Streaming multimedia quality is impacted by two main factors: capacity constraint and packet loss. To match the capacity constraint while preserving real-time playout, media scaling can be used to discard the encoded multimedia content that has the least impact on perceived video quality. To limit the impact of lost packets, repair techniques, e.g. forward error correction (FEC), can be used to repair frames damaged by packet loss. However, adding data to facilitate repair requires further reduction of the original multimedia data, making the decision of how much repair data to use of critical importance. Assuming a limited network capacity and the availability of an estimate of the current packet loss rate along a flow path, selecting the best distribution of FEC packets for video frames with inherent interframe encoding dependencies can be cast as a constraint optimization problem that attempts to optimize the quality of the video stream. This thesis presents an Adjusting Repair and Media scaling with Operations Research (ARMOR) system. An analytical model is derived for streaming video with FEC and media scaling. Given parameters to represent network loss as well as video frame types and sizes, if the number of FEC packets per video frame type and media scaling pattern is specified, the model can estimate the video quality at the receiver side. The model is then used in an operations research algorithm to adjust the FEC strength and media scaling level to yield the best quality under the capacity constraint. Four different combinations of FEC type and media scaling method are studied: Media Independent FEC with Temporal Scaling (MITS), Media Independent FEC with Quality Scaling (MIQS), Media Independent FEC with Temporal and Quality Scaling (MITQS), and Media Dependent FEC with Quality Scaling (MDQS). The analytical experiments show: 1) adjusting FEC always achieves a higher video quality than streaming video without FEC or with a fixed amount of FEC; 2) Quality Scaling usually works better than Temporal Scaling; and 3) Media Dependent FEC (MDFEC) is typically less effective than Media Independent FEC (MIFEC). A user study is presented with results from 74 participants analysis shows that the ARMOR model can accurately estimate users¡¯perceptual quality. Well-designed simulations and a realistic system implementation suggests the ARMOR system can practically improve the quality of streaming video.

Abstract not available

Real time applications over IP network became widely used in different fields; social video conference, online educational lectures, industrial, military, and online robotic medical surgery. Online medical surgery over IP network has experienced rapid growth in the last few years primarily due to advances in technology (e.g., increased bandwidth; new cameras, monitors, and coder/decoders (CODECs)) and changes in the medical care environment (e.g., increased outpatient care, remote surgeries). The purpose of this study was to examine and analyze the impact of IP networks parameters; delay, jitter, throughput, and drop packet on the performance of real-time medical surgery videos sent across different IP networks; native IPv6, native IPv4, 6to4 and 6in4 tunneling transition mechanisms and compare the behavior of video packets over IP networks. The impact of each parameter over IP networks is examined by using different video codecs MPEG-1, MPEG-2, and MPEG-4. This study has been carried out with two main parts; theoretical and practical part, the theoretical part of this study focused on the calculations of various delays in IP networks such as transmission, processing, propagation, and queuing delays for video packet, while the practical part includes; examining of video codecs throughput over IP networks by using jperf tool and examining delay, jitter, and packet drops for different packet sizes by using IDT-G tool and how these parameters can affect quality of received video. The obtained theoretical and practical results were presented in different tables and plotted into different graphs to show the performance of real time video over IP networks. These results confirmed that video codecs MPEG-1, MPEG-2, and MPEG-4 were highly impacted by encapsulation and de-capsulation process except MPEG-4 codec, MPEG-4 was the least impacted by IPv4, IPv6, and IP transition mechanisms concerning throughput and wastage bandwidth. It also indicated that using IPv6-to-4 and IPv6-in-4 tunneling mechanisms caused more bandwidth wastage, high delay, jitter, and packet drop than IPv4 and IPv6.

Thesis (M. App. Sc.)--Carleton University, 2005. / Includes bibliographical references (p. 71-76). Also available in electronic format on the Internet.

No description available.

The field of Video Transcoding has been evolving throughout the past ten years. The need for transcoding of video files has greatly increased because of the new upcoming standards which are incompatible with old ones. This thesis takes the method of using machine learning for video transcoding mode decisions and discusses ways to improve the process of generating the algorithm for implementation in different video transcoders. The transcoding methods used decrease the complexity in the mode decision inside the video encoder. Also methods which automate and improve results are discussed and implemented in two different sets of transcoders: H.263 to VP6 , and MPEG-2 to H.264. Both of these transcoders have shown a complexity loss of almost 50%. Video transcoding is important because the quantity of video standards have been increasing while devices usually can only decode one specific codec. / by Christopher Holder. / Thesis (M.S.C.S.)--Florida Atlantic University, 2008. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2008. Mode of access: World Wide Web.

