摘要:
Methods and devices for image and video coding using rolling intra prediction. The encoder selects a mode for a current block, the current block having a plurality of neighboring reference samples from an adjacent block, wherein the mode is associated with a prediction function. A predicted block of predicted pixels is constructed by initially determining at least some of the predicted pixels based on the prediction function with one or more of the neighboring reference samples as inputs to the prediction function, and by determining at least some other of the predicted pixels based on the prediction function with the at least some of the predicted pixels as inputs. The process proceeds to build the predicted block in a traversing order using predicted pixels of the same predicted block as inputs to the prediction function for determining other predicted pixels of the predicted block. The decoder performs the same prediction process.
摘要:
Methods and devices for video coding are described. When encoding a non-zero coefficient group (CG) prior to the last such group in a group scan ordering within a transform block, data representative of the true (x,y)-position of the last non-zero transform coefficient in a scan ordering within that CG is modified, to improve coding efficiency, based upon at least one of (a) an intra-prediction mode used to encode the block and (b) at least one coefficient group neighbouring that CG. Upon decoding a CG thus encoded, the modification is un-done to retrieve the true (x,y)-position.
摘要:
Methods and devices for encoding and decoding scalable video are described. In one aspect, a method of reconstructing, in a video decoder, an enhancement-layer image based upon a reconstructed reference-layer image using inter-layer prediction is described. The method includes reconstructing a reference-layer residual and a reference-layer prediction, wherein the reference-layer residual and the reference-layer prediction, when combined, form the reconstructed reference-layer image; up-sampling the reference-layer residual using a first up-sampling operation; up-sampling the reference-layer prediction using a second up-sampling operation different from the first up-sampling operation; generating an inter-layer prediction using the up-sampled reference-layer residual and the up-sampled reference-layer prediction; and reconstructing the enhancement-layer image based upon the inter-layer prediction.
摘要:
Methods and devices for modified coding of blocks of residuals in the case of transform skipping. To better align the data with assumptions upon which the entropy coding scheme is based, the block of residual data is permuted at the encoder prior to entropy coding. The block of reconstructed data is then inverse permuted at the decoder to recover the reconstructed block of residuals. The permutation may include 180 rotation of the block, which may be of particular benefit in the case of intra-coded residuals.
摘要:
Methods of encoding and decoding for video data for encoding or decoding motion vector difference components for inter-coded video are described. The sign of one of the components is hidden within the parity of the sum of the magnitudes of the horizontal and vertical difference components. The sign of the other of the components is explicitly signaled in the bitstream. The hidden sign may be assigned to the larger in magnitude of the two components. In other cases, the hidden sign may always be assigned to the horizontal or vertical component. In another case, the hidden sign may always be assigned to one component, unless that component is zero, in which case the hidden sign is assigned to the other component. In another case, both components may have their signs hidden, in which case the sign hiding is based on their respective parity, rather than the parity of their sum.
摘要:
Methods and devices for reconstructing coefficient levels from a bitstream of encoded video data for a coefficient group in a transform unit, using adaptive-threshold-based level coding. Threshold is set based upon level information from one or more previously-reconstructed coefficient groups in the transform unit. Threshold may be maximum number of level flags to decode for the coefficient group. Level information may include number of level flags decoded in previous coefficient groups. Previously-reconstructed coefficient groups may include coefficient group to the right and below the current coefficient group.