Dissertations / Theses on the topic 'Spatial scalability'
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Cary, Ariel. "Scaling Geospatial Searches in Large Spatial Databases." FIU Digital Commons, 2011. http://digitalcommons.fiu.edu/etd/548.
Full textMollevik, Johan. "Natural language interfaces over spatial data : investigations in scalability, extensibility and reliability." Licentiate thesis, Umeå universitet, Institutionen för datavetenskap, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-87705.
Full textThorne, Chris. "Origin-centric techniques for optimising scalability and the fidelity of motion, interaction and rendering." University of Western Australia. School of Computer Science and Software Engineering, 2008. http://theses.library.uwa.edu.au/adt-WU2008.0177.
Full textRicher, Gaëlle. "Passage à l'échelle pour la visualisation interactive exploratoire de données : approches par abstraction et par déformation spatiale." Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0264/document.
Full textInteractive visualization is helpful for exploring, understanding, and analyzing data. However, increasingly large and complex data challenges the efficiency of visualization systems, both visually and computationally. The visual challenge stems from human perceptual and cognitive limitations as well as screen space limitations while the computational challenge stems from the processing and memory limitations of standard computers.In this thesis, we present techniques addressing the two scalability issues for several interactive visualization applications.To address visual scalability requirements, we present a versatile spatial-distortion approach for linked emphasis on multiple views and an abstract and multi-scale representation based on parallel coordinates. Spatial distortion aims at alleviating the weakened emphasis effect of highlighting when applied to small-sized visual elements. Multiscale abstraction simplifies the representation while providing detail on demand by pre-aggregating data at several levels of detail.To address computational scalability requirements and scale data processing to billions of items in interactive times, we use pre-computation and real-time computation on a remote distributed infrastructure. We present a system for multi-/dimensional data exploration in which the interactions and abstract representation comply with a visual item budget and in return provides a guarantee on network-related interaction latencies. With the same goal, we compared several geometric reduction strategies for the reconstruction of density maps of large-scale point sets
Tchappi, haman Igor. "Dynamic Multilevel and Holonic Model for the Simulation of a Large-Scale Complex System with Spatial Environment : Application to Road Traffic Simulation." Thesis, Bourgogne Franche-Comté, 2020. http://www.theses.fr/2020UBFCA004.
Full textNowadays, with the emergence of connected objects and cars, road traffic systems become more and more complex and exhibit hierarchical behaviours at several levels of detail. The multilevel modeling approach is an appropriate approach to represent traffic from several perspectives. Multilevel models are also an appropriate approach to model large-scale complex systems such as road traffic. However, most of the multilevel models of traffic proposed in the literature are static because they use a set of predefined levels of detail and these representations cannot change during simulation. Moreover, these multilevel models generally consider only two levels of detail. Few works have been interested on the dynamic multilevel traffic modeling.This thesis proposes a holonic multilevel and dynamic traffic model for large scale traffic systems. The dynamic switching of the levels of detail during the execution of the simulation allows to adapt the model to the constraints related to the quality of the results or to the available computing resources.The proposal extends the DBSCAN algorithm in the context of holonic multi-agent systems. In addition, a methodology allowing a dynamic transition between the different levels of detail is proposed. Multilevel indicators based on standard deviation are also proposed in order to assess the consistency of the simulation results
Lhuillier, Yves. "Architecture et programmation spatiale." Paris 11, 2005. http://www.theses.fr/2005PA112267.
Full textCurrent processor and multiprocessor architectures are almost all based on the Von Neumann paradigm. Based on this paradigm, one can build a general-purpose computer using very few transistors. The performance improvement of Von Neumann processors was mainly due to the increase in clock frequency of silicon technologies. Because clock frequency may no longer increase as quickly, there is a growing consensus on on-chip concurrent architectures being a major route for the efficient exploitation of an increasing number of transistors. In this thesis, we first introduce a new computing model, the “Blob Computing” defining both an architecture and a language, that is intrinsically designed to exploit space. Through this model, we also want to outline that revisiting some of the principles of today's computing paradigm has the potential of overcoming major limitations of current architectures. Finaly, we propose an implementation of the “Blob Computing” main ideas on more traditional architectures (multithreaded processors). Thanks to this implementation, we advocate that research efforts should further focus on striking the right balance between architecture, compiler and user effort. Especially, we show that letting the user reasonably effortlessly pass information on program parallel properties and making the architecture ``aware'' of this additional information is a promising path for futur processors scalability
Mrak, Marta. "Motion scalability for video coding with flexible spatio-temporal decompositions." Thesis, Queen Mary, University of London, 2007. http://qmro.qmul.ac.uk/xmlui/handle/123456789/1907.