Orientador: Yuzo Iano / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-16T03:46:01Z (GMT). No. of bitstreams: 1 Araujo_AndreFilgueirasde_M.pdf: 3583920 bytes, checksum: afbfc9cf561651fe74a6a3d075474fc8 (MD5) Previous issue date: 2010 / Resumo: Este trabalho tem como objetivo principal a elaboração de um novo algoritmo responsável por tornar mais eficiente a estimação de movimento do codec Dirac. A estimação de movimento é uma etapa crítica à codificação de vídeo, na qual se encontra a maior parte do seu processamento. O codec Dirac, recentemente lançado, tem como base técnicas diferentes das habitualmente utilizadas nos codecs mais comuns (como os da linha MPEG). O Dirac objetiva alcançar eficiência comparável aos melhores codecs da atualidade (notadamente o H.264/AVC). Desta forma, este trabalho apresenta inicialmente estudos comparativos visando à avaliação de métodos de estado da arte de estimação de movimento e do codec Dirac, estudos que fornecem a base de conhecimento para o algoritmo que é proposto na sequência. A proposta consiste no algoritmo Modified Hierarchical Enhanced Adaptive Rood Pattern Search (MHEARPS). Este apresenta desempenho superior aos outros algoritmos de relevância em todos os casos analisados, provendo em média complexidade 79% menor mantendo a qualidade de reconstrução. / Abstract: The main purpose of this work is to design a new algorithm which enhance motion estimation in Dirac video codec. Motion estimation is a critical stage in video coding, in which most of the processing lies. Dirac codec, recently released, is based on techniques different from the usually employed (as in MPEG-based codecs). Dirac video codec aims at achieving efficiency comparable to the best codecs (such as H.264/AVC). This work initially presents comparative studies of state-of-the-art motion estimation techniques and Dirac codec which support the conception of the algorithm which is proposed in the sequel. The proposal consists in the algorithm Modified Hierarchical Enhaced Adaptive Rood Pattern Search (MHEARPS). This presents superior performance when compared to other relevant algorithms in every analysed case, providing on average 79% less computations with similar video reconstruction quality. / Mestrado / Telecomunicações e Telemática / Mestre em Engenharia Elétrica

