and graphics based Web content to more information-rich streaming media content, such as audio and video. With the dramatic increase of network bandwidth and the advancement of technologies on media authoring, encoding, and distribution, media traffic on the Internet has increased explosively and now accounts for the majority of traffic volume. Modern Internet streaming services have utilized various techniques to improve the quality of streaming media delivery. Proxy server is one of the main solutions used to improve Internet QoS, especially for the QoS of streaming media. Replacement algorithm optimization is the core of caching model research. However, existing techniques for caching text and image resources are not appropriate for the rapidly growing number of continuous media streams. Based on the concept of hit ratio, this paper makes use of 0-1 knapsack problem to set up a hit ratio model of proxy cache, by use of which a proxy cache policy is presented. As compared with the classical dynamic streaming scheduling strategies, the proposed algorithm is shown that it can make full use of space of proxy cache, and also get a higher hit ratio.

Two-Step Fair Scheduling of Continuous Media Streams over Error-Prone Wireless Channels

In wireless cellular networks, streaming of continuous media (with strict QoS requirements) over wireless links is challenging due to their inherent unreliability characterized by location-dependent, bursty errors. To address this challenge, we present a two-step scheduling algorithm for a base station to provide streaming of continuous media to wireless clients over the error-prone wireless links. The proposed algorithm is capable of minimizing the packet loss rate of individual clients in the presence of error bursts, by transmitting packets in the round-robin manner and also adopting a mechanism for channel prediction and swapping.

Continuous-Time Collaborative Prefetching of Continuous Media

The real-time streaming of bursty continuous media, such as variable-bit rate encoded video, to buffered clients over networks can be made more efficient by collaboratively prefetching parts of the ongoing streams into the client buffers. The existing collaborative prefetching schemes have been developed for discrete time models, where scheduling decisions for all ongoing streams are typically made for one frame period at a time. This leads to inefficiencies as the network bandwidth is not utilized for some duration at the end of the frame period when no video frame ldquofitsrdquo into the remaining transmission capacity in the schedule. To overcome this inefficiency, we conduct in this paper an extensive study of collaborative prefetching in a continuous-time model. In the continuous-time model, video frames are transmitted continuously across frame periods, while making sure that frames are only transmitted if they meet their discrete playout deadlines. We specify a generic framework for continuous-time collaborative prefetching and a wide array of priority functions to be used for making scheduling decisions within the framework. We conduct an algorithm-theoretic study of the resulting continuous-time prefetching algorithms and evaluate their fairness and starvation probability performance through simulations. We find that the continuous-time prefetching algorithms give favorable fairness and starvation probability performance.

Streaming of Continuous Media for Distance Education Systems

Distance education created new challenges regarding the delivery of large size isochronous continuous streaming media (SM) objects. In this paper, we consider the design of a framework for customized SM presentations, where each presentation consists of a number of SM objects that should be retrieved and displayed to the user in a coherent fashion. We describe a retrieval optimizer (Prime) that captures the flexibilities and requirements imposed by the user query, user profile, and session profile. Then, it determines how this query script should be imposed against the continuous media (CM) server to reduce contention. We also provide a cost model to evaluate each proposed plan. Finally, we explain the role of memory buffering in alleviating the server bandwidth fragmentation problem. Our preliminary experimental results show the feasibility and effectiveness of our proposed model and techniques in generating near optimal retrieval.

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.

Performance evaluation for VBR Continuous Media File Server admission control

AbstractA file server for continuous media must provide resource guarantees and only admit requests that do not violate the resource availability. This paper addresses the admission performance of a server that explicitly considers the variable bit rate nature of the continuous media streams. A prototype version of the server has been implemented and evaluated in several heterogeneous environments. The two system resources for which admission control is evaluated are the disk bandwidth and the network bandwidth. Performance results from both measurement and simulation are shown with respect to different admission methods and varying scenarios of stream delivery patterns. We show that the vbrSim algorithm developed specifically for the server outperforms the other options for disk admission especially with request patterns that have staggered arrivals, while the network admission control algorithm is able to utilize a large percentage of the network bandwidth available. We also show the interactions between the limits of these two resources and how a system can be configured without wasted capacity on either one of the resources. Copyright © 2004 John Wiley & Sons, Ltd.

Aggregated smoothing: Considering all streams simultaneously for transmission of variable-bit-rate encoded video objects

Transmission of continuous media streams has been a challenging problem of multimedia service. Lots of works have been done trying to figure out the best solution for this problem, and some works presented the optimal solution for transmitting the stored video using smoothing schemes applied to each individual stream. But those smoothing schemes considered only one stream, not the whole streams being serviced, to apply themselves, which could only achieve local optimum not the global optimum. Most of all, they did not exploit statistical multiplexing gain that can be obtained before smoothing. In this paper, we propose a new smoothing scheme that deals with not an individual stream but the whole streams being serviced simultaneously to achieve the optimal network bandwidth utilization and maximize the number of streams that can be serviced simultaneously. We formally proved that the proposed scheme not only provides deterministic QoS for each client but also maximizes number of clients that can be serviced simultaneously and hence achieves maximum utilization of transmission bandwidth.

