Block artefact reduction

A decoder comprising:

• a non-transitory computer-readable memory including instructions for generating a reconstructed frame by decoding an encoded bitstream;
• and
• a processor, operatively coupled to the non-transitory computer-readable memory, for receiving the instructions from the non-transitory computer-readable memory and executing the instructions to:
• obtain encoded block data from the encoded bitstream, the encoded block data corresponding to a current block from the reconstructed frame;
• generate reconstructed block data for the current block based on the encoded block data using transform coefficient continuity smoothing, wherein transform coefficient continuity smoothing includes:
• for a block boundary of the current block:
• in response to a determination that adjacent block data corresponding to an adjacent block spatially adjacent to the current block along the block boundary is available, performing transform coefficient continuity smoothing based on the current block, the adjacent block, and the block boundary;
• and
• include the reconstructed block data in the reconstructed frame;
• and
• output the reconstructed frame.

A method comprising:

• generating, by a processor executing instructions stored on a non-transitory computer-readable medium, a reconstructed frame by decoding an encoded bitstream, wherein decoding includes:
• obtaining encoded block data from the encoded bitstream, the encoded block data corresponding to a current block from the reconstructed frame and including two-dimensional transform coefficients for the current block;
• generating reconstructed block data for the current block based on the encoded block data using transform coefficient continuity smoothing, wherein transform coefficient continuity smoothing includes:
• for a block boundary of the current block:
• in response to a determination that adjacent block data corresponding to an adjacent block spatially adjacent to the current block along the block boundary is available, performing transform coefficient continuity smoothing based on the current block, the adjacent block, and the block boundary, wherein performing transform coefficient continuity smoothing based on the current block and the adjacent block includes:
• determining one-dimensional transform coefficients for the current block based on the block boundary and the two-dimensional transform coefficients for the current block;
• and
• determining intermediate two-dimensional transform coefficients for the current block based on the two-dimensional transform coefficients for the current block and a difference between the one-dimensional transform coefficients for the current block and one-dimensional transform coefficients for the adjacent block;
• and
• including the reconstructed block data in the reconstructed frame;
• and
• outputting the reconstructed frame.