Apparatus and Method of Sample Adaptive Offset for Luma and Chroma Components

Abstract

A method and apparatus for processing reconstructed video using in-loop filter in a video coding system are disclosed. The method uses chroma in-loop filter indication to indicate whether chroma components are processed by in-loop filter when the luma in-loop filter indication indicates that in-loop filter processing is applied to the luma component. An additional flag may be used to indicate whether the in-loop filter processing is applied to an entire picture using same in-loop filter information or each block of the picture using individual in-loop filter information. Various embodiments according to the present invention to increase efficiency are disclosed, wherein various aspects of in-loop filter information are taken into consideration for efficient coding such as the property of quadtree-based partition, boundary conditions of a block, in-loop filter information sharing between luma and chroma components, indexing to a set of in-loop filter information, and prediction of in-loop filter information.

1 . A method for processing reconstructed video using Sample Adaptive Offset in a video decoder, the method comprising:
 deriving reconstructed video data from a video bitstream, wherein the reconstructed video data comprises luma component and chroma components;   receiving chroma Sample Adaptive Offset indication from the video bitstream if luma Sample Adaptive Offset indication in the video bitstream indicates that Sample Adaptive Offset processing is applied to the luma component;   determining chroma Sample Adaptive Offset information if the chroma Sample Adaptive Offset indication indicates that the Sample Adaptive Offset processing is applied to the chroma components; and   applying the Sample Adaptive Offset processing to the chroma components according to the chroma Sample Adaptive Offset information if the chroma Sample Adaptive Offset indication indicates that the Sample Adaptive Offset processing is applied to the chroma components.   
     
     
         2 . The method of  claim 1 , wherein the chroma Sample Adaptive Offset indication uses a single chroma Sample Adaptive Offset flag for the chroma components to share. 
     
     
         3 . The method of  claim 1 , wherein the chroma Sample Adaptive Offset indication uses individual chroma Sample Adaptive Offset flags for the chroma components respectively. 
     
     
         4 . The method of  claim 1 , wherein a chroma picture area of the reconstructed video is partitioned into chroma blocks and the chroma Sample Adaptive Offset is applied to the chroma blocks; wherein the chroma Sample Adaptive Offset information is received from the video bitstream if a current reconstructed chroma block corresponding to one of the chroma components is a new partition; the chroma Sample Adaptive Offset information is derived from a target chroma block if the current reconstructed chroma block is not said new partition; and wherein the current reconstructed chroma block is merged with the target chroma block selected from one or more candidate chroma blocks corresponding to one or more neighboring chroma blocks of the current reconstructed chroma block. 
     
     
         5 . The method of  claim 4 , wherein the chroma Sample Adaptive Offset information is determined based on a merge flag in the video bitstream if said one or more neighboring chroma blocks contain more than one neighboring chroma block; and wherein the chroma Sample Adaptive Offset information is inferred if said one or more neighboring chroma blocks contain one neighboring chroma block. 
     
     
         6 . The method of  claim 5 , wherein at least one of said one or more candidate chroma blocks is eliminated from merging with the current reconstructed chroma block according to quadtree-partition property and merge information of said one or more candidate chroma blocks. 
     
     
         7 . The method of  claim 1 , wherein a picture area of the reconstructed video is partitioned into blocks; wherein luma Sample Adaptive Offset and the chroma Sample Adaptive Offset are applied to luma blocks and chroma blocks respectively; and wherein partition information for the chroma components are derived from the partition information for the luma component. 
     
     
         8 . The method of  claim 7 , wherein the chroma components share the chroma Sample Adaptive Offset information. 
     
     
         9 . The method of  claim 7 , wherein the picture area of the reconstructed video is partitioned into the blocks using quadtree partition; and wherein quadtree-based syntax for the chroma components is derived from the quadtree-based syntax for the luma component. 
     
     
         10 . The method of  claim 1 , wherein a picture area of the reconstructed video is partitioned into blocks; wherein luma Sample Adaptive Offset and the chroma Sample Adaptive Offset are applied to luma blocks and chroma blocks using luma Sample Adaptive Offset information and the chroma Sample Adaptive Offset information respectively; and wherein the luma Sample Adaptive Offset information associated with each luma block or the chroma Sample Adaptive Offset information associated with each chroma block is encoded using an index pointing to a first set of luma Sample Adaptive Offset information or a second set of chroma Sample Adaptive Offset information. 
     