Real-time disk scanning for timely retrieval of continuous media objects

In recent years, demands for multimedia applications have rapidly grown with the advances in computing power and network technology. To fulfill the demands, it is crucial to establish the multimedia information systems supporting continuous media (CM) streams without hiccups. Many useful methods have been proposed in the past so that CM steams with VCR-quality can be supported. Although these earlier approaches can be used for the service of VCR-quality streams, they cannot provide a good system performance for the CM streams with various playback rates and rather short durations of playback. In the paper, we propose a new CM playback method that consists of bulk-scanning and an earliest-deadline-first style scheduling algorithm. Our proposed method provides both good response times and high I/O utilization using the efficient disk scheduling. In addition, our mechanism for admission control makes CM streams never experience hiccups until the ends of playback. Through experimental analyses, we show the performance advantages of the proposed method over the earlier methods.

A scalable bandwidth guaranteed distributed continuous media file system using network attached autonomous disks

Repository for continuous media data differs from that of the traditional text-based data both in storage space and streaming bandwidth requirements. The file systems used for continuous media streams need to support large volumes and high bandwidth. We propose a scalable distributed continuous media file system built using autonomous disks. Autonomous disks are attached directly to the network and are able to perform lightweight processing. We discuss different ways to realize the autonomous disk, and describe a prototype implementation on a Linux platform using PC-based hardware. We present the basic requirements of the continuous media file system and present the design methodology and a prototype Linux-based implementation of the distributed file system that supports the requirements. We present experimental results on the performance of the proposed file system prototyped using autonomous disks. We show that the performance of the file system scales linearly with the number of disks and the number of clients. The file system performs much superior to NFS running on the same hardware platform and can deliver higher raw disk bandwidth to the applications. We also present bandwidth and time sensitive read/write procedures for the file system and show that the file system can provide strict bandwidth guarantees for continuous media streams.

Packet Permutation: A Robust Transmission Technique for Continuous Media Streaming Over the Internet

With the growing popularity of the Internet, there is an increasing demand to deliver continuous media (CM) streams over the Internet. However, packets may be damaged or lost during transmission over the current Internet. In particular, periodic network overloads often result in bursty packet losses, degrading the perceptual quality of CM streaming. In this paper, we focus on reducing the impact of this bursty loss behavior. We propose a novel robust end-to-end transmission scheme, referred to as packet permutation (PP), to deliver pre-compressed continuous media streams over the Internet. At the server side, PP permutes, prior to transmission, the normal packet delivery sequence of CM streams in a specific way. The packets are then re-permuted at the receiver side before they are presented to the application. In this way, the probability of losing a large number of packets within each CM frame can be significantly reduced. To validate the effectiveness of PP, a series of trace-driven simulations are conducted. Our results show that for a given quality of service (QoS) requirement of CM streaming, PP greatly reduces the overhead required by traditional error control schemes, such as forward error correction (FEC) and feedback/retransmission-based schemes.

QoS-adaptive bandwidth scheduling in continuous media streaming

In this paper, we present a QoS-adaptive admission control and resource scheduling framework for continuous media (CM) servers. The framework consists of two parts. One is a reserve-based admission control mechanism in which new streams, arriving during periods of congestion, are offered lower QoS, instead of being blocked. The other part is a scheduler for continuous media with dynamic resource allocation to achieve higher utilization than non-dynamic schedulers by effectively sharing available resources among contending streams and by reclamation which is a scheduler-initiated negotiation to reallocate resources among streams to improve overall QoS. This soft-QoS framework recognizes that CM applications can generally tolerate certain variations on QoS parameters; that is, it exploits the findings about human tolerance to degradation in quality of multimedia streams. Using our policy, we could increase the number of simultaneously running clients that could be supported and could ensure a good response ratio and better resource utilization under heavy traffic requirements. Our admission control and scheduling strategy provides three principle advantages over conventional mechanisms. First, it guarantees better total system utilization. Second, it provides better disk utilization and larger admission ratio for input CM streams, which is a major advantage. Third, it still presents acceptable play-out qualities compared to the conventional greedy admission control algorithm.

