O trabalho apresentado nesta dissertação trata do desenvolvimento de um mecanismo para adaptação automática de ví?deo MPEG-4 ao vivo, de modo a atender as necessidades ou capacidades atuais de usuários e do sistema. Um dos desafios dessa área é capturar e representar as informações necessárias para realizar a adaptação. Assim, utilizando técnicas da área de computação ciente de contexto, foi desenvolvido um modelo extensível para representação de dispositivos. Também foram desenvolvidos métodos automáticos e semi-automáticos para capturar as informações necessárias. Neste trabalho foi adotado o modelo de recodificação de vídeo, o qual pode gerar atrasos que inviabilizam a adaptação de vídeo ao vivo em aplicações interativas. Assim, este trabalho realizou uma avaliação do impacto causado pela recodificação no atraso total, fim-a-fim, percebido pelo usuário. / This work presents the development of a mechanism to automatically adapt MPEG-4 live video, in a way to response the actual necessities or capacities of users or systems. One of the challanges in this area is to capture and represent the information needed to adapting content. Thus, using context aware computing techniques, an extensible model has been developed, which can be used to represent devices. It has also been developed automatic and semi-automatic methods to capture the needed information. In this work, the transcoding model has been adopted, which may generate latency, making difficult to use transcoding with interactive applications. In this way, this work has evaluated the impact caused by the transcoding when compared to the end-to-end total delay perceived by the user.

Aujourd'hui, de nombreux appareils sont capables de capturer des vidéos en Full HD et d'utiliser une connexion réseau pour accéder à Internet. La popularisation des dispositifs et les efforts continus pour améliorer la qualité du réseau ont apporté un environnement propice à l'essor de la diffusion en direct. De par la grande quantité de contenu généré par les utilisateurs, la diffusion de flux en direct présente de nouveaux défis. Dans cette thèse, nous nous intéressons à la distribution et au transcodage des systèmes de diffusion en direct. Pour étudier les différent aspects des systèmes de diffusion en direct nous avons besoin de les caractériser et d'évaluer les solutions proposées avec des traces pertinentes. Par conséquent, notre première contribution est un ensemble de données et son analyse, contenant trois mois de traces de deux services de streaming en direct. Ensuite, nous avons exploré et développé des solutions pour la distribution du contenu produit par ces platesformes. L'un des défis est l'hétérogénéité de popularité des flux. Ceci implique généralement un surdimensionnement des services et par conséquent un gaspillage de ressources. Enfin, nous nous sommes focalisés sur les difficultés posées par le transcodage des flux en direct. Les opérations de transcodage sont coûteuses en ressources CPU et sont des étapes clés pour le Streaming à Débit Adaptatif (SDA). Nous montrons que le SDA est capable de réduire le coût en bande passante pour la distribution et d'augmenter la qualité d'expérience des téléspectateurs en échange d'un coût en ressources CPU. Pour comprendre le compromis entre les avantages et les coûts, nous formulons deux problèmes de gestion. / Today many devices are capable to capture full HD videos and to use its network connection to access Internet. The popularization of devices and continuous efforts to increase network quality has brought a proper environment for the rise of live streaming. Associated to the large scale of Users Generated Content (UGC), live streaming presents new challenges. In this thesis we target the delivery and transcoding of live streaming systems.First, to study the aspects we target of live streaming systems we need to characterize them and evaluate the proposed solutions with relevant traces. Therefore our first contribution is a data set, and its analysis, containing three months traces of two UGC live streaming services.Second, we explored and developed solutions for the delivery of the content produced by these platforms. One of the challenges is the heterogeneity among streams popularity, which generally implies over-provisioning and consequently resource waste. We show that there is a trade-off between the number of servers involved to broadcast the streams and the bandwidth usage among the servers. We also stress the importance to predict streams popularity in order to efficiently place them on the servers.Lastly, we target the difficulties concerning transcoding of live streams. The transcoding operations over streams are computing consuming and are key operations on adaptive bit rate streaming. We show that adaptive streaming is able to reduce the delivery bandwidth cost and to increase viewer quality of experience at the cost of computing resources. We formulate two management problems to address the trade-off between benefits and costs.

Next-generation network architectures support complex services in the data-path of routers. A key challenge is the integration of multiple policy constraints from senders, receivers, and network providers when using such services. We introduce a multi-party service specification framework based on our “service socket” API. We illustrate the operation of this approach in an IPTV scenario that uses a video transcoding service implemented on a Cisco ISR platform.

