91 |
Metody a prostředky pro hodnocení kvality obrazu / Methods and Tools for Image and Video Quality AssessmentSlanina, Martin January 2009 (has links)
Disertační práce se zabývá metodami a prostředky pro hodnocení kvality obrazu ve videosekvencích, což je velmi aktuální téma, zažívající velký rozmach zejména v souvislosti s digitálním zpracováním videosignálů. Přestože již existuje relativně velké množství metod a metrik pro objektivní, tedy automatizované měření kvality videosekvencí, jsou tyto metody zpravidla založeny na porovnání zpracované (poškozené, například komprimací) a originální videosekvence. Metod pro hodnocení kvality videosekvení bez reference, tedy pouze na základě analýzy zpracovaného materiálu, je velmi málo. Navíc se takové metody převážně zaměřují na analýzu hodnot signálu (typicky jasu) v jednotlivých obrazových bodech dekódovaného signálu, což je jen těžko aplikovatelné pro moderní komprimační algoritmy jako je H.264/AVC, který používá sofistikovené techniky pro odstranění komprimačních artefaktů. V práci je nejprve podán stučný přehled dostupných metod pro objektivní hodnocení komprimovaných videosekvencí se zdůrazněním rozdílného principu metod využívajících referenční materiál a metod pracujících bez reference. Na základě analýzy možných přístupů pro hodnocení video sekvencí komprimovaných moderními komprimačními algoritmy je v dalším textu práce popsán návrh nové metody určené pro hodnocení kvality obrazu ve videosekvencích komprimovaných s využitím algoritmu H.264/AVC. Nová metoda je založena na sledování hodnot parametrů, které jsou obsaženy v transportním toku komprimovaného videa, a přímo souvisí s procesem kódování. Nejprve je provedena úvaha nad vlivem některých takových parametrů na kvalitu výsledného videa. Následně je navržen algoritmus, který s využitím umělé neuronové sítě určuje špičkový poměr signálu a šumu (peak signal-to-noise ratio -- PSNR) v komprimované videosekvenci -- plně referenční metrika je tedy nahrazována metrikou bez reference. Je ověřeno několik konfigurací umělých neuronových sítí od těch nejjednodušších až po třívrstvé dopředné sítě. Pro učení sítí a následnou analýzu jejich výkonnosti a věrnosti určení PSNR jsou vytvořeny dva soubory nekomprimovaných videosekvencí, které jsou následně komprimovány algoritmem H.264/AVC s proměnným nastavením kodéru. V závěrečné části práce je proveden rozbor chování nově navrženého algoritmu v případě, že se změní vlastnosti zpracovávaného videa (rozlišení, střih), případně kodéru (formát skupiny současně kódovaných snímků). Chování algoritmu je analyzováno až do plného vysokého rozlišení zdrojového signálu (full HD -1920 x 1080 obrazových bodů).
|
92 |
Aplicação de metaheurísticas no desenvolvimento de um modelo de otimização para o processo de codificação de áudio do Sistema Brasileiro de Televisão DigitalHarff, Maurício 21 March 2013 (has links)
Submitted by William Justo Figueiro (williamjf) on 2015-07-08T20:56:12Z
No. of bitstreams: 1
03b.pdf: 3126214 bytes, checksum: 0f98dbf86ae74816af91944aa7dec80f (MD5) / Made available in DSpace on 2015-07-08T20:56:12Z (GMT). No. of bitstreams: 1
03b.pdf: 3126214 bytes, checksum: 0f98dbf86ae74816af91944aa7dec80f (MD5)
Previous issue date: 2013 / Nenhuma / A qualidade perceptual alcançada pelos codificadores de áudio depende diretamente da escolha de seus parâmetros. O codificador MPEG-4 AAC (Advanced Audio Coding), utilizado no Sistema Brasileiro de Televisão Digital (SBTVD), possui em sua estrutura uma etapa composta por um laço de iteração para escolher os parâmetros do codificador, de maneira dinâmica durante o processo de codificação. Este processo de escolha pode ser definido como um problema de Pesquisa Operacional, sendo um problema de Seleção de Partes, denominado como o Problema de Codificação AAC. A estrutura existente no codificador de referência, não resolve este problema de maneira ótima. Desta forma, este trabalho propõe o