From f5b0f6d547b5978eaf60280e26669d3534d7c1ab Mon Sep 17 00:00:00 2001 From: Joao Carreira Date: Thu, 19 Jul 2018 17:49:59 +0100 Subject: [PATCH] Clean after PA comments --- 010_Introduction/Introduction.tex | 27 +++++++++++++++++---------- 1 file changed, 17 insertions(+), 10 deletions(-) diff --git a/010_Introduction/Introduction.tex b/010_Introduction/Introduction.tex index 6a63dc2..a700fe3 100755 --- a/010_Introduction/Introduction.tex +++ b/010_Introduction/Introduction.tex @@ -12,7 +12,7 @@ Over the recent years new advances in video compression and networking technolog The increasing diversity of services, the demands for high quality multimedia and the growing popularity of \ac{uhd} formats (\emph{e.g.}, $4k\times2k$ or $8k\times4k$ resolution and beyond) are pushing technologies forward and opening new research directions. Moreover, the emerging new video formats with increased resolutions have created stronger needs for higher coding efficiency, beyond the previous standards, i.e., the MPEG-4/\ac{h264}~\cite{H264AVCStandard2003,H264OverviewJul2003}. Such need has been driven not only by higher resolutions but also by stereoscopic and multi-view video formats, which increase the number of viewpoints that need to be captured, coded and delivered simultaneously. -Moreover, the traffic generated by mobile multimedia applications \HIGHLIGHT{[XX]} and different video services with ever increasing popularity, e.g., Netflix, impose new challenges to the existing networks. +Moreover, the ever increasing traffic generated by mobile multimedia applications \cite{CiscoMobile1621_Feb2017} and different video services with ever increasing popularity, e.g., Netflix, impose new challenges to the existing networks. To cope with such demanding requirements a new coding standard was developed by the ITU-T \ac{vceg} and the \ac{iso}/\ac{iec} \ac{mpeg} standardisation organisations, referred to as H.265 - \ac{hevc}~\cite{H265StandardFeb2018,HEVCOverviewDez2012}. \glsunset{h264} @@ -23,13 +23,15 @@ The coding flexibility and efficiency of \ac{hevc}, results from the use of new However, it is known that higher coding efficiency leads to lower robustness to transmission errors and data loss. Therefore, the new coding tools in \ac{hevc} bring not only high compression efficiency~\cite{HEVCComparisonDec2012}, but also some other disadvantages, such as increased complexity~\cite{PerformanceComplexityDez2012} and inherent reduction in error robustness. -%\begin{figure}[tb] -%\centering -%%\includegraphics[width=0.5\columnwidth]{./010_Introduction/HEVCTransmissionStack} +\begin{figure}[tb] +\centering +%\includegraphics[width=0.5\columnwidth]{./010_Introduction/HEVCTransmissionStack} %\includegraphics[width=0.7\columnwidth]{./010_Introduction/HEVCTransmissionStackOverview} %\caption{System layer stack compatible with \ac{hevc} video transmission~\cite{HEVCLayerIntegrationDez2012}.} -%\label{fig:HEVCStack} -%\end{figure} +\input{./010_Introduction/RobustVideoSystem.tikz} +\caption{Generalised diagram of a robust video transmission system.} +\label{fig:HEVCStack} +\end{figure} %\cite{StudyHEVCErrorsDez2012} Earlier studies about the error robustness characteristics of \ac{hevc} have shown that in general the use of high efficiency coding tools results in poor error resilience performance, in comparison with previous standards. @@ -68,21 +70,26 @@ Although the \ac{ec} methods have been developed during the past years for \ac{h \section{\HIGHLIGHT{Main objectives and contributions}} + + + The research objectives of this thesis are focused in robust error resilience for efficient error concealment in highly efficiency video decoders. Thus, this work investigates novel techniques to increase the video quality of \ac{hevc} bitstreams delivered through error-prone networks. The following objectives were pursued in this work: \begin{enumerate} -\item \textbf{evaluation study of the error robustness:} the first objective of this research work is to evaluate the robustness against transmission errors of highly efficiently coded video +\item +\textbf{evaluation study of the error robustness:} the first objective of this research work is to evaluate the robustness against transmission errors of highly efficiently coded video. The study conclusions aimed at finding relevant research directions to increase the error robust of coded streams. The results and conclusions of this study were published in the conference paper \ref{Conf:ErrorResilience} and are part of the journal paper \ref{Journal:TwoStage} (see Appendix \ref{Appen:Papers}). -\item \textbf{robust video coding:} At the encoder side, novel techniques to extend the existing error robustness of highly predictive video coding techniques are investigated in order to increase the received video quality over error-prone networks. +\item +\textbf{robust video coding:} At the encoder side, novel techniques to extend the existing error robustness of highly predictive video coding techniques are investigated in order to increase the received video quality over error-prone networks. This research topic resulted in a new method to reduce the error propagation in motion vector coding algorithms published in the conference paper \ref{Conf:DynamicTMVP}. Moreover, a novel two-stage approach was devised to improve the error robustness of highly efficiently coded video at the encoder and streaming levels, resulting in two conference publications \ref{Conf:MotionVectorRedundancies} and \ref{Conf:Chkb}, and a journal publication \ref{Journal:TwoStage}. \item \textbf{robust video decoding:} error concealment techniques are used to increase the error robustness of video decoder and improve the perceived video quality. -The paradigm of error concealment are evaluated at the encoder side, as part of the encoding process, in order to optimise the reconstruction process at the decoder side. +The paradigm of error concealment are evaluated at the encoder side, as part of the encoding process, in order to optimise the reconstruction process at the decoder side. This research resulted in a novel error concealment-aware technique to optimise the error concealment process at the encoder-side, which was proposed for intra-frame only in the conference paper \ref{Conf:ConcAware} and for a generic robust video transmission in the journal \ref{Journal:ConcAware}. %\item \textbf{jointly error resilience and concealment:} the ultimate goal of this research work is to strike a balance between the designed error resilience and error concealment techniques so as to meet higher quality demands for different video contents characteristics and network conditions. \end{enumerate} -\HIGHLIGHT{Contributions} +%\HIGHLIGHT{Contributions} %Finally, the ultimate goal of this research work is to strike a balance between the designed error resilience and error concealment techniques so as to meet a set of \ac{qos}/\ac{qoe} requirements. %Since the ultimate quality judgement is made by end users, subjective tests will constitute a part of the research work in order to validate the objective gains reported as a result of the deployment of various proposed and implemented methods. Given the importance of the \ac{hevc} standard in the near future, the simulation scenarios will be defined based on practical service requirements, such as, bit rate allocation, transmission delay and required QoS.