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Revert consists of to consists in

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jfmcarreira
2018-12-14 00:55:04 +00:00
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021_VideoCoding/VideoCodingReview.tex
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@@ -466,14 +466,14 @@ The underlying idea of inter-frame prediction is to estimate the current frame f
\subsubsection{Motion estimation and compensation} \subsubsection{Motion estimation and compensation}
Motion estimation consists of searching for a block with the highest similarity with the current block to be predicted (\ac{pu} in \ac{hevc}), using block-matching algorithms over previously encoded frames, i.e. the reference frames. Motion estimation consists in searching for a block with the highest similarity with the current block to be predicted (\ac{pu} in \ac{hevc}), using block-matching algorithms over previously encoded frames, i.e. the reference frames.
Typically, reference frames correspond to past or future temporally adjacent frames. Typically, reference frames correspond to past or future temporally adjacent frames.
The frame encoding order determines which references are selected and which future frames are available. The frame encoding order determines which references are selected and which future frames are available.
The reference block that results in the lowest error is selected as the best block for prediction. The reference block that results in the lowest error is selected as the best block for prediction.
To identify the best matching block to be used for motion compensation, the difference between the target and the reference block positions is encoded as a two-dimensional \ac{mv}. To identify the best matching block to be used for motion compensation, the difference between the target and the reference block positions is encoded as a two-dimensional \ac{mv}.
The \ac{hevc} allows for either one or two \acs{mv} to be used for each \ac{pu}. Video frames of type P are predicted from one single reference (one \ac{mv}), while frame of type B are predicted from two references (two \acs{mv}). The \ac{hevc} allows for either one or two \acs{mv} to be used for each \ac{pu}. Video frames of type P are predicted from one single reference (one \ac{mv}), while frame of type B are predicted from two references (two \acs{mv}).
This results in uni-direction or bi-directional coding, respectively. This results in uni-direction or bi-directional coding, respectively.
Furthermore, weighted prediction can also be used, which consists of scaling and offset operations performed on the prediction block to improve efficiency. Furthermore, weighted prediction can also be used, which consists in scaling and offset operations performed on the prediction block to improve efficiency.
The \acs{mv} only refer to frames included in a reference frame list, where each frame is identified by an index. Therefore, to fully describe inter-frame prediction a combination of two parameters is required: \ac{mv} and reference frame index. The \acs{mv} only refer to frames included in a reference frame list, where each frame is identified by an index. Therefore, to fully describe inter-frame prediction a combination of two parameters is required: \ac{mv} and reference frame index.
Since MPEG-2, motion estimation/compensation has been performed using blocks of variable size. Since MPEG-2, motion estimation/compensation has been performed using blocks of variable size.
022_ErrorResilience/RobustTransmissionReview.tex
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@@ -511,7 +511,7 @@ The usage of this operator for \ac{ec} was evaluated in \cite{IntraConc2010,Fine
The conventional methods used to recover missing frames in the temporal domain are the so-called \ac{fc} and \ac{mc}. The conventional methods used to recover missing frames in the temporal domain are the so-called \ac{fc} and \ac{mc}.
These \ac{ec} methods were implemented for the \ac{h264} reference software in \cite{H264RefConc2006}. These \ac{ec} methods were implemented for the \ac{h264} reference software in \cite{H264RefConc2006}.
The \ac{fc} method consists of repeating (copying) the frame that has the shortest temporal distance, in order to substitute the missing one, into the time instant where the loss occurred. The \ac{fc} method consists in repeating (copying) the frame that has the shortest temporal distance, in order to substitute the missing one, into the time instant where the loss occurred.
The \ac{mc} method uses the motion information of the closest frame to recover the missing one, thus the missing pixels are recovered through motion compensation. The \ac{mc} method uses the motion information of the closest frame to recover the missing one, thus the missing pixels are recovered through motion compensation.
Previous works and simulation results showed that the \ac{mc} method achieves higher quality in the reconstructed frames in most cases~\cite{BiDirMC2011,2DRecursiveRefinement2010}. However, the complexity increases with the implementation of the \ac{mc} method, when compared with \ac{fc}. Previous works and simulation results showed that the \ac{mc} method achieves higher quality in the reconstructed frames in most cases~\cite{BiDirMC2011,2DRecursiveRefinement2010}. However, the complexity increases with the implementation of the \ac{mc} method, when compared with \ac{fc}.