desenvolvimento e implementação de um modelo de uma estrutura de simulação, para encontrar os parâmetros do codificador de áudio MPEG-4 AAC, de maneira a otimizar a qualidade perceptual do áudio, para uma determinada taxa de bits (bit rate). A implementação da estrutura de otimização foi desenvolvida em linguagem C, utilizando as metaheurísticas Busca Tabu e Algoritmo Genético em uma estrutura híbrida. Através da minimização da métrica ANMR (Average Noise-to-Mask Ratio), o algoritmo procura identificar a melhor configuração dos parâmetros internos do codificador MPEG-4 AAC, de maneira que possa garantir uma qualidade perceptual para o sinal áudio. Os resultados obtidos utilizando a estrutura híbrida de otimização apresentaram valores menores para a métrica ANMR, ou seja, uma melhor qualidade perceptual de áudio, quando comparados com os resultados obtidos com o codificador de referência MPEG-4 AAC. / The perceptual quality achieved by audio encoders depends directly on the choice of its parameters. The MPEG-4 AAC (Advanced Audio Coding), used in the Brazilian Digital Television System (BDTS), has a step in its structure that consists in iteration loop to choose the parameters of the encoder dynamically during the encoding process. This selection process can be defined as a problem of Operational Research, being a Part Selection Problem, termed as AAC Encoding Problem. The structure in the reference encoder not solves this problem optimally. Thus, this paper proposes the development and implementation of a model simulation of a structure, to find the internal parameters of the MPEG-4 AAC audio encoder, so as to optimize the perceptual audio quality for a given bit rate. The implementation of the optimization framework was developed in ANSI C programming language, using the Tabu Search and Genetic Algorithm metaheuristics in a hybrid structure. Through the minimization of the ANMR (Average Noise-to-Mask Ratio) metric, the algorithm tries to identify the best configuration of internal parameters of the MPEG-4 AAC. The results obtained using the optimization hybrid structure achieve lower values for the ANMR metric, i.e., an better perceptual audio quality, compared with the obtained with the reference encoder MPEG-4 AAC.
|
93 |
Porovnání možností komprese multimediálních signálů / Comparison of Multimedia Signal Compression PossibilitiesŠpaček, Milan January 2013 (has links)
Thesis deals with multimedia signal comparison of compression options focused on video and advanced codecs. Specifically it describes the encoding and decoding of video recordings according to the MPEG standard. The theoretical part of the thesis describes characteristic properties of the video signal and justification for the need to use recording and transmission compression. There are also described methods for elimination of encoded video signal redundancy and irrelevance. Further on are discussed ways of measuring the video signal quality. A separate chapter is focused on the characteristics of currently used and promising codecs. In the practical part of the thesis were created functions in Matlab environment. These functions were implemented into graphic user interface that simulates the activity of functional blocks of the encoder and decoder. Based on user-specified input parameters it performs encoding and decoding of any given picture, composed of images in RGB format, and displays the outputs of individual functional blocks. There are implemented algorithms for the initial processing of the input sequence including sub-sampling, as well as DCT, quantization, motion compensation and their inverse operations. Separate chapters are dedicated to the realisation of codec description in the Matlab environment and to the individual processing steps output. Further on are mentioned compress algorithm comparisons and the impact of parameter change onto the final signal. The findings are summarized in conclusion.
