An experimental dynamic RAM video cache

As technological advances continue to be made, the demand for more efficient distributed multimedia systems is also affirmed. Current support for end-to-end QoS is still limited; consequently mechanisms are required to provide flexibility in resource loading. One such mechanism, caching, may be introduced both in the end-system and network to facilitate intelligent load balancing and resource management. We introduce new work at Lancaster University investigating the use of transparent network caches for MPEG-2. A novel architecture is proposed, based on router-oriented caching and the employment of large scale dynamic RAM as the sole caching medium. The architecture also proposes the use of the ISO/IEC standardised DSM-CC protocol as a basic control infrastructure and the caching of pre-built transport packets (UDP/IP) in the data plane. Finally, the work discussed is in its infancy and consequently focuses upon the design and implementation of the caching architecture rather than an investigation into performance gains, which we intend to make in a continuation of the work

Digital television applications

Studying development of interactive services for digital television is a leading edge area of work as there is minimal research or precedent to guide their design. Published research is limited and therefore this thesis aims at establishing a set of computing methods using Java and XML technology for future set-top box interactive services. The main issues include middleware architecture, a Java user interface for digital television, content representation and return channel communications. The middleware architecture used was made up of an Application Manager, Application Programming Interface (API), a Java Virtual Machine, etc., which were arranged in a layered model to ensure the interoperability. The application manager was designed to control the lifecycle of Xlets; manage set-top box resources and remote control keys and to adapt the graphical device environment. The architecture of both application manager and Xlet forms the basic framework for running multiple interactive services simultaneously in future set-top box designs. User interface development is more complex for this type of platform (when compared to that for a desktop computer) as many constraints are set on the look and feel (e.g., TV-like and limited buttons). Various aspects of Java user interfaces were studied and my research in this area focused on creating a remote control event model and lightweight drawing components using the Java Abstract Window Toolkit (AWT) and Java Media Framework (JMF) together with Extensible Markup Language (XML). Applications were designed aimed at studying the data structure and efficiency of the XML language to define interactive content. Content parsing was designed as a lightweight software module based around two parsers (i.e., SAX parsing and DOM parsing). The still content (i.e., text, images, and graphics) and dynamic content (i.e., hyperlinked text, animations, and forms) can then be modeled and processed efficiently. This thesis also studies interactivity methods using Java APIs via a return channel. Various communication models are also discussed that meet the interactivity requirements for different interactive services. They include URL, Socket, Datagram, and SOAP models which applications can choose to use in order to establish a connection with the service or broadcaster in order to transfer data. This thesis is presented in two parts: The first section gives a general summary of the research and acts as a complement to the second section, which contains a series of related publications.reviewe

