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Whiteman, Don, and Greg Glen. "Compression Methods for Instrumentation Video." International Foundation for Telemetering, 1995. http://hdl.handle.net/10150/611516.
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International Telemetering Conference Proceedings / October 30-November 02, 1995 / Riviera Hotel, Las Vegas, Nevada<br>Video compression is typically required to solve the bandwidth problems related to the transmission of instrumentation video. The use of color systems typically results in bandwidth requirements beyond the capabilities of current receiving and recording equipment. The HORACE specification, IRIG-210, was introduced as an attempt to provide standardization between government test ranges. The specification provides for video compression in order to alleviate the bandwidth problems associated with instrumentation video and is intended to assure compatibility, data quality, and performance of instrumentation video systems. This paper provides an overview of compression methods available for instrumentation video and summarizes the benefits of each method and the problems associated with different compression methods when utilized for instrumentation video. The affects of increased data link bit error rates are also discussed for each compression method. This paper also includes a synopsis of the current HORACE specification, a proposed Vector HORACE specification for color images and hardware being developed to meet both specifications.
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Jung, Agata. "Comparison of Video Quality Assessment Methods." Thesis, Blekinge Tekniska Högskola, Institutionen för tillämpad signalbehandling, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-15062.
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Context: The newest standard in video coding High Efficiency Video Coding (HEVC) should have an appropriate coder to fully use its potential. There are a lot of video quality assessment methods. These methods are necessary to establish the quality of the video. Objectives: This thesis is a comparison of video quality assessment methods. Objective is to find out which objective method is the most similar to the subjective method. Videos used in tests are encoded in the H.265/HEVC standard. Methods: For testing MSE, PSNR, SSIM methods there is special software created in MATLAB. For VQM method downloaded software was used for testing. Results and conclusions: For videos watched on mobile device: PSNR is the most similar to subjective metric. However for videos watched on television screen: VQM is the most similar to subjective metric. Keywords: Video Quality Assessment, Video Quality Prediction, Video Compression, Video Quality Metrics
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Toivonen, T. (Tuukka). "Efficient methods for video coding and processing." Doctoral thesis, University of Oulu, 2008. http://urn.fi/urn:isbn:9789514286957.
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This thesis presents several novel improvements to video coding algorithms, including block-based motion estimation, quantization selection, and video filtering. Most of the presented improvements are fully compatible with the standards in general use, including MPEG-1, MPEG-2, MPEG-4, H.261, H.263, and H.264.
For quantization selection, new methods are developed based on the rate-distortion theory. The first method obtains locally optimal frame-level quantization parameter considering frame-wise dependencies. The method is applicable to generic optimization problems, including also motion estimation. The second method, aimed at real-time performance, heuristically modulates the quantization parameter in sequential frames improving significantly the rate-distortion performance. It also utilizes multiple reference frames when available, as in H.264. Finally, coding efficiency is improved by introducing a new matching criterion for motion estimation which can estimate the bit rate after transform coding more accurately, leading to better motion vectors.
For fast motion estimation, several improvements on prior methods are proposed. First, fast matching, based on filtering and subsampling, is combined with a state-of-the-art search strategy to create a very quick and high-quality motion estimation method. The successive elimination algorithm (SEA) is also applied to the method and its performance is improved by deriving a new tighter lower bound and increasing it with a small constant, which eliminates a larger part of the candidate motion vectors, degrading quality only insignificantly. As an alternative, the multilevel SEA (MSEA) is applied to the H.264-compatible motion estimation utilizing efficiently the various available block sizes in the standard.
Then, a new method is developed for refining the motion vector obtained from any fast and suboptimal motion estimation method. The resulting algorithm can be easily adjusted to have the desired tradeoff between computational complexity and rate-distortion performance. For refining integer motion vectors into half-pixel resolution, a new very quick but accurate method is developed based on the mathematical properties of bilinear interpolation.
Finally, novel number theoretic transforms are developed which are best suited for two-dimensional image filtering, including image restoration and enhancement, but methods are developed with a view to the use of the transforms also for very reliable motion estimation.
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Begaint, Jean. "Towards novel inter-prediction methods for image and video compression." Thesis, Rennes 1, 2018. http://www.theses.fr/2018REN1S038/document.
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En raison de la grande disponibilité des dispositifs de capture vidéo et des nouvelles pratiques liées aux réseaux sociaux, ainsi qu’à l’émergence des services en ligne, les images et les vidéos constituent aujourd’hui une partie importante de données transmises sur internet. Les applications de streaming vidéo représentent ainsi plus de 70% de la bande passante totale de l’internet. Des milliards d’images sont déjà stockées dans le cloud et des millions y sont téléchargés chaque jour. Les besoins toujours croissants en streaming et stockage nécessitent donc une amélioration constante des outils de compression d’image et de vidéo. Cette thèse vise à explorer des nouvelles approches pour améliorer les méthodes actuelles de prédiction inter-images. De telles méthodes tirent parti des redondances entre images similaires, et ont été développées à l’origine dans le contexte de la vidéo compression. Dans une première partie, de nouveaux outils de prédiction inter globaux et locaux sont associés pour améliorer l’efficacité des schémas de compression de bases de données d’image. En associant une compensation géométrique et photométrique globale avec une prédiction linéaire locale, des améliorations significatives peuvent être obtenues. Une seconde approche est ensuite proposée qui introduit un schéma de prédiction inter par régions. La méthode proposée est en mesure d’améliorer les performances de codage par rapport aux solutions existantes en estimant et en compensant les distorsions géométriques et photométriques à une échelle semi locale. Cette approche est ensuite adaptée et validée dans le cadre de la compression vidéo. Des améliorations en réduction de débit sont obtenues, en particulier pour les séquences présentant des mouvements complexes réels tels que des zooms et des rotations. La dernière partie de la thèse se concentre sur l’étude des méthodes d’apprentissage en profondeur dans le cadre de la prédiction inter. Ces dernières années, les réseaux de neurones profonds ont obtenu des résultats impressionnants pour un grand nombre de tâches de vision par ordinateur. Les méthodes basées sur l’apprentissage en profondeur proposées à l’origine pour de l’interpolation d’images sont étudiées ici dans le contexte de la compression vidéo. Des améliorations en terme de performances de codage sont obtenues par rapport aux méthodes d’estimation et de compensation de mouvements traditionnelles. Ces résultats mettent en évidence le fort potentiel de ces architectures profondes dans le domaine de la compression vidéo<br>Due to the large availability of video cameras and new social media practices, as well as the emergence of cloud services, images and videos constitute today a significant amount of the total data that is transmitted over the internet. Video streaming applications account for more than 70% of the world internet bandwidth. Whereas billions of images are already stored in the cloud and millions are uploaded every day. The ever growing streaming and storage requirements of these media require the constant improvements of image and video coding tools. This thesis aims at exploring novel approaches for improving current inter-prediction methods. Such methods leverage redundancies between similar frames, and were originally developed in the context of video compression. In a first approach, novel global and local inter-prediction tools are associated to improve the efficiency of image sets compression schemes based on video codecs. By leveraging a global geometric and photometric compensation with a locally linear prediction, significant improvements can be obtained. A second approach is then proposed which introduces a region-based inter-prediction scheme. The proposed method is able to improve the coding performances compared to existing solutions by estimating and compensating geometric and photometric distortions on a semi-local level. This approach is then adapted and validated in the context of video compression. Bit-rate improvements are obtained, especially for sequences displaying complex real-world motions such as zooms and rotations. The last part of the thesis focuses on deep learning approaches for inter-prediction. Deep neural networks have shown striking results for a large number of computer vision tasks over the last years. Deep learning based methods proposed for frame interpolation applications are studied here in the context of video compression. Coding performance improvements over traditional motion estimation and compensation methods highlight the potential of these deep architectures
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Grundmann, Matthias. "Computational video: post-processing methods for stabilization, retargeting and segmentation." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/47596.
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In this thesis, we address a variety of challenges for analysis and enhancement of Computational Video. We present novel post-processing methods to bridge the difference between professional and casually shot videos mostly seen on online sites. Our research presents solutions to three well-defined problems: (1) Video stabilization and rolling shutter removal in casually-shot, uncalibrated videos; (2) Content-aware video retargeting; and (3) spatio-temporal video segmentation to enable efficient video annotation. We showcase several real-world applications building on these techniques.
We start by proposing a novel algorithm for video stabilization that generates stabilized videos by employing L1-optimal camera paths to remove undesirable motions. We compute camera paths that are optimally partitioned into constant, linear and parabolic segments mimicking the camera motions employed by professional cinematographers. To achieve this, we propose a linear programming framework to minimize the first, second, and third derivatives of the resulting camera path. Our method allows for video stabilization beyond conventional filtering, that only suppresses high frequency jitter. An additional challenge in videos shot from mobile phones are rolling shutter distortions. Modern CMOS cameras capture the frame one scanline at a time, which results in non-rigid image distortions such as shear and wobble. We propose a solution based on a novel mixture model of homographies parametrized by scanline blocks to correct these rolling shutter distortions. Our method does not rely on a-priori knowledge of the readout time nor requires prior camera calibration. Our novel video stabilization and calibration free rolling shutter removal have been deployed on YouTube where they have successfully stabilized millions of videos. We also discuss several extensions to the stabilization algorithm and present technical details behind the widely used YouTube Video Stabilizer.
We address the challenge of changing the aspect ratio of videos, by proposing algorithms that retarget videos to fit the form factor of a given device without stretching or letter-boxing. Our approaches use all of the screen's pixels, while striving to deliver as much video-content of the original as possible. First, we introduce a new algorithm that uses discontinuous seam-carving in both space and time for resizing videos. Our algorithm relies on a novel appearance-based temporal coherence formulation that allows for frame-by-frame processing and results in temporally discontinuous seams, as opposed to geometrically smooth and continuous seams. Second, we present a technique, that builds on the above mentioned video stabilization approach. We effectively automate classical pan and scan techniques by smoothly guiding a virtual crop window via saliency constraints.