|
94 |
Error-robust coding and transformation of compressed hybered hybrid video streams for packet-switched wireless networksHalbach, Till January 2004 (has links)
<p>This dissertation considers packet-switched wireless networks for transmission of variable-rate layered hybrid video streams. Target applications are video streaming and broadcasting services. The work can be divided into two main parts.</p><p>In the first part, a novel quality-scalable scheme based on coefficient refinement and encoder quality constraints is developed as a possible extension to the video coding standard H.264. After a technical introduction to the coding tools of H.264 with the main focus on error resilience features, various quality scalability schemes in previous research are reviewed. Based on this discussion, an encoder decoder framework is designed for an arbitrary number of quality layers, hereby also enabling region-of-interest coding. After that, the performance of the new system is exhaustively tested, showing that the bit rate increase typically encountered with scalable hybrid coding schemes is, for certain coding parameters, only small to moderate. The double- and triple-layer constellations of the framework are shown to perform superior to other systems.</p><p>The second part considers layered code streams as generated by the scheme of the first part. Various error propagation issues in hybrid streams are discussed, which leads to the definition of a decoder quality constraint and a segmentation of the code stream to transmit. A packetization scheme based on successive source rate consumption is drafted, followed by the formulation of the channel code rate optimization problem for an optimum assignment of available codes to the channel packets. Proper MSE-based error metrics are derived, incorporating the properties of the source signal, a terminate-on-error decoding strategy, error concealment, inter-packet dependencies, and the channel conditions. The Viterbi algorithm is presented as a low-complexity solution to the optimization problem, showing a great adaptivity of the joint source channel coding scheme to the channel conditions. An almost constant image qualiity is achieved, also in mismatch situations, while the overall channel code rate decreases only as little as necessary as the channel quality deteriorates. It is further shown that the variance of code distributions is only small, and that the codes are assigned irregularly to all channel packets.</p><p>A double-layer constellation of the framework clearly outperforms other schemes with a substantial margin. </p><p>Keywords — Digital lossy video compression, visual communication, variable bit rate (VBR), SNR scalability, layered image processing, quality layer, hybrid code stream, predictive coding, progressive bit stream, joint source channel coding, fidelity constraint, channel error robustness, resilience, concealment, packet-switched, mobile and wireless ATM, noisy transmission, packet loss, binary symmetric channel, streaming, broadcasting, satellite and radio links, H.264, MPEG-4 AVC, Viterbi, trellis, unequal error protection</p>
|
95 |
Error-robust coding and transformation of compressed hybered hybrid video streams for packet-switched wireless networksHalbach, Till January 2004 (has links)
This dissertation considers packet-switched wireless networks for transmission of variable-rate layered hybrid video streams. Target applications are video streaming and broadcasting services. The work can be divided into two main parts. In the first part, a novel quality-scalable scheme based on coefficient refinement and encoder quality constraints is developed as a possible extension to the video coding standard H.264. After a technical introduction to the coding tools of H.264 with the main focus on error resilience features, various quality scalability schemes in previous research are reviewed. Based on this discussion, an encoder decoder framework is designed for an arbitrary number of quality layers, hereby also enabling region-of-interest coding. After that, the performance of the new system is exhaustively tested, showing that the bit rate increase typically encountered with scalable hybrid coding schemes is, for certain coding parameters, only small to moderate. The double- and triple-layer constellations of the framework are shown to perform superior to other systems. The second part considers layered code streams as generated by the scheme of the first part. Various error propagation issues in hybrid streams are discussed, which leads to the definition of a decoder quality constraint and a segmentation of the code stream to transmit. A packetization scheme based on successive source rate consumption is drafted, followed by the formulation of the channel code rate optimization problem for an optimum assignment of available codes to the channel packets. Proper MSE-based error metrics are derived, incorporating the properties of the source signal, a terminate-on-error decoding strategy, error concealment, inter-packet dependencies, and the channel conditions. The Viterbi algorithm is presented as a low-complexity solution to the optimization problem, showing a great adaptivity of the joint source channel coding scheme to the channel conditions. An almost constant image qualiity is achieved, also in mismatch situations, while the overall channel code rate decreases only as little as necessary as the channel quality deteriorates. It is further shown that the variance of code distributions is only small, and that the codes are assigned irregularly to all channel packets. A double-layer constellation of the framework clearly outperforms other schemes with a substantial margin. Keywords — Digital lossy video compression, visual communication, variable bit rate (VBR), SNR scalability, layered image processing, quality layer, hybrid code stream, predictive coding, progressive bit stream, joint source channel coding, fidelity constraint, channel error robustness, resilience, concealment, packet-switched, mobile and wireless ATM, noisy transmission, packet loss, binary symmetric channel, streaming, broadcasting, satellite and radio links, H.264, MPEG-4 AVC, Viterbi, trellis, unequal error protection
