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Abstract(s)
Os sistemas de difusão de televisão digital (Digital Video Broadcasting (DVB) [1], em In glês) apresentam um elevado tempo de mudança de canal (zapping). Este tempo resulta de vários fatores, por exemplo o tempo de bloqueio da frequência do sintonizador, o tempo de análise da sinalização do DVB, o tempo de inicialização do sistema de acesso ao conteúdo, o tempo de espera até ser recebido o início de um bloco de vídeo descodificável (tipicamente o início de um grupo de imagens, em Inglês Group of Pictures (GOP)), ou o tempo de atraso introduzido pelo buffer.
Vários métodos têm sido apresentados para reduzir o tempo de zapping. Uma das soluções mais recentes é o envio de partes da stream, a pedido, através de unicast sobre uma rede IP, que consiste na transmissão do canal que se pretende reproduzir de uma forma mais rápida, de modo a que o utilizador possa estar a ver o canal enquanto é feita a sintonização do canal recebido por DVB.
O objetivo deste trabalho é investigar uma técnica eficiente de mudança rápida de canal utilizando streams unicast sobre IP e desenvolver um componente software que a implemente, para ser integrada nos sistemas modernos de transmissão de vídeo em broadcast. Este componente compreende software no lado do servidor IP e do cliente, designadamente na Set-Top Box (STB) do utilizador.
Digital Video Broadcasting (DVB) systems typically suffer from a high channel change (zapping) time. This is due to multiple factors, namely: i) tuner frequency lock time; ii) parsing of DVB signaling; iii) content access system initialization; iv) delay until the beginning of a decodable video block is received (typically the start of a Group of Pictures); and v) buffering time. Several methods have been exploited to reduce zapping time, including channel pretun ing, in which other streams are tuned in the background and are ready to be displayed as soon as required, companion streams, where low quality streams with lower buffer requirements are also broadcast, and delivery of stream chunks, on request, via unicast on top of an IP network. The goal of this work is to develop a software component to integrate in modern video broadcast systems to support efficient fast channel change using unicast streams over IP. Such component is comprised of both the server software and the client/set-top-box (STB) software. This system will also be used as a base to support and test the imple mentation of other features that aim at providing a smooth and fast channel change for DVB systems.
Digital Video Broadcasting (DVB) systems typically suffer from a high channel change (zapping) time. This is due to multiple factors, namely: i) tuner frequency lock time; ii) parsing of DVB signaling; iii) content access system initialization; iv) delay until the beginning of a decodable video block is received (typically the start of a Group of Pictures); and v) buffering time. Several methods have been exploited to reduce zapping time, including channel pretun ing, in which other streams are tuned in the background and are ready to be displayed as soon as required, companion streams, where low quality streams with lower buffer requirements are also broadcast, and delivery of stream chunks, on request, via unicast on top of an IP network. The goal of this work is to develop a software component to integrate in modern video broadcast systems to support efficient fast channel change using unicast streams over IP. Such component is comprised of both the server software and the client/set-top-box (STB) software. This system will also be used as a base to support and test the imple mentation of other features that aim at providing a smooth and fast channel change for DVB systems.
Description
Keywords
DVB-C Mudança rápida de canal Protocolos de transporte Multimedia streaming Digital video broadcast Fast channel change Transport protocols
Citation
MOREIRA, Pedro Tiago Fernandes – Unicast assisted system for fast channel change on DVB-C. Lisboa: Instituto Superior de Engenharia de Lisboa, 2021. Dissertação de Mestrado.
Publisher
Instituto Superior de Engenharia de Lisboa