Full textHerrou, Glenn. "Résolution Spatio-temporelle Adaptative pour un Codage à Faible Complexité des Formats Vidéo Émergents." Thesis, Rennes, INSA, 2019. http://www.theses.fr/2019ISAR0020.
Full textThe definition of the latest Ultra-High Definition TV (UHDTV) standard aims to increase the user’s quality of experience by introducing new video signal features such as 4K and High Frame-Rate (HFR). However, these new features multiply by a factor 8 the amount of data to be processed before transmission to the end user.In addition to this new format, broadcasters and Over-The-Top (OTT) content providers have to encode videos in different formats and at different bitrates due to the wide variety of devices with heterogeneous video format and network capacities used by consumers.SHVC, the scalable extension of the latest video coding standard High Efficiency Video Coding (HEVC) is a promising solution to address these issues but its computationally demanding architecture reaches its limit with the encoding and decoding of the data-heavy newly introduced immersive video features of the UHDTV video format.The objective of this thesis is thus to investigate lightweight scalable encoding approaches based on the adaptation of the spatio-temporal resolution. The first part of this document proposes two pre-processing tools, respectively using polyphase and wavelet frame-based approaches, to achieve spatial scalability with a slight complexity overhead.Then, the second part of this thesis addresses the design of a more conventional dual-layer scalable architecture using an HEVC encoder in the Base Layer (BL) for backward compatibility and a proposed low-complexity encoder, based on the local adaptation of the spatial resolution, for the Enhancement Layer (EL).Finally, the last part of this thesis investigates spatiotemporal resolution adaptation. A variable frame-rate algorithm is first proposed as pre-processing. This solution has been designed to locally and dynamically detect the lowest frame-rate that does not introduce visible motion artifacts. The proposed variable frame-rate and adaptive spatial resolution algorithms are then combined to offer a lightweight scalable coding of 4K HFR video contents
Cortés, Rudyar. "Scalable location-temporal range query processing for structured peer-to-peer networks." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066106/document.
Full textIndexing and retrieving data by location and time allows people to share and explore massive geotagged datasets observed on social networks such as Facebook, Flickr, and Twitter. This scenario known as a Location Based Social Network (LBSN) is composed of millions of users, sharing and performing location-temporal range queries in order to retrieve geotagged data generated inside a given geographic area and time interval. A key challenge is to provide a scalable architecture that allow to perform insertions and location-temporal range queries from a high number of users. In order to achieve this, Distributed Hash Tables (DHTs) and the Peer-to-Peer (P2P) computing paradigms provide a powerful building block for implementing large scale applications. However, DHTs are ill-suited for supporting range queries because the use of hash functions destroy data locality for the sake of load balance. Existing solutions that use a DHT as a building block allow to perform range queries. Nonetheless, they do not target location-temporal range queries and they exhibit poor performance in terms of query response time and message traffic. This thesis proposes two scalable solutions for indexing and retrieving geotagged data based on location and time
Trocan, Maria. "Décompositions spatio-temporelles et allocation de débit en utilisant les coupures de graphe pour le codage vidéo scalable." Paris, ENST, 2007. http://www.theses.fr/2007ENST0032.
Full textThe recent progress in wavelet-based video coding led to the emergence of a new generation of scalable video schemes, whose performance is comparable to that of the best hybrid codecs. The t+2D subband coding methods exploit the temporal interframe redundancy by applying an open-loop temporal wavelet transform over the frames of a video sequence. The temporally-filtered subband frames are further spatially decomposed and entropy coded. Due to their inherent multiresolution signal representation, wavelet-based coding schemes have the potential to support temporal, spatial and SNR scalability. This is the main reason for chosing the scalable lifting-based wavelet-coding paradigm as the conceptual development framework for this thesis work. The objective of this thesis consists of the analysis and design of an efficient scalable video-coding system. In a first time, we are interested in the construction and optimization of motion-compensated temporal coding schemes, in order to enhance both the objective and subjective coding quality. Moreover, we describe a better representation of the temporal subbands by using anisotropic spatial decompositions. Finally, we improve the entropy coding by designing a graph-cut solvable energy functional for the Lagrangian rate-distortion optimization problem
Trocan, Maria. "Décompositions spatio-temporelles et allocation de débit en utilisant les coupures de graphe pour le codage vidéo scalable /." Paris : École nationale supérieure des télécommunications, 2008. http://catalogue.bnf.fr/ark:/12148/cb412736552.