|
96 |
Μελέτη εφαρμογής για τη σύγκλιση και ενοποίηση αμφίδρομων ευρυζωνικών δικτύων για την παροχή ιατρικών υπηρεσιών με τη χρήση τηλεματικής στην υγείαΚαρδαράς, Κωνσταντίνος Χ. 17 December 2008 (has links)
Σκοπός της εργασίας είναι να μελετηθεί ο τρόπος, οι τεχνολογίες, οι υπηρεσίες
και οι περιορισμοί οι οποίοι εμφανίζονται στην παροχή υπηρεσιών υγείας σε έκτακτα
περιστατικά με τη χρήση τηλεματικής. Για την επικοινωνία των φορητών συσκευών
παρακολούθησης των ασθενών με τους σταθμούς βάσης επιλέχθηκε το ασύρματο
δίκτυο Wi-Fi για το οποιο μελετήθηκαν μια σειρά από παραμέτρους οι οποίες
συμβάλουν είτε θετικά είτε αρνητικά κατά περίπτωση. Η παρακολούθηση και η
αποστολή των κρίσιμων διοδυναμικών παραμέτρων ενός ασθενούς επιτεύχθηκε με τη
χρήση φορητής/φορετής Βιοιατρικής ζώνης η οποία παρέχει τον εξοπλισμό
ανίχνευσης και επεξεργασίας των σημάτων καθώς επίσης και τον εξοπλισμό
ασύρματης δικτύωσης με το κέντρο παρακολούθησης. Σημαντικός τομέας της
μελέτης αποτελεί η πρόταση για μεταφορά δεδομένων μέσα από ασύρματα δικτύα
διανομής επίγειας ψηφιακής τηλεόρασης και των γραμμών μεταφοράς ηλεκτρικής
ενέργειας μέσης τάσης. Το δεύτερο κομμάτι της εργασίας επικεντρώνεται στην
παροχή υπηρεσιών βίντεο για ιατρικούς σκοπούς για την αντιμετώπιση
προγραμματισμένων και έκτακτων περιστατικών. Εκεί αναλύονται οι τεχνικές
συμπίεσης και επεξεργασίας της εικόνας και προτείνεται η χρήση του πρωτοκόλλου
MPEG-4 για την αποδοτικότητα και την πιστότητα στην αναπαραγόμενη εικόνα. Η
εργασία κλείνει με τη διεξαγωγή μιας πειραματικής διαδικασίας αναλύοντας τα
χαρακτηριστικά της ποιότητας της εικόνας βίντεο από μια λαπαροσκοπική επέμβαση.
Ο συνδυασμός όλων των παραπάνω οδηγεί στην κατασκευή ενός υβριδικού
συστήματος τηλειατρικης το οποιο έχει τη δυνατότητα να αντιμετωπίσει έκτακτα
ιατρικά περιστατικά σε αντίξοες συνθήκες. / The present thesis is a full analytical study for the implementation of
technologies, the services and constrains that appears in the provision of medical
emergency services with the use of a telematics network. The communication of the
portable monitoring equipment with a medical station is accomplished through the
wireless WiFi infrastructure. Critical biosignals wireless transmission is accomplished
through a wearable biomedical belt that contains the sensory as well as the processing
devices. One section of in this study proposes alternative network infrastructures to be
used, in particular the Digital terrestrial TV network and the transmission of IP data
over the power lines. The last section deals with the provisioning of a MPEG-4
medical video service. Critical parameters are the image and compression techniques
that degrade the video picture quality. A video sample from a laparoscope’s surgery is
analyzed that shows how various quality parameters affect the perceived picture
quality in the decomposition section.
|
97 |
Codage vidéo hybride basé contenu par analyse/synthèse de donnéesMoinard, Matthieu 01 July 2011 (has links) (PDF)
Les travaux de cette thèse sont destinés à la conception d'outils algorithmiques permettant d'accroître le facteur de compression des standards actuels de codage vidéo, tels que H.264/AVC. Pour cela, une étude préalable portant sur un ensemble de méthodes de restauration d'image a permis d'identifier et d'inspecter deux axes de recherche distincts. La première partie est fondée sur des méthodes d'analyse et de synthèse de texture. Ce type de procédé, aussi connu sous le nom de template matching, est couramment utilisé dans un contexte de codage vidéo pour prédire une portion de la texture de l'image suite à l'analyse de son voisinage. Nous avons cherché à améliorer le modèle de prédiction en prenant en compte les spécificités d'un codeur vidéo de type H.264/AVC. En particulier, la fonction débit/distorsion utilisée dans les schémas de codage vidéo normatifs se base sur une mesure objective de la qualité. Ce mécanisme est par nature incompatible avec le concept de synthèse de texture, dont l'efficacité est habituellement mesurée selon des critères purement perceptuels. Cette contradiction a motivé le travail de notre première contribution. La deuxième partie des travaux de cette thèse s'inspire des méthodes de régularisation d'image basée sur la minimisation de la variation totale. Des méthodes ont été élaborées originellement dans le but d'améliorer la qualité d'une image en fonction de la connaissance a priori des dégradations qu'elle a subies. Nous nous sommes basés sur ces travaux pour concevoir un modèle de prédiction des coefficients transformés obtenus à partir d'une image naturelle, qui a été intégré dans un schéma de codage vidéo conventionnel.
