Ubiquitous Scalable Graphics: An End-to-End Framework using Wavelets

Advances in ubiquitous displays and wireless communications have fueled the emergence of exciting mobile graphics applications including 3D virtual product catalogs, 3D maps, security monitoring systems and mobile games. Current trends that use cameras to capture geometry, material reflectance and other graphics elements means that very high resolution inputs is accessible to render extremely photorealistic scenes. However, captured graphics content can be many gigabytes in size, and must be simplified before they can be used on small mobile devices, which have limited resources, such as memory, screen size and battery energy. Scaling and converting graphics content to a suitable rendering format involves running several software tools, and selecting the best resolution for target mobile device is often done by trial and error, which all takes time. Wireless errors can also affect transmitted content and aggressive compression is needed for low-bandwidth wireless networks. Most rendering algorithms are currently optimized for visual realism and speed, but are not resource or energy efficient on mobile device. This dissertation focuses on the improvement of rendering performance by reducing the impacts of these problems with UbiWave, an end-to-end Framework to enable real time mobile access to high resolution graphics using wavelets. The framework tackles the issues including simplification, transmission, and resource efficient rendering of graphics content on mobile device based on wavelets by utilizing 1) a Perceptual Error Metric (PoI) for automatically computing the best resolution of graphics content for a given mobile display to eliminate guesswork and save resources, 2) Unequal Error Protection (UEP) to improve the resilience to wireless errors, 3) an Energy-efficient Adaptive Real-time Rendering (EARR) heuristic to balance energy consumption, rendering speed and image quality and 4) an Energy-efficient Streaming Technique. The results facilitate a new class of mobile graphics application which can gracefully adapt the lowest acceptable rendering resolution to the wireless network conditions and the availability of resources and battery energy on mobile device adaptively

Adaptive network abstraction layer packetization for low bit rate H.264/AVC video transmission over wireless mobile networks under cross layer optimization

Master'sMASTER OF ENGINEERIN

Error resilience and concealment techniques for high-efficiency video coding

This thesis investigates the problem of robust coding and error concealment in High Efficiency Video Coding (HEVC). After a review of the current state of the art, a simulation study about error robustness, revealed that the HEVC has weak protection against network losses with significant impact on video quality degradation. Based on this evidence, the first contribution of this work is a new method to reduce the temporal dependencies between motion vectors, by improving the decoded video quality without compromising the compression efficiency. The second contribution of this thesis is a two-stage approach for reducing the mismatch of temporal predictions in case of video streams received with errors or lost data. At the encoding stage, the reference pictures are dynamically distributed based on a constrained Lagrangian rate-distortion optimization to reduce the number of predictions from a single reference. At the streaming stage, a prioritization algorithm, based on spatial dependencies, selects a reduced set of motion vectors to be transmitted, as side information, to reduce mismatched motion predictions at the decoder. The problem of error concealment-aware video coding is also investigated to enhance the overall error robustness. A new approach based on scalable coding and optimally error concealment selection is proposed, where the optimal error concealment modes are found by simulating transmission losses, followed by a saliency-weighted optimisation. Moreover, recovery residual information is encoded using a rate-controlled enhancement layer. Both are transmitted to the decoder to be used in case of data loss. Finally, an adaptive error resilience scheme is proposed to dynamically predict the video stream that achieves the highest decoded quality for a particular loss case. A neural network selects among the various video streams, encoded with different levels of compression efficiency and error protection, based on information from the video signal, the coded stream and the transmission network. Overall, the new robust video coding methods investigated in this thesis yield consistent quality gains in comparison with other existing methods and also the ones implemented in the HEVC reference software. Furthermore, the trade-off between coding efficiency and error robustness is also better in the proposed methods

