Mobile phones, tablet computers, laptops, desktops, and large screen displays are increasingly available to individuals for information access, often simultaneously. Dominant content access protocols, such as HTTP/1.1, do not take advantage of this device multiplicity and support information access from single devices only. Changing devices means restarting an information session. Using devices in conjunction with each other poses several challenges, which include the presentation of content on devices with diverse form factors and propagation of the content changes across these devices. In this dissertation, I report on the design and implementation of MIDAS - architecture and a prototype system for multi-device presentations. I propose a framework, called 12C, for characterizing multi-device systems and evaluate MIDAS within this framework. MIDAS is designed as a middleware that can work with multiple client-server architectures, such as the Web and context-aware Trellis, a non-Web hypertext system. It presents information content simultaneously on devices with diverse characteristics without requiring sensor-enhanced environments. The system adapts content elements for optimal presentation on the target device while also striving to retain fidelity with the original form from a human perceptual perspective. MIDAS reconfigures its presentation in response to user actions, availability of devices, and environmental context, such as a user's location or the time of day. I conducted a pilot study that explored human perception of similarity when image attributes such as size and color depth are modified in the process of presenting images on different devices. The results indicated that users tend to prefer scaling of images to color-depth reduction but gray scaling of images is preferable to either modification. Not all images scale equally gracefully; those dominated by natural elements or manmade structures scale exceptionally well. Images that depict recognizable human faces or textual elements should be scaled only to an extent that these features retain their integrity. Attributes of the 12C framework describe aspects of multi-device systems that include infrastructure, presentation, interaction, interface, and security. Based on these criteria, MIDAS is a flexible infrastructure, which lends itself to several content distribution and interaction strategies by separating client- and server-side configuration.

The phenomenal growth in the use of the World Wide Web often places a heavy load on networks and servers, threatening to increase Web server response time and raising scalability issues for both the network and the server. With the advances in the field of optical networking and the increasing use of broadband technologies like cable modems and DSL, the server and not the network, is more likely to be the bottleneck. Many clients are willing to receive a degraded, less resource intensive version of the requested content as an alternative to connection failures. In this thesis, we present an adaptive content delivery system that transparently switches content depending on the load on the server in order to serve more clients. Our system is designed to work for dynamic Web pages and streaming multimedia traffic, which are not currently supported by other adaptive content approaches. We have designed a system which is capable of quantifying the load on the server and then performing the necessary adaptation. We designed a streaming MPEG server and client which can react to the server load by scaling the quality of frames transmitted. The main benefits of our approach include: transparent content switching for content adaptation, alleviating server load by a graceful degradation of server performance and no requirement of modification to existing server software, browsers or the HTTP protocol. We experimentally evaluate our adaptive server system and compare it with an unadaptive server. We find that adaptive content delivery can support as much as 25% more static requests, 15% more dynamic requests and twice as many multimedia requests as a non-adaptive server. Our, client-side experiments performed on the Internet show that the response time savings from our system are quite significant.

This thesis provides a novel architecture for the creation and management of virtual multimedia adaptation services offered by a multimedia-enabled cloud. The aim of the proposed scheme is to provide an optimal yet a transparent user access to adapted media contents while isolating them from the heterogeneity of the utilized devices, diversity of media formats, as well as the details of the adaptation services and performance variations of the underlying network. This goal is achieved through the development of service virtualization models that provide various levels of abstraction of the actual physical services and their performance parameters. Such virtual models offer adaptation functions by comprising adaptation services with accordance to their parameters. Additionally, parameters describing the functional specifics of the adaptation functions, as well as multimedia content features, are organized into a hierarchical structure that facilitates extraction of the virtual models capable of satisfying the conditions expressed by the user requests. At the same time the paramter/feature organization structure itself is flexible enough to allow users to specify media delivery requests at various levels of request details (e.g., summarize video vs. drop specific frames). As a result, in response to a user request for a multimedia content, an optimal virtual service adaptation path is calculated, describing the needed media adaptation operations as well as the appropriate mapping to the physical resources capable of executing such functions. The selection of the adaptation path is done with the use of a novel performance-history based selection mechanism that takes into account the performance variations and relations of the services in a dynamically changing environment of multimedia clouds. A number of experiments are conducted to demonstrate the potential of the proposed work in terms of the enhanced processing time and service quality.

