[0062] Inter prediction, which may also be referred to as temporal prediction, motion compensation, or motion-compensated prediction, reduces temporal redundancy. In inter prediction the sources of prediction are previously decoded pictures. Intra prediction utilizes the fact that adjacent pixels within the same picture are likely to be correlated. Intra prediction can be performed in spatial or transform domain, i.e., either sample values or transform coefficients can be predicted. When applied in spatial domain, the sample values of adjacent neighboring blocks are used in predicting the sample values of a current block. Intra prediction is typically exploited in intra coding, where no inter prediction is applied. 

[0063] One outcome of the coding procedure is a set of coding parameters, such as motion vectors and quantized transform coefficients. Many parameters can be entropy-coded more efficiently if they are predicted first from spatially or temporally neighboring parameters. For example, a motion vector may be predicted from spatially adjacent motion vectors and only the difference relative to the motion vector predictor may be coded. 

[0064] A motion vector may be regarded as a two-dimensional Euclidean vector used for inter prediction to indicate the position of a prediction block within a reference picture relative to the position of a block being predicted, such as a current prediction unit being encoded or decoded. A motion vector may point to a fractional sample location, in which case sample values of the prediction block may be interpolated from the sample values of the reference picture. 

[0065] In-picture prediction may be defined to collectively comprise but is not necessarily limited to one or more of the following: spatial prediction of coding parameters (e.g. spatial motion vector prediction), intra prediction, intra block copy prediction, in-loop filtering across blocks, and context state updating across blocks in context-adaptive entropy coding. The definition of in-picture prediction may be adjusted depending on the context of referring to the term. 

[0066] The decoder reconstructs the output video by applying prediction means similar to the encoder to form a predicted representation of the pixel blocks (using the motion or spatial information created by the encoder and stored in the compressed representation) and prediction error decoding (inverse operation of the prediction error coding recovering the quantized prediction error signal in spatial pixel domain). After applying prediction and prediction error decoding means the decoder sums up the prediction and prediction error signals (pixel values) to form the output video frame. The decoder (and encoder) can also apply additional filtering means to improve the quality of the output video before passing it for display and/or storing it as prediction reference for the forthcoming frames in the video 