Full textCapobianco, Julien. "Codage audio stéréo avancé." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066712/document.
Full textDuring the last ten years, technics for joint coding exploiting relations and redundancies between channels have been developped in order to further reduce the amount of information needed to represent multichannel audio signals.In this document, we focus on the coding of stereo audio signals where prior informations on the nature of sources in presence, their number or the manner they are spatialized is unknown. Such signals are actually the most representative in commercial records of music industry and in multimedia entertainment in general. To address the coding problematic of these signals, we study parametric and signal approaches, where both of them are often mixed.In this context, three types of approaches are used. The spatial parametric approach reduce the number of audio channels of the signal to encode and recreate the original number of channels from reduced channels and spatial parameters extracted from original channels. The signal approach keep the original number of channels, but encode mono signals, built from the combination of the original ones and containing less redundancies. Finally, the hybrid approach introduced in the MPEG USAC standard keep the two channels of a stereo signal, but one is a mono downmix and the other is a residual signal, resulting from a prediction on the downmix, where prediction parameters are encoded as side information.In this document, we first analyse the characteristics of a stereo audio signal coming from a commercial recording and the associated production techniques. This study lead us to consider the relations between the emitter parametric models, elaborated from our analysis of commercial recording production techniques, and the receiver models which are the basis of spatial parametric coding. In the light of these considerations, we present and study the three approaches mentioned earlier. For the parametric approach, we show that transparency cannot be achieved for most of the stereo audio signals, we have a reflection on parametric representations and we propose techniques to improve the audio quality and further reduce the bitrate of their parameters. These improvements are obtained by applying a better segmentation on the signal, based on the significant transient, by exploiting perceptive characteristics of some spatial cues and by adapting the estimation of spatial cues. As the hybrid approach has been recently standardized in MPEG USAC, we propose a full review of it, then we develop a new coding technique to optimize the allocation of the residual bands when the residual is not used on the whole bandwidth of the signal to encode. In the conclusion, we discuss about the future of the general spatial audio coding and we show the importance of developping new technics of segmentation and classification for audio signals to further adapt the coding to the content of the signal
Samrouth, Khouloud. "Représentation et compression à haut niveau sémantique d’images 3D." Thesis, Rennes, INSA, 2014. http://www.theses.fr/2014ISAR0025/document.
Full textDissemination of multimedia data, in particular the images, continues to grow very significantly. Therefore, developing effective image coding schemes remains a very active research area. Today, one of the most innovative technologies in this area is the 3D technology. This 3D technology is widely used in many domains such as entertainment, medical imaging, education and very recently in criminal investigations. There are different ways of representing 3D information. One of the most common representations, is to associate a depth image to a classic colour image called texture. This joint representation allows a good 3D reconstruction, as the two images are well correlated, especially along the contours of the depth image. Therefore, in comparison with conventional 2D images, knowledge of the depth of field for 3D images provides an important semantic information about the composition of the scene. In this thesis, we propose a scalable 3D image coding scheme for 2D + depth representation with advanced functionalities, which preserves all the semantics present in the images, while maintaining a significant coding efficiency. The concept of preserving the semantics can be translated in terms of features such as an automatic extraction of regions of interest, the ability to encode the regions of interest with higher quality than the background, the post-production of the scene and the indexing. Thus, firstly we introduce a joint and scalable 2D plus depth coding scheme. First, texture is coded jointly with depth at low resolution, and a method of depth data compression well suited to the characteristics of the depth maps is proposed. This method exploits the strong correlation between the depth map and the texture to better encode the depth map. Then, a high resolution coding scheme is proposed in order to refine the texture quality. Next, we present a global fine representation and contentbased coding scheme. Therefore, we propose a representation and coding scheme based on "Depth of Interest", called "3D Autofocus". It consists in a fine extraction of objects, while preserving the contours in the depth map, and it allows to automatically focus on a particular depth zone, for a high rendering quality. Finally, we propose 3D image segmentation, providing a high consistency between colour, depth and regions of the scene. Based on a joint exploitation of the colour and depth information, this algorithm allows the segmentation of the scene with a level of granularity depending on the intended application. Based on such representation of the scene, it is possible to simply apply the same previous 3D Autofocus, for Depth of Interest extraction and coding. It is remarkable that both approaches ensure a high spatial coherence between texture, depth, and regions, allowing to minimize the distortions along object of interest's contours and then a higher quality in the synthesized views
Trujillo, Rasúa Rolando. "Privacy in rfid and mobile objects." Doctoral thesis, Universitat Rovira i Virgili, 2012. http://hdl.handle.net/10803/86942.