Finally, we introduce an efficient and scalable technique for spatio-temporal segmentation of long video sequences using a hierarchical graph-based algorithm. We begin by over-segmenting a volumetric video graph into space-time regions grouped by appearance. We then construct a "region graph" over the obtained segmentation and iteratively repeat this process over multiple levels to create a tree of spatio-temporal segmentations. This hierarchical approach generates high quality segmentations, and allows subsequent applications to choose from varying levels of granularity. We demonstrate the use of spatio-temporal segmentation as users interact with the video, enabling efficient annotation of objects within the video.
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Coria, Mendoza Lino Evgueni. "Low-complexity methods for image and video watermarking." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/571.
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For digital media, the risk of piracy is aggravated by the ease to copy and distribute the content. Watermarking has become the technology of choice for discouraging people from creating illegal copies of digital content. Watermarking is the practice of imperceptibly altering the media content by embedding a message, which can be used to identify the owner of that content. A watermark message can also be a set of instructions for the display equipment, providing information about the content’s usage restrictions. Several applications are considered and three watermarking solutions are provided.
First, applications such as owner identification, proof of ownership, and digital fingerprinting are considered and a fast content-dependent image watermarking method is proposed. The scheme offers a high degree of robustness against distortions, mainly additive noise, scaling, low-pass filtering, and lossy compression. This method also requires a small amount of computations. The method generates a set of evenly distributed codewords that are constructed via an iterative algorithm. Every message bit is represented by one of these codewords and is then embedded in one of the image’s 8 × 8 pixel blocks. The information in that particular block is used in the embedding so as to ensure robustness and image fidelity.
Two watermarking schemes designed to prevent theatre camcorder piracy are also presented. In these methods, the video is watermarked so that its display is not permitted if a compliant video player detects the watermark. A watermark that is robust to geometric distortions (rotation, scaling, cropping) and lossy compression is required in order to block access to media content that has been recorded with a camera inside a movie theatre. The proposed algorithms take advantage of the properties of the dual-tree complex wavelet transform (DT CWT). This transform offers the advantages of both the regular and the complex wavelets (perfect reconstruction, approximate shift invariance and good directional selectivity). Our methods use these characteristics to create watermarks that are robust to geometric distortions and lossy compression. The proposed schemes are simple to implement and outperform comparable methods when tested against geometric distortions.
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Maucho, Geoffrey Sunday. "Weighted distortion methods for error resilient video coding." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=110392.
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Wireless and Internet video applications are hampered by bit errors and packet errors, respectively. In addition, packet losses in best effort Internet applications limit video communication applications. Because video compression uses temporal prediction, compressed video is especially susceptible to the problem of transmission errors in one frame propagating into subsequent frames. It is therefore necessary to develop methods to improve the performance of compressed video in the face of channel impairments. Recent work in this area has focused on estimating the end-to-end distortion, which is shown to be useful in building an error resilient encoder. However, these techniques require an accurate estimate of the channel conditions, which is not always accessible for some applications.Recent video compression standards have adopted a Rate Distortion Optimization (RDO) framework to determine coding options that address the trade-off between rate and distortion. In this dissertation, error robustness is added to the RDO framework as a design consideration. This dissertation studies the behavior of motion-compensated prediction (MCP) in a hybrid video coder, and presents techniques of improving the performance in an error prone environment. An analysis of the motion trajectory gives us insight on how to improve MCP without explicit knowledge of the channel conditions. Information from the motion trajectory analysis is used in a novel way to bias the distortion used in RDO, resulting in an encoded bitstream that is both error resilient and bitrate efficient.We also present two low complexity solutions that exploit past inter-frame dependencies. In order to avoid error propagation, regions of a frame are classified according to their potential of having propagated errors. By using this method, we are then able to steer the MCP engine towards areas that are considered ``safe" for prediction. Considering the impact error propagation may have in a RDO framework, our work enhances the overall perceived quality of compressed video while maintaining high coding efficiency. Comparison with other error resilient video coding techniques show the advantages offered by the weighted distortion techniques we present in this dissertation.<br>Les applications vidéo pour l'Internet et les systèmes de communication sans fil sont respectivement entravées par les erreurs de paquets et de bits. De plus, les pertes de paquets des meilleures applications Internet limitent les communications vidéo. Comme la compression vidéo utilise des techniques de prédiction temporelle, les transmissions de vidéos comprimés sont particulièrement sensibles aux erreurs se propageant d'une trame à l'autre. Il est donc nécessaire de développer des techniques pour améliorer la performance de la compression vidéo face au bruit des canaux de transmission. De récents travaux sur le sujet ont mis l'emphase sur l'estimation de la distorsion point-à-point, technique utile pour construire un codeur vidéo tolérant aux erreurs. Ceci étant dit, cette approche requiert une estimation précise des conditions du canal de transmission, ce qui n'est pas toujours possible pour certaines applications.Les standards de compression récents utilisent un cadre d'optimisation dèbit distorsion (RDO) afin de déterminer les options de codage en fonction du compromis souhaité entre distorsion et taux de transmission. Dans cette thèse, nous ajoutons la robustesse aux erreurs au cadre RDO en tant que critère de conception. Nous étudions le comportement de la prédiction de mouvement compensé (MCP) dans un codeur vidéo hybride et présentons des techniques pour en améliorer la performance dans des environnements propices aux erreurs. L'analyse de la trajectoire du mouvement nous permet d'améliorer la MCP sans connatre explicitement les conditions du canal de transmission. L'information de l'analyse de la trajectoire du mouvement est utilisée de façon à contrer le biais de la distorsion utilisée dans le cadre RDO, ce qui permet d'obtenir un encodage binaire d'un taux eficace et résistant aux erreurs. Nous présentons également deux techniques à faible complexité qui exploitent la dépendance entre la trame à coder et les trames qui précèdent. Afin d'éviter la propagation des erreurs, les régions d'une trame sont classées en fonction de leur potentiel à contenir des erreurs propagées. Avec cette méthode, nous sommes ` même de diriger l'outil MCP vers les régions où la prédiction peut être faite de façon "sécuritaire". Considérant l'impact que peut avoir la propagation des erreurs dans un cadre RDO, nos travaux améliorent la qualité globale perçue de vidéos comprimés tout en maintenant de bons taux de transmission. Des comparaisons avec les meilleures techniques robustes de codage vidéo présentement utilisées démontrent les avantages offerts par les techniques de distorsion pondérée présentées dans cette thèse.
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Naghdinezhad, Amir. "Error resilient methods in scalable video coding (SVC)." Thesis, McGill University, 2014. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=121379.
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With the rapid development of multimedia technology, video transmission over unreliable channels like Internet and wireless networks, is widely used. Channel errors can result in a mismatch between the encoder and the decoder, and because of the predictive structures used in video coding, the errors will propagate both temporally and spatially. Consequently, the quality of the received video at the decoder may degrade significantly. In order to improve the quality of the received video, several error resilient methods have been proposed. Furthermore, in addition to compression efficiency and error robustness, flexibility has become a new multimedia requirement in advanced multimedia applications. In these applications such as video conferencing and video streaming, compressed video is transmitted over heterogeneous networks with a broad range of clients with different requirements and capabilities in terms of power, bandwidth and display resolution, simultaneously accessing the same coded video. The scalable video coding concept was proposed to address the flexibility issue by generating a single bit stream that meets the requirement of these users. This dissertation is concerned with novel contributions in the area of error resilience for scalable extension of H.264/AVC. The first part of the dissertation focuses on modifying the conventional prediction structure in order to reduce the propagation of error to succeeding frames. We propose two new prediction structures that can be used in temporal and spatial scalability of SVC. The proposed techniques improve the previous methods by efficiently exploiting the Intra macroblocks (MBs) in the reference frames and exponential decay of error propagation caused by the introduced leaky prediction.In order to satisfy both coding efficiency and error resilience in error prone channels, we combine error resilience mode decision technique with the proposed prediction structures. The end-to-end distortion of the proposed prediction structure is estimated and used instead of the source coding distortion in the rate distortion optimization. Furthermore, accurately analysing the utility of each video packet in unequal error protection techniques is a critical and usually very complex process. We present an accurate low complexity utility estimation technique. This technique estimates the utility of each network abstraction layer (NAL) by considering the error propagation to future frames. Also, a low delay version of this technique, which can be used in delay constrained applications, is presented.<br>La révolution technologique de l'information et des communications a donné lieu à un élargissement du marché des applications multimédias. Sur des canaux non fiables comme Internet et les réseaux sans fil, la présence des erreurs de transmission est considérée comme l'une des principales causes de la dégradation de la qualité vidéo au niveau du récepteur. Et en raison des structures de prédiction utilisées dans le codage vidéo, ces erreurs ont tendance à se propager à la fois temporellement et spatialement. Par conséquent, la qualité de la vidéo reçue risque de se dégrader d'une façon considérable. Afin de minimiser ce risque, des outils qui permettent de renforcer la robustesse contre les erreurs ont été proposés. En plus de la résistance aux erreurs, la flexibilité est devenue une nouvelle exigence dans des applications multimédias comme la vidéo conférence et la vidéo en streaming. En effet, la vidéo compressée est transmise sur des réseaux hétérogènes avec un large éventail de clients ayant des besoins différents et des capacités différentes en termes de puissance, de résolution vidéo et de bande passante, d'où la nécessite d'une solution pour l'accès simultané à la même vidéo codée. La scalabilité est venue répondre aux exigences de tous ces utilisateurs.Cette thèse, élaborée dans le cadre du développement de la version scalable de la norme H.264/AVC (aussi connue sous le nom de SVC), présente des idées innovantes dans le domaine de la résilience aux erreurs. La première partie de la thèse expose deux nouvelles structures de prédiction qui aident à renforcer la résistance aux erreurs. Les structures proposées peuvent être utilisées dans la scalabilité temporelle et spatiale et visent essentiellement à améliorer les méthodes antérieures en exploitant de manière plus efficace les MBs "Intra" dans les images de référence et en profitant de la prédiction "Leaky" qui permet de réduire de façon exponentielle la propagation des erreurs de transmission.Afin de satisfaire à la fois l'efficacité du codage et la résilience aux erreurs, nous avons combiné les techniques proposées avec les modules de décision. En plus, une estimation de la distorsion de bout en bout a été utilisée dans le calcul du coût des différents modes. En outre, analyser avec précision l'importance de chaque paquet de données vidéo dans de telles structures est un processus critique et généralement très complexe. Nous avons proposé une méthode simple et fiable pour cette estimation. Cette méthode consiste à évaluer l'importance de chaque couche d'abstraction réseau (NAL) en considérant la propagation des erreurs dans les images futures. En plus, une version avec un faible délai de réponse a été présentée.
