Method and apparatus of sub-block deblocking in video coding
Method and apparatus for constrained de-blocking filter are disclosed. According to one method, a current block is partitioned into a plurality of sub-blocks using SDIP (Short Distance Intra Prediction mod). A first Bs (boundary strength) for an internal block boundary of the plurality of sub-blocks is determined by setting the first Bs to a second Bs of an Intra-coded boundary block of the current block. De-blocking process is applied, using the first Bs, to reconstructed samples across the internal block boundary of the plurality of sub-blocks to generate filtered-reconstructed samples. In another method, the current block is partitioned into two sub-blocks using SBT (sub-block transform) horizontally or vertically and the first Bs (boundary strength) is determined for an internal block boundary between the two sub-blocks by setting the first Bs to a second Bs of a non-zero cbf (coded block flag) block of the two sub-blocks in step.
1. A method of de-blocking of reconstructed picture for video encoding or video decoding, the method comprising:
receiving input data related to a current block in a current picture at a video encoder side or a video bitstream corresponding to compressed data including the current block in the current picture at a video decoder side, wherein the current block is partitioned into a plurality of sub-blocks using SDIP (Short Distance Intra Prediction Mode);
setting a first Bs (boundary strength) for an internal block boundary of the plurality of sub-blocks, including
determining presence or absence of a target boundary shared by the current block and a target block that is an Intra-coded block,
setting the first Bs to a value that is the same as a second Bs of the target boundary in a case that the target boundary is determined as presence, and
setting the first Bs to a selected strength value in a case that the target boundary is determined as absence;
applying de-blocking process using the first Bs to reconstructed samples across the internal block boundary of the plurality of sub-blocks to generate filtered-reconstructed samples; and
providing a filtered decoded picture including the filtered-reconstructed samples.
2. The method of claim 1 , wherein the internal block boundary of the plurality of sub-blocks is aligned with an N×N de-blocking grids, wherein N is a positive integer.
3. The method of claim 2 , wherein the N is equal to 8 or 4.
4. The method of claim 1 , wherein the current block is partitioned into two or four sub-blocks in a horizontal or vertical direction using the SDIP if each partitioned sub-block has at least 16 samples.
5. The method of claim 1 , wherein a current sub-block of the plurality of sub-blocks is used to predict a next sub-block of the plurality of sub-blocks.
6. The method of claim 1 , wherein the selected strength value corresponds to 1 or 2.
7. An apparatus for video coding, the apparatus comprising one or more electronic circuits or processors arranged to:
receive input data related to a current block in a current picture at a video encoder side or a video bitstream corresponding to compressed data including the current block in the current picture at a video decoder side, wherein the current block is partitioned into a plurality of sub-blocks using SDIP (Short Distance Intra Prediction Mode);
set a first Bs (boundary strength) for an internal block boundary of the plurality of sub-blocks by performing operations including
determination of presence or absence of a target boundary shared by the current block and a target block that is an Intra-coded block,
setting of the first Bs to a value that is the same as a second Bs of the target boundary in a case that the target boundary is determined as presence, and
setting of the first Bs to a selected strength value in a case that the target boundary is determined as absence;
apply de-blocking process using the first Bs to reconstructed samples across the internal block boundary of the plurality of sub-blocks to generate filtered-reconstructed samples; and
provide a filtered decoded picture including the filtered-reconstructed samples.
8. The apparatus of claim 7 , wherein the selected strength value corresponds to 1 or 2.
9. The apparatus of claim 7 , wherein the internal block boundary is aligned with an N×N de-blocking grids, wherein N is a positive integer.
10. The apparatus of claim 9 , wherein the N is equal to 8 or 4.