Orientador: Ricardo da Silva Torres / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Computação / Made available in DSpace on 2018-08-19T18:14:01Z (GMT). No. of bitstreams: 1 AlmeidaJunior_JurandyGomesde_D.pdf: 7003455 bytes, checksum: 9f2b66a600d6b6ae595b02265ceb1585 (MD5) Previous issue date: 2011 / Resumo: Avanços recentes na tecnologia têm permitido o aumento da disponibilidade de dados de vídeo, criando grandes coleções de vídeo digital. Isso tem despertado grande interesse em sistemas capazes de gerenciar esses dados de forma eficiente. Fazer uso eficiente de informações de vídeo requer o desenvolvimento de ferramentas poderosas capazes de extrair representações semânticas de alto nível a partir de características de baixo nível do conteúdo de vídeo. Devido à complexidade desse material, existem cinco desafios principais na concepção de tais sistemas: (1) dividir o fluxo de vídeo em trechos manuseáveis de acordo com a sua estrutura de organização, (2) implementar algoritmos para codificar as propriedades de baixo nível de um trecho de vídeo em vetores de características, (3) desenvolver medidas de similaridade para comparar esses trechos a partir de seus vetores, (4) responder rapidamente a consultas por similaridade sobre uma enorme quantidade de sequências de vídeo e (5) apresentar os resultados de forma amigável a um usuário. Inúmeras técnicas têm sido propostas para atender a tais requisitos. A maioria dos trabalhos existentes envolve algoritmos e métodos computacionalmente custosos, em termos tanto de tempo quanto de espaço, limitando a sua aplicação apenas ao ambiente acadêmico e/ou a grandes empresas. Contrário a essa tendência, o mercado tem mostrado uma crescente demanda por dispositivos móveis e embutidos. Nesse cenário, é imperativo o desenvolvimento de técnicas tanto eficazes quanto eficientes a fim de permitir que um público maior tenha acesso a tecnologias modernas. Nesse contexto, este trabalho apresenta cinco abordagens originais voltadas a análise, indexação e recuperação de vídeos digitais. Todas essas contribuições são somadas na construção de um sistema de gestão de vídeos por conteudo computacionalmente rápido, capaz de atingir a um padrão de qualidade similar, ou até mesmo superior, a soluções atuais / Abstract: Recent advances in the technology have enabled the increase of the availability of video data, creating large digital video collections. This has spurred great interest in systems that are able to manage those data in a efficient way. Making efficient use of video information requires the development of powerful tools to extract high-level semantics from low-level features of the video content. Due to the complexity of the video material, there are five main challenges in designing such systems: (1) to divide the video stream into manageable segments according to its organization structure; (2) to implement algorithms for encoding the low-level features of each video segment into feature vectors; (3) to develop similarity measures for comparing these segments by using their feature vectors; (4) to quickly answer similarity queries over a huge amount of video sequences; and (5) to present the list of results in a user-friendly way. Numerous techniques have been proposed to support such requirements. Most of existing works involve algorithms and methods which are computationally expensive, in terms of both time and space, limiting their application to the academic world and/or big companies. Contrary to this trend, the market has shown a growing demand for mobile and embedded devices. In this scenario, it is imperative the development of techniques so effective as efficient in order to allow more people have access to modern technologies. In this context, this work presents five novel approaches for the analysis, indexing, and retrieval of digital videos. All these contributions are combined to create a computationally fast system for content-based video management, which is able to achieve a quality level similar, or even superior, to current solutions / Doutorado / Ciência da Computação / Doutor em Ciência da Computação

Orientadores: Yuzo Iano, Rangel Arthur / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-21T22:39:06Z (GMT). No. of bitstreams: 1 Beltrao_GabrielTedgue_M.pdf: 7074938 bytes, checksum: 0a2d464733f2fb5dcc14430cc1844758 (MD5) Previous issue date: 2012 / Resumo: As transformadas derivadas da DCT são amplamente utilizadas para compressão de vídeo. Recentemente, muitos autores têm destacado que os resíduos de predição normalmente apresentam estruturas direcionais que não podem ser eficientemente representadas pela DCT convencional. Nesse contexto, muitas transformadas direcionais têm sido propostas como forma de suplantar a deficiência da DCT em lidar com tais estruturas. Apesar do desempenho superior das transformadas direcionais sobre a DCT convencional, para a sua aplicação na compressão de vídeo é necessário avaliar o aumento no tempo de codificação e a complexidade para sua implementação. Este trabalho propõe um rápido algoritmo para se estimar as direções existentes em um bloco antes da aplicação das transformadas direcionais. O codificador identifica as direções predominantes em cada bloco e aplica apenas a transformada referente àquela direção. O algoritmo pode ser usado em conjunto com qualquer proposta de transformadas direcionais que utilize a técnica de otimização por taxa-distorção (RDO) para a seleção da direção a ser explorada, reduzindo a complexidade de implementação a níveis similares a quando apenas a DCT convencional é utilizada / Abstract: DCT-based transforms are widely adopted for video compression. Recently, many authors have highlighted that prediction residuals usually have directional structures that cannot be efficiently represented by conventional DCT. In this context, many directional transforms have been proposed as a way to overcome DCT's deficiency in dealing with such structures. Although directional transforms have superior performance over the conventional DCT, for application in video compression it is necessary to evaluate increase in coding time and complexity for its implementation. This work proposes a fast algorithm for estimating blocks directions before applying directional transforms. The encoder identifies predominant directions in each block, and only applies the transform referent to that direction. The algorithm can be used in conjunction with any proposed algorithm for directional transforms that uses the rate-distortion optimization (RDO) process for selection of the direction to be explored; reducing implementation complexity to similar levels when only conventional DCT is used / Mestrado / Telecomunicações e Telemática / Mestre em Engenharia Elétrica

The purpose of this project is to investigate the differences between psychoacoustic principles and genetic algorithms (GA0). These will be discussed separately. The review will also compare the compression ratio and the quality of the decompressed files decoded by these two methods.