Methods and apparatuses of sample adaptive offset processing for video coding
A video coding system determines a Sample Adaptive Offset (SAO) type for a current reconstructed block, and determines SAO offsets for the current reconstructed block and checks if all SAO offsets are zeros except for a last SAO offset if the SAO type is Edge Offset (EO) or Band Offset (BO). A new value for the last SAO offset is derived at an encoding end or an original value for the last SAO offset is derived at a decoding end if all SAO offsets except for the last SAO offset are zeros. The SAO offsets are used for applying SAO processing to the current block and the current block is encoded or decoded. The original value for the last SAO offset is used in SAO processing and the new value for the last SAO offset is signaled in a video bitstream.
1. A method of video processing for a video coding system, the method comprising:
receiving input data associated with a current reconstructed block in a current picture;
determining a Sample Adaptive Offset (SAO) type for the current reconstructed block;
determining a plurality of SAO offsets for the current reconstructed block and checking if all SAO offsets are zeros except for a last SAO offset if the SAO type for the current reconstructed block is Edge offset (EO) or Band Offset (BO);
if all SAO offsets except for the last SAO offset are zeros, deriving a new value for the last SAO offset when encoding the current reconstructed block or deriving an original value for the last SAO offset when decoding the current reconstructed block, wherein the new value for the last SAO offset is derived by subtracting the original value for the last SAO offset by one, and the original value for the last SAO offset is derived by adding one to a received value for the last SAO offset;
applying SAO processing to the current reconstructed block according to the SAO offsets, wherein the original value for the last SAO offset is used in SAO processing and the new value for the last SAO offset is signaled in a video bitstream; and
encoding or decoding the current reconstructed block.
2. The method of claim 1 , wherein the current reconstructed block is for a luminance (luma) component, four SAO offsets are determined for the current reconstructed block, and the last SAO offset is the fourth SAO offset.
3. The method of claim 1 , wherein the current reconstructed block is for a chrominance (chroma) component, eight SAO offsets are determined for the current reconstructed block and another reconstructed block for another chroma component, and the last SAO offset is the eighth SAO offset.
4. The method of claim 1 , wherein the SAO processing is skipped if the SAO type for the current reconstructed block is OFF.
5. The method of claim 1 , wherein the current reconstructed block is a Coding Tree Block (CTB).
6. An apparatus of processing video data in a video coding system, the apparatus comprising one or more electronic circuits configured for:
receiving input data associated with a current reconstructed block in a current picture;
determining a Sample Adaptive Offset (SAO) type for the current reconstructed block;
determining a plurality of SAO offsets for the current reconstructed block and checking if all SAO offsets are zeros except for a last SAO offset if the SAO type for the current reconstructed block is Edge offset (EO) or Band Offset (BO);
if all SAO offsets except for the last SAO offset are zeros, deriving a new value for the last SAO offset when encoding the current reconstructed block or deriving an original value for the last SAO offset when decoding the current reconstructed block, wherein the new value for the last SAO offset is derived by subtracting the original value for the last SAO offset by one, and the original value for the last SAO offset is derived by adding one to a received value for the last SAO offset;
applying SAO processing to the current reconstructed block according to the SAO offsets, wherein the original value for the last SAO offset is used in SAO processing and the new value for the last SAO offset is signaled in a video bitstream; and
encoding or decoding the current reconstructed block.
7. A non-transitory computer readable medium storing program instruction causing a processing circuit of an apparatus to perform video processing method, and the method comprising:
receiving input data associated with a current reconstructed block in a current picture;
determining a Sample Adaptive Offset (SAO) type for the current reconstructed block;
determining a plurality of SAO offsets for the current reconstructed block and checking if all SAO offsets are zeros except for a last SAO offset if the SAO type for the current reconstructed block is Edge offset (EO) or Band Offset (BO);
if all SAO offsets except for the last SAO offset are zeros, deriving a new value for the last SAO offset when encoding the current reconstructed block or deriving an original value for the last SAO offset when decoding the current reconstructed block, wherein the new value for the last SAO offset is derived by subtracting the original value for the last SAO offset by one, and the original value for the last SAO offset is derived by adding one to a received value for the last SAO offset;
applying SAO processing to the current reconstructed block according to the SAO offsets, wherein the original value for the last SAO offset is used in SAO processing and the new value for the last SAO offset is signaled in a video bitstream; and
encoding or decoding the current reconstructed block.