Full textEls sistemes RFID permeten la identificació ràpida i automàtica d’etiquetes RFID a través d’un canal de comunicació sense fils. Aquestes etiquetes són dispositius amb cert poder de còmput i amb capacitat d’emmagatzematge de informació. Es per això que els objectes que porten una etiqueta RFID adherida permeten la lectura d’una quantitat rica i variada de dades que els descriuen i caracteritzen, com per exemple un codi únic d’identificació, el nom, el model o la data d’expiració. A més, aquesta informació pot ser llegida sense la necessitat d’un contacte visual entre el lector i l’etiqueta, la qual cosa agilitza considerablement els processos d’inventariat, identificació o control automàtic. Per a que l’ús de la tecnologia RFID es generalitzi amb èxit, es convenient complir amb diversos objectius: eficiència, seguretat i protecció de la privacitat. No obstant això, el disseny de protocols d’identificació segurs, privats i escalables, es un repte difícil d’abordar dades les restriccions computacionals de les etiquetes RFID i la seva naturalesa sense fils. Es per això que, en la present tesi, partim de protocols d’identificació segurs i privats, i mostrem com es pot aconseguir escalabilitat mitjançant una arquitectura distribuïda i col•laborativa. D’aquesta manera, la seguretat i la privacitat s’aconsegueixen mitjançant el propi protocol d’identificació, mentre que l’escalabilitat s’aconsegueix per mitjà de nous protocols col•laboratius que consideren la posició espacial i temporal de les etiquetes RFID. Independentment dels avenços en protocols d’identificació sense fils, existeixen atacs que poden passar exitosament qualsevol d’aquests protocols sense necessitat de conèixer o descobrir claus secretes vàlides, ni de trobar vulnerabilitats a les seves implantacions criptogràfiques. La idea d’aquestos atacs, coneguts com atacs de “relay”, consisteix en crear inadvertidament un pont de comunicació entre una etiqueta legítima i un lector legítim. D’aquesta manera, l’adversari utilitza els drets de l’etiqueta legítima per passar el protocol d’autentificació utilitzat pel lector. Es important tindre en compte que, dada la naturalesa sense fils dels protocols RFID, aquests tipus d’atacs representen una amenaça important a la seguretat en sistemes RFID. En aquesta dissertació proposem un nou protocol que, a més d’autentificació, realitza una revisió de la distància a la qual es troben el lector i l’etiqueta. Aquests tipus de protocols es coneixen com a “distance-boulding protocols”, els quals no prevenen aquests tipus d’atacs, però si que poden frustrar-los amb alta probabilitat. Per últim, afrontem els problemes de privacitat associats amb la publicació de informació recol•lectada a través de sistemes RFID. En concret, ens concentrem en dades de mobilitat, que també poden ser proveïdes per altres sistemes àmpliament utilitzats tals com el sistema de posicionament global (GPS) i el sistema global de comunicacions mòbils. La nostra solució es basa en la coneguda noció de privacitat “k-anonymity” i parcialment en micro-agregació. Per a aquesta finalitat, definim una nova funció de distància entre trajectòries amb la qual desenvolupen dos mètodes diferents d’anonimització de trajectòries.
Radio Frequency Identification (RFID) is a technology aimed at efficiently identifying and tracking goods and assets. Such identification may be performed without requiring line-of-sight alignment or physical contact between the RFID tag and the RFID reader, whilst tracking is naturally achieved due to the short interrogation field of RFID readers. That is why the reduction in price of the RFID tags has been accompanied with an increasing attention paid to this technology. However, since tags are resource-constrained devices sending identification data wirelessly, designing secure and private RFID identification protocols is a challenging task. This scenario is even more complex when scalability must be met by those protocols. Assuming the existence of a lightweight, secure, private and scalable RFID identification protocol, there exist other concerns surrounding the RFID technology. Some of them arise from the technology itself, such as distance checking, but others are related to the potential of RFID systems to gather huge amount of tracking data. Publishing and mining such moving objects data is essential to improve efficiency of supervisory control, assets management and localisation, transportation, etc. However, obvious privacy threats arise if an individual can be linked with some of those published trajectories. The present dissertation contributes to the design of algorithms and protocols aimed at dealing with the issues explained above. First, we propose a set of protocols and heuristics based on a distributed architecture that improve the efficiency of the identification process without compromising privacy or security. Moreover, we present a novel distance-bounding protocol based on graphs that is extremely low-resource consuming. Finally, we present two trajectory anonymisation methods aimed at preserving the individuals' privacy when their trajectories are released.
