Patent TW-202137761-A (TW)
Title: Coding concepts for a transformed representation of a sample block
Inventor: BROSS BENJAMIN
IPC: H04N19/13
Filed: 2020-11-26
Abstract: Decoder for decoding a transformed representation of a sample block (84) into a data stream (14), configured to decode a coefficient position information (100) from the data stream. The coefficient position information is indicative of a first coded coefficient position (102) within a transform coefficient block (104). The decoder is configured to check (107) whether the first coded coefficient position (102) is located within a predetermined subarea (106) of the transform coefficient block. If the first coded coefficient position (102) is located inside the predetermined subarea (106) of the transform coefficient block, the decoder is configured to check (111), using transformation information (108) transmitted in the data stream, whether a transform underlying the transform coefficient block (104) is within a first set (132) of one or more available transforms of a set (130) of available transforms or a second set (134) of one or more available transforms of the set of available transforms. If the transform underlying the transform coefficient block is within the first set (132) of one or more available transforms, the decoder is configured to decode (109) the values of the transform coefficients of the transform coefficient block which are, along the first coefficient scan order (110), located from the first coded coefficient position onwards to a last scanned position (101), and infer that transform coefficients (112) of the transform coefficient block which are, along the first coefficient scan order, located upstream the first coded coefficient position are zero, and if the transform underlying the transform coefficient block is within the second set (134) of one or more available transforms, decode (113) values of transform coefficients of the transform coefficient block which are located within the predetermined subarea and are, along a second coefficient scan order (114), located from the first coded coefficient position onwards to the last scanned position (101), and infer that transform coefficients (116) of the transform coefficient block which are, along the first coefficient scan order, located upstream the first coded coefficient position and transform coefficients of the transform coefficient block which are located outside the predetermined subarea are zero. The transform underlying the transform coefficient block along with the transform coefficient block defines the transformed representation, and the second coefficient scan order (114) scans the transform coefficients within the predetermined subarea (106) without scanning any transform coefficient outside the predetermined subarea between the transform coefficients within the predetermined subarea (106), and the first coefficient scan order (110) scans the transform coefficients in a manner so that there are one or more transform coefficients (118) outside the predetermined subarea (106) which are scanned by the first coefficient scan order (110) between two transform coefficients (120) located inside the predetermined subarea (106).