|
98 |
Implementation and Evaluation of MPEG-4 Simple Profile Decoder on a Massively Parallel Processor ArraySavas, Suleyman January 2011 (has links)
The high demand of the video decoding has pushed the developers to implement the decoders on parallel architectures. This thesis provides the deliberations about the implementation of an MPEG-4 decoder on a massively parallel processor array (MPPA), Ambric 2045, by converting the CAL actor language implementation of the decoder. This decoder is the Xilinx model of the MPEG-4 Simple Profile decoder and consists of four main blocks; parser, acdc, idct2d and motion. The parser block is developed in another thesis work [20] and the rest of the decoder, which consists of the other three blocks, is implemented in this thesis work. Afterwards, in order to complete the decoder, the parser block is combined with the other three blocks. Several methods are developed for conversion purposes. Additionally, a number of other methods are developed in order to overcome the constraints of the ambric architecture such as no division support. At the beginning, for debugging purposes, the decoder is implemented on a simulator which is designed for Ambric architecture. Finally the implementation is uploaded to the Ambric 2045 chip and tested with different input streams. The performance of the implementation is analyzed and satisfying results are achieved when compared to the standards which are in use in the market. These performance results can be considered as satisfying for any real-time application as well. Furthermore, the results are compared with the results of the CAL implementation, running on a single 2GHz i7 intel processor, in terms of speed and efficiency. The Ambric implementation runs 4,7 times faster than the CAL implementation when a small input stream (300 frames with resolution of 176x144) is used. However, when a large input stream (384 frames with resolution of 720x480) is used, the Ambric implementation shows a performance which is approximately 32 times better than the CAL implementation, in terms of decoding speed and throughput. The performance may increase further together with the size of the input stream up to some point.
|
99 |
Workshop Audiovisuelle MedienEibl, Maximilian, Kürsten, Jens, Ritter, Marc 03 June 2009 (has links) (PDF)
Audiovisuelle Medien stellen Archive vor zunehmende Probleme. Ein stark wachsender (Web-)TV-Markt mit Sende- oder Rohmaterial, zunehmender Einsatz von medial aufbereitetem Lehrmaterial in Schulen, Hochschulen und Firmen, die Verbreitung der Videoanalyse als Forschungs- und Lehrmethode, die Ausbreitung von Überwachungskameras sowie die immer günstigeren Produktionsbedingungen vom professionellen Produzenten bis zum Heimvideo sind nur einige Stichworte um die neuen quantitativen Dimensionen zu umreißen. Die archivarischen und dokumentarischen Werkzeuge sind heute mit dieser Situation überfordert.
Der Workshop versucht hier Probleme und Lösungsmöglichkeiten zu umreißen und beschäftigt sich mit den technologischen Fragestellungen rund um die Archivierung audiovisueller Medien, seien es analoge, digitalisierte oder digitale Medien. Dabei werden zum einen die technologischen Probleme angesprochen, die zum Aufbau und Management eines Archivs bewältigt werden müssen. Zum anderen wird der praktische Einsatz von der Gestaltung der Benutzungsoberfläche bis zur Frage des Umgangs mit kritischem Material diskutiert.
|
100 |
Workshop Audiovisuelle MedienEibl, Maximilian, Kürsten, Jens, Ritter, Marc 03 June 2009 (has links)
Audiovisuelle Medien stellen Archive vor zunehmende Probleme. Ein stark wachsender (Web-)TV-Markt mit Sende- oder Rohmaterial, zunehmender Einsatz von medial aufbereitetem Lehrmaterial in Schulen, Hochschulen und Firmen, die Verbreitung der Videoanalyse als Forschungs- und Lehrmethode, die Ausbreitung von Überwachungskameras sowie die immer günstigeren Produktionsbedingungen vom professionellen Produzenten bis zum Heimvideo sind nur einige Stichworte um die neuen quantitativen Dimensionen zu umreißen. Die archivarischen und dokumentarischen Werkzeuge sind heute mit dieser Situation überfordert.
