Abstract: A method of decoding coding blocks of a coding tree unit for an image frame, from a bitstream. The method comprises determining a chroma format of the image frame, the chroma format having chroma channels of the image frame being subsampled relative to a luma channel of the image frame; and determining, based on the determined chroma format, a size of a chroma coding block of one of the chroma channels of the coding tree unit, wherein the chroma coding block is collocated with a plurality of corresponding luma blocks. The method comprises determining the chroma coding block is encoded using intra prediction if the determined size of the chroma block is a predetermined minimum chroma block size; and decoding the coding blocks of the coding tree using intra prediction for the chroma coding block and inter prediction for at least one of the plurality of corresponding luma coding blocks.

Abstract: A method of decoding coding blocks of a coding tree unit for an image frame, from a bitstream. The method comprises determining a chroma format of the image frame, the chroma format having chroma channels of the image frame being subsampled relative to a luma channel of the image frame; and determining, based on the determined chroma format, a size of a chroma coding block of one of the chroma channels of the coding tree unit, wherein the chroma coding block is collocated with a plurality of corresponding luma blocks. The method comprises determining the chroma coding block is encoded using intra prediction if the determined size of the chroma block is a predetermined minimum chroma block size; and decoding the coding blocks of the coding tree using intra prediction for the chroma coding block and inter prediction for at least one of the plurality of corresponding luma coding blocks.

Abstract: A method of decoding coding blocks of a coding tree unit for an image frame, from a bitstream. The method comprises determining a chroma format of the image frame, the chroma format having chroma channels of the image frame being subsampled relative to a luma channel of the image frame; and determining, based on the determined chroma format, a size of a chroma coding block of one of the chroma channels of the coding tree unit, wherein the chroma coding block is collocated with a plurality of corresponding luma blocks. The method comprises determining the chroma coding block is encoded using intra prediction if the determined size of the chroma block is a predetermined minimum chroma block size; and decoding the coding blocks of the coding tree using intra prediction for the chroma coding block and inter prediction for at least one of the plurality of corresponding luma coding blocks.

Abstract: A method of decoding coding blocks of a coding tree unit for an image frame, from a bitstream. The method comprises determining a chroma format of the image frame, the chroma format having chroma channels of the image frame being subsampled relative to a luma channel of the image frame; and determining, based on the determined chroma format, a size of a chroma coding block of one of the chroma channels of the coding tree unit, wherein the chroma coding block is collocated with a plurality of corresponding luma blocks. The method comprises determining the chroma coding block is encoded using intra prediction if the determined size of the chroma block is a predetermined minimum chroma block size; and decoding the coding blocks of the coding tree using intra prediction for the chroma coding block and inter prediction for at least one of the plurality of corresponding luma coding blocks.

Abstract: A method of decoding coding blocks of a coding tree unit for an image frame, from a bitstream. The method comprises determining a chroma format of the image frame, the chroma format having chroma channels of the image frame being subsampled relative to a luma channel of the image frame; and determining, based on the determined chroma format, a size of a chroma coding block of one of the chroma channels of the coding tree unit, wherein the chroma coding block is collocated with a plurality of corresponding luma blocks. The method comprises determining the chroma coding block is encoded using intra prediction if the determined size of the chroma block is a predetermined minimum chroma block size; and decoding the coding blocks of the coding tree using intra prediction for the chroma coding block and inter prediction for at least one of the plurality of corresponding luma coding blocks.

Abstract: A method of decoding coding blocks of a coding tree unit in an image. The method comprises obtaining the coding tree unit in the image from a bitstream, the coding tree unit having chroma channels and a luma channel; and determining luma split options for the luma channel of the coding tree unit according to dimensions of a region of the coding tree unit. The method also comprises determining chroma split options for the chroma channels of the coding tree unit according to dimensions of a region of the coding tree unit, the chroma split options being different to the luma split options, the allowable chroma split options resulting in chroma intra predicted blocks with a minimum size of 16 samples; and decoding the coding blocks by determining flags from the bitstream to select one of the determined luma split options and one of the determined chroma split options.

