A video encoding method includes (i) determining a current bit rate of a communication channel between a destination device and a source device that stores an input video frame, and (ii) generating a current reconstructed frame and an encoded bitstream at least in part via inter-frame coding of a current input video frame of a sequence of input video frames using a previously-generated reconstructed frame generated at least in part via inter-frame coding of a previous input video frame. The current reconstructed frame is a compressed version of the current input video frame. When both (i) a subsequent bit rate, determined after said inter-frame coding, is less than a threshold and (ii) the current bit rate exceeds the threshold, the method includes: (a) generating a downscaled reconstructed frame at least in part by downscaling the current reconstructed frame; and (b) appending the encoded bitstream with a bit sequence representing the downscaled reconstructed frame.

A method of coding implemented by a decoding device, comprising initializing a dedicated buffer for intra block copy (IBC) referencing, when a current coding tree unit (CTU) to be decoded is a first CTU of a CTU row, determining whether a current block in the current CTU is predicted using IBC mode, obtaining an IBC block vector for the current block when the current block is predicted using IBC mode, and obtaining predicted sample values for the current block, based on reference samples from the dedicated buffer and the IBC block vector for the current block.

A method of coding implemented by a decoding device, comprising initializing a dedicated buffer for intra block copy (IBC) referencing, when a current coding tree unit (CTU) to be decoded is a first CTU of a CTU row, determining whether a current block in the current CTU is predicted using IBC mode, obtaining an IBC block vector for the current block when the current block is predicted using IBC mode, and obtaining predicted sample values for the current block, based on reference samples from the dedicated buffer and the IBC block vector for the current block.

An image decoding method is disclosed in the present specification. An image decoding method according to the present invention may include: determining a position of a co-located block of a current block within a co-located picture (co-located picture); determining a representative motion vector of the current block by using motion information at the position of the co-located block; and deriving motion information on a sub-block included in the current block by using the representative motion vector.

An image decoding method is disclosed in the present specification. An image decoding method according to the present invention may include: determining a position of a co-located block of a current block within a co-located picture (co-located picture); determining a representative motion vector of the current block by using motion information at the position of the co-located block; and deriving motion information on a sub-block included in the current block by using the representative motion vector.

A video coder receives data from a bitstream for a block of pixels to be encoded or decoded as a current block of a current picture of a video. Upon determining that an applied block setting of the current block satisfies a threshold condition, the video coder generates a first prediction based on a first motion information for a first prediction unit of the current block. The video coder generates a second prediction based on a second motion information for a second prediction unit of the current block. The video coder generates a third prediction based on the first and second motion information for an overlap prediction region that is defined based on a partitioning between the first prediction unit and the second prediction unit. The video coder encodes or decodes the current block by using the first, second, and third predictions.

A video decoding apparatus is provided for decoding a sequence of pictures, some of which have different resolutions. The apparatus decodes, from a high-level syntax structure of the sequence, a first syntax element for specifying a reference size of pictures referring to the high-level syntax structure and a second syntax element for specifying a picture size scaled from the reference size of the picture referring to the high-level syntax structure. The apparatus predicts a current block, by modifying a sample position in a reference picture indicated by a motion vector of the current block based on the first and second syntax elements.

A video decoding apparatus is provided for decoding a sequence of pictures, some of which have different resolutions. The apparatus decodes, from a high-level syntax structure of the sequence, a first syntax element for specifying a reference size of pictures referring to the high-level syntax structure and a second syntax element for specifying a picture size scaled from the reference size of the picture referring to the high-level syntax structure. The apparatus predicts a current block, by modifying a sample position in a reference picture indicated by a motion vector of the current block based on the first and second syntax elements.

A coding method for coding an image to be coded using a reference image includes identifying a reference area being a part of the reference image, the reference area corresponding to an area to be coded being an area obtained by dividing the image to be coded, and obtaining a predicted area with respect to the area to be coded, by prediction using the reference area. The area to be coded and the reference area have different sizes and/or different shapes. In the identifying, the reference area is identified by utilizing a difference between a manner of projection of an object corresponding to the area to be coded and a manner of projection of the object corresponding to the reference area, due to an operation performed on a camera when the image to be coded and the reference image are acquired.

A coding method for coding an image to be coded using a reference image includes identifying a reference area being a part of the reference image, the reference area corresponding to an area to be coded being an area obtained by dividing the image to be coded, and obtaining a predicted area with respect to the area to be coded, by prediction using the reference area. The area to be coded and the reference area have different sizes and/or different shapes. In the identifying, the reference area is identified by utilizing a difference between a manner of projection of an object corresponding to the area to be coded and a manner of projection of the object corresponding to the reference area, due to an operation performed on a camera when the image to be coded and the reference image are acquired.