This thesis provides a novel architecture for the creation and management of virtual multimedia adaptation services offered by a multimedia-enabled cloud. The aim of the proposed scheme is to provide an optimal yet a transparent user access to adapted media contents while isolating them from the heterogeneity of the utilized devices, diversity of media formats, as well as the details of the adaptation services and performance variations of the underlying network. This goal is achieved through the development of service virtualization models that provide various levels of abstraction of the actual physical services and their performance parameters. Such virtual models offer adaptation functions by comprising adaptation services with accordance to their parameters. Additionally, parameters describing the functional specifics of the adaptation functions, as well as multimedia content features, are organized into a hierarchical structure that facilitates extraction of the virtual models capable of satisfying the conditions expressed by the user requests. At the same time the paramter/feature organization structure itself is flexible enough to allow users to specify media delivery requests at various levels of request details (e.g., summarize video vs. drop specific frames). As a result, in response to a user request for a multimedia content, an optimal virtual service adaptation path is calculated, describing the needed media adaptation operations as well as the appropriate mapping to the physical resources capable of executing such functions. The selection of the adaptation path is done with the use of a novel performance-history based selection mechanism that takes into account the performance variations and relations of the services in a dynamically changing environment of multimedia clouds. A number of experiments are conducted to demonstrate the potential of the proposed work in terms of the enhanced processing time and service quality.

[pt] Serviços para disseminação de informações (serviços push) têm sido amplamente utilizados, em particular para aplicações envolvendo usuários móveis. Estes serviços geralmente atendem a dispositivos com recursos bem diferenciados e em contextos de execução (conectividade sem fio, reserva de energia, etc.) distintos, fazendo necessário adaptar o conteúdo difundido dinamica- e individualmente para cada cliente. Uma vez que muitas adaptações de conteúdo envolvem operações custosas e demandam alto poder de processamento, estas não devem ser realizadas nos clientes móveis. Por outro lado, executar no servidor, as adaptações para cada cliente móvel, torna- se pouco eficiente e escalável. Assim, em tais serviços, é comum utilizar-se intermediários dedicados às adaptações de conteúdo (de acordo com o contexto) dos clientes. Comunicação assíncrona, como publish/subscribe, é considerada por muitos como a mais apropriada para este tipo de serviço. Por outro lado, sistemas para adaptação de conteúdo sensível a contexto não dão suporte a este tipo de comunicação, até porque a adaptação precisa ser individual, e portanto conflita com o paradigma de comunicação um-para-muitos. Neste trabalho apresentamos uma arquitetura para sistemas publish/subscribe com adaptação sensível a contexto, que utiliza um algoritmo que otimiza a adaptação de conteúdo para grandes conjuntos de clientes de uma difusão. / [en] Services for information dissemination (push services) are being widely used, in particular for applications involving mobile users. These services generally serve devices with diferent resources and with distinct execution contexts (wireless connectivity, energy source, etc.), making it necessary to adapt disseminated content individual and dynamically for each client. Since many content adaptations involve costly operations and demand high processing power, these should not be executed at the mobile clients. On the other hand, it is neither efficient nor scalable to execute the adaptations for each mobile client at the server. Thus, in such services, it is common to use proxies dedicated to content adaptations (based on the context) of clients. Asynchronous communication, such as publish/- subscribe, is considered the most appropriate form of communication for this type of service. On the other hand, systems for context-aware content adaptation do not support this type of communication. In this thesis we present an architecture for publish/subscribe systems with context-aware content adaptation, that uses an algorithm that optimizes the content adaptation for large sets of clients.

