The present disclosure provides methods for picture processing. The method can include: receiving a bitstream comprising a set of pictures; determining, according to the received bitstream, whether a virtual boundary is signaled at a sequence level for the set of pictures; in response to the virtual boundary being signaled at the sequence level, determining a position of the virtual boundary for the set of pictures, the position being bounded by a range signaled in the received bitstream; and disabling in-loop filtering operations across the virtual boundary.

A method of decoding an image, includes obtaining at least one offset for a picture, deriving a variable for scaling for the picture based on the at least one offset, and performing inter prediction based on the variable for scaling for the picture. The at least one offset is defined with a direction of scaling.

Initial value is selected when motion estimation is performed using predicted motion vector in video codec in which multiple references are allowed, and coding amount of motion vectors is reduced using predicted motion vector. Motion vector encoding apparatus includes predicted motion vector generator that generates adjacent motion vectors of current block with respect to each of reference pictures and generates each predicted motion vector of the current block from the generated adjacent motion vectors, motion estimator that determines final motion vector of the current block and final reference picture corresponding to the final motion vector with regard to search regions of the reference pictures, differential unit that obtains difference between the final motion vector of the current block and final predicted motion vector corresponding to the determined final reference picture among the predicted motion vectors, and unit for encoding information about the final reference picture and the difference.

Initial value is selected when motion estimation is performed using predicted motion vector in video codec in which multiple references are allowed, and coding amount of motion vectors is reduced using predicted motion vector. Motion vector encoding apparatus includes predicted motion vector generator that generates adjacent motion vectors of current block with respect to each of reference pictures and generates each predicted motion vector of the current block from the generated adjacent motion vectors, motion estimator that determines final motion vector of the current block and final reference picture corresponding to the final motion vector with regard to search regions of the reference pictures, differential unit that obtains difference between the final motion vector of the current block and final predicted motion vector corresponding to the determined final reference picture among the predicted motion vectors, and unit for encoding information about the final reference picture and the difference.

Control data for a motion-constrained tile set (“MCTS”) indicates that inter-picture prediction processes within a specified set of tiles are constrained to reference only regions within the same set of tiles in previous pictures in decoding (or encoding) order. For example, a video encoder encodes multiple pictures partitioned into tiles to produce encoded data. The encoder outputs the encoded data along with control data (e.g., in a supplemental enhancement information message) that indicates that inter-picture prediction dependencies across tile set boundaries are constrained for a given tile set of one or more of the tiles. A video decoder or other tool receives the encoded data and MCTS control data, and processes the encoded data. Signaling and use of MCTS control data can facilitate region-of-interest decoding and display, transcoding to limit encoded data to a selected set of tiles, loss robustness, parallelism in encoding and/or decoding, and other video processing.

In one implementation, an apparatus is provided for encoding or decoding video information. The apparatus comprises a memory unit configured to store video information associated with a base layer and/or an enhancement layer. The apparatus further comprises a processor operationally coupled to the memory unit. In one embodiment, the processor is configured to determine a scaling factor based on spatial dimension values associated with the base and enhancement layers such that the scaling factor is constrained within a predetermined range. The processor is also configured to spatially scale an element associated with the base layer or enhancement layer using the scaling factor and a temporal motion vector scaling process.

In one implementation, an apparatus is provided for encoding or decoding video information. The apparatus comprises a memory unit configured to store video information associated with a base layer and/or an enhancement layer. The apparatus further comprises a processor operationally coupled to the memory unit. In one embodiment, the processor is configured to determine a scaling factor based on spatial dimension values associated with the base and enhancement layers such that the scaling factor is constrained within a predetermined range. The processor is also configured to spatially scale an element associated with the base layer or enhancement layer using the scaling factor and a temporal motion vector scaling process.

Disclosed are methods and apparatuses for image data encoding/decoding. A method for decoding a 360-degree image includes the steps of: receiving a bitstream obtained by encoding a 360-degree image; generating a prediction image by making reference to syntax information obtained from the received bitstream; adding the generated prediction image to a residual image obtained by dequantizing and inverse-transforming the bitstream, so as to obtain a decoded image; and reconstructing the decoded image into a 360-degree image according to a projection format. Therefore, the performance of image data compression can be improved.

Various innovations facilitate the use of intra-picture prediction modes such as palette prediction mode, intra block copy mode, intra line copy mode and intra string copy mode by an encoder or decoder when wavefront parallel processing (“WPP”) is enabled. For example, for a palette coding/decoding mode, an encoder or decoder predicts a palette for an initial unit in a current WPP row of a picture using previous palette data from a previous unit in a previous WPP row of the picture. Or, as another example, for an intra copy mode (e.g., intra block copy mode, intra string copy mode, intra line copy mode), an encoder enforces one or more constraints attributable to the WPP, or a decoder receives and decodes encoded data that satisfies one or more constraints attributable to WPP.

Various innovations facilitate the use of intra-picture prediction modes such as palette prediction mode, intra block copy mode, intra line copy mode and intra string copy mode by an encoder or decoder when wavefront parallel processing (“WPP”) is enabled. For example, for a palette coding/decoding mode, an encoder or decoder predicts a palette for an initial unit in a current WPP row of a picture using previous palette data from a previous unit in a previous WPP row of the picture. Or, as another example, for an intra copy mode (e.g., intra block copy mode, intra string copy mode, intra line copy mode), an encoder enforces one or more constraints attributable to the WPP, or a decoder receives and decodes encoded data that satisfies one or more constraints attributable to WPP.