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Isgro, Francesco. "Geometric methods for video sequence analysis and applications." Thesis, Heriot-Watt University, 2001. http://hdl.handle.net/10399/495.
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Kies, Jonathan K. "Empirical Methods for Evaluating Video-Mediated Collaborative Work." Diss., Virginia Tech, 1997. http://hdl.handle.net/10919/30537.
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Advancements in computer technology are making video conferencing a viable communication medium for desktop computers. These same advancements are changing the structure and means by which information workers conduct business. From a human factors perspective, however, the study of new communication technologies and their relationships with end users presents a challenging research domain. This study employed two diverse research approaches to the problem of reduced video frame rate in desktop video conferencing. In the first study, a psychophysical method was used to evaluate video image quality as a function of frame rate for a series of different scenes. Scenes varied in terms of level of detail, velocity of panning, and content. Results indicate that for most scenes, differences in frame rate become less detectable above approximately 10 frames per second (fps), suggesting a curvilinear relationship between image quality and frame rate. For a traditional conferencing scene, however, a linear increase in frame rate produced a linear improvement in perceived image quality. High detail scenes were perceived to be of lower quality than the low detail scenes, while panning velocity had no effect. In the second study, a collection of research methods known as ethnography was used to examine long-term use of desktop video by collaborators in a real work situation. Participants from a graduate course met each week for seven weeks and worked on a class project under one of four communication conditions: face-to-face, 1 fps, 10 fps, and 25 fps. Dependent measures included interviews, questionnaires, interaction analysis measures, and ethnomethodology. Recommendations are made regarding the utility and expense of each method with respect to uncovering human factors issues in video-mediated collaboration. It is believed that this research has filled a significant gap in the human factors literature of advanced telecommunications and research methodology.<br>Ph. D.
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Guilluy, Wilko. "Video stabilization : A synopsis of current challenges, methods and performance evaluation." Thesis, Sorbonne Paris Cité, 2018. http://www.theses.fr/2018USPCD094.
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Le développement continu de capteurs vidéo et leurs miniaturisations ont étendus leurs usages dans diverses applications allant de la vidéo-surveillance aux systèmes de chirurgie assisté par ordinateur et l’analyse de mouvements physiques et de phénomènes astrophysiques. De nos jours, il est devenu possible de capturer des séquences vidéos dans n’importe quel environnement, sans de lourds et complexes ajustements comme c’était le cas avec les anciens capteurs vidéos. Cependant,l’aisance à accéder à l’information visuelle à travers des capteurs de plus en plus faciles à manipuler a conduit à une situation où le nombre de vidéos distribuées sur internet est en progression constante et il devient difficile de corriger efficacement toutes les déformations et artefacts qui découlent de l’acquisition du signal. Par exemple, plus de 600000 de vidéos sont chargées sur Youtube chaque jour. Une des dégradations les plus gênantes pour la vision humaine est liée à l’instabilité de l’image due aux mouvements de la caméra lors de l’acquisition du signal. Cette source de dégradations se manifeste sous la forme d’oscillations incontrôlées de la trame entière et peut être accompagnée par un effet de flou.Cela affecte la qualité de l’image et produit un inconfort visuel. Il existe des solutions mécaniques telles que les tripodes, chariots, stabilisateurs électroniques ou des technologies s’appuyant sur les gyroscopes qui empêchent les effets de flou ou les oscillations. Cependant, leur utilisation reste limitée à des applications professionnelles et en conséquence, la plupart des vidéos amateurs contiennent des mouvements de caméra non intentionnels. Dans ce contexte, l’utilisation de méthodes numériques, souvent nommées stabilisation de vidéos numérique, semble être une solution prometteuse. La stabilisation numérique cherche à crée une nouvelle vidéo montrant la même scène mais en supprimant toutes les composantes non intentionnels du mouvement de caméra. La stabilisation vidéo est utile pour améliorer la qualité et le confort visuel du spectateur, mais peut aussi servir d’étape de prétraitement pour de nombreux procédés d’analyse vidéo utilisant le mouvement, tel que la soustraction de l’arrière-plan ou le suivi d’objet<br>The continuous development of video sensors and their miniaturization has extended their use in various applications ranging from video surveillance systems to computer-assisted surgery and the analysis of physical and astronomical phenomena. Nowadays it becomes possible to capture video sequences in any environment and without any heavy and complex adjustments as was the case with the old video acquisition sensors. However, the ease in accessing visual information through the increasingly easy-to-handle sensors has led to a situation where the number of videos distributed over the Internet is constantly increasing and it becomes difficult to effectively correct all the distortions and artifacts that may result from the signal acquisition. As an example, more than 600000 hours of videos are uploaded each day on Youtube. One of the most perceptually annoying degradation is related to the image instability due to camera movement during the acquisition. This source of degradation manifests as uncontrolled oscillationsof the whole frames and may be accompanied with a blurring effect. This affectsthe perceptual image quality and produces visual discomfort. There exist some hardware solutions such as tripods, dollies, electronic image stabilizers or gyroscope based technologies that prevent video from blurriness and oscillations.However, their use is still limited to professional applications and as a result, most amateur videos contain unintended camera movements. In this context, the use of software tools, often referred to as Digital Video Stabilization (DVS), seems to be the most promising solution. Digital video stabilization aims at creating a new video showing the same scene but removing all the unintentional components of camera motion. Video stabilization is useful in order to increase the quality and the visual comfort of the viewer, but can also serve as a pre-processing step in many video analysis processes that use object motion, such as backgrounds ubstraction or object tracking
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Le, Thuc Trinh. "Video inpainting and semi-supervised object removal." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLT026/document.
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De nos jours, l'augmentation rapide de les vidéos crée une demande massive d'applications d'édition de vidéos. Dans cette thèse, nous résolvons plusieurs problèmes relatifs au post-traitement vidéo. Nous nous concentrons sur l'application de suppression d'objets en vidéo. Pour mener à bien cette tâche, nous l'avons divisé en deux problèmes: (1) une étape de segmentation des objets vidéo pour sélectionner les objets à supprimer et (2) une étape d'inpainting vidéo pour remplir les zones endommagées. Pour le problème de la segmentation vidéo, nous concevons un système adapté aux applications de suppression d’objets avec différentes exigences en termes de précision et d’efficacité. Notre approche repose sur la combinaison de réseaux de neurones convolutifs (CNN) pour la segmentation et de la méthode classique de suivi des masks. Nous adoptons des réseaux de segmentation d’images et les appliquons à la casse vidéo en effectuant une segmentation image par image. En exploitant à la fois les formations en ligne et hors ligne avec uniquement une annotation de première image, les réseaux sont en mesure de produire une segmentation extrêmement précise des objets vidéo. En outre, nous proposons un module de suivi de masque pour assurer la continuité temporelle et un module de liaison de masque pour assurer la cohérence de l'identité entre les trames. De plus, nous présentons un moyen simple d’apprendre la couche de dilatation dans le masque, ce qui nous aide à créer des masques appropriés pour l’application de suppression d’objets vidéo.Pour le problème d’inpainting vidéo, nous divisons notre travail en deux catégories basées sur le type de fond. En particulier, nous présentons une méthode simple de propagation de pixels guidée par le mouvement pour traiter les cas d’arrière-plan statiques. Nous montrons que le problème de la suppression d'objets avec un arrière-plan statique peut être résolu efficacement en utilisant une technique simple basée sur le mouvement. Pour traiter le fond dynamique, nous introduisons la méthode d’inpainting vidéo en optimisant une fonction d’énergie globale basée sur des patchs. Pour augmenter la vitesse de l'algorithme, nous avons proposé une extension parallèle de l'algorithme 3D PatchMatch. Pour améliorer la précision, nous intégrons systématiquement le flux optique dans le processus global. Nous nous retrouvons avec une méthode d’inpainting vidéo capable de reconstruire des objets en mouvement ainsi que de reproduire des textures dynamiques tout en fonctionnant dans des délais raisonnables.Enfin, nous combinons les méthodes de segmentation des objets vidéo et d’inpainting vidéo dans un système unifié pour supprimer les objets non souhaités dans les vidéos. A notre connaissance, il s'agit du premier système de ce type. Dans notre système, l'utilisateur n'a qu'à délimiter approximativement dans le premier cadre les objets à modifier. Ce processus d'annotation est facilité par l'aide de superpixels. Ensuite, ces annotations sont affinées et propagées dans la vidéo par la méthode de segmentation des objets vidéo. Un ou plusieurs objets peuvent ensuite être supprimés automatiquement à l’aide de nos méthodes d’inpainting vidéo. Il en résulte un outil de montage vidéo informatique flexible, avec de nombreuses applications potentielles, allant de la suppression de la foule à la correction de scènes non physiques<br>Nowadays, the rapid increase of video creates a massive demand for video-based editing applications. In this dissertation, we solve several problems relating to video post-processing and focus on objects removal application in video. To complete this task, we divided it into two problems: (1) A video objects segmentation step to select which objects to remove and (2) a video inpainting step to filling the damaged regions.For the video segmentation problem, we design a system which is suitable for object removal applications with different requirements in terms of accuracy and efficiency. Our approach relies on the combination of Convolutional Neural Networks (CNNs) for segmentation and the classical mask tracking method. In particular, we adopt the segmentation networks for image case and apply them to video case by performing frame-by-frame segmentation. By exploiting both offline and online training with first frame annotation only, the networks are able to produce highly accurate video object segmentation. Besides, we propose a mask tracking module to ensure temporal continuity and a mask linking module to ensure the identity coherence across frames. Moreover, we introduce a simple way to learn the dilation layer in the mask, which helps us create suitable masks for video objects removal application.For the video inpainting problem, we divide our work into two categories base on the type of background. In particular, we present a simple motion-guided pixel propagation method to deal with static background cases. We show that the problem of objects removal with a static background can be solved efficiently using a simple motion-based technique. To deal with dynamic background, we introduce video inpainting method by optimization a global patch-based energy function. To increase the speed of the algorithm, we proposed a parallel extension of the 3D PatchMatch algorithm. To improve accuracy, we systematically incorporate the optical flow in the overall process. We end up with a video inpainting method which is able to reconstruct moving objects as well as reproduce dynamic textures while running in a reasonable time.Finally, we combine the video objects segmentation and video inpainting methods into a unified system to removes undesired objects in videos. To the best of our knowledge, this is the first system of this kind. In our system, the user only needs to approximately delimit in the first frame the objects to be edited. These annotation process is facilitated by the help of superpixels. Then, these annotations are refined and propagated through the video by the video objects segmentation method. One or several objects can then be removed automatically using our video inpainting methods. This results in a flexible computational video editing tool, with numerous potential applications, ranging from crowd suppression to unphysical scenes correction
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Tiwari, Mayank. "Bit-rate allocation for multiple video streams dual-frame video coding and competitive equilibrium methods /." Diss., [La Jolla] : University of California, San Diego, 2010. http://wwwlib.umi.com/cr/ucsd/fullcit?p3402999.