This thesis provides a novel architecture for the creation and management of virtual multimedia adaptation services offered by a multimedia-enabled cloud. The aim of the proposed scheme is to provide an optimal yet a transparent user access to adapted media contents while isolating them from the heterogeneity of the utilized devices, diversity of media formats, as well as the details of the adaptation services and performance variations of the underlying network. This goal is achieved through the development of service virtualization models that provide various levels of abstraction of the actual physical services and their performance parameters. Such virtual models offer adaptation functions by comprising adaptation services with accordance to their parameters. Additionally, parameters describing the functional specifics of the adaptation functions, as well as multimedia content features, are organized into a hierarchical structure that facilitates extraction of the virtual models capable of satisfying the conditions expressed by the user requests. At the same time the paramter/feature organization structure itself is flexible enough to allow users to specify media delivery requests at various levels of request details (e.g., summarize video vs. drop specific frames). As a result, in response to a user request for a multimedia content, an optimal virtual service adaptation path is calculated, describing the needed media adaptation operations as well as the appropriate mapping to the physical resources capable of executing such functions. The selection of the adaptation path is done with the use of a novel performance-history based selection mechanism that takes into account the performance variations and relations of the services in a dynamically changing environment of multimedia clouds. A number of experiments are conducted to demonstrate the potential of the proposed work in terms of the enhanced processing time and service quality.

O trabalho apresentado nesta tese trata do desenvolvimento de técnicas com suporte à ciência de contexto, baseadas nos padrões MPEG-4 e MPEG-7, para personalizar e adaptar conteúdo em TV Interativa. Um dos desafios dessa área é desenvolvimento de programas personalizados com rico conteúdo multimídia, com alta interatividade e que, além disso, sejam acessíveis a partir de uma variedade de dispositivos (fixos ou móveis), atendendo às expectativas de interação e de acesso dos usuários. Grande parte do problema está no fato de que os modos encontrados na literatura para representar, descrever e compor programas de TV Interativa não oferecem suporte a contexto, não permitem a separação entre descrições de programas e descrições de objetos e possuem baixa granulosidade de segmentação. Essas características dificultam e, em alguns casos, impedem o desenvolvimento de aplicações avançadas em TV Interativa. As técnicas desenvolvidas neste trabalho são baseadas em esquemas de descrição, compatíveis com o padrão MPEG-7, e na segmentação de programas em objetos MPEG-4. Os esquemas são utilizados para descrever a estrutura, a composição e a semântica de programas e de seus objetos componentes. Também foi definida e implantada uma infra-estrutura para produção, distribuição e consumo de programas. A utilização conjunta da infra-estrutura e das técnicas permite o desenvolvimento de aplicações avançadas em TV Interativa. Como um exemplo dessas aplicações, foi desenvolvido um serviço automático para personalizar e adaptar programas de TV Interativa, permitindo que um usuário possa acessar, sob demanda, programas especialmente produzidos para ele, contendo apenas assuntos de seu interesse e permitindo que o acesso possa ser realizado por dispositivos fixos ou móveis. / The work presented in this thesis developed techniques with context-awareness support, based on the MPEG-4 and MPEG-7 standards, in order to personalize and to adapt Interactive TV content. One of the challenges in this area is the development of personalized programs with rich multimedia content, high interactivity and accessibility through a variety of devices (mobile and non-mobile). Most part of the problem is that the approaches found in literature do not provide context support, do not allow separation between programs and objects descriptions and have low level of segmentation granularity. These features make difficult or impossible, in some cases, the development of Interactive TV applications. The techniques developed in this work are based on MPEG-7 compliant schemes and on programs segmentation into MPEG-4 objects. The schemes are used to describe structure, composition and semantics of programs and component objects. An infra-structure to creation, delivery and consumption of Interactive TV programs was also defined. The joint utilization of infra-structure and techniques allows for the development of Interactive TV advanced applications. As an example of these applications, this work developed an automatic Interactive TV personalization and adaptation service. This service allows a user to access, on-demand, a program specially designed to match his interests and allowing content access through devices with mobile and non-mobile features.