The evolution of computer communications and the Internet has led to the emergence of a large number of communication technologies with widely different capabilities and characteristics. While this multitude of technologies provides a wide array of possibilities it also creates a complex and heterogeneous environment for higher-layer communication protocols. Specific link technologies, as well as overall network heterogeneity, can hamper user-perceived performance or impede end-to-end throughput. In this thesis we examine two transport layer centered approaches to improve performance. The first approach addresses the decrease in user satisfaction that occurs when web waiting times become too long. Increased transport layer flexibility with regards to reliability, together with error-resilient image coding, is used to enable a new trade-off. The user is given the possibility to reduce waiting times, at the expense of image fidelity. An experimental examination of this new functionality is provided, with a focus on image-coding aspects. The results show that reduced waiting times can be achieved, and user studies indicate the usefulness of this new trade-off. The second approach concerns the throughput degradations that can occur as a consequence of link and transport layer interactions. An experimental evaluation of the GSM environment shows that when negative interactions do occur, they are coupled to large variability in link layer round-trip times rather than simply to poor radio conditions. Another type of interaction can occur for link layers which expose higher layers to residual bit errors. Residual bit errors create an ambiguity problem for congestion controlled transport layer protocols which cannot correctly determine the cause for a loss. This ambiguity leads to an unnecessary throughput degradation. To mitigate this degradation, loss differentiation and notification mechanisms are proposed and experimentally evaluated from both performance and fairness perspectives. The results show that considerable performance improvements can be realized. However, there are also fairness implications that need to be taken into account since the same mechanisms that improve performance may also lead to unfairness towards flows that do not employ loss differentiation.

<p>Browsing the Web on a distant screen may very often become user’s unpleasant experience. Such a situation may happen in a living room environment, where the user attempts to browse the Web on TV sitting at 10-foot distance from the screen. In a vast number of web sites that the user is able to request, many may contain, for instance, tiny text characters, which would become unreadable when watched from the distance. On the other hand, also navigation through the Web offerings can become troublesome. Especially, when the user is only equipped with the commonly used remote controller, interaction with the displayed content may prove inefficient. Therefore, methods to overcome content visibility and navigation problems become challenging. In this thesis we perceive living room environment as a good scenario, in which web-enabled handheld devices could further be utilized to interact with Consumer Electronics products, such as TVs. This sort of interaction should make an advantage of publically available Web resources to have them displayed on TV and controlled from the distance by the user who is equipped with, for instance, a web-enabled mobile phone. We think that such an interaction approach would become beneficial in several ways, making the Web browsing routine an interactive, possibly a group activity. Discussed in this thesis solutions are the first step of automatic transformations of web content into a form that can be rendered on Web4CE (Web for Consumer Electronics) products. A particularly important aspect of the proposed system is the concept of request/response HTTP message processing and HTML modification. According to this approach, living room browsing activity should be achievable without the need to re-author already existing web sites.</p>

The environment of knowledge exchange between computation and biology elicits a contemporary approach towards architecture. Computation, as an overarching mode of thinking, instructs the analysis, understanding and reinterpretation of the un-formal structure of natural organizations (such as systematic construct, information flow, and process through time) for architectural form generation. Consequently, the computing theory originates a mind-shift where processes, relations, and dependencies are a major concern for reconsidering and re-comprehending the environment. Besides, computation presents universal modes of thinking and tools for modeling, within which transdisciplinary studies and knowledge interchange between distinct disciplines are flourished. This thesis will discuss architectural form generation through interpreting computation as &ldquo / transcoding&rdquo / and an interface, while nature will be regarded as a &ldquo / model&rdquo / and a source for learning. A case study will be conducted by analyzing cactus plants and their common generative logic in the framework of computation. Consequently, the produced computational model of cactus plants will be scrutinized for probable outcomes, questioning what such a re-interpretation of natural systems may imply for architecture.