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Paul, Baldine-Brunel. "Video Compression based on iterated function systems." Diss., Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/13553.
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Chung, How James T. H. "Robust video coding methods for next generation communication networks." Thesis, University of Bristol, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364957.
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Malindi, Phumzile. "Methods for providing rural telemedicine with quality video transmission." Thesis, Cape Peninsula University of Technology, 2007. http://hdl.handle.net/20.500.11838/1197.
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Thesis (DTech (Electrical engineering))--Cape Peninsula University of Technology, Cape Town, 2007<br>Telemedicine has been identified as a tool to distnllUte medical expertise to medically
underserved rural community. However, due to the underdeveloped or non-existent
telecommunication infrastructure, which is needed as the platform for telemedicine, the
full benefits of telemedicine are yet to be realized in most parts of South Africa and
Africa as a whole.
This study aims to explore ways on how to provide lP-based lCI system that can be used
as a communication platform for telemedicine in rural areas. In order to emulate the onsite
face-to-face consultation experience, the rural telemedicine system must be able to
provide quality video transmission. Quality video is also important in order for the
physician at the distant end to be able to make correct diagnosis. Hence the main focus of
this study is on ways ofproviding quality video over lP-based multiservice network.
A conceptual model of a rural area network that can be used for rural telemedicine has
been deVeloped, and different access technologies that can be used for rural areas are
presented. Techniques for compesating IP best effort datagram delivery are provided.
Factors that can affect the quality of video transmission on an lP-based packet network
are identified, and a holistic approach to mitigate them is proposed. That includes
adopting coding techniques that will provide coding efficiency, high quality video that is
consistent at high and low bit rates, resilience to transmission errors, scalability, and
network friendliness, which will result in perceived quality improvement, highcompression
efficiency, and possibility of transportation over different networks.
Secondly, it also includes mechanisms to compensate for packet networks idiosyncrasy,
especially JP best-effort debilities, in order to meet the latency and jitter requirements of
real-time video traffic.
For video coding, H.264 is proposed as it meets most of the encoding requirements listed
above, and for prioritising and protecting.video traffic from JP network's best-effort
debilities a combination of differential services (DiflServ) and multi-protocol label
switching (MPLS) have been adopted, where DiflServ is used for traffic classification
and MPLS is used for traffic engineering and fast-rerouting in the event of route failure.
To verify and validate the proposed solutions, modelling and simulation has been used,
where the Network Simulator (NS-2.93) has been used to simulate network functions,
and PSNR, VQM score and double stimulus impairment scale (DSIS) have been used for
evaluating video quality.
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Navarro, Diego. "Biofeedback Interaction : Applying Physiological Methods to Entertainment Video Games." Licentiate thesis, Blekinge Tekniska Högskola, Institutionen för datavetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-20730.
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Biofeedback interaction offers interesting opportunities for video games since it allows player physiological information to be used in novel interaction techniques. Despite several contributions in the area, biofeedback interaction faces a set of challenges relating to its design and implementation. First, it has mainly been used as a method to replace more traditional interaction devices, such as gamepads, mice or keyboards. Also, few of the previous interaction techniques have made an essential use of physiological data: exploring possibilities that could only be developed by involving physiological inputs. This dissertation explores how different physiological methods, such as electroencephalography, eye tracking, electrocardiography, electrodermal activity, or electromyography, could be used in the design and development of natural user interaction techniques that might be applied to entertainment video games, highlighting technical details for the appropriate use of physiological signals. The research also discusses interaction design principles from a human-computer interaction perspective, evaluates several novel biofeedback interaction techniques with a set of user studies, and proposes ethical considerations for the appropriate exposure to virtual reality and physiological sensor technology. Results show that the use of biofeedback inputs in novel interaction techniques, vary in complexity and functionality depending on the type of measurements used. They also showed that biofeedback interaction can positively affect player experience since it allows games and virtual reality applications to synchronize with player physiology, making of playing games a personalized experience. Results highlighted that biofeedback interaction can significantly affect player performance, being influenced by the interaction complexity and the reliability of the sensor technology used.
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Piatrik, Tomas. "Image clustering and Video Summarisation using ant-inspired methods." Thesis, University of London, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.509746.
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Snowden, Kelly E. "Teacher Perceptions of the Flipped Classroom: Using Video Lectures Online to Replace Traditional In-class Lectures." Thesis, University of North Texas, 2012. https://digital.library.unt.edu/ark:/67531/metadc149663/.
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Advancements in media technologies have resulted in increased student usage causing teachers to struggle to be able to engage and hold student’s interest in a typical classroom. As students’ needs change, the field of education changes. One strategy that is gaining in popularity among teachers is the implementation of the “flipped classroom” also known as the “inverted classroom” or “reverse instruction” - a method incorporates technology to “flip” or “reverse” what is typically done in class with what is typically done as homework. Through teacher interviews of eight core teachers, this study attempts to discover teacher perceptions of the use of this method. Results of the study reveal that perceptions of the method are more positive among teachers who typically use lecture as a primary mode of information dissemination.
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Balster, Eric J. "Video compression and rate control methods based on the wavelet transform." Columbus, Ohio : Ohio State University, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1086098540.
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Thesis (Ph. D.)--Ohio State University, 2003.<br>Title from first page of PDF file. Document formatted into pages; contains xxv, 142 p.; also includes graphics. Includes abstract and vita. Advisor: Yuan F. Zheng, Dept. of Electrical and Computer Engineering. Includes bibliographical references (p. 135-142).
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Kjelsvik, Iselin. "Paper Based Video Prototyping : A study of methods for low fidelity video prototypes in usability testing." Thesis, Umeå universitet, Institutionen för informatik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-45114.
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In the field of Human Computer Interaction (HCI), low fidelity prototypes are a well-established method with solidly defined advantages and disadvantages. Further development of different methods within this field is constantly evolving, and this paper describes the concept of one of these methods, low fidelity video prototypes. It gives a brief introduction to low fidelity video prototyping methods, advantages and disadvantages. The video prototype is compared to paper prototyping, which lies closest to it in the low-fi family. I explain my methods for developing a paper prototype, a video prototype based on this prototype, the testing of both prototypes, and the results of these tests. Video prototyping is more effective than paper prototyping in certain aspects because the tests themselves demand less people, and less time to walk through the test. It is easy to go through the task in the users own pace. It is a useful method on its own, and can also be effective as a complement to other low-fi prototypes. They are easier to test on larger groups and to share over distance. It is easy to produce, edit and refine video prototypes with modern animating tools.
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Wang, Jue. "Foreground segmentation in images and video : methods, systems, and applications /." Thesis, Connect to this title online; UW restricted, 2007. http://hdl.handle.net/1773/6130.
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Elangovan, Premkumar. "Novel source coding methods for optimising real time video codecs." Thesis, Bucks New University, 2009. http://bucks.collections.crest.ac.uk/9767/.
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The quality of the decoded video is affected by errors occurring in the various layers of the protocol stack. In this thesis, disjoint errors occurring in different layers of the protocol stack are investigated with the primary objective of demonstrating the flexibility of the source coding layer. In the first part of the thesis, the errors occurring in the editing layer, due to the coexistence of different video standards in the broadcast market, are addressed. The problems investigated are ‘Field Reversal’ and ‘Mixed Pulldown’. Field Reversal is caused when the interlaced video fields are not shown in the same order as they were captured. This results in a shaky video display, as the fields are not displayed in chronological order. Additionally, Mixed Pulldown occurs when the video frame-rate is up-sampled and down-sampled, when digitised film material is being standardised to suit standard televisions. Novel image processing algorithms are proposed to solve these problems from the source coding layer. In the second part of the thesis, the errors occurring in the transmission layer due to data corruption are addressed. The usage of block level source error-resilient methods over bit level channel coding methods are investigated and improvements are suggested. The secondary objective of the thesis is to optimise the proposed algorithm’s architecture for real-time implementation, since the problems are of a commercial nature. The Field Reversal and Mixed Pulldown algorithms were tested in real time at MTV (Music Television) and are made available commercially through ‘Cerify’, a Linux-based media testing box manufactured by Tektronix Plc. The channel error-resilient algorithms were tested in a laboratory environment using Matlab and performance improvements are obtained.
