Method and apparatus for reduction of deblocking filter

1. A method of deblocking reconstructed video in a video coding system, the method comprising:

receiving reconstructed pixel data, wherein the reconstructed pixel data is configured into LCUs (largest coding units) and each LCU is divided into blocks;

identifying a first horizontal edge group comprising one or more horizontal block edges between two LCUs from horizontal block edges of the blocks in the LCUs;

identifying a second horizontal edge group comprising remaining horizontal block edges not included in the first edge group from horizontal block edges of the blocks in the LCUs;

applying first vertical filtering to the reconstructed pixel data corresponding to one or more first horizontal lines above a first horizontal block edge in the first horizontal edge group; and

applying second vertical filtering to the reconstructed pixel data corresponding to one or more second horizontal lines above a second horizontal block edge in the second horizontal edge group, wherein a first number of said one or more first horizontal lines is smaller than a second number of said one or more second horizontal lines.

2. The method of claim 1 , wherein the first number is one.

3. The method of claim 2 , wherein said one or more first horizontal lines are stored in one line buffer, and wherein said one line buffer is shared with intra prediction process used in the video coding system.

4. The method of claim 1 , wherein additional pixel data corresponding to one or more third horizontal lines above the first horizontal block edge are used to determine filter decision and/or filter operation for the first vertical filtering, and wherein the additional pixel data is stored in a sub-sampled pattern.

5. The method of claim 4 , wherein the additional pixel data corresponds to the reconstructed pixel data or intermediate pixel data.

6. An apparatus of deblocking reconstructed video in a video coding system, the apparatus comprising:

circuitry configured to receive reconstructed pixel data, wherein the reconstructed pixel data is configured into LCUs (largest coding units) and each LCU is divided into blocks;

circuitry configured to identify a first horizontal edge group comprising one or more horizontal block edges between two LCUs from horizontal block edges of the blocks in the LCUs;

circuitry configured to identify a second horizontal edge group comprising remaining horizontal block edges not included in the first edge group from horizontal block edges of the blocks in the LCUs;

circuitry configured to apply first vertical filtering to the reconstructed pixel data corresponding to one or more first horizontal lines above a first horizontal block edge in the first horizontal edge group; and

circuitry configured to apply second vertical filtering to the reconstructed pixel data corresponding to one or more second horizontal lines above a second horizontal block edge in the second horizontal edge group, wherein a first number of said one or more first horizontal lines is smaller than a second number of said one or more second horizontal lines.

7. The apparatus of claim 6 , wherein the first number is one.

8. The apparatus of claim 7 , wherein said one or more first horizontal lines are stored in one line buffer, and wherein said one line buffer is shared with intra prediction process used in the video coding apparatus.

9. The apparatus of claim 6 , wherein additional pixel data corresponding to one or more third horizontal lines above the first horizontal block edge are used to determine filter decision and/or filter operation for the first vertical filtering, and wherein the additional pixel data is stored in a sub-sampled pattern.

10. The apparatus of claim 9 , wherein the additional pixel data corresponds to the reconstructed pixel data or intermediate pixel data.