DIAS, Sandra Maria Soeiro. Registros numéricos de crianças do 2º ano do ensino fundamental: diversidade e relações. 2015. 151f. – Dissertação (Mestrado) – Universidade Federal do Ceará, Programa de Pós-graduação em Educação Brasileira, Fortaleza (CE), 2015. / Submitted by Márcia Araújo (marcia_m_bezerra@yahoo.com.br) on 2016-04-07T15:05:44Z No. of bitstreams: 1 2015_dis_smsdias.pdf: 8080108 bytes, checksum: a4d30ab0872a57c55d96d512f913389e (MD5) / Approved for entry into archive by Márcia Araújo(marcia_m_bezerra@yahoo.com.br) on 2016-04-08T14:44:54Z (GMT) No. of bitstreams: 1 2015_dis_smsdias.pdf: 8080108 bytes, checksum: a4d30ab0872a57c55d96d512f913389e (MD5) / Made available in DSpace on 2016-04-08T14:44:54Z (GMT). No. of bitstreams: 1 2015_dis_smsdias.pdf: 8080108 bytes, checksum: a4d30ab0872a57c55d96d512f913389e (MD5) Previous issue date: 2015 / The Decimal Numbering System – DNS is an essential mathematical knowledge at the beginning of Basic Education, which student requires the ability to read and write numerals using various types of records – pictorial, with objects, with digits, with letters – as explained by theory of Semiotics Representation Registers. It must be noted also the importance of oral communication – listening and speaking – in all subject learning processes. This research, qualitative, held in a public school in the municipality of Caucaia, aimed to: i) identify the relationship between the diversity of numerical records of children in the 2nd year of elementary school; ii) know the students representative records of the 2nd year of elementary school writing numbers with 2, 3 and 4 orders; and iii) interpret the students with knowledge of numerical records 2, 3 and 4 orders. Two instruments were applied: the Instrument 1 had numerals 2 and 3 orders and the Instrument 2 had numerals with four orders. The participants were 14 students of 2nd year of elementary school, who had their knowledge analyzed by different types, listed by Barguil (2015), and in the light of the theory of Numerical Transcoding (OROZCO, 2005), which classifies errors as syntactic or lexicon. The questions were about the comparison of numerals and the record numbers, with digits and letters, noting the relationship of this with orality. Data analysis was organized in two stages: i) performance of students in each issue; and ii) the overall performance of each student in all matters. The results revealed a significant amount of syntactical errors, which are referred to in verbal expression, as well as indicate the orality as the main starting point for the correct construction of these records, which indicate the need to expand the use of records of diversity for learning DNS. / O Sistema de Numeração Decimal – SND é um conhecimento matemático essencial no início da Educação Básica, o qual requer do estudante a habilidade de ler e escrever numerais utilizando variados tipos de registros – pictórico, com objetos, com algarismos, com letras – conforme explica a Teoria dos Registros de Representação Semiótica. Há de se destacar, ainda, a importância da oralidade – escuta e fala – em todos os processos de aprendizagem do sujeito. Esta pesquisa, de natureza qualitativa, realizada em uma escola pública do município de Caucaia, objetivou: i) identificar a relação entre a diversidade de registros numéricos de crianças do 2º ano do Ensino Fundamental; ii) conhecer os registros de representação de estudantes do 2º ano do Ensino Fundamental na escrita de números com 2, 3 e 4 ordens; e iii) interpretar os conhecimentos discentes com registros numéricos de 2, 3 e 4 ordens. Foram aplicados dois instrumentos: o Instrumento 1 tinha numerais com 2 e 3 ordens e o Instrumento 2 tinha numerais com 4 ordens. Participaram da pesquisa 14 estudantes do 2º ano do Ensino Fundamental, que tiveram seus conhecimentos analisados mediante diferentes tipologias, elencadas por Barguil (2015), e à luz da teoria da Transcodificação Numérica (OROZCO, 2005), que classifica os erros como sintático ou léxico. As questões versavam sobre a comparação de numerais e o registro numérico, com algarismos e letras, observando a relação desse com a oralidade. A análise dos dados foi organizada em duas etapas: i) desempenho dos estudantes em cada questão; e ii) desempenho global de cada estudante em todas as questões. Os resultados revelaram uma expressiva quantidade de erros sintáticos, que se referenciam na expressão verbal, bem como indicam a oralidade como o principal ponto de partida para a construção correta destes registros, sinalizando a necessidade de ampliar o uso de diversidades de registros para a aprendizagem do SND.