Le, Guen Benjamin. "Adaptation du contenu spatio-temporel des images pour un codage par ondelettes." Phd thesis, Université Rennes 1, 2008. http://tel.archives-ouvertes.fr/tel-00355207.
Full textDans cette thèse, nous proposons d'aborder le problème d'adaptativité sous un angle différent. L'idée est de déformer le contenu d'une image pour l'adapter au noyau d'ondelette séparable standard. La déformation est modélisée par un maillage déformable et le critère d'adaptation utilisé est le coût de description de l'image déformée. Une minimisation énergétique similaire à une estimation de mouvement est mise en place pour calculer les paramètres du maillage. A l'issue de cette phase d'analyse, l'image est représentée par une image déformée de moindre coût de codage et par les paramètres de déformation. Après codage, transmission et décodage de ces inforrnations, l'image d'origine peut être synthétisée en inversant la déformation. Les performances en compression de ce schéma par analyse-synthèse spatiales sont étudiées et comparées à celles de JPEG2000. Visuellement, on observe une meilleure reconstruction des contours des images avec une atténuation significative de l'effet rebond.
Conservant l'idée d'adapter le contenu des images à un noyau de décomposition fixe, nous proposons ensuite un schéma de codage par analyse-synthèse spatio-temporelles dédié à la vidéo. L'analyse prend en entrée un groupe d'images (GOF) et génère en sortie un groupe d'images déformées dont le contenu est adapté à une décomposition 3D horizontale-verticale-temporelle fixe. Le schéma est conçu de sorte qu'une seule géométrie soit estimée et transmise pour l'ensemble du GOF. Des résultats de compression sont présentés en utilisant le maillage déformable pour modéliser la géométrie et le mouvement. Bien qu'une seule géométrie soit encodée, nous montrons que son coût est trop important pour permettre une amélioration significative de la qualité visuelle par rapport à un schéma par analyse-synthèse exploitant uniquement le mouvement.
Morand, Claire. "Segmentation spatio-temporelle et indexation vidéo dans le domaine des représentations hiérarchiques." Thesis, Bordeaux 1, 2009. http://www.theses.fr/2009BOR13888/document.
Full textThis thesis aims at proposing a solution of scalable object-based indexing of HD video flow compressed by MJPEG2000. In this context, on the one hand, we work in the hierarchical transform domain of the 9/7 Daubechies' wavelets and, on the other hand, the scalable representation implies to search for multiscale methods, from low to high resolution. The first part of this manuscript is dedicated to the definition of a method for automatic extraction of objects having their own motion. It is based on a combination of a robust global motion estimation with a morphological color segmentation at low resolution. The obtained result is then refined following the data order of the scalable flow. The second part is the definition of an object descriptor which is based on the multiscale histograms of the wavelet coefficients. Finally, the performances of the proposed method are evaluated in the context of scalable content-based queries
Chen, Bo-Cun, and 陳柏村. "Content-Aware Spatial Scalability for Scalable Video Coding." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/45327816437853937519.
Full text國立清華大學
電機工程學系
100
The scalable extension of H.264/AVC (SVC) supports video cropping or uniform-scaling to create different lower resolution video content. However, it will cause information loss, important object deformation or unable to keep important object size in the different lower resolution. Therefore, we want to combine video retargeting with spatial scalability of the H.264/SVC to make sure generating different lower resolution video content can keep essential visual regions and condensing unimportant content. In this thesis, we proposed content-aware spatial scalability for scalable video coding. First of all, we use a mosaic-guide video retargeting method to preserve the important content in the spatial base layer. Moreover, we proposed a low overhead side information coder and several non-homogeneous interlayer prediction coding tools to mitigate the bit-rate overhead in the spatial enhancement layer. The experimental results demonstrate the proposed method not only preserves subjective quality of important content in the lower resolution sequence, but also only has an average 4.17%-4.98% bit-rate overhead.
