Deblocking filter for video coding

An apparatus for processing video data comprising a processor and a non-transitory memory with instructions thereon, wherein the instructions upon execution by the processor, cause the processor to:

• identify, for applying a deblocking filtering process to a first video block and a second video block of a video during a conversion between the first and second video blocks and a bitstream of the video, at least one boundary at a vertical edge and/or a horizontal edge of the first and second video blocks, wherein the at least one boundary includes a prediction subblock boundary;
• determine a boundary strength of the at least one boundary;
• decide whether to turn on or off a filter for the at least one boundary based on the boundary strength;
• select a strength of the filter in case the filter is turned on;
• and
• perform the conversion based on the selecting, wherein the boundary strength is determined based on whether an absolute difference between a horizontal or vertical component of block vectors used in a prediction of the first and second video blocks is greater than or equal to a threshold in case that both the first and second video blocks are coded using an intra block copy prediction mode, wherein the threshold is a non-integer, and wherein the prediction subblock boundary includes a prediction unit boundary introduced by a subblock-based temporal motion vector predictor mode or an affine motion compensation mode, and wherein the deblocking filtering process is applied on an 8x8 grid for the prediction subblock boundary.

A non-transitory computer-readable storage medium storing instructions that cause a processor to:

• identify, for applying a deblocking filtering process to a first video block and a second video block of a video during a conversion between the first and second video blocks and a bitstream of the video, at least one boundary at a vertical edge and/or a horizontal edge of the first and second video blocks, wherein the at least one boundary includes a prediction subblock boundary;
• determine a boundary strength of the at least one boundary;
• decide whether to turn on or off a filter for the at least one boundary based on the boundary strength;
• select a strength of the filter in case the filter is turned on;
• and
• perform the conversion based on the selecting, wherein the boundary strength is determined based on whether an absolute difference between a horizontal or vertical component of block vectors used in a prediction of the first and second video blocks is greater than or equal to a threshold in case that both the first and second video blocks are coded using an intra block copy prediction mode, wherein the threshold is a non-integer, and wherein the prediction subblock boundary includes a prediction unit boundary introduced by a subblock-based temporal motion vector predictor mode or an affine motion compensation mode, and wherein the deblocking filtering process is applied on an 8x8 grid for the prediction subblock boundary.