ATOM : a distributed system for video retrieval via ATM networks

The convergence of high speed networks, powerful personal computer processors and improved storage technology has led to the development of video-on-demand services to the desktop that provide interactive controls and deliver Client-selected video information on a Client-specified schedule. This dissertation presents the design of a video-on-demand system for Asynchronous Transfer Mode (ATM) networks, incorporating an optimised topology for the nodes in the system and an architecture for Quality of Service (QoS). The system is called ATOM which stands for Asynchronous Transfer Mode Objects. Real-time video playback over a network consumes large bandwidth and requires strict bounds on delay and error in order to satisfy the visual and auditory needs of the user. Streamed video is a fundamentally different type of traffic to conventional IP (Internet Protocol) data since files are viewed in real-time, not downloaded and then viewed. This streaming data must arrive at the Client decoder when needed or it loses its interactive value. Characteristics of multimedia data are investigated including the use of compression to reduce the excessive bit rates and storage requirements of digital video. The suitability of MPEG-1 for video-on-demand is presented. Having considered the bandwidth, delay and error requirements of real-time video, the next step in designing the system is to evaluate current models of video-on-demand. The distributed nature of four such models is considered, focusing on how Clients discover Servers and locate videos. This evaluation eliminates a centralized approach in which Servers have no logical or physical connection to any other Servers in the network and also introduces the concept of a selection strategy to find alternative Servers when Servers are fully loaded. During this investigation, it becomes clear that another entity (called a Broker) could provide a central repository for Server information. Clients have logical access to all videos on every Server simply by connecting to a Broker. The ATOM Model for distributed video-on-demand is then presented by way of a diagram of the topology showing the interconnection of Servers, Brokers and Clients; a description of each node in the system; a list of the connectivity rules; a description of the protocol; a description of the Server selection strategy and the protocol if a Broker fails. A sample network is provided with an example of video selection and design issues are raised and solved including how nodes discover each other, a justification for using a mesh topology for the Broker connections, how Connection Admission Control (CAC) is achieved, how customer billing is achieved and how information security is maintained. A calculation of the number of Servers and Brokers required to service a particular number of Clients is presented. The advantages of ATOM are described. The underlying distributed connectivity is abstracted away from the Client. Redundant Server/Broker connections are eliminated and the total number of connections in the system are minimized by the rule stating that Clients and Servers may only connect to one Broker at a time. This reduces the total number of Switched Virtual Circuits (SVCs) which are a performance hindrance in ATM. ATOM can be easily scaled by adding more Servers which increases the total system capacity in terms of storage and bandwidth. In order to transport video satisfactorily, a guaranteed end-to-end Quality of Service architecture must be in place. The design methodology for such an architecture is investigated starting with a review of current QoS architectures in the literature which highlights important definitions including a flow, a service contract and flow management. A flow is a single media source which traverses resource modules between Server and Client. The concept of a flow is important because it enables the identification of the areas requiring consideration when designing a QoS architecture. It is shown that ATOM adheres to the principles motivating the design of a QoS architecture, namely the Integration, Separation and Transparency principles. The issue of mapping human requirements to network QoS parameters is investigated and the action of a QoS framework is introduced, including several possible causes of QoS degradation. The design of the ATOM Quality of Service Architecture (AQOSA) is then presented. AQOSA consists of 11 modules which interact to provide end-to-end QoS guarantees for each stream. Several important results arise from the design. It is shown that intelligent choice of stored videos in respect of peak bandwidth can improve overall system capacity. The concept of disk striping over a disk array is introduced and a Data Placement Strategy is designed which eliminates disk hot spots (i.e. Overuse of some disks whilst others lie idle.) A novel parameter (the B-P Ratio) is presented which can be used by the Server to predict future bursts from each video stream. The use of Traffic Shaping to decrease the load on the network from each stream is presented. Having investigated four algorithms for rewind and fast-forward in the literature, a rewind and fast-forward algorithm is presented. The method produces a significant decrease in bandwidth, and the resultant stream is very constant, reducing the chance that the stream will add to network congestion. The C++ classes of the Server, Broker and Client are described emphasizing the interaction between classes. The use of ATOM in the Virtual Private Network and the multimedia teaching laboratory is considered. Conclusions and recommendations for future work are presented. It is concluded that digital video applications require high bandwidth, low error, low delay networks; a video-on-demand system to support large Client volumes must be distributed, not centralized; control and operation (transport) must be separated; the number of ATM Switched Virtual Circuits (SVCs) must be minimized; the increased connections caused by the Broker mesh is justified by the distributed information gain; a Quality of Service solution must address end-to-end issues. It is recommended that a web front-end for Brokers be developed; the system be tested in a wide area A TM network; the Broker protocol be tested by forcing failure of a Broker and that a proprietary file format for disk striping be implemented

Modelo e implementação de um serviço de datacasting para televisão digital

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-graduação em Engenharia ElétricaA difusão de dados, conhecida como datacasting, se mostra como a base para o surgimento de novos serviços na Televisão Digital (TVD). Neste contexto, este trabalho busca propor e implementar um modelo fim a fim de datacasting, direcionado à difusão de aplicativos e demais dados correlacionados, que suporte esses novos serviços. O modelo foi baseado em especificações abertas de TVD, assim como em trabalhos encontrados na Literatura. Foram estudados os mecanismos de difusão de dados sobre os padrões de TVD, utilizados pelos sistemas abertos, assim como investigadas suas principais características, vantagens e desvantagens. A implementação foi concretizada através do desenvolvimento de parte dos componentes previstos no modelo, e da integração destes com determinadas soluções de softwares livres já existentes

ULE Robust Header Compression For Ip-Based Communication Over Digital Video Broadcasting-Satellite (DVB-S) [TK5104. T261 2008 f rb].