Lai, Yu-Fan, and 賴昱帆. "Design of An Intra Predictor with Spatial Scalability for Scalable Video Decoding." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/18677824417682053058.
Full text國立交通大學
電子工程系所
97
Scalable Video Coding (SVC) extension of the H.264/AVC is the latest standard in video coding. It has achieved significant improvements in coding efficiency with an increased degree of supported scalability relative to the scalable profiles of prior video coding standards. For supporting spatial scalable coding, SVC follows the conventional approach of multilayer coding. In each spatial layer, motion-compensated prediction and intra-prediction are employed as for single-layer coding. But in order to improve coding efficiency in comparison to simulcasting different spatial resolutions, additional so-called inter-layer prediction mechanisms are incorporated. In particular, H.264/AVC compatible bitstream needs to be decoded in the base layer of SVC. Therefore, a SVC decoder must support both traditional H.264 decoding and SVC extension decoding. Specifically, we propose a high profile SVC intra prediction engine which is composed of two major prediction modules, basic prediction module and Intra_BL prediction module. Basic prediction module is used to decode the traditional H.264 intra prediction. In order to reduce the buffer size for supporting macroblock-adaptive frame field (MBAFF) coding which is supported in high profile, we optimize the buffer size via upper, left, and corner data reuse sets (DRS) to reuse the pixels and improve the cost and access efficiency. In Luma_8x8 decoding process, we simplify the RSF process via a base-mode predictor and optimize the processing latency and buffer cost. For the Intra_BL prediction module which is used to decode the new intra prediction type called “Intra_BL”, we propose an Intra_BL prediction engine that consists of banked SRAM, basic horizontal interpolator, basic vertical interpolator and extended vertical interpolator. We also optimize the architecture of interpolators to have better area efficiency than direct implementation. Based on our preliminary Intra_BL prediction module design, we further propose a power efficient Intra_BL prediction module. By applying a second stage of register sets in memory hierarchy and equality determination before basic interpolation process, a total of 46.43% power consumption can be reduced. Finally, the architecture of this power efficient SVC intra prediction engine is implemented in a 90nm technology with a total area of 42756 NAND2 CMOS gates under working frequency of 145 MHz. The power consumption is 0.292 mW and 2.86 mW under frequency of 100 MHz and 145 MHz for H.264 and SVC, respectively. This design can achieve real-time processing requirement for HD1080 format video in 30fps under the working frequency of 100MHz in H.264, and for a maximum two spatial layers with HD720 and HD1080 scalable format video in 30fps under the working frequency of 145MHz in SVC.
Chi, Pey-Ru, and 紀珮茹. "H.264/SVC Rate Allocation for Spatial Scalability Based on Perceptual Quality Metric." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/68311967548729114089.
Full text國立中央大學
通訊工程研究所
97
H.264 scalable extension (SVC), which is constructed based on H.264/AVC, is the most recent scalable video coding standard. It offers three scalabilities in spatial, temporal, and quality, to meet multiple requirements simultaneously. Spatial scalability that can support multiple display resolutions with a wide range of bitrates is used widely. How to efficiently allocate a given total bitrate among multiple layers under the bandwidth constraint is an important issue and should be solved at first. The base layer is usually treated more important than the enhancement layer because the information in base layer will often be re-used in enhancement layers. Therefore, under a bandwidth constraint, we usually run SVC by fixing the Qutization Parameter (QP) or the bitrate of the base layer while adaptively adjusting the ones of the enhancement layers. However, it is observed that Human Visual System (HVS) is more sensitive to higher resolution videos; in other words, the quality degradation at higher layers to human eyes would be more serious than that at lower layers. The main objective of this work is to achieve best and equal quality for each resolution layer under a given bandwidth constraint. This thesis proposes a rate allocation method for SVC spatial scalability based on perceptual quality metric. We utilize the subjective metric, instead of conventional objective measurement PSNR, to measure video quality. Each resolution layer is measured by the quality metric and allocated with the corresponding rate to have similar quality. The disadvantage of the conventional fixed QP scheme that the higher resolution layer has worse subjective quality is improved. In simulations, several video sequences with various total rate constraints are experimented. The proposed method can efficiently allocate the rate for each layer with almost the same video quality in subjective measurement.
