Simplified processing of weighted prediction syntax and semantics using a bit depth variable for high precision data
Particular embodiments may remove a condition check in the semantics for checking a high-precision data flag. This simplifies the semantics used in the encoding and decoding process. In this case, even if the high-precision data flag is not set, the value of the weighted prediction syntax element is set by the BitDepth variable. However, even if the BitDepth is not considered high-precision data, such as 8 bits, the range for the weighted prediction syntax element is still the same as the fixed value. For example, the syntax elements luma_offset_l0[i], luma_offset_l1[i], delta_chroma_offset_l0[i][j], and delta_chroma_offset_l1[i][j] use the variable BitDepth as described above whether the flag extended_precision_processing_flag is enabled and not enabled to indicate whether the bit depth is above a threshold.
1. A method comprising:
setting a first range for a variable associated with a bit depth representing a number of bits in pixels of a reference picture used in coding a video containing a current picture;
determining a weighting factor for performing weighted prediction for a current unit of the current picture;
using the weighting factor to weight pixels of a first reference unit of a first reference picture when performing motion compensation for the current unit; and
setting a second value for a weighted prediction syntax element associated with the weighting factor, the second value being set using the first range irrespective of whether an extended precision flag is enabled or not enabled, the extended precision flag indicating whether the bit depth is above a threshold, wherein the second value for the weighted prediction syntax element is within a range set by the first range and is an offset for a prediction value used in performing motion compensation when coding the current picture of the video.
2. The method of claim 1 , wherein a condition check of a status for the extended precision flag is not performed in conjunction with setting the second value.
3. The method of claim 1 , wherein the weighted prediction syntax element is for applying the offset for a first component of the prediction value.
4. The method of claim 3 , wherein the first component comprises a luma component of a video.
5. The method of claim 3 , wherein the range comprises −(1<<(BitDepth Y −1) to (1<<(BitDepth Y −1)−1, wherein BitDepth Y is a variable for a luma component.
6. The method of claim 1 , wherein the weighted prediction syntax element is for applying a difference of the offset for a first component of the prediction value.
7. The method of claim 6 , wherein the first component comprises a chroma component of a video.
8. The method of claim 6 , the range comprises −(1<<(BitDepth C −1) to (1<<(BitDepth C −1)−1, wherein BitDepth C is a variable for a chroma component.
9. The method of claim 8 , wherein the offset for the first component is derived using:
Clip3(−(1<<(BitDepth C −1), (1<<(BitDepth C −1)−1, (delta_chroma_offset_l0[i][j]−(((1<<(BitDepth C −1))*ChromaWeightL0[i][j])>>Chroma Log 2WeightDenom)+(1<<(BitDepth C −1))), where BitDepth C is the variable for the first component.