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Yu, L. "Statistic oriented video coding and streaming methods with future insight." Thesis, University of Liverpool, 2016. http://livrepository.liverpool.ac.uk/3007276/.
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Do, Quoc Bao. "Adaptive Post-processing Methods for Film and Video Quality Enhancement." Paris 13, 2011. http://www.theses.fr/2011PA132030.
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L'introduction des nouvelles technologies numériques de traitement et de codage de contenus visuels dans l'industrie du film a permis de réaliser de grandes avancées dans le monde du cinéma. En effet, l'automatisation de certaines tâches lourdes et la maîtrise des outils numériques ont ainsi permis de réaliser des gains de productivité de qualité considérables et des conditions de travail de plus en plus flexibles et maîtrisables. Dans ce travail de thèse, nous poursuivons cet effort de développement de solutions de traitement automatique pour améliorer la qualité des films numériques haute définition. La qualité d'image est un facteur important dans l'industrie du film qu'il convient de maîtriser. Nous nous intéressons ainsi à quelques artéfacts et limitations des outils et processus de production qui affectent la qualité de l'image. Il s'agit des artéfacts de codage tels que les effets de blocs et l'effet de Gibbs (ringing), le bruit de grain et le cas d'une distorsion couleur appelée "écho d'étalonnage". Pour chaque distorsion ou artéfact, un traitement adaptatif, respectant la fidélité d'image et la cohérence visuelle, est proposé et évalué au moyen de mesures objectives. Les résultats obtenus sont très prometteurs et démontrent l'efficacité des méthodes proposées. Des perspectives réalistes sont envisages pour améliorer et étendre les solutions développées à d'autres types contenus multimédia<br>The introduction of new digital processing and coding techniques of visual contents in the film industry has allowed filmmakers to achieve great technological and commercial advancements. Indeed, the automation of certain complex tasks has enabled to achieve productivity gains and has made advances in terms of reliability and technical accuracy. The picture quality is one of the most important factors in the #lm industry. The main objective of the thesis work is then to propose new methods for improving the quality of high de#nition video in the context of digital cinema. Here we focus on some known annoying artifacts and distortions. A new and less studied artifact occurring during the color processing of the film is also analyzed. All the proposed solutions are developed in a highly constrained environment dictated by the cinema post-production framework. The performances of the developed methods are evaluated using some objective measures and criteria. The obtained results show that the proposed methods can provide efficient solutions for improving HD film quality. Some perspectives for extending these solutions to other visual contents are considered
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Af, Malmborg Harald. "Evaluation of Car Engine Sound Design Methods in Video Games." Thesis, Luleå tekniska universitet, Institutionen för ekonomi, teknik, konst och samhälle, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-84627.
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Realistic interactions with sound objects in video games are a contributing factor to the overall immersion. Car engine sound design is an area where the auditory feedback from driving would have an impact on that immersion. For this study, three methods for designing car engine sounds are evaluated. A traditional method in the game sound industry is to use several sampled audio recordings for the reproduction of engine sounds, which is in this study represented as a sample-based model. The sample-based model is evaluated together with a model using granular synthesis in an in-game scenario. A less common method is to use physical modeling, which is in this study evaluated together with the other two models in a listening test. Results show the granular synthesis model to be the most realistic, and the physical model to be the least preferred.
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Wang, Tian. "Abnormal detection in video streams via one-class learning methods." Thesis, Troyes, 2014. http://www.theses.fr/2014TROY0018/document.
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La vidéosurveillance représente l’un des domaines de recherche privilégiés en vision par ordinateur. Le défi scientifique dans ce domaine comprend la mise en œuvre de systèmes automatiques pour obtenir des informations détaillées sur le comportement des individus et des groupes. En particulier, la détection de mouvements anormaux de groupes d’individus nécessite une analyse fine des frames du flux vidéo. Dans le cadre de cette thèse, la détection de mouvements anormaux est basée sur la conception d’un descripteur d’image efficace ainsi que des méthodes de classification non linéaires. Nous proposons trois caractéristiques pour construire le descripteur de mouvement : (i) le flux optique global, (ii) les histogrammes de l’orientation du flux optique (HOFO) et (iii) le descripteur de covariance (COV) fusionnant le flux optique et d’autres caractéristiques spatiales de l’image. Sur la base de ces descripteurs, des algorithmes de machine learning (machines à vecteurs de support (SVM)) mono-classe sont utilisés pour détecter des événements anormaux. Deux stratégies en ligne de SVM mono-classe sont proposées : la première est basée sur le SVDD (online SVDD) et la deuxième est basée sur une version « moindres carrés » des algorithmes SVM (online LS-OC-SVM)<br>One of the major research areas in computer vision is visual surveillance. The scientific challenge in this area includes the implementation of automatic systems for obtaining detailed information about the behavior of individuals and groups. Particularly, detection of abnormal individual movements requires sophisticated image analysis. This thesis focuses on the problem of the abnormal events detection, including feature descriptor design characterizing the movement information and one-class kernel-based classification methods. In this thesis, three different image features have been proposed: (i) global optical flow features, (ii) histograms of optical flow orientations (HOFO) descriptor and (iii) covariance matrix (COV) descriptor. Based on these proposed descriptors, one-class support vector machines (SVM) are proposed in order to detect abnormal events. Two online strategies of one-class SVM are proposed: The first strategy is based on support vector description (online SVDD) and the second strategy is based on online least squares one-class support vector machines (online LS-OC-SVM)
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Blasi, Saverio G. "High efficiency prediction methods for current and next generation video coding." Thesis, Queen Mary, University of London, 2014. http://qmro.qmul.ac.uk/xmlui/handle/123456789/26263.
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Consumption and production of video signals drastically changed in recent years. Due to the advances in digital consumer technology and the growing availability of fast and reliable internet connections, an increasing amount of digital video sequences are being produced, stored and shared every day in different parts of the world. Video signals are inherently larger in size than other types of multimedia signals. For this reason in order to allow transmission and storage of such data, more efficient compression technology is needed. In this thesis novel methods for enhancing the efficiency of current and next generation video codecs are investigated. Several aspects of interest to video coding technology are taken into account, from computational complexity and compliance to standardisation efforts, to compression efficiency and quality of the decoded signals. Compression can be achieved exploiting redundancies by computing a prediction of a part of the signal using previously encoded portions of the signal. Novel prediction methods are proposed in this thesis based on analytical or statistical models with the aim of providing a solid theoretical basis to support the algorithmic implementation. It is shown in the thesis that appropriately defined synthetic content can be introduced in the signal to compensate for the lack of certain characteristics in the original content. Some of the methods proposed in this thesis aim to target a broader set of use cases than those typically addressed by conventional video coding methods, such as ultra high definition content or coding under high quality conditions.
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Wige, Eugen [Verfasser]. "Methods for Improved Video Compression Using Image Noise Modeling / Eugen Wige." München : Verlag Dr. Hut, 2015. http://d-nb.info/1069019844/34.
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Karlsson, Linda S. "Spatio-Temporal Pre-Processing Methods for Region-of-Interest Video Coding." Licentiate thesis, Mid Sweden University, Department of Information Technology and Media, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-51.
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<p>In video transmission at low bit rates the challenge is to compress the video with a minimal reduction of the percieved quality. The compression can be adapted to knowledge of which regions in the video sequence are of most interest to the viewer. Region of interest (ROI) video coding uses this information to control the allocation of bits to the background and the ROI. The aim is to increase the quality in the ROI at the expense of the quality in the background. In order for this to occur the typical content of an ROI for a particular application is firstly determined and the actual detection is performed based on this information. The allocation of bits can then be controlled based on the result of the detection.</p><p>In this licenciate thesis existing methods to control bit allocation in ROI video coding are investigated. In particular pre-processing methods that are applied independently of the codec or standard. This makes it possible to apply the method directly to the video sequence without modifications to the codec. Three filters are proposed in this thesis based on previous approaches. The spatial filter that only modifies the background within a single frame and the temporal filter that uses information from the previous frame. These two filters are also combined into a spatio-temporal filter. The abilities of these filters to reduce the number of bits necessary to encode the background and to successfully re-allocate these to the ROI are investigated. In addition the computational compexities of the algorithms are analysed.</p><p>The theoretical analysis is verified by quantitative tests. These include measuring the quality using both the PSNR of the ROI and the border of the background, as well as subjective tests with human test subjects and an analysis of motion vector statistics.</p><p>The qualitative analysis shows that the spatio-temporal filter has a better coding efficiency than the other filters and it successfully re-allocates the bits from the foreground to the background. The spatio-temporal filter gives an improvement in average PSNR in the ROI of more than 1.32 dB or a reduction in bitrate of 31 % compared to the encoding of the original sequence. This result is similar to or slightly better than the spatial filter. However, the spatio-temporal filter has a better performance, since its computational complexity is lower than that of the spatial filter.</p>
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Drevery, Chad W. J. "Adaptive sampling and interpolation methods for digital image and video coding." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0015/MQ48060.pdf.
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Le, Grice Bronwen. "Video prompting and increasing assistance : a comparison of two prompting methods." Thesis, University of Canterbury. School of Educational Studies and Human Development, 1989. http://hdl.handle.net/10092/2176.
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Training mentally retarded people to use devices such as computers
and video recorders gives them control over their learning
and access to information and recreational activities. This
study aimed to train four moderately and severely retarded people
to use a video-recorder and a microcomputer. A video was made
for each task based on detailed task analyses. Two training methods
were used: increasing assistance, where a pause in performance
was followed by first a non-verbal, then a verbal, then
a gestural, and finally a physical prompt as necessary; and video prompts
in which each step of the task analysis was demonstrated
on a video monitor and followed by an opportunity to perform
the step. A multiple-baseline design across subjects was used.
Maintenance, and transfer (generalisation) to another trainer
situation, and model of micro-computer and videorecorder
were examined. Both methods successfully trained the
subjects to perform the tasks. Those who were initially trained
by increasing assistance showed more transfer to the second task.
