Method and apparatus for in-loop filtering

1. A method for in-loop processing of reconstructed video data, wherein the reconstructed video data is partitioned into image units, horizontal deblocking is applied to the reconstructed video data across vertical image-unit boundaries and then vertical deblocking operates on n pixels of horizontal-deblocked video data on each side of horizontal image-unit boundaries, and vertical filter parameters of the vertical deblocking are derived based on n horizontal-deblocked lines on each side of the horizontal image-unit boundaries, wherein n is a first integer, the method comprising:

receiving the reconstructed video data for a current image unit, wherein the reconstructed video data includes n reconstructed lines from line p 0 to line p n−1 above a horizontal image-unit boundary and line p 0 is closest to the horizontal image-unit boundary;

applying the horizontal deblocking to at least one of said n reconstructed lines to generate at least one horizontal-deblocked line for line p n−1 ; and

applying sample adaptive offset (SAO) processing to at least one horizontal-deblocked line for line p n based on the horizontal-deblocked line for line p n−1 ; and

wherein the above steps are performed before a neighboring image unit below the current image unit arrives.

2. The method of claim 1 , further comprising:

storing one line p n of deblocking filter (DF) output pixels for applying SAO processing on line p n−1 when the neighboring image unit below the current image unit arrives.

3. The method of claim 1 , wherein all of said n reconstructed lines are horizontal deblocked before the neighboring image unit below the current image unit arrives, the method further comprises:

storing said n horizontal-deblocked lines in one or more line buffers;

reading said n horizontal-deblocked lines from said one or more line buffers; and

applying the vertical deblocking to said n horizontal-deblocked lines when the neighboring image unit below the current image unit arrives.

4. The method of claim 1 , wherein the image unit corresponds to a Largest Coding Unit (LCU), a slice, or a tile.

5. The method of claim 1 , wherein at least line p 0 of said n reconstructed lines is not horizontal deblocked before the neighboring image unit below the current image unit arrives.

6. The method of claim 5 , further comprising:

storing said reconstructed line for line p 0 in a line buffer;

reading said reconstructed line for line p 0 from said line buffer; and

performing Intra prediction based on said reconstructed line for line p 0 and coded data for the neighboring image unit below the current image unit to generate reconstructed video for the neighboring image unit below the current image unit.

7. The method of claim 6 , further comprising:

applying the horizontal deblocking, after said performing Intra prediction, to said reconstructed line for line p 0 to generate one horizontal-deblocked line for line p 0 ; and

applying the vertical deblocking to said one horizontal-deblocked line for line p 0 .

8. The method of claim 5 , wherein lines p 0 to p K−1 of said n reconstructed lines are not horizontal deblocked before the neighboring image unit below the current image unit arrives, the method further comprises:

storing said reconstructed lines for lines p 0 to p K−1 and horizontal-deblocked lines for lines p K to p n−1 in one or more line buffers before the neighboring image unit below the current image unit arrives, wherein 1<K<n, and K is a second integer.

9. The method of claim 5 , further comprising storing filter decision information for the horizontal filtering of the current image unit when the neighboring image unit below the current image unit becomes available.

10. The method of claim 5 , further comprising storing at least partial derived information associated with at least one portion of one reconstructed line or one horizontal-deblocked line above the horizontal image-unit boundary, wherein said partial derived information is used for the horizontal deblocking or SAO processing, and wherein the horizontal deblocking or SAO processing is applied to said at least one portion of one reconstructed line or one horizontal-deblocked line above the horizontal image-unit boundary when the neighboring image unit below the current image unit becomes available.

11. An apparatus for in-loop processing of reconstructed video data, wherein the reconstructed video data is partitioned into image units, horizontal deblocking is applied to the reconstructed video data across vertical image-unit boundaries and then vertical deblocking operates on n pixels of horizontal-deblocked video data on each side of horizontal image-unit boundaries, and vertical filter parameters of the vertical deblocking are derived based on n horizontal-deblocked lines on each side of the horizontal image-unit boundaries, wherein n is a first integer, the apparatus comprising:

means for receiving the reconstructed video data for a current image unit, wherein the reconstructed video data includes n reconstructed lines from line p 0 to line p n−1 above a horizontal image-unit boundary and line p 0 is closest to the horizontal image-unit boundary;

means for applying the horizontal deblocking to at least one of said n reconstructed lines to generate at least one horizontal-deblocked line for line p n−1 ; and

means for applying sample adaptive offset (SAO) processing on at least one horizontal-deblocked line for line p n based on the horizontal-deblocked line for line p n−1 ; and

wherein the above steps are performed before a neighboring image unit below the current image unit arrives.

12. The apparatus of claim 11 , further comprising:

means for storing one line p n of deblocking filter (DF) output pixels for applying SAO processing on line p n−1 when the neighboring image unit below the current image unit arrives.

13. The apparatus of claim 11 , wherein all of said n reconstructed lines are horizontal deblocked before the neighboring image unit below the current image unit arrives, the apparatus further comprises:

means for storing said n horizontal-deblocked lines in one or more line buffers;

means for reading said n horizontal-deblocked lines from said one or more line buffers; and

means for applying the vertical deblocking to said n horizontal-deblocked lines when the neighboring image unit below the current image unit arrives.

14. The apparatus of claim 11 , wherein the image unit corresponds to a Largest Coding Unit (LCU), a slice, or a tile.

15. The apparatus of claim 11 , wherein at least line p 0 of said n reconstructed lines is not horizontal deblocked before the neighboring image unit below the current image unit arrives.

16. The apparatus of claim 15 , further comprising:

means for storing said reconstructed line for line p 0 in a line buffer;

means for reading said reconstructed line for line p 0 from said line buffer; and

means for performing Intra prediction based on said reconstructed line for line p 0 and coded data for the neighboring image unit below the current image unit to generate reconstructed video for the neighboring image unit below the current image unit.

17. The apparatus of claim 16 , further comprising:

means for applying the horizontal deblocking, after said performing Intra prediction, to said reconstructed line for line p 0 to generate one horizontal-deblocked line for line p 0 ; and

means for applying the vertical deblocking to said one horizontal-deblocked line for line p 0 .

18. The apparatus of claim 15 , wherein lines p 0 to p K−1 of said n reconstructed lines are not horizontal deblocked before the neighboring image unit below the current image unit arrives, the apparatus further comprises:

storing said reconstructed lines for lines p 0 to p K−1 and horizontal-deblocked lines for lines p K to p n−1 in one or more line buffers before the neighboring image unit below the current image unit arrives, wherein 1<K<n, and K is a second integer.

19. The apparatus of claim 15 , further comprising storing filter decision information for the horizontal filtering of the current image unit when the neighboring image unit below the current image unit becomes available.

20. The apparatus of claim 15 , further comprising means for storing at least partial derived information associated with at least one portion of one reconstructed line or one horizontal-deblocked line above the horizontal image-unit boundary, wherein said partial derived information is used for the horizontal deblocking or SAO processing, and wherein the horizontal deblocking or SAO processing is applied to said at least one portion of one reconstructed line or one horizontal-deblocked line above the horizontal image-unit boundary when the neighboring image unit below the current image unit becomes available.