Protocole de routage à chemins multiples pour des réseaux ad hoc

Ad hoc networks consist of a collection of wireless mobile nodes which dynamically exchange data without reliance on any fixed based station or a wired backbone network. They are by definition self-organized. The frequent topological changes make multi-hops routing a crucial issue for these networks. In this PhD thesis, we propose a multipath routing protocol named Multipath Optimized Link State Routing (MP-OLSR). It is a multipath extension of OLSR, and can be regarded as a hybrid routing scheme because it combines the proactive nature of topology sensing and reactive nature of multipath computation. The auxiliary functions as route recovery and loop detection are introduced to improve the performance of the network. The usage of queue length metric for link quality criteria is studied and the compatibility between single path and multipath routing is discussed to facilitate the deployment of the protocol. The simulations based on NS2 and Qualnet softwares are performed in different scenarios. A testbed is also set up in the campus of Polytech’Nantes. The results from the simulator and testbed reveal that MP-OLSR is particularly suitable for mobile, large and dense networks with heavy network load thanks to its ability to distribute the traffic into different paths and effective auxiliary functions. The H.264/SVC video service is applied to ad hoc networks with MP-OLSR. By exploiting the scalable characteristic of H.264/SVC, we propose to use Priority Forward Error Correction coding based on Finite Radon Transform (FRT) to improve the received video quality. An evaluation framework called SVCEval is built to simulate the SVC video transmission over different kinds of networks in Qualnet. This second study highlights the interest of multiple path routing to improve quality of experience over self-organized networks.Les réseaux ad hoc sont constitués d’un ensemble de nœuds mobiles qui échangent des données sans infrastructure de type point d’accès ou artère filaire. Ils sont par définition auto-organisés. Les changements fréquents de topologie des réseaux ad hoc rendent le routage multi-sauts très problématique. Dans cette thèse, nous proposons un protocole de routage à chemins multiples appelé Multipath Optimized Link State Routing (MP-OLSR). C’est une extension d’OLSR à chemins multiples qui peut être considérée comme une méthode de routage hybride. En effet, MP-OLSR combine la caractéristique proactive de la détection de topologie et la caractéristique réactive du calcul de chemins multiples qui est effectué à la demande. Les fonctions auxiliaires comme la récupération de routes ou la détection de boucles sont introduites pour améliorer la performance du réseau. L’utilisation de la longueur des files d’attente des nœuds intermédiaires comme critère de qualité de lien est étudiée et la compatibilité entre routage à chemins multiples et chemin unique est discutée pour faciliter le déploiement du protocole. Les simulations basées sur les logiciels NS2 et Qualnet sont effectuées pour tester le routage MP-OLSR dans des scénarios variés. Une mise en œuvre a également été réalisée au cours de cette thèse avec une expérimentation sur le campus de Polytech’Nantes. Les résultats de la simulation et de l’expérimentation révèlent que MP-OLSR est particulièrement adapté pour les réseaux mobiles et denses avec des trafics élevés grâce à sa capacité à distribuer le trafic dans des chemins différents et à des fonctions auxiliaires efficaces. Au niveau application, le service vidéo H.264/SVC est appliqué à des réseaux ad hoc MP-OLSR. En exploitant la hiérarchie naturelle délivrée par le format H.264/SVC, nous proposons d’utiliser un codage à protection inégale (PFEC) basé sur la Transformation de Radon Finie (FRT) pour améliorer la qualité de la vidéo à la réception. Un outil appelé SVCEval est développé pour simuler la transmission de vidéo SVC sur différents types de réseaux dans le logiciel Qualnet. Cette deuxième étude témoigne de l’intérêt du codage à protection inégale dans un routage à chemins multiples pour améliorer une qualité d’usage sur des réseaux auto-organisés

Beyond Transmitting Bits: Context, Semantics, and Task-Oriented Communications

Communication systems to date primarily aim at reliably communicating bit sequences. Such an approach provides efficient engineering designs that are agnostic to the meanings of the messages or to the goal that the message exchange aims to achieve. Next generation systems, however, can be potentially enriched by folding message semantics and goals of communication into their design. Further, these systems can be made cognizant of the context in which communication exchange takes place, thereby providing avenues for novel design insights. This tutorial summarizes the efforts to date, starting from its early adaptations, semantic-aware and task-oriented communications, covering the foundations, algorithms and potential implementations. The focus is on approaches that utilize information theory to provide the foundations, as well as the significant role of learning in semantics and task-aware communications

