Methods and apparatuses for video coding

Abstract

Aspects of the disclosure provide methods and apparatuses for video encoding/decoding. An apparatus for video decoding includes processing circuitry that decodes prediction information for a current block in a current coded picture. The prediction information indicates a motion vector predictor index (MVP_idx) for selecting a motion vector predictor in a motion vector predictor list. The processing circuitry determines whether the MVP_idx is smaller than a threshold. When the MVP_idx is determined to be smaller than the threshold, the processing circuitry decodes a motion vector difference (MVD) corresponding to the motion vector predictor and reconstructs the current block based on the motion vector predictor and the MVD. When the MVP_idx is determined to be equal to or larger than the threshold, the processing circuitry reconstructs the current block based on the motion vector predictor without the MVD which is not signaled in the coded video sequence.

What is claimed is: 
     
         1 . A method for motion vector difference (MVD) coding in image coding, comprising:
 determining a motion vector predictor and a corresponding MVD representing motion information for a current block; and   encoding prediction information by processing circuitry, the prediction information indicating the motion vector predictor and the motion vector difference (MVD) for the current block, wherein the MVD includes plural syntax elements and no more than one of the plural syntax elements of the MVD is coded using context coding.   
     
     
         2 . The method according to  claim 1 , wherein each one of the plural syntax elements comprises two flags, each of the two flags indicating a value of the respective syntax element for one of two directional components. 
     
     
         3 . The method according to  claim 2 , wherein all of the plural syntax elements of the MVD are coded with equal probability and none of the plural syntax elements are coded using context coding. 
     
     
         4 . The method according to  claim 2 , wherein
 the two flags corresponding to a first syntax element of the MVD are context coded,   the two flags of the first syntax element indicating whether an absolute value of the MVD is greater than 0 in each of the two directional components, and   all syntax elements of the MVD that are not the first syntax element are coded with equal probability.   
     
     
         5 . The method according to  claim 2 , wherein
 the two flags corresponding to a first syntax element of the MVD are context coded,   the two flags of the first syntax element indicating whether an absolute value of the MVD is greater than 1 in each of the two directional components, and   all syntax elements of the MVD that are not the first syntax element are coded with equal probability.   
     
     
         6 . The method according to  claim 2 , wherein the plural syntax elements consist of a first syntax element indicating whether an absolute value of the MVD is greater than 0, a second syntax element indicating the absolute value of the MVD minus 1, and a third syntax element indicating a sign of the MVD. 
     
     
         7 . The method according to  claim 6 , wherein
 all of the plural syntax elements of the MVD are context coded, and   the second syntax element is binarized with a K-th order Exponential-Golomb binarization, where K is one of 0, 2, or 3.   
     
     
         8 . The method according to  claim 2 , wherein
 a later signaled one of the two flags of one of the plural syntax elements is context coded based on an earlier signaled one of the two flags of the one of the plural syntax elements.   
     
     
         9 . The method according to  claim 2 , wherein,
 a first syntax element of the plural syntax elements indicates whether the MVD is greater than 0, and   in response to an earlier signaled one of the two flags of the first syntax element indicating that a corresponding component is not greater than 0, a later signaled one of the two flags of the first syntax element is bypass coded.   
     
     
         10 . A apparatus for coding a motion vector difference (MVD) in image coding, comprising:
 processing circuitry configured to
 determine a motion vector predictor and a corresponding MVD representing motion information for a current block; and 
 encode prediction information, the prediction information indicating the motion vector predictor and the motion vector difference (MVD) for the current block, wherein the MVD includes plural syntax elements and no more than one of the plural syntax elements of the MVD is coded using context coding. 
   
     
     
         11 . The apparatus according to  claim 10 , wherein each one of the plural syntax elements comprises two flags, each of the two flags indicating a value of the respective syntax element for one of two directional components. 
     
     
         12 . The apparatus according to  claim 11 , wherein all of the plural syntax elements of the MVD are coded with equal probability and none of the plural syntax elements are coded using context coding. 
     
     
         13 . The apparatus according to  claim 11 , wherein
 the two flags corresponding to a first syntax element of the MVD are context coded,   the two flags of the first syntax element indicating whether an absolute value of the MVD is greater than 0 in each of the two directional components, and   all syntax elements of the MVD that are not the first syntax element are coded with equal probability.   
     
     
         14 . The apparatus according to  claim 11 , wherein
 the two flags corresponding to a first syntax element of the MVD are context coded,   the two flags of the first syntax element indicating whether an absolute value of the MVD is greater than 1 in each of the two directional components, and   all syntax elements of the MVD that are not the first syntax element are coded with equal probability.   
     
     
         15 . The apparatus according to  claim 11 , wherein the plural syntax elements consist of a first syntax element indicating whether an absolute value of the MVD is greater than 0, a second syntax element indicating the absolute value of the MVD minus 1, and a third syntax element indicating a sign of the MVD. 
     
     
         16 . The apparatus according to  claim 15 , wherein
 all of the plural syntax elements of the MVD are context coded, and   the second syntax element is binarized with a K-th order Exponential-Golomb binarization, where K is one of 0, 2, or 3.   
     
     
         17 . The apparatus according to  claim 11 , wherein
 a later signaled one of the two flags of one of the plural syntax elements is context coded based on an earlier signaled one of the two flags of the one of the plural syntax elements.   
     
     
         18 . The apparatus according to  claim 11 , wherein,
 a first syntax element of the plural syntax elements indicates whether the MVD is greater than 0, and   in response to an earlier signaled one of the two flags of the first syntax element indicating that a corresponding component is not greater than 0, a later signaled one of the two flags of the first syntax element is bypass coded.   
     
     
         19 . A non-transitory computer-readable storage medium storing computer-readable instructions thereon, which, when executed by a computer, cause the computer to perform a method for motion vector difference (MVD) coding in image coding, the method comprising:
 determining a motion vector predictor and a corresponding MVD representing motion information for a current block; and   encoding prediction information, the prediction information indicating the motion vector predictor and the motion vector difference (MVD) for the current block, wherein the MVD includes plural syntax elements and no more than one of the plural syntax elements of the MVD is coded using context coding.