Deblocking filtering at coding block or subblock boundary

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:

• determine, for subblocks of a current video block of a video which is coded with a subblock temporal motion vector predictor mode or an affine prediction mode, subblock boundaries to which a deblocking filter is to be applied according to a rule;
• and
• perform a conversion between the current video block and a bitstream of the video based on the determining,
• wherein the rule specifies that when determining the subblock boundaries, a first deblocking filter length for a first vertical subblock boundary of the subblock boundaries at a first horizontal position (x1) and a first vertical position (y1) inside the current video block is determined based on checking one or both of i) whether a boundary at a horizontal position (x1+dx) and the first vertical position (y1) is a transform block boundary or not, ii) whether a boundary at a horizontal position (x1−dx) and the first vertical position (y1) is a transform block boundary or not, where dx is an integer greater or equal to 0.

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

• determine, for subblocks of a current video block of a video which is coded with a subblock temporal motion vector predictor mode or an affine prediction mode, subblock boundaries to which a deblocking filter is to be applied according to a rule;
• and
• perform a conversion between the current video block and a bitstream of the video based on the determining,
• wherein the rule specifies that when determining the subblock boundaries, a first deblocking filter length for a first vertical subblock boundary of the subblock boundaries at a first horizontal position (x1) and a first vertical position (y1) inside the current video block is determined based on checking one or both of i) whether a boundary at a horizontal position (x1+dx) and the first vertical position (y1) is a transform block boundary or not, ii) whether a boundary at a horizontal position (x1−dx) and the first vertical position (y1) is a transform block boundary or not, where dx is an integer greater or equal to 0.

A non-transitory computer-readable recording medium storing a bitstream of a video which is generated by a method performed by a video processing apparatus, wherein the method comprises:

• determining, for subblocks of a current video block of a video which is coded with a subblock temporal motion vector predictor mode or an affine prediction mode, subblock boundaries to which a deblocking filter is to be applied according to a rule;
• and
• generating the bitstream based on the determining,
• wherein the rule specifies that when determining the subblock boundaries, a first deblocking filter length for a first vertical subblock boundary of the subblock boundaries at a first horizontal position (x1) and a first vertical position (y1) inside the current video block is determined based on checking one or both of i) whether a boundary at a horizontal position (x1+dx) and the first vertical position (y1) is a transform block boundary or not, ii) whether a boundary at a horizontal position (x1−dx) and the first vertical position (y1) is a transform block boundary or not, where dx is an integer greater or equal to 0.