Abstract: A method of decoding a coding unit of a coding tree from a coding tree unit of an image frame from a video bitstream, the coding unit having a primary colour channel and at least one secondary colour channel. The method comprises determining a coding unit including the primary colour channel and the at least one secondary colour channel according to decoded split flags of the coding tree unit; decoding a first index to select a kernel for the primary colour channel and a second index to select a kernel for the at least one secondary colour channel; selecting a first kernel according to the first index and a second kernel according to the second index; and decoding the coding unit by applying the first kernel to residual coefficients of the primary colour channel and the second kernel to residual coefficients of the at least one secondary colour channel.

Abstract: A method of decoding a plurality of coding units from a bitstream to produce an image frame, the coding units being the result of decompositions of coding tree units, the plurality of coding units forming one or more contiguous portions of the bitstream. The method comprises determining a subdivision level for each portion of the bitstream, each subdivision level being applicable to the coding units of the respective contiguous portion of the bitstream; decoding a quantisation parameter delta for each of a number of areas, each area based on decomposition of coding tree units into coding units of each contiguous portion of the bitstream and the corresponding determined subdivision level; determining a quantisation parameter for each area according to the decoded delta quantisation parameter for the area and the quantisation parameter of an earlier coding unit of the image frame; decoding using the determined quantisation parameter of each area.

Abstract: A method of decoding coding blocks of a coding tree unit in an image. The method comprises obtaining the coding tree unit in the image from a bitstream, the coding tree unit having chroma channels and a luma channel; and determining luma split options for the luma channel of the coding tree unit according to dimensions of a region of the coding tree unit. The method also comprises determining chroma split options for the chroma channels of the coding tree unit according to dimensions of a region of the coding tree unit, the chroma split options being different to the luma split options, the allowable chroma split options resulting in chroma intra predicted blocks with a minimum size of 16 samples; and decoding the coding blocks by determining flags from the bitstream to select one of the determined luma split options and one of the determined chroma split options.

Abstract: Decoding an image frame from a bitstream, the image frame being divided into a plurality of coding tree units. The method comprises decoding a maximum transform block size constraint and or a maximum coding tree unit (CTU) size constraint from the bitstream; and decoding a maximum enabled transform block size and/or a maximum enabled CTU size from the bitstream. The decoded maximum enabled transform block size is less than or equal to the decoded maximum transform block size constraint. The decoded maximum enabled CTU size is less than or equal to the decoded maximum CTU size constraint. Determining each of the one or more transform blocks for each of the plurality of coding tree units according to the decoded maximum enabled transform block size, maximum enabled CTU and split flags decoded from the bitstream; and decode each of the determined one or more transform blocks from the bitstream.

Abstract: A method of decoding coding blocks of a coding tree unit in an image. The method comprises obtaining the coding tree unit in the image from a bitstream, the coding tree unit having chroma channels and a luma channel; and determining luma split options for the luma channel of the coding tree unit according to dimensions of a region of the coding tree unit. The method also comprises determining chroma split options for the chroma channels of the coding tree unit according to dimensions of a region of the coding tree unit, the chroma split options being different to the luma split options, the allowable chroma split options resulting in chroma intra predicted blocks with a minimum size of 16 samples; and decoding the coding blocks by determining flags from the bitstream to select one of the determined luma split options and one of the determined chroma split options.

Abstract: A method of decoding coding blocks of a coding tree unit in an image. The method comprises obtaining the coding tree unit in the image from a bitstream, the coding tree unit having chroma channels and a luma channel; and determining luma split options for the luma channel of the coding tree unit according to dimensions of a region of the coding tree unit. The method also comprises determining chroma split options for the chroma channels of the coding tree unit according to dimensions of a region of the coding tree unit, the chroma split options being different to the luma split options, the allowable chroma split options resulting in chroma intra predicted blocks with a minimum size of 16 samples; and decoding the coding blocks by determining flags from the bitstream to select one of the determined luma split options and one of the determined chroma split options.

