Video decoding method and apparatus, and video encoding method and apparatus

Abstract

Provided are a video encoding or decoding method and apparatus, which, during video encoding and decoding processes, determine whether an intra prediction mode of the current block is a DC mode, when the intra prediction mode of the current block is the DC mode, in a case where lengths of a height and a width of the current block are the same, determine an average of upper reference samples of the current block and left reference samples of the current block, as a DC value, and in a case where the lengths of the height and the width of the current block are different from each other, determine a weighted average value, which is determined by determining an average of the upper reference samples of the current block as an upper DC value, determine an average of the left reference samples of the current block as a left DC value, and combining the upper value and the left DC value with a predetermined weight, as a DC value, and perform intra prediction on the current block, based on the DC value.

1 . A video decoding method comprising:
 determining whether an intra prediction mode of a current block is a DC mode;   when the intra prediction mode of the current block is the DC mode,   in a case where lengths of a height and a width of the current block are the same, determining an average of upper reference samples of the current block, which are samples of an upper adjacent block located in the upper side of the current block, and left reference samples of the current block, which are samples of a left adjacent block located in the left side of the current block, as a DC value, and   in a case where the lengths of the height and the width of the current block are different from each other, determining a weighted average value, determined by determining an average of the upper reference samples of the current block as an upper DC value, determining an average of the left reference samples of the current block as a left DC value, and combining the upper DC value and the left DC value with a predetermined weight, as a DC value; and   performing intra prediction on the current block, based on the DC value.   
     
     
         2 . The video decoding method of  claim 1 , wherein, in a case where the intra prediction mode of the current block is the DC mode and the lengths of the height and the width of the current block are different from each other,
 when the width is greater than the height, the average of the upper reference samples of the current block is determined as a DC value, and   when the height is greater than the width, the average of the left reference samples of the current block is determined as a DC value.   
     
     
         3 . The video decoding method of  claim 1 , wherein, in a case where a right adjacent block located in the right side of the current block is previously reconstructed,
 when the intra prediction mode of the current block is the DC mode and the lengths of the height and the width of the current block are the same, an average of the upper reference samples and right reference samples of the current block, which are samples of the right adjacent block located in the right side of the current block is determined as a DC value, and   when the intra prediction mode of the current block is the DC mode and the lengths of the height and the width of the current block are different from each other, a weighted average value, which is determined by determining the average of the upper reference samples as an upper DC value, determining an average of the right reference samples as a right DC value, and combining the upper DC value and the right DC value with a predetermined weight, is determined as a DC value.   
     
     
         4 . The video decoding method of  claim 3 , wherein, in a case where the intra prediction mode of the current block is the DC mode and the lengths of the height and the width of the current block are different from each other,
 when the width is greater than the height, the average of the upper reference samples is determined as a DC value, and   when the height is greater than the width, the average of the right reference samples is determined as a DC value.   
     
     
         5 . The video decoding method of  claim 1 , wherein, among reference samples of the current block, a sample value of a reference sample closest to reference samples having no sample value, among reference samples having a sample value, is determined as a sample value of the reference samples having no sample value. 
     
     
         6 . The video decoding method of  claim 1 , wherein, among reference samples of the current block, an average value of reference samples having a sample value is determined as a sample value of reference samples having no sample value. 
     
     
         7 . The video decoding method of  claim 1 , wherein, among reference samples of the current block, a predetermined default value is determined as a sample value of reference samples having no sample value. 
     
     
         8 . A video encoding method comprising:
 determining whether an intra prediction mode of a current block is a DC mode;   when the intra prediction mode of the current block is the DC mode,   in a case where lengths of a height and a width of the current block are the same, determining an average of upper reference samples of the current block, which are samples of an upper adjacent block located in the upper side of the current block, and left reference samples of the current block, which are samples of a left adjacent block located in the left side of the current block, as a DC value, and   in a case where the lengths of the height and the width of the current block are different from each other, determining a weighted average value, determined by determining an average of the upper reference samples of the current block as an upper DC value, determining an average of the left reference samples of the current block as a left DC value, and combining the upper DC value and the left DC value with a predetermined weight, as a DC value; and   performing intra prediction on the current block, based on the DC value.   
     
