Bit depth variable for high precision data in weighted prediction syntax and semantics

One or more computer-readable memory or storage devices storing encoded data as part of a bitstream of video data, the encoded data being organized to facilitate decoding by a video decoder performing operations, the video decoder being implemented using memory and one or more processing units, the operations comprising:

• identifying one or more weight flags signaled in the bitstream that indicates presence of weighting factors for at least one of a luma component and/or a chroma component;
• determining a first weighting factor for performing weighted prediction for a current unit of a current picture the first weighting factor for weighting pixels of a first reference unit of a first reference picture when performing motion compensation for the current unit;
• determining a second weighting factor for weighting pixels of a second reference unit of a second reference picture when performing motion compensation for the current unit,
• wherein when weighting factors for a luma component is present:
• determining from a signaled delta_luma_weight_10 syntax element a difference of the first weighting factor and the second weighting factor applied to a luma prediction value for list 0 prediction using a variable RefPicList0[i] for a first luma component, and
• deriving a variable LumaWeightL0 associated with the luma component weighting factors, wherein when the one or more weight flags indicates presence of the weighting factor for a luma component, LumaWeightL0 is derived to be equal to (1<<luma_log2_weight_denom)+delta_luma_weight_10 in a range of −(1<<(BitDepthy−1)), (1<<(BitDepthy−1)−1), inclusive,
• wherein luma_log2_weight_denom is a base 2 logarithm of a denominator for all luma weighting factors, and BitDepthy is a bit depth for the luma component of the respective reference picture;
• and
• wherein when weighting factors for a chroma component is present:
• determining from a delta_chroma_weight_10[i][j] syntax element a difference of the first weighting factor and the second weighting factor applied to a chroma prediction value for list 0 prediction using a variable RefPicList0[i] with j equal to 0 for Cb or j equal to 1 for Cr for a second component;
• and
• deriving a variable ChromaWeightL0 associated with the chroma component weighting factor, wherein when the one or more weight flags indicates presence of the weighting factor for a chroma component, ChromaWeightL0 is derived to be equal to ((1<<(luma_log2_weight_denom+delta_chroma_log2_weight_denom))+delta_ch roma_weight_10, delta_chroma_weight_10 in a range of −(1<<(BitDepthc−1)), ((1<<BitDepthc−1)−1), inclusive,
• wherein delta_chroma_log2_weight_denom is a difference of a base 2 logarithm of a denominator for all chroma weighting factors, and BitDepthc is a bit depth for the chroma component of the respective reference picture;
• wherein the delta_chroma_weight_10[i][j] syntax element is within the range set by the ChromaWeightL0, and
• wherein the second component comprises a chroma component of the first reference unit or the second reference unit;
• wherein a variable ChromaArrayType is used at least in part to derive a pred_weight_table based upon if (ChromaArrayType !=0).

A computing device comprising:

• a video encoder for video data configured to provide a bitstream and perform operations comprising:
• providing one or more weight flags signaled in the bitstream that indicates presence of weighting factors for at least one of a luma component and/or a chroma component;
• wherein a first weighting factor for performing weighted prediction for a current unit of a current picture the first weighting factor for weighting pixels of a first reference unit of a first reference picture when performing motion compensation for the current unit;
• wherein a second weighting factor for weighting pixels of a second reference unit of a second reference picture when performing motion compensation for the current unit,
• wherein when weighting factors for a luma component is present:
• providing from a signaled delta_luma_weight_10 syntax element a difference of the first weighting factor and the second weighting factor applied to a luma prediction value for list 0 prediction using a variable RefPicList0[i] for a first luma component, and
• wherein a variable LumaWeightL0 associated with the luma component weighting factors, wherein when the one or more weight flags indicates presence of the weighting factor for a luma component, LumaWeightL0 is derived to be equal to (1<<luma_log2_weight_denom)+delta_luma_weight_10 in a range of −(1<<(BitDepthy−1)), (1<<(BitDepthy−1)−1), inclusive,
• wherein luma_log2_weight_denom is a base 2 logarithm of a denominator for all luma weighting factors, and BitDepthy is a bit depth for the luma component of the respective reference picture;
• and
• wherein when weighting factors for a chroma component is present:
• providing from a delta_chroma_weight_10[i][j] syntax element a difference of the first weighting factor and the second weighting factor applied to a chroma prediction value for list 0 prediction using a variable RefPicList0[i] with j equal to 0 for Cb or j equal to 1 for Cr for a second component;
• and
• wherein a variable ChromaWeightL0 associated with the chroma component weighting factor, wherein when the one or more weight flags indicates presence of the weighting factor for a chroma component, ChromaWeightL0 is derived to be equal to ((1<<(luma_log2_weight_denom+delta_chroma_log2_weight_denom))+delta_ch roma_weight_10, delta_chroma_weight10 in a range of −(1<<(BitDepthc−1)), ((1<<BitDepthc−1)−1), inclusive,
• wherein delta_chroma_log2_weight_denom is a difference of a base 2 logarithm of a denominator for all chroma weighting factors, and BitDepthc is a bit depth for the chroma component of the respective reference picture;
• wherein the delta_chroma_weight_10[i][j] syntax element is within the range set by the ChromaWeightL0, and
• wherein the second component comprises a chroma component of the first reference unit or the second reference unit;
• wherein a variable ChromaArrayType is used at least in part to derive a pred_weight_table based upon if (ChromaArrayType !=0).