Abstract: A method of decoding coding blocks of a coding tree unit in an image. The method comprises obtaining the coding tree unit in the image from a bitstream, the coding tree unit having chroma channels and a luma channel; and determining luma split options for the luma channel of the coding tree unit according to dimensions of a region of the coding tree unit. The method also comprises determining chroma split options for the chroma channels of the coding tree unit according to dimensions of a region of the coding tree unit, the chroma split options being different to the luma split options, the allowable chroma split options resulting in chroma intra predicted blocks with a minimum size of 16 samples; and decoding the coding blocks by determining flags from the bitstream to select one of the determined luma split options and one of the determined chroma split options.

Abstract: A method of decoding a coding unit from a coding tree unit of an image frame from a video bitstream. The method comprises determining a scan pattern for a transform block the scan pattern progressing from a current collection to a next collection of the plurality of collections after completing scanning of the current collection; decoding residual coefficients from the video bitstream according to the scan pattern; determining a multiple transform selection index for the coding unit, decoding the multiple transform selection index from the video bitstream if a last significant coefficient encountered along the scan pattern is at or within a threshold cartesian location of the transform block, and determining the multiple transform selection index to indicate that multiple transform selection is not used if the last significant residual coefficient position of the transform block along the scan pattern outside the threshold location; and transforming the decoded residual coefficients.

Abstract: The present disclosure provides a method 1200 of decoding a transform block in an image frame from a bitstream. The method comprises decoding a single truncated unary binarisation from the bitstream, the single truncated unary binarisation being used for a horizontal transform and a vertical transform of a transform block of the image frame. The method then determines a type of the horizontal and vertical transform based on the decoded single truncated unary binarisation and decodes the transform block in the image frame by applying the determined type of horizontal and vertical transform to the transform block of the image.

Abstract: Decoding a coding unit of a coding tree from a coding tree unit, the coding unit having a luma colour channel and at least one chroma colour channel. Decoding a luma transform skip flag for a luma transform block; decoding at least one chroma transform skip flag, each chroma transform skip flag corresponding to one of at least one chroma transform block; determining a secondary transform index by decoding a secondary transform index if at least one of the luma transform skip flag and the at least one chroma transform skip flags indicates that a transform of the transform block is not to be skipped, and determining the secondary transform index to indicate that a secondary transform is not to be applied if all of the luma transform skip flag and the at least one chroma transform skip flags indicate transforms of the respective transform blocks are to be skipped.

Abstract: The present disclosure provides a method 1200 of decoding a transform block in an image frame from a bitstream. The method comprises decoding a single truncated unary binarisation from the bitstream, the single truncated unary binarisation being used for a horizontal transform and a vertical transform of a transform block of the image frame. The method then determines a type of the horizontal and vertical transform based on the decoded single truncated unary binarisation and decodes the transform block in the image frame by applying the determined type of horizontal and vertical transform to the transform block of the image.

Abstract: The present disclosure provides a method 1200 of decoding a transform block in an image frame from a bitstream. The method comprises decoding a single truncated unary binarisation from the bitstream, the single truncated unary binarisation being used for a horizontal transform and a vertical transform of a transform block of the image frame. The method then determines a type of the horizontal and vertical transform based on the decoded single truncated unary binarisation and decodes the transform block in the image frame by applying the determined type of horizontal and vertical transform to the transform block of the image.

Abstract: The present disclosure provides a method 1200 of decoding a transform block in an image frame from a bitstream. The method comprises decoding a single truncated unary binarisation from the bitstream, the single truncated unary binarisation being used for a horizontal transform and a vertical transform of a transform block of the image frame. The method then determines a type of the horizontal and vertical transform based on the decoded single truncated unary binarisation and decodes the transform block in the image frame by applying the determined type of horizontal and vertical transform to the transform block of the image.

Abstract: The present disclosure provides a method 1200 of decoding a transform block in an image frame from a bitstream. The method comprises decoding a single truncated unary binarisation from the bitstream, the single truncated unary binarisation being used for a horizontal transform and a vertical transform of a transform block of the image frame. The method then determines a type of the horizontal and vertical transform based on the decoded single truncated unary binarisation and decodes the transform block in the image frame by applying the determined type of horizontal and vertical transform to the transform block of the image.