Browsing the Web on a distant screen may very often become user’s unpleasant experience. Such a situation may happen in a living room environment, where the user attempts to browse the Web on TV sitting at 10-foot distance from the screen. In a vast number of web sites that the user is able to request, many may contain, for instance, tiny text characters, which would become unreadable when watched from the distance. On the other hand, also navigation through the Web offerings can become troublesome. Especially, when the user is only equipped with the commonly used remote controller, interaction with the displayed content may prove inefficient. Therefore, methods to overcome content visibility and navigation problems become challenging. In this thesis we perceive living room environment as a good scenario, in which web-enabled handheld devices could further be utilized to interact with Consumer Electronics products, such as TVs. This sort of interaction should make an advantage of publically available Web resources to have them displayed on TV and controlled from the distance by the user who is equipped with, for instance, a web-enabled mobile phone. We think that such an interaction approach would become beneficial in several ways, making the Web browsing routine an interactive, possibly a group activity. Discussed in this thesis solutions are the first step of automatic transformations of web content into a form that can be rendered on Web4CE (Web for Consumer Electronics) products. A particularly important aspect of the proposed system is the concept of request/response HTTP message processing and HTML modification. According to this approach, living room browsing activity should be achievable without the need to re-author already existing web sites.

Video transcoding is the process of converting compressed video signals to adapt video characteristics such as video bit rate, video resolution, or video codec, so as to meet the specifications of communication channels and endpoint devices. A straightforward transcoding solution is to fully decode and encode the video. However this method is computationally expensive and thus unsuitable in applications with tight resource constraints such as in software-based real-time environment. Therefore, efficient transcoding meth- ods are required to reduce the transcoding complexity while preserving video quality. Prior transcoding methods are suitable for video coding standards such as H.264/AVC and MPEG-2. H.265/HEVC has introduced new coding concepts, e.g., the quad-tree-based block structure, that are fundamentally different from those in prior standards. These concepts require existing transcoding methods to be adapted and novel solutions to be developed. This work primarily addressed the issue of efficient HEVC transcoding for bit rate adaptation (reduction). The goal is to understand the transcoding behaviour for some straightforward transcoding strategies, and to subsequently optimize the complexity/quality trade-off by providing heuristics to reduce the number of coding options to evaluate. A transcoder prototype is developed based on the HEVC reference software HM-8.2. The proposed transcoder reduces the transcoding time compared to full decoding and encoding by at least 80% while inducing a coding performance drop within a margin for 5%. The thesis has been carried out in collaboration with Ericsson Research in Stockholm / Video content is produced daily through variety of electronic devices, however, storing and transmitting video signals in raw format is impractical due to its excessive resource requirement. Today popular video coding standards such as MPEG-4 and H.264 are used to compress the video signals before storing and transmitting. Accordingly, efficient video coding plays an important role in video communications. While video applications become wide-spread, there is a need for high compression and low complexity video coding algorithms that preserve image quality. Standard organizations ISO, ITO, VCEG of ITU-T, and collaboration of many companies have developed video coding standards in the past to meet video coding requirements of the day. The Advanced Video Coding (AVC/H.264) standard is the most widely used video coding method. AVC is commonly known to be one of the major standards used in Blue Ray devices for video compression. It is also widely used by video streaming services, TV broadcasting, and video conferencing applications. Currently the most important development in this area is the introduction of H.265/HEVC standard which has been finalized in January 2013. The aim of standardization is to produce video compression specification that is capable of compression twice as effective as H.264/AVC standard in terms of coding complexity and quality. There is a wide range of platforms that receive digital video. TVs, personal computers, mobile phones, and tablets each have different computational, display, and connectivity capabilities, thus video has to be converted to meet the specifications of target platform. This conversion is achieved through video transcoding. For transcoding, straightforward solution is to decode the compressed video signal and re-encode it to the target compression format, but this process is computationally complex. Particularly in real-time applications, there is a need to exploit the information that is already available through the compressed video bit-stream to speed-up the conversion. The objective of this thesis is to investigate efficient transcoding methods for HEVC. Using decode/re-encode as the performance reference, methods for advanced transcoding will be investigated. / 0760609667 Bäckgårdsvägen 49, 14341 Stockholm

