The present disclosure provides systems and methods for wrap-around motion compensation. One exemplary method comprises: receiving a wrap-around motion compensation flag; determining whether a wrap-around motion compensation is enabled based on the wrap-around motion compensation flag; in response to a determination that the wrap-around motion compensation is enabled, receiving data indicating a difference between a width of the picture and an offset used for determining a horizontal wrap-around position; and performing a motion compensation according to the wrap-around motion compensation flag and the difference.

A device for decoding video data includes a memory configured to store video data; and one or more processors implemented in circuitry and configured to: determine that a boundary block of a picture of the video data is bi-directional inter-predicted using a first motion vector and a second motion vector, the boundary block having an edge that touches an edge of the picture; decode the picture, including decoding the boundary block; form a first intermediate padding block using the first motion vector; form a second intermediate padding block using the second motion vector; form a padding block using the first intermediate padding block and the second intermediate padding block; and assign padding values of the padding block to a padding region of the picture neighboring the boundary block on an opposite side of the edge of the picture.

A device for decoding video data includes a memory configured to store video data; and one or more processors implemented in circuitry and configured to: determine that a boundary block of a picture of the video data is bi-directional inter-predicted using a first motion vector and a second motion vector, the boundary block having an edge that touches an edge of the picture; decode the picture, including decoding the boundary block; form a first intermediate padding block using the first motion vector; form a second intermediate padding block using the second motion vector; form a padding block using the first intermediate padding block and the second intermediate padding block; and assign padding values of the padding block to a padding region of the picture neighboring the boundary block on an opposite side of the edge of the picture.

Aspects of the disclosure provide methods and apparatuses for video encoding/decoding. In some examples, an apparatus for video decoding includes receiving circuitry and processing circuitry. The processing circuitry receives a bitstream carrying a plurality of pictures, and determines at least a motion compensation padding (MCP) block that is located in an MCP area outside of a picture and next to a picture boundary of the picture. The processing circuitry derives, according to a plurality of candidates with positions located at the picture boundary within the picture, a motion vector of the MCP block for motion compensated boundary padding, and reconstructs at least a sample in the MCP block according to the derived motion vector for the motion compensated boundary padding.

Aspects of the disclosure provide methods and apparatuses for video encoding/decoding. In some examples, an apparatus for video decoding includes receiving circuitry and processing circuitry. The processing circuitry receives a bitstream carrying a plurality of pictures, and determines at least a motion compensation padding (MCP) block that is located in an MCP area outside of a picture and next to a picture boundary of the picture. The processing circuitry derives, according to a plurality of candidates with positions located at the picture boundary within the picture, a motion vector of the MCP block for motion compensated boundary padding, and reconstructs at least a sample in the MCP block according to the derived motion vector for the motion compensated boundary padding.

A method for decoding a 360-degree image includes: 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; combining the generated prediction image with 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. Here, generating the prediction image includes: checking, from the syntax information, prediction mode accuracy for a current block to be decoded; determining whether the checked prediction mode accuracy corresponds to most probable mode (MPM) information obtained from the syntax information; and when the checked prediction mode accuracy does not correspond to the MPM information, reconfiguring the MPM information according to the prediction mode accuracy for the current block.

Innovations in intra-picture prediction with multiple candidate reference lines available are described herein. For example, intra-picture prediction for a current block uses a non-adjacent reference line of sample values to predict the sample values of the current block. This can improve the effectiveness of the intra-picture prediction when the reference line of sample values that is adjacent the current block includes significant capture noise, significant quantization error, or significantly different values (compared to the current block) due to an occlusion. Innovations described herein include, but are not limited to, the following: intra-picture prediction with multiple candidate reference lines available; encoding/decoding of reference line indices using prediction; filtering of reference sample values; residue compensation; weighted prediction; mode-dependent padding to replace unavailable reference sample values; using in-loop-filtered reference sample values; encoder-side decisions for selecting reference lines; and post-filtering of predicted sample values.

A video coder is configured to determine a reference block of a reference picture for prediction of a current block of a current picture using motion information and to generate a set of reference samples for the current block of the current picture. To generate the set of reference samples, the video coder is configured to perform reference sample clipping on the reference block of the reference picture based on a size of the reference picture. The video coder is further configured to generate a prediction block for the current block of the current picture based on the set of reference samples.

Aspects of the disclosure provide method and apparatus for video coding. In the method, which of a combination of vertical padding and horizontal padding is performed is determined to determine padded values of a reference block in a neighboring left coding tree unit (CTU) included in a fixed search range of blocks in a current CTU. The padded values are determined based on a block vector that points to the reference block and a position of a current block in the CTU. At least a sample of the current block is reconstructed based on one of (i) the padded values of the reference block and (ii) reconstructed samples of the reference block based on availability of the reference block in the fixed search range. The left CTU is padded using a combination of the vertical and the horizontal padding.

A video signal processing method comprises obtaining a merge subblock index for a current block for which a parameter for subblock-based inter prediction is derived from a surrounding block; obtaining control point motion vectors for control points of the current block, based on the merge subblock index, the merge subblock index being related to one candidate in a subblock-based merge candidate list; applying one or more offsets to the control point motion vectors, based on a merge with motion vector direction index for refining the control point motion vectors; determining a motion vector for each subblock based on the respective positions of the subblocks in the current block and the control point motion vectors to which the one or more offsets have been applied; and generating prediction samples for the current block based on a reference picture related to the subblock merge index and the motion vectors for each subblock.