     
         11 . The method of  claim 10 , wherein a first set size corresponding to a number of luma Sample Adaptive Offset information in the first set is updated when new luma Sample Adaptive Offset information is signaled or a second set size corresponding to the number of the chroma Sample Adaptive Offset information in the second set is updated when new chroma Sample Adaptive Offset information is signaled. 
     
     
         12 . The method of  claim 11 , wherein a first bit length to represent the first set size or a second bit length to represent the second set size is dynamically adjusted to accommodate the first set size or the second set size. 
     
     
         13 . The method of  claim 1 , wherein the Sample Adaptive Offset processing applied to the chroma components replaces exterior data from one or more other chroma picture areas with known data or current chroma picture area data or the Sample Adaptive Offset processing is skipped if the Sample Adaptive Offset processing for the current chroma picture area refers to the exterior data. 
     
     
         14 . The method of  claim 13 , wherein a control flag is used to indicate whether the Sample Adaptive Offset processing replaces exterior data or whether to skip the Sample Adaptive Offset processing if the Sample Adaptive Offset processing for the current chroma picture area refers to the exterior data. 
     
     
         15 . The method of  claim 14 , wherein the control flag is a sequence level flag or a picture level flag. 
     
     
         16 . The method of  claim 14 , wherein the control flag is shared by multiple Sample Adaptive Offsets. 
     
     
         17 . The method of  claim 1 , wherein a picture area of the reconstructed video is partitioned into blocks; wherein luma Sample Adaptive Offset and the chroma Sample Adaptive Offset are applied to luma blocks and chroma blocks using luma Sample Adaptive Offset information and the chroma Sample Adaptive Offset information respectively; and wherein the luma Sample Adaptive Offset information or the chroma Sample Adaptive Offset information for a current block is respectively predicted by the luma Sample Adaptive Offset information or the chroma Sample Adaptive Offset information for one or more other blocks. 
     
     
         18 . The method of  claim 17 , wherein the luma Sample Adaptive Offset information or the chroma Sample Adaptive Offset information for the current block is respectively predicted by the luma Sample Adaptive Offset information or the chroma Sample Adaptive Offset information corresponding to one or more neighboring blocks of the current block. 
     
     
         19 . (canceled) 
     
     
         20 . A method for processing reconstructed video using in-loop filter in a video decoder, wherein a picture area of the reconstructed video is partitioned into blocks and the in-loop filter is applied to the blocks, the method comprising:
 deriving reconstructed video data comprising reconstructed block from a video bitstream;   receiving in-loop filter information from the video bitstream if a current reconstructed block is a new partition;   deriving the in-loop filter information from a target block if the current reconstructed block is not said new partition, wherein the current reconstructed block is merged with the target block selected from one or more candidate blocks corresponding to one or more neighboring blocks of the current reconstructed block; and   applying in-loop filter processing to the current reconstructed block using the in-loop filter information.   
     
     
         21 . The method of  claim 20 , wherein said deriving the in-loop filter information is based on a merge flag in the video bitstream if said one or more neighboring blocks contain more than one neighboring block; and wherein said deriving the in-loop filter information is inferred if said one or more neighboring blocks contain one neighboring block. 
     
     
         22 . The method of  claim 20 , wherein at least one of said one or more candidate blocks is eliminated from merging with the current reconstructed block according to quadtree-partition property and merge information of said one or more candidate blocks. 
     
     
         23 . A method for processing reconstructed video using Sample Adaptive Offset in a video encoder, the method comprising:
 deriving reconstructed video data comprising luma component and chroma components;   incorporating chroma Sample Adaptive Offset indication in a video bitstream if luma Sample Adaptive Offset indication indicates that Sample Adaptive Offset processing is applied to the luma component;   incorporating chroma Sample Adaptive Offset information in the video bitstream if the chroma Sample Adaptive Offset indication indicates that the Sample Adaptive Offset processing is applied to the chroma components; and   applying the Sample Adaptive Offset processing to the chroma components according to the chroma Sample Adaptive Offset information if the chroma Sample Adaptive Offset indication indicates that the Sample Adaptive Offset processing is applied to the chroma components.   
     