Untuk selama 35 tahun, Internet telah berkembang dan bertumbuh dengan pesat. Disebabkan pembangunan yang mendadak, permintaan capaian Internet menjadi kian popular di mana-mana saja melalui pelbagai jenis media, Over a span of thirty five years, the Internet has developed and grown rapidly. Due to its rapid growth, the demand for Internet access today is everywhere and over every possible medium such as satellite communications

Utilizing Open Source in Terrestrial Digital TV Broadcasting

Indonesian terrestrial TV broadcasting has just started its migration to digital standard. Digitalization offers more roles for software development in various functional blocks of digital TV system. This paper presents utilization of open-source softwares in assessing some aspects of terrestrial digital TV system. We propose technical specification and measurement standard operating procedure for basic services using DVB-T standard, and set-up a softwarebased platform based on open source softwares for testing a DVB-T set-top-box

Access Services Based on MHP Interactive Applications

In this paper it is described how interactive applications can be used to provide access services for people with disabilities in digital television. MHP (Multimedia Home Platform) is a standardized middleware to develop interactive applications in digital television. In this way, the interactive applications become tools for the provision of the access services. These features have been exploited in a research project to create a subtitle application for the deaf and hard of hearing people and an accessible electronic program guide for blind people

Image compression in interactive applications in digital video broadcasting

V interaktivních aplikacích digitálního televizního vysílání se v hojné míře používají komprimované obrazy. V doktorské práci jsou prezentovány nové metody zefektivnění jejich přenosu v sítích digitálního televizního vysílání. Byly navrženy metody na principu adaptivní prostorové filtrace pro zlepšení vizuálního vjemu komprimovaných obrazů. Nová metoda optimalizace spočívá v aplikaci těchto metod na více komprimované (tedy datově menší) obrazy a zlepšení jejich vizuální kvality až v aplikaci. Dále byly analyzovány nové metody komprese JPEG2000 a H.264 pro kompresi obrazů. V práci je rovněž prezentována nová původní kombinovaná metoda komprese obrazů určených pro standardní a vysoké prostorové televizní rozlišení.Compressed images are used very frequently in interactive applications in digital video broadcasting. New methods increasing efficiency of the image transmission in digital video broadcasting networks are proposed. Adaptive spatial filtering methods have been proposed for enhancement of the visual perception of the compressed images. New optimalization method is based on application of the filtering algorithms on more compressed images (data size are reduced). Visual quality enhancement is processed in interactive application. Further, new compression methods JPEG2000 and H.264 for image compression have been analysed. Novel compound image compression method for standard and high spatial television resolution is proposed in the thesis.

Everything You Wanted to Know About MPEG-7: Part 1

Part I of this article provides an overview of the development, functionality, and applicability of MPEG-7. We ll first present the role of MPEG-7 within the context of past MPEG standards. We then outline ideas of what should be possible using MPEG-7 technology. In Part II, we ll discuss the description of MPEG-7 s concepts, terminology, and requirements. We ll then compare MPEG-7 to other approaches on multimedia content description

Multimedia player implementation on embedded systems

Thesis (Master)--Izmir Institute of Technology, Electronics and Communication Engineering, Izmir, 2008Includes bibliographical references (leaves: 85-88)Text in English; Abstract: Turkish and Englishxi, 90 leavesThere has been a surge in the number of digital audio and video content in recent years. Advances in the compression and storage technologies and improvements in the speed of internet connection have enabled widespread use of multimedia content. A wide variety of devices have been introduced to decode and play these media contents.Initially designed as a mere voice communication device, the mobile phones nowadays come equipped with a variety of multimedia capabilities including media players despite their limited system resources.Nowadays, huge servers host dramatically increased audio and video contents Users prefer to watch these contents while streaming rather than downloading them first. So, streaming media players are responsible to present multimedia contents without annoying interrupts.This thesis firstly introduces challenges in design and implementation of a streaming media player and then proposes solutions. Main challenges are keeping audio-video synchronization and server-client synchronization and detecting stream type, handling of multithreaded operations and buffer management. Audio-video synchronization problem is solved by using audio as master stream. Server-client synchronization problem is solved by designing a playback mechanism that keeps synchronization with the server by tuning the playback rate of a streaming media without losing lip-sync between audio and video. The proposed streaming player also has a feature of identifying the type of a media stream very rapidly without using a discrete stream inspector module. The presented design is heavily multithreaded which is implemented on Linux platform, moreover it is also convenient for and implementable on any multithreaded platform