Systems and methods for decoding a coded video stream are provided. A method includes receiving a coded video stream that includes an access unit, including a picture; signaling a first flag, in an access unit delimiter of the coded video stream, that indicates whether the access unit includes either or neither one from among an intra random access point (IRAP) picture and a gradual decoding refresh (GDR) picture; signaling a second flag, in a picture header of the coded video stream, that indicates whether the picture is the IRAP picture; and decoding the picture, as a current picture, based on the signaling of the first flag and the second flag, wherein a value of the first flag and a value of the second flag are aligned.

Systems and methods for decoding a coded video stream are provided. A method includes receiving a coded video stream that includes an access unit, including a picture; signaling a first flag, in an access unit delimiter of the coded video stream, that indicates whether the access unit includes either or neither one from among an intra random access point (IRAP) picture and a gradual decoding refresh (GDR) picture; signaling a second flag, in a picture header of the coded video stream, that indicates whether the picture is the IRAP picture; and decoding the picture, as a current picture, based on the signaling of the first flag and the second flag, wherein a value of the first flag and a value of the second flag are aligned.

A video decoder, encoder, and corresponding methods for processing video data for an image block and a particular reference picture index to predict the image block are disclosed that utilize adaptive weighting of reference pictures to enhance video compression, where a decoder includes a reference picture weighting factor unit for determining a weighting factor corresponding to the particular reference picture index; an encoder includes a reference picture weighting factor assignor for assigning a weighting factor corresponding to the particular reference picture index; and a method for decoding includes receiving a reference picture index with the data that corresponds to the image block, determining a weighting factor for each received reference picture index, retrieving a reference picture for each index, motion compensating the retrieved reference picture, and multiplying the motion compensated reference picture by the corresponding weighting factor to form a weighted motion compensated reference picture.

A video decoder, encoder, and corresponding methods for processing video data for an image block and a particular reference picture index to predict the image block are disclosed that utilize adaptive weighting of reference pictures to enhance video compression, where a decoder includes a reference picture weighting factor unit for determining a weighting factor corresponding to the particular reference picture index; an encoder includes a reference picture weighting factor assignor for assigning a weighting factor corresponding to the particular reference picture index; and a method for decoding includes receiving a reference picture index with the data that corresponds to the image block, determining a weighting factor for each received reference picture index, retrieving a reference picture for each index, motion compensating the retrieved reference picture, and multiplying the motion compensated reference picture by the corresponding weighting factor to form a weighted motion compensated reference picture.

Systems, methods, and instrumentalities for sub-block motion derivation and motion vector refinement for merge mode may be disclosed herein. Video data may be coded (e.g., encoded and/or decoded). A collocated picture for a current slice of the video data may be identified. The current slice may include one or more coding units (CUs). One or more neighboring CUs may be identified for a current CU. A neighboring CU (e.g., each neighboring CU) may correspond to a reference picture. A (e.g., one) neighboring CU may be selected to be a candidate neighboring CU based on the reference pictures and the collocated picture. A motion vector (MV) (e.g., collocated MV) may be identified from the collocated picture based on an MV (e.g., a reference MV) of the candidate neighboring CU. The current CU may be coded (e.g., encoded and/or decoded) using the collocated MV.

Systems, methods, and instrumentalities for sub-block motion derivation and motion vector refinement for merge mode may be disclosed herein. Video data may be coded (e.g., encoded and/or decoded). A collocated picture for a current slice of the video data may be identified. The current slice may include one or more coding units (CUs). One or more neighboring CUs may be identified for a current CU. A neighboring CU (e.g., each neighboring CU) may correspond to a reference picture. A (e.g., one) neighboring CU may be selected to be a candidate neighboring CU based on the reference pictures and the collocated picture. A motion vector (MV) (e.g., collocated MV) may be identified from the collocated picture based on an MV (e.g., a reference MV) of the candidate neighboring CU. The current CU may be coded (e.g., encoded and/or decoded) using the collocated MV.

An image encoding apparatus comprises a selector configured to select a prediction operation, for prediction of samples of a current region of a current image with respect to one or more of a group of reference samples, from a set of candidate prediction operations, at least some of which define, as an intra-image prediction operation, a prediction direction between a current sample to be predicted and a group of reference samples in the same image; and an intra-image predictor configured to derive predicted samples of a current image region from reference samples of the same image in response to selection, by the selector, of an intra-image prediction operation for the current image region; in which: the current region comprises at least a subset of a current coding tree unit (CTU) in an array of CTUs; the group of references samples is disposed, with respect to the current image region at one or more predetermined sides of the current image region; and the selector is configured to inhibit the selection of a prediction operation for the current region, for which at least some of the reference samples at one or more of the predetermined sides of the current image region are disposed in a CTU other than the current CTU.

An image encoding apparatus comprises a selector configured to select a prediction operation, for prediction of samples of a current region of a current image with respect to one or more of a group of reference samples, from a set of candidate prediction operations, at least some of which define, as an intra-image prediction operation, a prediction direction between a current sample to be predicted and a group of reference samples in the same image; and an intra-image predictor configured to derive predicted samples of a current image region from reference samples of the same image in response to selection, by the selector, of an intra-image prediction operation for the current image region; in which: the current region comprises at least a subset of a current coding tree unit (CTU) in an array of CTUs; the group of references samples is disposed, with respect to the current image region at one or more predetermined sides of the current image region; and the selector is configured to inhibit the selection of a prediction operation for the current region, for which at least some of the reference samples at one or more of the predetermined sides of the current image region are disposed in a CTU other than the current CTU.

An electronic apparatus performs a method of coding video data. The method includes receiving, from a bitstream of the video data, a first syntax that indicates an affine motion model enabled for a current coding block, estimating parameters of the affine motion model using gradients of motion vectors of multiple spatial neighboring blocks of the current coding block, and constructing motion vectors of the affine motion model for the current coding block by using the estimated parameters. In some embodiments, constructing motion vectors further includes converting the estimated parameters into control point motion vectors (CPMVs), and adding the CPMVs into a current affine merge candidate list. In some embodiments, constructing motion vectors further includes deriving a motion vector predictor for an affine mode.

An electronic apparatus performs a method of coding video data. The method includes receiving, from a bitstream of the video data, a first syntax that indicates an affine motion model enabled for a current coding block, estimating parameters of the affine motion model using gradients of motion vectors of multiple spatial neighboring blocks of the current coding block, and constructing motion vectors of the affine motion model for the current coding block by using the estimated parameters. In some embodiments, constructing motion vectors further includes converting the estimated parameters into control point motion vectors (CPMVs), and adding the CPMVs into a current affine merge candidate list. In some embodiments, constructing motion vectors further includes deriving a motion vector predictor for an affine mode.