O trabalho apresentado nesta tese trata do desenvolvimento de técnicas com suporte à ciência de contexto, baseadas nos padrões MPEG-4 e MPEG-7, para personalizar e adaptar conteúdo em TV Interativa. Um dos desafios dessa área é desenvolvimento de programas personalizados com rico conteúdo multimídia, com alta interatividade e que, além disso, sejam acessíveis a partir de uma variedade de dispositivos (fixos ou móveis), atendendo às expectativas de interação e de acesso dos usuários. Grande parte do problema está no fato de que os modos encontrados na literatura para representar, descrever e compor programas de TV Interativa não oferecem suporte a contexto, não permitem a separação entre descrições de programas e descrições de objetos e possuem baixa granulosidade de segmentação. Essas características dificultam e, em alguns casos, impedem o desenvolvimento de aplicações avançadas em TV Interativa. As técnicas desenvolvidas neste trabalho são baseadas em esquemas de descrição, compatíveis com o padrão MPEG-7, e na segmentação de programas em objetos MPEG-4. Os esquemas são utilizados para descrever a estrutura, a composição e a semântica de programas e de seus objetos componentes. Também foi definida e implantada uma infra-estrutura para produção, distribuição e consumo de programas. A utilização conjunta da infra-estrutura e das técnicas permite o desenvolvimento de aplicações avançadas em TV Interativa. Como um exemplo dessas aplicações, foi desenvolvido um serviço automático para personalizar e adaptar programas de TV Interativa, permitindo que um usuário possa acessar, sob demanda, programas especialmente produzidos para ele, contendo apenas assuntos de seu interesse e permitindo que o acesso possa ser realizado por dispositivos fixos ou móveis. / The work presented in this thesis developed techniques with context-awareness support, based on the MPEG-4 and MPEG-7 standards, in order to personalize and to adapt Interactive TV content. One of the challenges in this area is the development of personalized programs with rich multimedia content, high interactivity and accessibility through a variety of devices (mobile and non-mobile). Most part of the problem is that the approaches found in literature do not provide context support, do not allow separation between programs and objects descriptions and have low level of segmentation granularity. These features make difficult or impossible, in some cases, the development of Interactive TV applications. The techniques developed in this work are based on MPEG-7 compliant schemes and on programs segmentation into MPEG-4 objects. The schemes are used to describe structure, composition and semantics of programs and component objects. An infra-structure to creation, delivery and consumption of Interactive TV programs was also defined. The joint utilization of infra-structure and techniques allows for the development of Interactive TV advanced applications. As an example of these applications, this work developed an automatic Interactive TV personalization and adaptation service. This service allows a user to access, on-demand, a program specially designed to match his interests and allowing content access through devices with mobile and non-mobile features.

A popularização de aplicativos e dispositivos capazes de produzir, exibir e editar conteúdos multimídia fez surgir a necessidade de se adaptar, modificar e customizar diferentes tipos de mídia a diferentes necessidades do usuário. Nesse contexto, a área de Personalização e Adaptação de Conteúdo busca desenvolver soluções que atendam a tais necessidades. Sistemas de personalização, em geral, necessitam conhecer os dados presentes na mídia, surgindo, assim, a necessidade de uma indexação do conteúdo presente na mídia. No caso de vídeo digital, os esforços para a indexação automática utilizam como passo inicial a segmentação de vídeos em unidades de informação menores, como tomadas e cenas. A segmentação em cenas, em especial, é um desafio para pesquisadores graças a enorme variedade entre os vídeos e a própria ausência de um consenso na definição de cena. Diversas técnicas diferentes para a segmentação em cenas são reportadas na literatura. Uma técnica, em particular, destaca-se pelo baixo custo computacional: a técnica baseada em coerências visual. Utilizando-se operações de histogramas, a técnica objetiva-se a comparar tomadas adjacentes em busca de similaridades que poderiam indicar a presença de uma cena. Para melhorar os resultados obtidos, autores de trabalhos com tal enfoque utilizam-se de outras características, capazes de medir a \"quantidade de movimento\" das cenas, como os vetores de movimento. Assim, este trabalho apresenta uma técnica de segmentação de vídeo digital em tomadas e em cenas através da coerência visual e do fluxo óptico. Apresenta-se, ainda, uma série de avaliações de eficácia e de desempenho da técnica ao segmentar em tomadas e em cenas uma base de vídeo do domínio filmes / The popularization of applications and devices capable of producing, displaying and editing multimedia content did increase the need to adapt, modify and customize different types of media for different user needs. In this context, the area of Personalization and Content Adaptation seeks to develop solutions that meet these needs. Personalization systems, in general, need to know the data present in the media, thus needing for a media indexing process. In the case of digital video, the efforts for automatic indexing usually involves, as an initial step, to segment videos into smaller information units, such as shots and scenes. The scene segmentation, in particular, is a challenge to researchers due to the huge variety among the videos and the very absence of a consensus on the scene definition. Several scenes segmentation techniques are reported in the literature. One technique in particular stands out for its low computational cost: those techniques based on visual coherence. By using histograms, the technique compares adjacent shots to find similar shots which may indicate the presence of a scene. To improve the results, some related works uses other features to evaluate the motion dynamics of the scenes using features such as motion vectors. In this sense, this work presents a digital video segmentation technique for shots and scenes, using visual coherence and optical flow as its features. It also presents a series of evaluation in terms of effectiveness and performance of the technique when segmenting scenes and shots of a custom video database of the film domain