     
         24 . The method of  claim 23 , wherein a chroma picture area of the reconstructed video is partitioned into chroma blocks and the chroma Sample Adaptive Offset is applied to the chroma blocks; wherein the chroma Sample Adaptive Offset information is incorporated in the video bitstream if a current reconstructed chroma block corresponding to one of the chroma components is a new partition; the chroma Sample Adaptive Offset information is derived from a target chroma block if the current reconstructed chroma block is not said new partition; and wherein the current reconstructed chroma block is merged with the target chroma block selected from one or more candidate chroma blocks corresponding to one or more neighboring chroma blocks of the current reconstructed chroma block. 
     
     
         25 . The method of  claim 23 , wherein a picture area of the reconstructed video is partitioned into blocks; wherein luma Sample Adaptive Offset and the chroma Sample Adaptive Offset are applied to luma blocks and chroma blocks respectively; and wherein partition information for the chroma components are derived from the partition information for the luma component. 
     
     
         26 . The method of  claim 23 , wherein a picture area of the reconstructed video is partitioned into blocks; wherein luma Sample Adaptive Offset and the chroma Sample Adaptive Offset are applied to luma blocks and chroma blocks using luma Sample Adaptive Offset information and the chroma Sample Adaptive Offset information respectively; and wherein the luma Sample Adaptive Offset information associated with each luma block or the chroma Sample Adaptive Offset information associated with each chroma block is encoded using an index pointing to a first set of luma Sample Adaptive Offset information or a second set of chroma Sample Adaptive Offset information. 
     
     
         27 . The method of  claim 23 , wherein a picture area of the reconstructed video is partitioned into blocks; wherein luma Sample Adaptive Offset and the chroma Sample Adaptive Offset are applied to luma blocks and chroma blocks using luma Sample Adaptive Offset information and the chroma Sample Adaptive Offset information respectively; and wherein the luma Sample Adaptive Offset information or the chroma Sample Adaptive Offset information for a current block is provided using prediction based on the luma Sample Adaptive Offset information or the chroma Sample Adaptive Offset information for one or more other blocks. 
     
     
         28 . (canceled) 
     
     
         29 . A method for processing reconstructed video using in-loop filter in a video encoder, wherein a picture area of the reconstructed video is partitioned into blocks and the in-loop filter is applied to the blocks, the method comprising:
 deriving reconstructed video data;   incorporating in-loop filter information in a video bitstream if a current reconstructed block is a new partition;   incorporating the in-loop filter information in the video bitstream based on a target block if the current reconstructed block is not said new partition, wherein the current reconstructed block is merged with the target block selected from one or more candidate blocks corresponding to one or more neighboring blocks of the current reconstructed block; and   applying in-loop filter processing to the current reconstructed block using the in-loop filter information.   
     
     
         30 . An apparatus for processing reconstructed video using Sample Adaptive Offset in a video decoder, the apparatus comprising:
 means for deriving reconstructed video data from a video bitstream, wherein the reconstructed video data comprises luma component and chroma components;   means for receiving chroma Sample Adaptive Offset indication from the video bitstream if luma Sample Adaptive Offset indication in the video bitstream indicates that Sample Adaptive Offset processing is applied to the luma component;   means for determining chroma Sample Adaptive Offset information if the chroma Sample Adaptive Offset indication indicates that the Sample Adaptive Offset processing is applied to the chroma components; and   means for applying the Sample Adaptive Offset processing to the chroma components according to the chroma Sample Adaptive Offset information if the chroma Sample Adaptive Offset indication indicates that the Sample Adaptive Offset processing is applied to the chroma components.   
     
     
         31 . The apparatus of  claim 30 , wherein a chroma picture area of the reconstructed video is partitioned into chroma blocks and the chroma Sample Adaptive Offset is applied to the chroma blocks; wherein the chroma Sample Adaptive Offset information is received from the video bitstream if a current reconstructed chroma block corresponding to one of the chroma components is a new partition; the chroma Sample Adaptive Offset information is derived from a target chroma block if the current reconstructed chroma block is not said new partition; and wherein the current reconstructed chroma block is merged with the target chroma block selected from one or more candidate chroma blocks corresponding to one or more neighboring chroma blocks of the current reconstructed chroma block. 
     