Huang, Hong Siang, and 黃泓翔. "An Adaptive Mechanism with Spatial Scalability for H.264/SVC Inter-layer Fast Mode Decision." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/hxa2m3.
Full text國立臺北科技大學
電腦與通訊研究所
102
H.264/AVC has been successfully applied in many applications. Although a very good trade-off between visual quality and bit-rate expense can be obtained by using H.264/AVC, the generated bit stream is not applicable to all the applications due to limited bandwidth available or processing capability of decoder. For this reason, the H.264/SVC that is capable of generating bit-stream with different visual quality has been developed. In H.264/SVC, bit streams with different quality can be generated in one time during the coding process. The SVC provides flexible spatial, temporal, and quality setting to adapt itself to different coding requirements. Based on our observation, we find that the process of motion estimation takes more than 80% of the computational complexity during the coding process. In addition, more computations are required for higher enhancement layer. To alleviate the computational burden of the encoder, we focus on the fast mode decision of enhancement layer when spatial scalability is considered. By using the relationship between base layer and enhancement layer, the most probable prediction mode of enhancement layer can be confined to a small subset. In addition, we also find a relationship between the motion vector strength of the collocated macroblock in the base layer and corresponding macroblocks in the enhancement layer so that the prediction mode in the enhancement layer can be determined in a more efficient manner. As we can see in the experiment, an average time-saving of 84.14% can be obtained by using the proposed approach with only a minor degradation on the bit-rate and PSNR performance when compared with JSVM9.18 reference software.
Jiang, Yan-ting, and 江彥廷. "Quality Estimation for H.264/SVC Spatial Scalability based on a New Quantization Distortion Model." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/81656358005251732964.
Full text國立中央大學
通訊工程研究所
99
Scalable Video Coding (SVC) provides efficient compression for the video bitstream equipped with various scalable configurations. H.264 scalable extension (H.264/SVC) is the most recent scalable coding standard. It involves state-of-the-art inter-layer prediction to provide higher coding efficiency than previous standards. Moreover, the requirements for the video quality on distinct situations like link conditions or video contents are usually different. Therefore, how to efficiently provide suitable video quality to users under different situations is an important issue. This work proposes a Quantization-Distortion (Q-D) model for H.264/SVC spatial scalability to estimate video quality before real encoding is performed. We introduce the residual decomposition for three inter-layer prediction types: residual prediction, intra prediction, and motion prediction. The residual can be decomposed to previous distortion and prior-residual that can be estimated before encoding. For single layer, they are distortion of previous frame and difference between two original frames. Then, the distortion can be modeled as a function of quantization step and prior-residual. In simulations, the proposed model can estimate the actual Q-D curves for each inter-layer prediction, and the accuracy of the model is up to 94.98%.
Syu, Jhe-wei, and 許哲維. "Fast Inter-Layer Motion Estimation Algorithm on Spatial Scalability in H.264/AVC Scalable Extension." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/52s9c2.
Full text國立中央大學
通訊工程研究所
97
With the improvements of video coding technology, network infrastructures, storage capacity, and CPU computing capability, the applications of multimedia systems become wider and more popular. Therefore, how to efficiently provide video sequences to users under different constraints is very important, and scalable video coding is one of the best solutions to this problem. H.264 scalable extension (SVC) that is constructed based on H.264/AVC is the most recent scalable video coding standard. SVC utilizes the inter-layer prediction to substantially improve the coding efficiency comparing with the prior scalable video coding standards. Nevertheless, this technique results in extremely large computation complexity which obstructs it from practical use. Especially on spatial scalability, the complexity of the enhancement layer motion estimation occupies above 90% of the total complexity. The main objective of this work is to reduce the computation complexity while maintaining both the video quality and the bit-rate. This thesis proposes a fast inter-layer motion estimation algorithm on temporal and spatial scalabilities for SVC. We utilize the relation between two motion vector predictors from the base layer as well as the enhancement layer respectively and the correlation between all the modes to reduce the number of search times. The simulation results show that the proposed algorithm can save the computation complexity up to 67.4% compared to JSVM9.12 with less than 0.0476dB video quality degradation.
Veerapandian, Lakshmi. "A spatial scalable video coding with selective data transmission using wavelet decomposition." Thesis, 2010. http://hdl.handle.net/2440/61956.
Full textThesis (M.Eng.Sc.) -- University of Adelaide, School of Electrical and Electronic Engineering, 2010