Those trained by video prompting showed higher levels of skill
maintenance and transfer to other situations. The results of
this study demonstrate the utility of video prompts and suggest
their application to training everyday behaviour chains.
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Brasnett, Paul. "Sequential Monte-Carlo methods for object tracking and replacement in video." Thesis, University of Bristol, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.442196.
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Climent, Perez Pau. "Smart video surveillance of pedestrians : fixed, aerial, and multi-camera methods." Thesis, Kingston University, 2016. http://eprints.kingston.ac.uk/37298/.
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Crowd analysis from video footage is an active research topic in the field of computer vision. Crowds can be analaysed using different approaches, depending on their characteristics. Furthermore, analysis can be performed from footage obtained through different sources. Fixed CCTV cameras can be used, as well as cameras mounted on moving vehicles. To begin, a literature review is provided, where research works in the the fields of crowd analysis, as well as object and people tracking, occlusion handling, multi-view and sensor fusion, and multi-target tracking are analyses and compared, and their advantages and limitations highlighted. Following that, the three contributions of this thesis are presented: in a first study, crowds will be classified based on various cues (i.e. density, entropy), so that the best approaches to further analyse behaviour can be selected; then, some of the challenges of individual target tracking from aerial video footage will be tackled; finally, a study on the analysis of groups of people from multiple cameras is proposed. The analysis entails the movements of people and objects in the scene. The idea is to track as many people as possible within the crowd, and to be able to obtain knowledge from their movements, as a group, and to classify different types of scenes. An additional contribution of this thesis, are two novel datasets: on the one hand, a first set to test the proposed aerial video analysis methods; on the other, a second to validate the third study, that is, with groups of people recorded from multiple overlapping cameras performing different actions.
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Isupova, Olga. "Machine learning methods for behaviour analysis and anomaly detection in video." Thesis, University of Sheffield, 2017. http://etheses.whiterose.ac.uk/17771/.
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Behaviour analysis and anomaly detection are key components of intelligent vision systems. Anomaly detection can be considered from two perspectives: abnormal events can be defined as those that violate typical activities or as a sudden change in behaviour. Topic modeling and change point detection methodologies, respectively, are employed to achieve these objectives. The thesis starts with development of novel learning algorithms for a dynamic topic model. Topics extracted by the learning algorithms represent typical activities happening within an observed scene. These typical activities are used for likelihood computation. The likelihood serves as a normality measure in anomaly detection decision making. A novel anomaly localisation procedure is proposed. In the considered dynamic topic model a number of topics, i.e., typical activities, should be specified in advance. A novel dynamic nonparametric hierarchical Dirichlet process topic model is then developed where the number of topics is determined from data. Conventional posterior inference algorithms require processing of the whole data through several passes. It is computationally intractable for massive or sequential data. Therefore, batch and online inference algorithms for the proposed model are developed. A novel normality measure is derived for decision making in anomaly detection. The latter part of the thesis considers behaviour analysis and anomaly detection within the change point detection methodology. A novel general framework for change point detection is introduced. Gaussian process time series data is considered and a change is defined as an alteration in hyperparameters of the Gaussian process prior. The problem is formulated in the context of statistical hypothesis testing and several tests suitable both for offline and online data processing and multiple change point detection are proposed. Theoretical properties of the proposed tests are derived based on the distribution of the test statistics.
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Rieger, James L., and Sherri L. Gattis. "A Comparison of Various Video Compression Methods for Use in Instrumentation Systems." International Foundation for Telemetering, 1993. http://hdl.handle.net/10150/608873.
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International Telemetering Conference Proceedings / October 25-28, 1993 / Riviera Hotel and Convention Center, Las Vegas, Nevada<br>Various forms of 'lossy' and 'lossless' encoding have been
implemented or proposed to allow compression of still and motion picture
images, with varying degrees of success which in turn depend on how
success is defined. Proponents of various systems claim 'compression
ratios' which by their nature defy comparison of one system with another
and suggest there actually may be something like a free lunch. This paper
compares various compression methods as well as the implications
involved in using them and what happens when different systems
encounter the problems associated with the uses of the restored picture.
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Shahid, Muhammad. "Methods for Objective and Subjective Video Quality Assessment and for Speech Enhancement." Doctoral thesis, Blekinge Tekniska Högskola [bth.se], Faculty of Engineering - Department of Applied Signal Processing, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-00603.
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The overwhelming trend of the usage of multimedia services has raised the consumers' awareness about quality. Both service providers and consumers are interested in the delivered level of perceptual quality. The perceptual quality of an original video signal can get degraded due to compression and due to its transmission over a lossy network. Video quality assessment (VQA) has to be performed in order to gauge the level of video quality. Generally, it can be performed by following subjective methods, where a panel of humans judges the quality of video, or by using objective methods, where a computational model yields an estimate of the quality. Objective methods and specifically No-Reference (NR) or Reduced-Reference (RR) methods are preferable because they are practical for implementation in real-time scenarios. This doctoral thesis begins with a review of existing approaches proposed in the area of NR image and video quality assessment. In the review, recently proposed methods of visual quality assessment are classified into three categories. This is followed by the chapters related to the description of studies on the development of NR and RR methods as well as on conducting subjective experiments of VQA. In the case of NR methods, the required features are extracted from the coded bitstream of a video, and in the case of RR methods additional pixel-based information is used. Specifically, NR methods are developed with the help of suitable techniques of regression using artificial neural networks and least-squares support vector machines. Subsequently, in a later study, linear regression techniques are used to elaborate the interpretability of NR and RR models with respect to the selection of perceptually significant features. The presented studies on subjective experiments are performed using laboratory based and crowdsourcing platforms. In the laboratory based experiments, the focus has been on using standardized methods in order to generate datasets that can be used to validate objective methods of VQA. The subjective experiments performed through crowdsourcing relate to the investigation of non-standard methods in order to determine perceptual preference of various adaptation scenarios in the context of adaptive streaming of high-definition videos. Lastly, the use of adaptive gain equalizer in the modulation frequency domain for speech enhancement has been examined. To this end, two methods of demodulating speech signals namely spectral center of gravity carrier estimation and convex optimization have been studied.
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McKernan, Brian. "Interactivity, Interdependence, and Intertextuality| The Meaning of Video Games in American Civil Society." Thesis, State University of New York at Albany, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=3591689.
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<p> In recent years the video game community has undergone a drastic transformation. What began as a communal pastime for programmers in federally-funded research laboratories during the late 1950s and 1960s has erupted into a multi-billion dollar industry enjoyed by millions of Americans. Reflecting this transformation, social scientists from a wide variety of fields have begun to explore video games' social significance. Sadly, so far very little work has examined video games from a sociological viewpoint. In this work I attempt to remedy this serious omission by adopting a cultural sociology framework to study video games' social meanings in three different mediated spaces, including <i>The New York Times,</i> the popular video game media outlet <i>Kotaku,</i> and the internet discussion forum NeoGAF. Consistent with recent work on entertainment commentary's capacity to function as an aesthetic public sphere, my analysis demonstrates that discussions occurring in all three spaces address broader sociopolitical concerns. However, the frequency in which these spaces engage in sociopolitical discussions, the type of topics they address, and the manner in which they do so vary. Consequently, my work adds new insight to the literature by highlighting how aesthetic public spheres are not isomorphic, but instead assume a variety of forms. Moreover, my work demonstrates how the particular type of aesthetic public sphere that an entertainment public facilitates is influenced by that entertainment public's position in civil society, the specific meaning the space attaches to the entertainment form under discussion, and civil society's overarching cultural structure. In this sense, my work strengthens the literature's understanding of entertainment's role in civil society by revealing the multiple forms entertainment commentary can assume and the sociological factors that influence the shape of these discourses.</p>
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Gommelet, David. "Methods for improving the backward compatible High Dynamic Range compression." Thesis, Rennes 1, 2018. http://www.theses.fr/2018REN1S033/document.
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Ces dernières années, les contenus vidéos ont évolué très rapidement. En effet, les télévisions (TV) ont rapidement évolué vers l’Ultra Haute résolution (UHD), la Haute Fréquence d’images (HFR) ou la stéréoscopie (3D). La tendance actuelle est à l’imagerie à Haute Dynamique de luminance (HDR). Ces technologies permettent de reproduire des images beaucoup plus lumineuses que celles des écrans actuels. Chacune de ces améliorations représente une augmentation du coût de stockage et nécessite la création de nouveaux standards de compression vidéo, toujours plus performant. La majorité des consommateurs est actuellement équipé de TV ayant une Dynamique Standard (SDR) qui ne supportent pas les contenus HDR et ils vont lentement renouveler leurs écrans pour un HDR. Il est donc important de délivrer un signal HDR qui puisse être décodé par ces deux types d’écrans. Cette rétro compatibilité est rendue possible par un outil appelé TMO (Tone Mapping Operator) qui transforme un contenu HDR en une version SDR. Au travers de cette thèse, nous explorons de nouvelles méthodes pour améliorer la compression HDR rétro compatible. Premièrement, nous concevons un TMO qui optimise les performances d’un schéma de compression scalable où une couche de base et d’amélioration sont envoyées pour reconstruire les contenus HDR et SDR. Il est démontré que le TMO optimal dépend seulement de la couche SDR de base et que le problème de minimisation peut être séparé en deux étapes consécutives. Pour ces raisons, nous proposons ensuite un autre TMO conçu pour optimiser les performances d’un schéma de compression utilisant uniquement une couche de base mais avec un modèle amélioré et plus précis. Ces deux travaux optimisent des TMO pour images fixes. Par la suite, la thèse se concentre sur l’optimisation de TMO spécifiques à la vidéo. Cependant, on y démontre que l’utilisation d’une prédiction pondérée pour la compression SDR est aussi bon voir meilleur que d’utiliser un TMO optimisé temporellement. Pour ces raisons, un nouvel algorithme et de nouveaux modes de prédictions pondérées sont proposés pour gérer plus efficacement la large diversité des changements lumineux dans les séquences vidéos<br>In recent years, video content evolved very quickly. Indeed, televisions (TV) quickly evolved to Ultra High Definition (UHD), High Frame Rate (HFR) or stereoscopy (3D). The recent trend is towards High Dynamic range (HDR). These new technologies allow the reproduction of much brighter images than for actual displays. Each of these improvements represents an increase in storage cost and therefore requires the creation of new video compression standards, always more efficient. The majority of consumers are currently equipped with Standard Dynamic Range (SDR) displays, that cannot handle HDR content. Consumers will slowly renew their display to an HDR one and it is therefore of great importance to deliver an HDR signal that can be decoded by both SDR and HDR displays. Such backward compatibility is provided by a tool called Tone Mapping Operator (TMO) which transforms an HDR content into an SDR version. In this thesis, we explore new methods to improve the backward compatible HDR compression. First, we design a Tone Mapping to optimize scalable compression scheme performances where a base and an enhancement layer are sent to reconstruct the SDR and HDR content. It is demonstrated that the optimum TMO only depends on the SDR base layer and that the minimization problem can be separated in two consecutive minimization steps. Based on these observations, we then propose another TMO designed to optimize the performances of compression schemes using only a base layer but with an enhanced and more precise model. Both of these works optimize TMO for still images. Thereafter, this thesis focuses on the optimization of video-specific TMO. However, we demonstrate that using a weighted prediction for the SDR compression is as good or even better than using a temporally optimized TMO. Therefore, we proposed a new weighted prediction algorithm and new weighted prediction modes to handle more efficiently the large diversity of brightness variations in video sequences
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von, dem Knesebeck Matthias. "Fast motion estimation methods for H.264 video coding on mobile devices." Thesis, University of British Columbia, 2010. http://hdl.handle.net/2429/28761.