Progressive transmission of medical images

A novel adaptive source-channel coding scheme for progressive transmission of medical images with a feedback system is therefore proposed in this dissertation. The overall design includes Discrete Wavelet Transform (DWT), Embedded Zerotree Wavelet (EZW) coding, Joint Source-Channel Coding (JSCC), prioritization of region of interest (RoI), variability of parity length based on feedback, and the corresponding hardware design utilising Simulink. The JSCC can achieve an efficient transmission by incorporating unequal error projection (UEP) and rate allocation. An algorithm is also developed to estimate the number of erroneous data in the receiver. The algorithm detects the address in which the number of symbols for each subblock is indicated, and reassigns an estimated correct data according to a decision making criterion, if error data is detected. The proposed system has been designed based on Simulink which can be used to generate netlist for portable devices. A new compression method called Compressive Sensing (CS) is also revisited in this work. CS exhibits many advantages in comparison with EZW based on our experimental results. DICOM JPEG2000 is an efficient coding standard for lossy or lossless multi-component image coding. However, it does not provide any mechanism for automatic RoI definition, and is more complex compared to our proposed scheme. The proposed system significantly reduces the transmission time, lowers computation cost, and maintains an error-free state in the RoI with regards to the above provided features. A MATLAB-based TCP/IP connection is established to demonstrate the efficacy of the proposed interactive and adaptive progressive transmission system. The proposed system is simulated for both binary and symmetric channel (BSC) and Rayleigh channel. The experimental results confirm the effectiveness of the design.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Multimedia

The nowadays ubiquitous and effortless digital data capture and processing capabilities offered by the majority of devices, lead to an unprecedented penetration of multimedia content in our everyday life. To make the most of this phenomenon, the rapidly increasing volume and usage of digitised content requires constant re-evaluation and adaptation of multimedia methodologies, in order to meet the relentless change of requirements from both the user and system perspectives. Advances in Multimedia provides readers with an overview of the ever-growing field of multimedia by bringing together various research studies and surveys from different subfields that point out such important aspects. Some of the main topics that this book deals with include: multimedia management in peer-to-peer structures & wireless networks, security characteristics in multimedia, semantic gap bridging for multimedia content and novel multimedia applications

Progressive transmission of medical images

A novel adaptive source-channel coding scheme for progressive transmission of medical images with a feedback system is therefore proposed in this dissertation. The overall design includes Discrete Wavelet Transform (DWT), Embedded Zerotree Wavelet (EZW) coding, Joint Source-Channel Coding (JSCC), prioritization of region of interest (RoI), variability of parity length based on feedback, and the corresponding hardware design utilising Simulink. The JSCC can achieve an efficient transmission by incorporating unequal error projection (UEP) and rate allocation. An algorithm is also developed to estimate the number of erroneous data in the receiver. The algorithm detects the address in which the number of symbols for each subblock is indicated, and reassigns an estimated correct data according to a decision making criterion, if error data is detected. The proposed system has been designed based on Simulink which can be used to generate netlist for portable devices. A new compression method called Compressive Sensing (CS) is also revisited in this work. CS exhibits many advantages in comparison with EZW based on our experimental results. DICOM JPEG2000 is an efficient coding standard for lossy or lossless multi-component image coding. However, it does not provide any mechanism for automatic RoI definition, and is more complex compared to our proposed scheme. The proposed system significantly reduces the transmission time, lowers computation cost, and maintains an error-free state in the RoI with regards to the above provided features. A MATLAB-based TCP/IP connection is established to demonstrate the efficacy of the proposed interactive and adaptive progressive transmission system. The proposed system is simulated for both binary and symmetric channel (BSC) and Rayleigh channel. The experimental results confirm the effectiveness of the desig