Made available in DSpace on 2016-06-02T19:05:22Z (GMT). No. of bitstreams: 1 DissMF.pdf: 2025508 bytes, checksum: f2e422deb152e992fd87b135fec6cd65 (MD5) Previous issue date: 2006-08-21 / The last decade was scenery of big transformations, among them the social revolution caused by Internet stand out, changing the way that people find information, communicate and buy products and services. Moreover, the convergence of telephony, informatics and consume electronic, supplies more and more mobile devices equipped with Internet access through wireless network. This changing caused a big problem to the Internet content available at Web: how the same content should be adjusted to different kinds of users witch have particular preferences, and be presented in mobile devices featured with a big diversity of functionalities? To solve this problem, many research proposals are been developed at content adaptation area. One challenge of this area is define, from a user request, witch adaptation services are necessary and these execute sequence. In order to have the best decision, delivery context and the available services have to be acknowledged. This information are described at profiles and rules, considering that nowadays the majority of proposed solutions are based in proprietary models and not compatibles among each other. As well, the discovery of services generally is strongly based on syntactic matching, what weak the discovery and composition of services. Intending to contribute with content adaptation area, this dissertation defines an ontology-based set of profiles and reused. Furthermore, shows how the rules have to be integrated with services profiles, providing a rules and profiles independent solution. Also are presented the benefits use of semantics at match and composition of services in an open environment such as the Web. The implementation and the case study of this proposition were based at a component-based content adaptation framework. With the purpose of extend its functionality, in order to support ontology, and others necessary functions, components were reused, adapted or created. This extensions made possible achieve the case study and the validation of proposed solution. / Esta última década foi cenário de grandes transformações, dentre estas destaca-se a revolução social que a Internet está promovendo, alterando a forma como as pessoas encontram informações, comunicam-se e compram produtos e serviços. Além disso, a convergência da telefonia, computação e eletrônica de consumo, está disponibilizando cada vez mais dispositivos móveis de acesso a Internet que se comunicam via redes sem fio. Essas mudanças causaram um grande problema para o conteúdo disponível na Web: como um mesmo conteúdo pode se adequar a diferentes tipos de usuário, que possuem suas próprias preferências, e ser apresentado em dispositivos móveis compostos por uma grande diversidade de características funcionais? Para resolver este problema, muitas pesquisas estão sendo realizadas no campo da adaptação de conteúdo. Um dos desafios nesse campo é definir, a partir de uma requisição do usuário, quais serviços de adaptação serão necessários e em que ordem estes serão executados. Para que essa decisão seja tomada corretamente são necessárias informações sobre o contexto de entrega e os serviços de adaptação disponíveis. Essas informações são descritas por meio de perfis e regras, sendo que no momento a maioria das soluções propostas se baseia em modelos proprietários e incompatíveis entre si. Além disso, a descoberta de serviços geralmente é amplamente baseada em comparações sintáticas, o que compromete a descoberta e composição de serviços. Com o objetivo de contribuir para a área de adaptação de conteúdo, esta dissertação define um conjunto de perfis e regras baseado em ontologias. Além disso, demonstra como as regras devem ser integradas aos perfis de serviços, proporcionando uma solução que seja independente de novos tipos de serviços e regras. Também são apresentados os benefícios que a descoberta e composição de serviços obtêm com o uso de semântica em um ambiente aberto como a Web. A implementação e o estudo de caso dessas propostas foi baseado num framework para adaptação de conteúdo baseado em componentes. Para estender a sua funcionalidade com o propósito de suportar ontologias, e outras funções necessárias, componentes foram reusados, adaptados e criados. Essa extensão viabilizou a realização do estudo de caso e a validar a solução proposta.