     
         32 . (canceled) 
     
     
         33 . An apparatus for processing reconstructed video using in-loop filter in a video decoder, wherein a picture area of the reconstructed video is partitioned into blocks and the in-loop filter is applied to the blocks, the apparatus comprising:
 means for deriving reconstructed video data comprising reconstructed block from a video bitstream;   means for receiving in-loop filter information from the video bitstream if a current reconstructed block is a new partition;   means for deriving the in-loop filter information from a target block if the current reconstructed block is not said new partition, wherein the current reconstructed block is merged with the target block selected from one or more candidate blocks corresponding to one or more neighboring blocks of the current reconstructed block; and   means for applying in-loop filter processing to the current reconstructed block using the in-loop filter information.   
     
     
         34 . The apparatus of  claim 33 , wherein said deriving the in-loop filter information is based on a merge flag in the video bitstream if said one or more neighboring blocks contain more than one neighboring block; and wherein said deriving the in-loop filter information is inferred if said one or more neighboring blocks contain one neighboring block. 
     
     
         35 . The apparatus of  claim 33 , wherein at least one of said one or more candidate blocks is eliminated from merging with the current reconstructed block according to quadtree-partition property and merge information of said one or more candidate blocks. 
     
     
         36 . An apparatus for processing reconstructed video using Sample Adaptive Offset in a video encoder, the apparatus comprising:
 means for deriving reconstructed video data comprising luma component and chroma components;   means for incorporating chroma Sample Adaptive Offset indication in a video bitstream if luma Sample Adaptive Offset indication indicates that Sample Adaptive Offset processing is applied to the luma component;   means for incorporating chroma Sample Adaptive Offset information in the video bitstream if the chroma Sample Adaptive Offset indication indicates that the Sample Adaptive Offset processing is applied to the chroma components; and   means for applying the Sample Adaptive Offset processing to the chroma components according to the chroma Sample Adaptive Offset information if the chroma Sample Adaptive Offset indication indicates that the Sample Adaptive Offset processing is applied to the chroma components.   
     
     
         37 . (canceled) 
     
     
         38 . An apparatus for processing reconstructed video using in-loop filter in a video encoder, wherein a picture area of the reconstructed video is partitioned into blocks and the in-loop filter is applied to the blocks, the apparatus comprising:
 means for deriving reconstructed video data;   means for incorporating in-loop filter information in a video bitstream if a current reconstructed block is a new partition;   means for incorporating the in-loop filter information in the video bitstream based on a target block if the current reconstructed block is not said new partition, wherein the current reconstructed block is merged with the target block selected from one or more candidate blocks corresponding to one or more neighboring blocks of the current reconstructed block; and   means for applying in-loop filter processing to the current reconstructed block using the in-loop filter information.   
     
     
         39 . A method for processing reconstructed video using Sample Adaptive Offset in a video decoder, the method comprising:
 deriving reconstructed video data from a video bitstream; and   applying block-based Sample Adaptive Offset processing to a block of the reconstructed video data, wherein a picture is divided into a plurality of blocks, and wherein each block may use Sample Adaptive Offset information associated with each block;   wherein the Sample Adaptive Offset information associated with a current block is shared by another block according to information incorporated in the video bitstream.   
     
     
         40 . The method of  claim 39 , wherein the Sample Adaptive Offset information associated with the current block is shared by one or more following blocks as indicated by a run signal. 
     
     
         41 . The method of  claim 40 , wherein the run signal is incorporated in a slice level. 
     
     
         42 . The method of  claim 39 , wherein the Sample Adaptive Offset information associated with the current block is shared by an above-block as indicated by a merge-above flag. 
     
     
         43 . The method of  claim 39 , wherein the Sample Adaptive Offset information associated with the current block is shared by one or more following blocks as indicated by a run-difference signal; wherein the run-difference signal is determined based on a difference between a current run and a prediction run; wherein the current run is associated with a first number of blocks following the current block to share the Sample Adaptive Offset information with the current block; and wherein the prediction run is associated with a second number of blocks following an above-block to share the Sample Adaptive Offset information with the above block. 
     
