METHOD AND APPARATUS FOR SAMPLE ADAPTIVE OFFSET CODING WITH SEPARATE SIGN AND MAG -NITUDE
A method and apparatus for encoding or decoding SAO (sample adaptive offset) parameters in a video encoder or decoder are disclosed. Embodiments according to the present invention encode or decode signs and magnitudes of SAO offset values separately for a region using band offset, where the signs are coded using bypass mode coding or fixed length coding. In one embodiment, the magnitudes of the SAO offset values for a region are grouped and coded together. If the SAO type is not band offset, the signs of the SAO offset values are omitted from the compressed data associated with the region. In another embodiment, the magnitude of the SAO offset value for band offset is checked to determine whether it is zero. If the magnitude of the SAO offset value is zero, there is no need to incorporate the sign of the SAO offset value in the compressed data.
1 . A method for decoding SAO (sample adaptive offset) parameters in a video decoder, the method comprising:
receiving compressed data associated with a region of a picture from a media or a processor;
decoding SAO type from the compressed data, wherein the SAO type comprises band offset;
decoding a sign part of multiple SAO offset values from the compressed data if the SAO type is the band offset, wherein the sign part is coded using bypass mode coding or fixed-length coding; and
decoding a magnitude part of the multiple SAO offset values if the SAO type is the band offset, wherein the magnitude part is coded using entropy coding.
2 . The method of claim 1 , the sign part of the multiple SAO offset values is omitted from the compressed data corresponding to the region of the picture if the SAO type is not the band offset.
3 . The method of claim 1 , further comprising checking magnitude of one multiple SAO offset value based on the magnitude part decoded when the SAO type is the band offset, wherein sign of said one multiple SAO offset value is omitted from the sign part of the multiple SAO offset values if the magnitude of said one multiple SAO offset value is zero.
4 . The method of claim 1 , wherein the sign part of the multiple SAO offset values corresponds to a first group associated with signs of the multiple SAO offset values, and the bypass mode coding or the fixed-length coding is applied to the first group.
5 . The method of claim 1 , wherein the magnitude part of the multiple SAO offset values corresponds to a second group associated with magnitudes of the multiple SAO offset values, and the entropy coding is applied to the second group.
6 . The method of claim 1 , wherein the entropy coding corresponds to context adaptive binary arithmetic coding or variable length coding.
7 . The method of claim 6 , wherein the magnitude part of the multiple SAO offset values is coded using variable length coding, and at least a portion of codewords for the magnitude part corresponds to unary coding, truncated unary coding, or exponential-Golomb coding.
8 . The method of claim 6 , wherein the magnitude part of the multiple SAO offset values is coded using context adaptive binary arithmetic coding, and at least a portion of codewords for the magnitude part corresponds to unary binarization, truncated unary binarization, or exponential-Golomb binarization.
9 . The method of claim 1 , wherein the SAO type further comprises edge offset and the multiple SAO offset values are unsigned values if the SAO type is the edge offset, and the method further comprises decoding the magnitude part of the multiple SAO offset values if the SAO type is the edge offset.
10 . A method for coding SAO (sample adaptive offset) parameters in a video encoder, the method comprising:
receiving SAO parameters associated with a region of a picture from a media or a processor, wherein the SAO parameters comprise a SAO type and multiple SAO offset values, the SAO type comprises band offset, and the multiple SAO offset values are signed values if the SAO type is the band offset;
encoding the SAO type;
applying bypass mode coding or fixed-length coding to a sign part of the multiple SAO offset values if the SAO type is the band offset; and
applying entropy coding to a magnitude part of the multiple SAO offset values if the SAO type is the band offset.
11 . The method of claim 10 , the sign part of the multiple SAO offset values is omitted from compressed data corresponding to the region of the picture if the SAO type is not the band offset.
12 . The method of claim 10 , further comprising checking magnitude of one multiple SAO offset value when the SAO type is the band offset, wherein sign of said one multiple SAO offset value is omitted from the sign part of the multiple SAO offset values if the magnitude of said one multiple SAO offset value is zero.
13 . The method of claim 10 , wherein the sign part of the multiple SAO offset values corresponds to a first group associated with signs of the multiple SAO offset values, and the bypass mode coding or the fixed-length coding is applied to the first group.
14 . The method of claim 10 , wherein the magnitude part of the multiple SAO offset values corresponds to a second group associated with magnitudes of the multiple SAO offset values, and the entropy coding is applied to the second group.
15 . The method of claim 10 , wherein the entropy coding corresponds to context adaptive binary arithmetic coding or variable length coding.
16 . The method of claim 15 , wherein the magnitude part of the multiple SAO offset values is coded using variable length coding, and at least a portion of codewords for the magnitude part corresponds to using unary coding, truncated unary coding, or exponential-Golomb coding.
17 . The method of claim 15 , wherein the magnitude part of the multiple SAO offset values is coded using context adaptive binary arithmetic coding, and at least a portion of codewords for the magnitude part corresponds to unary binarization, truncated unary binarization, or exponential-Golomb binarization.
18 . The method of claim 10 , wherein the SAO type further comprises edge offset and the multiple SAO offset values are unsigned values if the SAO type is the edge offset, and the method further comprises applying the entropy coding to the magnitude part of the multiple SAO offset values if the SAO type is the edge offset.
19 . An apparatus for decoding SAO (sample adaptive offset) parameters in a video decoder, the apparatus comprising:
means for receiving compressed data associated with a region of a picture from a media or a processor;
means for decoding SAO type from the compressed data, wherein the SAO type comprises band offset;
means for decoding a sign part of multiple SAO offset values from the compressed data if the SAO type is the band offset, wherein the sign part is coded using bypass mode coding or fixed-length coding; and
means for decoding a magnitude part of the multiple SAO offset values if the SAO type is the band offset, wherein the magnitude part is coded using entropy coding.
20 . An apparatus for coding SAO (sample adaptive offset) parameters in a video encoder, the apparatus comprising:
means for receiving SAO parameters associated with a region of a picture from a media or a processor, wherein the SAO parameters comprise a SAO type and multiple SAO offset values, the SAO type comprises band offset, and the multiple SAO offset values are signed values if the SAO type is the band offset;
means for encoding the SAO type;
means for applying bypass mode coding or fixed-length coding to a sign part of the multiple SAO offset values if the SAO type is the band offset; and
means for applying entropy coding to a magnitude part of the multiple SAO offset values if the SAO type is the band offset.