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Digital video is becoming an increasingly widespread application on a multitude of devices ranging from mobile devices to digital cinema. Technological advancements in processing speed and available bandwidth along with substantial improvements in compression techniques enable completely new applications and services for digital video content.
The most demanding task in video encoding is the motion estimation process which aims to identify similarities to previously transmitted video frames. Up to 90% of the processing requirements are attributable to this element.
In this thesis, we present three methods for encoding new and transcoding existing video content with significantly reduced computational complexity while maintaining both quality and bitrate.
The first method reduces the number of steps required to perform motion estimation by adaptively adjusting the search accuracy needed in distortion measurement.
The second method addresses the topic of mode decision in video encoding and provides an algorithm that allows an early decision about the most probable modes without the need to evaluate all 259 different combinations of block sizes.
The third method provides a multi-dimensional measure that facilitates evaluating only the most likely modes for efficiently transcoding existing pre-encoded content to lower resolutions with an arbitrary downscaling ratio. This is an important factor for the ever-growing number of devices and application scenarios that access existing pre-encoded content. Our method supplements existing fast transcoding schemes that primarily focus on efficiently determining motion vectors in transcoding.
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Arias, Martínez Pablo. "Variational methods for exemplar-based image inpainting and gradient-domain video editing." Doctoral thesis, Universitat Pompeu Fabra, 2013. http://hdl.handle.net/10803/125063.
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In this thesis we tackle two problems which deal with filling-in the information in a region of an image or a video, where the data is either missing or has to be replaced. These problems have applications in the context of image and video editing. The first is image inpainting, and aims at obtaining a visually plausible completion in a region in which data is missing due to damage or occlusion. The second problem concerns the propagation of an editing performed by a user in one or two reference frames of a video, throughout the rest of the video. Both problems are of theoretical interest since their analysis involves an understanding of the self-similarity in natural images and videos. At a high level, the common theme in both problems, is the exploitation and imposition of a model of redundancy (or
self-similarity) to fill-in missing parts of a signal.<br>En esta tesis consideramos dos problemas que tratan el completado de una
imagen o un video en una región en la que los datos o bien faltan (por
ejemplo porque han sido dañados) o bien tienen que ser sustituídos. Estos
problemas tienen aplicación en el contexto de edición de imagen y video. El
primero de estos problemas es el de inpainting de imágenes, cuyo objetivo
es dar una completación plausible en la región en la que faltan datos. El
segundo problema consiste en la propagación de una edición proporcionada
por un usuario en un cuadro de un video, a los demás cuadros. Además
de su aplicación práctica, ambos problemas son de interés teórico, ya que
su análisis requiere una compresión de la estructura de auto-similitud de
las imagenes y videos naturales. De hecho, a nivel conceptual ambos temas
tienen en común el cómo aprovechar e imponer la redundancia de una señal
para completar partes faltantes.
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Rasch, Jennifer [Verfasser]. "Signal Adaptive Methods To Optimize Prediction Signals in Video Coding / Jennifer Rasch." Berlin : epubli, 2019. http://d-nb.info/1199686522/34.
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Izmirliev, Antoan. "Methods for improving quality of block based compressed still and video images." Thesis, University of Strathclyde, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366928.
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Seyedebrahimi, Mirghiasaldin. "Quality-driven resource utilization methods for video streaming in wireless communication networks." Thesis, Aston University, 2015. http://publications.aston.ac.uk/27533/.
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This research is focused on the optimisation of resource utilisation in wireless mobile networks with the consideration of the users’ experienced quality of video streaming services. The study specifically considers the new generation of mobile communication networks, i.e. 4G-LTE, as the main research context. The background study provides an overview of the main properties of the relevant technologies investigated. These include video streaming protocols and networks, video service quality assessment methods, the infrastructure and related functionalities of LTE, and resource allocation algorithms in mobile communication systems. A mathematical model based on an objective and no-reference quality assessment metric for video streaming, namely Pause Intensity, is developed in this work for the evaluation of the continuity of streaming services. The analytical model is verified by extensive simulation and subjective testing on the joint impairment effects of the pause duration and pause frequency. Various types of the video contents and different levels of the impairments have been used in the process of validation tests. It has been shown that Pause Intensity is closely correlated with the subjective quality measurement in terms of the Mean Opinion Score and this correlation property is content independent. Based on the Pause Intensity metric, an optimised resource allocation approach is proposed for the given user requirements, communication system specifications and network performances. This approach concerns both system efficiency and fairness when establishing appropriate resource allocation algorithms, together with the consideration of the correlation between the required and allocated data rates per user. Pause Intensity plays a key role here, representing the required level of Quality of Experience (QoE) to ensure the best balance between system efficiency and fairness. The 3GPP Long Term Evolution (LTE) system is used as the main application environment where the proposed research framework is examined and the results are compared with existing scheduling methods on the achievable fairness, efficiency and correlation. Adaptive video streaming technologies are also investigated and combined with our initiatives on determining the distribution of QoE performance across the network. The resulting scheduling process is controlled through the prioritization of users by considering their perceived quality for the services received. Meanwhile, a trade-off between fairness and efficiency is maintained through an online adjustment of the scheduler’s parameters. Furthermore, Pause Intensity is applied to act as a regulator to realise the rate adaptation function during the end user’s playback of the adaptive streaming service. The adaptive rates under various channel conditions and the shape of the QoE distribution amongst the users for different scheduling policies have been demonstrated in the context of LTE. Finally, the work for interworking between mobile communication system at the macro-cell level and the different deployments of WiFi technologies throughout the macro-cell is presented. A QoEdriven approach is proposed to analyse the offloading mechanism of the user’s data (e.g. video traffic) while the new rate distribution algorithm reshapes the network capacity across the macrocell. The scheduling policy derived is used to regulate the performance of the resource allocation across the fair-efficient spectrum. The associated offloading mechanism can properly control the number of the users within the coverages of the macro-cell base station and each of the WiFi access points involved. The performance of the non-seamless and user-controlled mobile traffic offloading (through the mobile WiFi devices) has been evaluated and compared with that of the standard operator-controlled WiFi hotspots.
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Tarczyńska, Anna. "Methods of Text Information Extraction in Digital Videos." Thesis, Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-2656.
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Context The huge amount of existing digital video files needs to provide indexing to make it available for customers (easier searching). The indexing can be provided by text information extraction. In this thesis we have analysed and compared methods of text information extraction in digital videos. Furthermore, we have evaluated them in the new context proposed by us, namely usefulness in sports news indexing and information retrieval. Objectives The objectives of this thesis are as follows: providing a better understanding of the nature of text extraction; performing a systematic literature review on various methods of text information extraction in digital videos of TV sports news; designing and executing an experiment in the testing environment; evaluating available and promising methods of text information extraction from digital video files in the proposed context associated with video sports news indexing and retrieval; providing an adequate solution in the proposed context described above. Methods This thesis consists of three research methods: Systematic Literature Review, Video Content Analysis with the checklist, and Experiment. The Systematic Literature Review has been used to study the nature of text information extraction, to establish the methods and challenges, and to specify the effective way of conducting the experiment. The video content analysis has been used to establish the context for the experiment. Finally, the experiment has been conducted to answer the main research question: How useful are the methods of text information extraction for indexation of video sports news and information retrieval? Results Through the Systematic Literature Review we identified 29 challenges of the text information extraction methods, and 10 chains between them. We extracted 21 tools and 105 different methods, and analyzed the relations between them. Through Video Content Analysis we specified three groups of probability of text extraction from video, and 14 categories for providing video sports news indexation with the taxonomy hierarchy. We have conducted the Experiment on three videos files, with 127 frames, 8970 characters, and 1814 words, using the only available MoCA tool. As a result, we reported 10 errors and proposed recommendations for each of them. We evaluated the tool according to the categories mentioned above and offered four advantages, and nine disadvantages of the Tool mentioned above. Conclusions It is hard to compare the methods described in the literature, because the tools are not available for testing, and they are not compared with each other. Furthermore, the values of recall and precision measures highly depend on the quality of the text contained in the video. Therefore, performing the experiments on the same indexed database is necessary. However, the text information extraction is time consuming (because of huge amount of frames in video), and even high character recognition rate gives low word recognition rate. Therefore, the usefulness of text information extraction for video indexation is still low. Because most of the text information contained in the videos news is inserted in post-processing, the text extraction could be provided in the root: during the processing of the original video, by the broadcasting company (e.g. by automatically saving inserted text in separate file). Then the text information extraction will not be necessary for managing the new video files<br>The huge amount of existing digital video files needs to provide indexing to make it available for customers (easier searching). The indexing can be provided by text information extraction. In this thesis we have analysed and compared methods of text information extraction in digital videos. Furthermore, we have evaluated them in the new context proposed by us, namely usefulness in sports news indexing and information retrieval.