Competitive On-line Scheduling of Continuous-Media Streams

Multimedia applications require a guaranteed level of service for accessing continuous-media data. To obtain such guarantees, the database server where the data are residing must employ an admission control scheme to limit the number of clients that can be served concurrently. We investigate the problem of on-line admission control, where the decision of whether to accept or reject a request must be made without any knowledge about future requests. Employing competitive analysis techniques, we address the problem in its most general form with the following key contributions: (1) We prove a tight upper bound on the competitive ratio of the conventional Work-Conserving (WC) policy, showing that it is within a factor 1+Δ1−ρ of the optimal clairvoyant strategy, where Δ is the ratio of the maximum to minimum request length (i.e., time duration), and ρ is the maximum fraction of the server's bandwidth that a request can demand; (2) we prove a lower bound of Ω(logΔ1−ρ) on the competitive ratio of any deterministic or randomized admission control scheme, demonstrating an exponential gap between greedy and optimal on-line solutions; (3) we propose simple deterministic schemes based on the idea of bandwidth prepartitioning that guarantee competitive ratios within a small constant factor of logΔ (i.e., they are provably near-optimal) if ρ<1/⌈logΔ⌉; and (4) we introduce a novel admission control policy that partitions the server bandwidth based on the expected popularities of different request lengths and experimentally demonstrate its benefits compared to WC.

A prefetching protocol for continuous media streaming in wireless environments

Streaming of continuous media over wireless links is a notoriously difficult problem. This is due to the stringent quality of service (QoS) requirements of continuous media and the unreliability of wireless links. We develop a streaming protocol for the real-time delivery of prerecorded continuous media from (to) a central base station to (from) multiple wireless clients within a wireless cell. Our protocol prefetches parts of the ongoing continuous media streams into prefetch buffers in the clients (base station). Our protocol prefetches according to a join-the-shortest-queue (JSQ) policy. By exploiting rate adaptation techniques of wireless data packet protocols, the JSQ policy dynamically allocates more transmission capacity to streams with small prefetched reserves. Our protocol uses channel probing to handle the location-dependent, time-varying, and bursty errors of wireless links. We evaluate our prefetching protocol through extensive simulations with VBR MPEG and H.263 encoded video traces. Our simulations indicate that for bursty VBR video with an average rate of 64 kb/s and typical wireless communication conditions our prefetching protocol achieves client starvation probabilities on the order of 10/sup -4/ and a bandwidth efficiency of 90% with prefetch buffers of 128 kbytes.

Delay reduction techniques for playout buffering

Receiver synchronization of continuous media streams is required to deal with delay differences and variations resulting from delivery over packet networks such as the Internet. This function is commonly provided using per-stream playout buffers which introduce additional delay in order to produce a playout schedule which meets the synchronization requirements. Packets which arrive after their scheduled playout time are considered late and are discarded. In this paper, we present the Concord algorithm, which provides a delay-sensitive solution for playout buffering. It records historical information and uses it to make short-term predictions about network delay with the aim of not reacting too quickly to short-lived delay variations. This allows an application-controlled tradeoff of packet lateness against buffering delay, suitable for applications which demand low delay but can tolerate or conceal a small amount of late packets. We present a selection of results from an extensive evaluation of Concord using Internet traffic traces. We explore the use of aging techniques to improve the effectiveness of the historical information and hence, the delay predictions. The results show that Concord can produce significant reductions in buffering delay and delay variations at the expense of packet lateness values of less than 1%.

Scheduling Algorithms for Application‐Level QoS Support of Continuous Media Streams

AbstractThe Quality of Service (QoS) of real time applications is affected in a rather direct manner by the timely delivery of Application‐level Data Units (ADUs) which are typically mapped into several Network‐level Data Units (NDUs). As a consequence, it would be reasonable to associate a common deadline with all the NDUs in one ADU and develop a scheduling policy that aims to maximise the number of ADUs that are delivered by their respective deadlines. In the first part of the paper, an ADU‐based Earliest Due First (EDF) scheduling policy is investigated under periodic ADU arrival processes which are typical of continuous media streams. The proposed policy can be implemented in terms of a simple First ADU In – First ADU Out (FAI‐FAO) policy and it is shown to improve on the ADU dropping rate induced by FIFO policies of comparable complexity. In the second part of the paper, the more complex and effective Size‐Deadline Sensitive(SDS) scheduling policy is proposed and investigated under general ADU arrival processes. This policy is shown to be optimal in the sense that it maximises the number of complete ADUs scheduled for transmission at any point in time, by taking into consideration the associated diverse deadlines and the ADU sizes and combining the principles of two well known scheduling algorithms, the Earliest Due First (EDF) and the Shortest Job First (SJF). It is argued and illustrated that the proposed optimal scheduling leads in efficient actual service which under certain arrival processes is shown to be the optimal. Numerical results are presented and the induced ADU and NDU loss rates under the proposed policy are compared against those induced by the standard EDF and SJF policies.