     
         44 . The method of  claim 43 , wherein the run-difference signal is set to the current run if the prediction run is not available. 
     
     
         45 . The method of  claim 44 , wherein the current run is encoded using an unsigned variable length code if the prediction run is not available; and wherein the run-difference signal is encoded using a signed variable length code if the prediction run is available. 
     
     
         46 . The method of  claim 45 , wherein the unsigned variable length code or the signed variable length code is selected from a group consisting of k-th order exp-Golomb code, Golomb-Rice code, and CABAC code. 
     
     
         47 . The method of  claim 39 , wherein each block is a largest coding unit (LCU). 
     
     
         48 . The method of  claim 39 , wherein all the blocks in a current row share the Sample Adaptive Offset information with all the blocks in an above-row if a repeated-row flag indicates a repeated row; and wherein the Sample Adaptive Offset information is incorporated in the video bitstream if the repeated-row flag indicates a non-repeated row. 
     
     
         49 . The method of  claim 48 , wherein an enable-repeated-row flag is incorporated in the video bitstream to indicate whether the repeated-row flag is incorporated in the video bitstream for each row of blocks. 
     
     
         50 . The method of  claim 48 , wherein the repeated-row flag is omitted in the video bitstream for the picture consisting of one slice or for a first slice of a multi-slice picture using slice-independent Sample Adaptive Offset processing. 
     
     
         51 . The method of  claim 39 , wherein the Sample Adaptive Offset information associated with a current row of blocks is shared by one or more following rows of blocks as indicated by a row-run signal associated with a number of said one of more following rows. 
     
     
         52 . The method of  claim 51  wherein the row-run signal is represented by a fixed length code; and wherein bit length of the fixed length code is derived based on minimum row run and maximum row run. 
     
     
         53 . A method for processing reconstructed video using Sample Adaptive Offset in a video encoder, the method comprising:
 deriving reconstructed video data; and   applying block-based Sample Adaptive Offset processing to a block of the reconstructed video data, wherein a picture is divided into a plurality of blocks, and wherein each block may use Sample Adaptive Offset information associated with each block;   wherein the Sample Adaptive Offset information associated with a current block is shared by another block according to information incorporated in a video bitstream.   
     
     
         54 . The method of  claim 53 , further comprising incorporating a run signal in the video bitstream to indicate a number of one or more following blocks to share the Sample Adaptive Offset information associated with the current block. 
     
     
         55 . The method of  claim 54 , wherein the run signal is incorporated in a slice level. 
     
     
         56 . The method of  claim 54 , further comprising incorporating a merge-above flag in the video bitstream to indicate that the Sample Adaptive Offset information associated with the current block is shared by an above-block. 
     
     
         57 . The method of  claim 53 , further comprising incorporating a run-difference signal to indicate that the Sample Adaptive Offset information associated with the current block is shared by one or more following blocks as indicated by the run-difference signal; wherein the run-difference signal is determined based on a difference between a current run and a prediction run; wherein the current run is associated with a first number of blocks following the current block to share the Sample Adaptive Offset information with the current block; and wherein the prediction run is associated with a second number of blocks following an above-block to share the Sample Adaptive Offset information with the above block. 
     
     
         58 . An apparatus for processing reconstructed video using Sample Adaptive Offset in a video decoder, the apparatus comprising:
 means for deriving reconstructed video data from a video bitstream; and   means for applying block-based Sample Adaptive Offset processing to a block of the reconstructed video data, wherein a picture is divided into a plurality of blocks, and wherein each block may use Sample Adaptive Offset information associated with each block; wherein the Sample Adaptive Offset information associated with a current block is shared by another block according to information incorporated in the video bitstream.   
     
     
         59 . An apparatus for processing reconstructed video using Sample Adaptive Offset in a video encoder, the apparatus comprising:
 means for deriving reconstructed video data; and   means for applying block-based Sample Adaptive Offset processing to a block of the reconstructed video data, wherein a picture is divided into a plurality of blocks, and wherein each block may use Sample Adaptive Offset information associated with each block;   wherein the Sample Adaptive Offset information associated with a current block is shared by another block according to information incorporated in a video bitstream.