Method and device for processing video signal

Abstract

A video decoding method according to the present disclosure may comprise the steps of: determining whether an inverse transform is skipped in a current block; decoding a residual coefficient of the current block; and selectively applying the inverse transform to the residual coefficient on the basis of the determination. When decoding the residual coefficient, either a first syntax indicating whether the residual coefficient is greater than 0 or a second syntax indicating the absolute value of the residual coefficient may be selectively decoded.

What is claimed is: 
     
         1 . A video decoding method comprising:
 determining whether inverse transform is skipped for a current block;   decoding a residual coefficient of the current block; and   selectively applying the inverse transform to the residual coefficient based on the determination,   wherein when decoding the residual coefficient, one of a first syntax representing whether the residual coefficient is greater than 0 and a second syntax representing an absolute value of the residual coefficient is selectively decoded.   
     
     
         2 . The method of  claim 1 , wherein whether the first syntax is to be decoded or the second syntax is to be decoded is determined by comparing a threshold value with a number of bins decoded by using context information. 
     
     
         3 . The method of  claim 2 , wherein when at least one of the first syntax, at least one gt_N_flag representing whether the absolute value has a value greater than (2N−1) or a parity flag representing whether the absolute value is an even number is decoded, the number of bins decoded by using the context information increases. 
     
     
         4 . The method of  claim 1 , wherein when the first syntax is decoded and the first syntax represents that the residual coefficient has a non-zero value, gt_1_flag representing whether the absolute value of the residual coefficient has a value greater than 1 is additionally decoded. 
     
     
         5 . The method of  claim 4 , wherein when the gt_1_flag represents that the absolute value has the value greater than 1, a parity flag representing whether the absolute value is an even number and gt_2_flag representing whether the absolute value is greater than 3 is additionally decoded. 
     
     
         6 . The method of  claim 2 , wherein the threshold value is determined based on a size of the current block. 
     
     
         7 . A video encoding method comprising:
 determining whether transform is skipped for a current block;   quantizing a result that transform is applied or a result that transform is skipped; and   encoding a residual coefficient output as a result of the quantization,   wherein when encoding the residual coefficient, one of a first syntax representing whether the residual coefficient is greater than 0 and a second syntax representing an absolute value of the residual coefficient is selectively encoded.   
     
     
         8 . The method of  claim 8 , wherein whether the first syntax is to be encoded or the second syntax is to be encoded is determined by comparing a threshold value with a number of bins encoded by using context information. 
     
     
         9 . The method of  claim 8 , wherein when at least one of the first syntax, at least one gt_N_flag representing whether the absolute value has a value greater than (2N−1) or a parity flag representing whether the absolute value is an even number is encoded, the number of bins encoded by using the context information increases. 
     
     
         10 . The method of  claim 7 , wherein when the first syntax is encoded and the first syntax represents that the residual coefficient has a non-zero value, gt_1_flag representing whether the absolute value of the residual coefficient has a value greater than 1 is additionally encoded. 
     
     
         11 . The method of  claim 10 , wherein when the gt_1_flag represents that the absolute value has the value greater than 1, a parity flag representing whether the absolute value is an even number and gt_2_flag representing whether the absolute value is greater than 3 is additionally encoded. 
     
     
         12 . The method of  claim 8 , wherein the threshold value is determined based on a size of the current block. 
     
     
         13 . A computer readable recoding medium storing a bitstream encoded by a video encoding method, the video encoding method comprising:
 determining whether transform is skipped for a current block;   quantizing a result that transform is applied or a result that transform is skipped; and   encoding a residual coefficient output as a result of the quantization,   wherein when encoding the residual coefficient, one of a first syntax representing whether the residual coefficient is greater than 0 and a second syntax representing an absolute value of the residual coefficient is selectively encoded.