     
         9 . The video encoding method of  claim 8 , wherein, in a case where the intra prediction mode of the current block is the DC mode and the lengths of the height and the width of the current block are different from each other,
 when the width is greater than the height, the average of the upper reference samples of the current block is determined as a DC value, and   when the height is greater than the width, the average of the left reference samples of the current block is determined as a DC value.   
     
     
         10 . The video encoding method of  claim 8 , wherein, in a case where a right adjacent block located in the right side of the current block is previously encoded,
 when the intra prediction mode of the current block is the DC mode and the lengths of the height and the width of the current block are the same, an average of the upper reference samples and right reference samples of the current block, which are samples of the right adjacent block located in the right side of the current block is determined as a DC value, and   when the intra prediction mode of the current block is the DC mode and the lengths of the height and the width of the current block are different from each other, a weighted average value, which is determined by determining the average of the upper reference samples as an upper DC value, determining an average of the right reference samples as a right DC value, and combining the upper DC value and the right DC value with a predetermined weight, is determined as a DC value.   
     
     
         11 . The video encoding method of  claim 10 , wherein, in a case where the intra prediction mode of the current block is the DC mode and the lengths of the height and the width of the current block are different from each other,
 when the width is greater than the height, the average of the upper reference samples is determined as a DC value, and   when the height is greater than the width, the average of the right reference samples is determined as a DC value.   
     
     
         12 . A video decoding apparatus comprising:
 a memory; and   at least one processor connected to the memory,   wherein the at least one processor is configured to:   determine whether an intra prediction mode of a current block is a DC mode;   when the intra prediction mode of the current block is the DC mode,   in a case where lengths of a height and a width of the current block are the same, determine an average of upper reference samples of the current block, which are samples of an upper adjacent block located in the upper side of the current block, and left reference samples of the current block, which are samples of a left adjacent block located in the left side of the current block, as a DC value, and   in a case where the lengths of the height and the width of the current block are different from each other, determine a weighted average value, determined by determining an average of the upper reference samples of the current block as an upper DC value, determining an average of the left reference samples of the current block as a left DC value, and combining the upper DC value and the left DC value with a predetermined weight, as a DC value; and   perform intra prediction on the current block, based on the DC value.   
     
     
         13 . The video decoding apparatus of  claim 12 , wherein, in a case where the intra prediction mode of the current block is the DC mode and the lengths of the height and the width of the current block are different from each other,
 when the width is greater than the height, the average of the upper reference samples of the current block is determined as a DC value, and   when the height is greater than the width, the average of the left reference samples of the current block is determined as a DC value.   
     
     
         14 . The video decoding apparatus of  claim 12 , wherein, in a case where a right adjacent block located in the right side of the current block is previously reconstructed,
 when the intra prediction mode of the current block is the DC mode and the lengths of the height and the width of the current block are the same, an average of the upper reference samples and right reference samples of the current block, which are samples of the right adjacent block located in the right side of the current block is determined as a DC value, and   when the intra prediction mode of the current block is the DC mode and the lengths of the height and the width of the current block are different from each other, a weighted average value, which is determined by determining the average of the upper reference samples as an upper DC value, determining an average of the right reference samples as a right DC value, and combining the upper DC value and the right DC value with a predetermined weight, is determined as a DC value.   
     
     
         15 . The video decoding apparatus of  claim 14 , wherein, in a case where the intra prediction mode of the current block is the DC mode and the lengths of the height and the width of the current block are different from each other,
 when the width is greater than the height, the average of the upper reference samples is determined as a DC value, and   when the height is greater than the width, the average of the right reference samples is determined as a DC value.