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Haines, Cory. "Race, Gender, and Sexuality Representation in Contemporary Triple-A Video Game Narratives." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/94573.
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By conducting both qualitative and quantitative analysis of data from interviews and game content, I examine representations of race, gender, and sexuality in contemporary video-game narratives. I use data from interviews to show how they view their representations in this medium and to set categorical criteria for an interpretive content analysis. I analyze a sample of top-selling narrative-driven video games in the United States released from 2016-2019. My content coding incorporates aforementioned interview data as well as theoretical-based and intersectional concepts on video game characters and their narratives. The content analysis includes measures of narrative importance, narrative role, positivity of representation, and demographic categories of characters, though the scale of this study may not allow for a full test of intersectional theory of links between demographics and roles. Interview and content analysis results suggest an overrepresentation of white characters and extreme under-representation of non-white women.<br>I examine representations of race, gender, and sexuality in contemporary video-game narratives. I use data from interviews to show how people view their representations in video games and to set a guide for analyzing the games themselves. I analyze a sample of top-selling narrativedriven video games in the United States released from 2016-2019. My content coding incorporates aforementioned interview data as well as theoretical-based and intersectional concepts on video game characters and their narratives. The content analysis includes measures of narrative importance, narrative role, positivity of representation, and demographic categories of characters, though the scale of this study may not allow for a full test of intersectional theory of links between demographics and roles. Interview and content analysis results suggest an overrepresentation of white characters and extreme under-representation of non-white women.
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Hoorn, Ryno. "Comparison and evaluation of mass video notification methods used to assist Deaf people." Thesis, University of the Western Cape, 2012. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_2022_1370594013.
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<p>In South Africa, Deaf people communicate with one another and the broader community by means of South African Sign Language. The majority of Deaf people who have access to a mobile <br>phone (cell phone) use Short Message Service (SMS) to communicate and share information with hearing people, but seldom use it among themselves. It is assumed that video messaging <br>will be more accessible to Deaf people, since their <br>level of literacy may prevent them from making effective use of information that is disseminated via texting/SMS. The principal objective of the <br>esearch was to explore a cost-effective and efficient mass multimedia messaging system. The intention was to adapt a successful text-based mass notification system, developed by a <br>local nongovernmental organization (NGO), to accommodate efficient and affordable video mass messaging for Deaf people. The questions that underpin this research are: How should video- streaming mass-messaging methods be compared and evaluated to find the most suitable method to deliver an affordable and acceptable service to Deaf people? What transport vehicles <br> <br> <br>should be considered: Multimedia Message Service (MMS), the web, electronic mail, or a cell phone resident push/pullapplication? Which is the most cost effective? And, finally: How does the video quality of the various transport vehicles differ in terms of the clarity of the sign language as perceived by the Deaf? The soft-systems methodology and a mixed-methods methodology <br>were used to address the research questions. The soft-systems methodology was followed to manage the research process and the mixed-methods research methodology was followed to <br>collect data. Data was collected by means of experiments and semi-structured interviews. A prototype for mobile phone usage was developed and evaluated with Deaf members the NGO Deaf <br>Community of Cape Town. The technology and internet <br>usage of the Deaf participants provided background information. The Statistical Package for Social Science (SPSS) was used to analyse <br>the quantitative data, and content analysis was used to analyse the documents and interviews. All of the Deaf participants used their mobile phones for SMS and the majority (81.25%) used <br>English to type messages<br>however, all indicated that they would have preferred to use South Africa sign language on their mobile phones if it were available. And they were quite willing to pay between 75c and 80c per message for using such a video-messaging <br>service.Of the transport vehicles demonstrated, most Deaf people indic indicated that they preferred to use the SMS <br>prototype (with a web link to the video) rather than the MMS prototype with the video attached. They were, however, very concerned about the cost of using the system, as well as the quality of the sign language videos.</p>
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Zhang, Huimin. "User Behavior Analysis and Prediction Methods for Large-scale Video-on- demand System." Thesis, Uppsala universitet, Institutionen för informationsteknologi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-263261.
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Video-on-demand (VOD) systems are some of the best-known examples of 'next-generation' Internet applications. With their growing popularity, huge amount of video content imposes a heavy burden on Internet traffic which, in turns, influences the user experience of the systems. Predicting and pre- fetching relevant content before user requests is one of the popular methods used to reduce the start-up delay. In this paper, a typical VOD system is characterized and user's watching behavior is analyzed. Based on the characterization, two pre- fetching approaches based on user behavior are investigated. One is to prediction relevant content based on access history. The other is prediction based on user-clustering. The results clearly indicate the value of pre-fetching approaches for VOD systems and lead to the discussions on future work for further improvement.
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Chen, Jin. "Novel Bayesian methods for video super-resolution based on heavy-tailed statistical models." Thesis, University of Bristol, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.680379.
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In this thesis, we firstly introduce the application of the Generalized Gaussian Markov Random Field (GGMRF) to the problem of video super-resolution. The GGMRF prior is employed to perform a maximum a posteriori (MAP) estimation of the desired high-resolution image. Compared with traditional prior models, the GGMRF can describe the distribution of the high-resolution image much better and can also preserve better the discontinuities (edges) of the original image. Previous work had used GGMRF for image restoration in which the temporal dependencies among video frames are not considered. Since the corresponding energy function is convex, gradient descent optimisation techniques are used to solve the MAP estimation. Results show the super-resolved images using the GGMRF prior not only offers a good visual quality enhancement, but also contain a significantly smaller amount of noise. We then propose a Bayesian-based super resolution algorithm that uses approximations of symmetric alpha-stable (SaS) Markov Random Fields (MRF) as prior. The approximated SaS prior is employed to perform MAP estimation for the high-resolution (RR) image reconstruction process. Compared with other state-of-the-art prior models, the proposed prior can better capture the heavy tails of the distribution of the HR image. Thus, the edges of the reconstructed HR image are preserved better in our method. Since the corresponding energy function is non-convex, the graduated nonconvexity (GNC) method is used to solve the MAP estimation. Experiments confirm the better fit achieved by the proposed model to the actual data distribution and the consequent improvement in terms of visual quality over previously proposed super resolution algorithms . . A joint video fusion and super-resolution algorithm is also proposed in this thesis. The method addresses the problem of generating a high-resolution HR image from infrared (IR) and visible (VI) low-resolution (LR) images, in a Bayesian framework. In order to preserve better the discontinuities, a Generalized Gaussian Markov Random Field (MRF) is used to formulate the prior. Experimental results demonstrate that information from both visible and infrared bands is recovered from the LR frames in an effective way. Finally, a novel video super-resolution image reconstruction algorithm that based on low rank matrix completion algorithm is presented. The proposed algorithm addresses the problem of generating a HR image from several LR images, based on sparse representation and low-rank matrix completion. The approach represents observed LR frames in the form of sparse matrices and rearranges those frames into low dimensional constructions. Experimental results demonstrate that, high-frequency details in the super resolved images are recovered from the LR frames .
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Hemmati, Mahdi. "New Bandwidth Allocation Methods to Provide Quality-of-Experience Fairness for Video Streaming Services." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/36626.
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Video streaming over the best-effort networks is a challenging problem due to the time-varying and uncertain characteristics of the links. When multiple video streams are present in a network, they share and compete for the common bandwidth. In such a setting, a bandwidth allocation algorithm is required to distribute the available resources among the streams in a fair and efficient way. Specifically, it is desired to establish fairness across end-users' Quality of Experience (QoE).
In this research, we propose three novel methods to provide QoE-fair network bandwidth allocation among multiple video streaming sessions. First, we formulate the problem of bandwidth allocation for video flows in the context of Network Utility Maximization (NUM) framework, using sigmoidal utility functions, rather than conventional but unrealistic concave functions. An approximation algorithm for Sigmoidal Programming (SP) is utilized to solve the resulting nonconvex optimization problem, called NUM-SP. Simulation results indicate improvements of at least 60% in average utility/QoE and 45% in fairness, while using slightly less network resources, compared to two representative methods.
Subsequently, we take a collaborative decision-theoretic approach to the problem of rate adaptation among multiple video streaming sessions, and design a multi-objective foresighted optimization model for network resource allocation. A social welfare function is constructed to capture both fairness and efficiency objectives at the same time. Then, assuming a common altruistic goal for all network users, we use multi-agent decision processes to find the optimal policies for all players.
We propose a Decentralized Partially Observable Markov Decision Process (Dec-POMDP) model for the conventional IP networks and a Multi-agent Markov Decision Process (MMDP) model for the SDN-enabled wireless networks. By planning these cooperative decision process models, we find the optimal network bandwidth allocation that leads to social welfare maximization. Distributed multi-agent reinforcement learning algorithms are also designed and proposed as a low-complexity model-free solution to these optimization problems.
Simulations of the proposed methods show that the resulting optimal policies of the novel Social Utility Maximization (SUM) framework outperform existing approaches in terms of both efficiency and fairness. The Dec-POMDP model applied to a server-side rate adaptation results in 25% improvement in efficiency and 13% improvement in fairness, compared to one popular protocol of congestion control for multimedia streaming. Our performance evaluations also show that the MMDP model applied to a client-side rate adaptation like DASH improves efficiency, fairness, and social welfare by as much as 18%, 24%, and 25%, respectively compared to current state-of-the-art.