L'apparition de nouvelles technologies comme l'informatique en nuages (cloud computing) offre de nouvelles opportunités de traitement de l'information. Par exemple, il est désormais facile de stocker ses photos ou vidéos personnelles sur des serveurs distants. Il est également possible de partager ces contenus à travers ces mêmes serveurs, ou encore via les réseaux sociaux ou les plateformes de téléchargement. Cependant, ces données personnelles sont bien souvent accessibles par le fournisseur de service, essentiellement pour des raisons pratiques : par exemple adapter une vidéo pour qu'elle s'affiche au bon format quel que soit l'appareil utilisé pour la visionner, permettre le partage de ses contenus avec d’autres personnes, etc. Cela soulève cependant un problème de confidentialité de ces données personnelles, et de confiance dans le fournisseur du service. La cryptographie classique apporte des solutions à ce problème, mais soulève malheureusement celui de la maniabilité des données : il devient par exemple impossible d'adapter un contenu vidéo au bon format d'affichage puisque le fournisseur ne peut plus « voir » la vidéo. Une solution alternative réside toutefois dans le chiffrement homomorphe. Cet outil un peu magique de la cryptographie avancée apporte la même sécurité que les algorithmes de cryptographie classique, mais permet de plus de manipuler les données tout en conservant leur forme chiffrée. Il offre ainsi une nouvelle perspective pour les fournisseurs puisque ceux-ci peuvent continuer à traiter l'information sans être capable de la voir, et donc sans atteinte à la vie privée de leurs utilisateurs, se conformant ainsi au nouveau Règlement Général sur la Protection des Données (RGPD). Bien que le chiffrement homomorphe soit très souvent considéré comme insuffisamment mature, du fait de sa complexité algorithmique, cette thèse cherche à montrer son caractère prometteur, en s'intéressant à son usage pour le traitement d'images et de vidéos chiffrées à la source. Nous regardons ainsi les différents algorithmes qui constituent un encodeur d'image/vidéo (JPEG/H264 et HEVC) et les transformons en des circuits qui sont manipulables par des systèmes de chiffrement homomorphes. Nous proposons ainsi dans cette thèse le tout premier pipeline de compression d'images de type JPEG ("homomorphic-JPEG") sur des pixels qui sont chiffrés de bout-en-bout. Pour optimiser la gestion des données ainsi protégées, nous proposons également de nouveaux outils applicables à tous les schémas de chiffrement homomorphe sur les réseaux idéaux. Notre approche permet de maximiser le nombre de slots dans un chiffré et introduit de nouvelles fonctions pour manipuler ces différents slots de manière indépendante les uns des autres. Ces travaux de thèse ont abouti à la publication de deux articles dans des conférences internationales ainsi qu’à la soumission d'un article supplémentaire. / The emergence of new technologies like cloud computing brings new opportunities in information processing. For example it is easy today to send our personal pictures or videos to a remote server (Google Drive, OneDrive …). We can also share this content among the same servers or via social networks and streaming services. However, this personal data is often also available to the service provider, mainly for practical reasons e.g. to configure a video to have the right format regardless of the displayer (smartphone or computer), to share our data with other people, etc. This raises issues of privacy and trust into the service provider. Classical cryptography brings some answers to this kind of issues, yet leaving the problem of handling the encrypted data: e.g., it becomes impossible to reconfigure a video because the provider can no longer “see” it. An alternative solution is “homomorphic encryption”. It is a powerful tool of advanced cryptography which provides the same security as classical cryptography algorithms, but it still allows us to manipulate ciphertexts such their underlying plaintexts are modified. Consequently, it offers a new perspective to service providers since they can continue to process their clients’information without knowing what it contains. This allows them to provide privacy-preserving services and comply with the new General Data Protection Regulation (GDPR). Although it is considered that homomorphic encryption does not have enough maturity due to its large algorithmic complexity, in this thesis, we are trying to show its potential by using it in the context of image and video processing over the encrypted data. In this context, we look at the different algorithms in an image/video encoder (JPEG/H264 and HEVC) and transform them to circuits which can be manipulated by homomorphic encryption schemes. Our main contribution is to propose the first pipeline for an image compression of type JPEG (homomorphic-JPEG) running on end-to-end encrypted pixels. To optimize the management of the encrypted data, we also propose new tools applicable to existing homomorphic encryption schemes over the ring version of lattices. Our approach allows us to maximize the number of slots in some ciphertext and we introduce new functions allowing to handle these slots independently in the encrypted domain. This thesis work also lead to two publications to international conferences as well as the submission of an additional article.