Der Workshop versucht hier Probleme und Lösungsmöglichkeiten zu umreißen und beschäftigt sich mit den technologischen Fragestellungen rund um die Archivierung audiovisueller Medien, seien es analoge, digitalisierte oder digitale Medien. Dabei werden zum einen die technologischen Probleme angesprochen, die zum Aufbau und Management eines Archivs bewältigt werden müssen. Zum anderen wird der praktische Einsatz von der Gestaltung der Benutzungsoberfläche bis zur Frage des Umgangs mit kritischem Material diskutiert.:Interaction
MedioVis 2.0 - A novel User Interface for Seeking Audio-Visual Media Libraries
Harald Reiterer, Mathias Heilig and Sebastian Rexhausen
SIVA Suite – Konzeption eines Frameworks zur Erstellung von interaktiven Videos
B. Meixner, B. Siegel, G. Hölbling, H. Kosch und F. Lehner
Online-Werbung als digitales Kulturgut: Analyse, Erschließung und Archivierung
Christian Wolff
Beyond Basic Blanks – Vertrauenserhaltende, schrittweise Implementierung neuer Funktionen im Information Retrieval
Arne Berger
Beyond Basic Blanks – Akzeptanz adaptiver Annotations- und Rechercheoberflächen
Arne Berger
Media Usage
Nutzung von Mediatheken öffentlich-rechtlicher Fernsehsender
Sven Pagel, Carina Bischoff, Sebastian Goldstein und Alexander
Jürgens
Video-Tools im Schulunterricht: Psychologisch-pädagogische Forschung zur Nutzung audiovisueller Medien
Carmen Zahn, Karsten Krauskopf und Friedrich W. Hesse
Special Issues in Multimedia Archiving
Einsatz Pixelbasierter Datenfusion zur Objektklassifikation
Jan Thomanek, Holger Lietz, Basel Fardi, Gerd Wanielik
Grundlagen für das Retrieval rotationssymmetrischer Gefäße
Stefan Wagner, Christian Hörr, David Brunner und Guido Brunnett
Verschmelzendes Clustering in Artmap
Frederik Beuth und Marc Ritter
Von der Bildrepräsentation zur Objekterkennung – Bewegungsanalyse als mächtiges Werkzeug der automatischen Bildinterpretation
Tobias John, Basel Fardi und Gerd Wanielik
Aspekte zur Archivierung audiovisueller Unterlagen im Sächsischen Staatsarchiv
Stefan Gööck
FusionSystems GmbH Systeme zur Sensor-Daten-Fusion und Szeneninterpretation
Ullrich Scheunert und Basel Fardi
Multimedia Analysis and Retrieval
Visualisierung von Prozessketten zur Shot Detection
Marc Ritter
Textdetektion und -extraktion mit gewichteter DCT und mehrwertiger
Bildzerlegung
Stephan Heinich
Sprechererkennungssystem auf Basis der Vektorquantisierung mit Störgeräuschfilterung
Stephan Heinich
Metadatenstandards und –formate für audiovisuelle Inhalte
Jens Kürsten
Entwurf einer Service-orientierten Architektur als Erweiterung einer Plattform zum Programm-Austausch
Jens Kürsten
Untersuchungen zu semantischem Retrieval von Bildern mit Hilfe von MPEG7 anhand einer Beispielapplikation
Daniel Pötzinger
Distribution Aspects
Dynamische Distribution personalisierten Mobilfernsehens in hybriden Netzen
Albrecht Kurze, Robert Knauf und Arne Berger
Multimedia Archives – Music
Evaluation of an Image and Music Indexing Prototype
Peter Dunker, Ronny Paduschek, Christian Dittmar, Stefanie Nowak
and Matthias Gruhne
Aspekte inhaltlicher Modellierung von Musikdokumenten in digitalen
Archiven
Michael Rentzsch und Frank Seifert
|
Page generated in 0.0287 seconds