Patent ID: 9667986
Date: 2017-05-30
CPC Classifications: H04N

Claim:
1. A moving picture decoding device that decodes a bitstream in which moving pictures are coded by partitioning a first block, which is obtained by partitioning each picture of the moving pictures into predetermined sizes, into one or a plurality of second blocks, the device comprising: a decoding unit configured to extract size information of a block to derive a predictive quantization parameter and extract a differential quantization parameter of the second block by decoding the bitstream; a predictive quantization parameter deriving unit configured to derive a predictive quantization parameter of the second block using quantization parameters of a third block adjacent to the left of the second block and a fourth block adjacent to the top of the second block; and a quantization parameter generation unit configured to generate a quantization parameter of the second block by adding the differential quantization parameter of the second block and the predictive quantization parameter of the second block, wherein (a) when the size of the second block is equal to or larger than the size specified in the extracted size information to derive a predictive quantization parameter or the second block is a block located at a left top corner within the block of the size specified in the extracted size information to derive a predictive quantization parameter, the predictive quantization parameter deriving unit sets the quantization parameter of the third block as a first quantization parameter when the third block is at a position not beyond a boundary of the first block, sets a quantization parameter of a fifth block decoded immediately before the second block in a decoding order as the first quantization parameter when the third block is at a position beyond the boundary of the first block so as to set the first quantization parameter having a non-zero value regardless of the position for the boundary of the first block, sets the quantization parameter of the fourth block as a second quantization parameter when the fourth block is at a position not beyond the boundary of the first block, sets the quantization parameter of the fifth block as the second quantization parameter when the fourth block is at a position beyond the boundary of the first block so as to set the second quantization parameter having a non-zero value regardless of the position for the boundary of the first block, and derives an average of the first and second quantization parameters as the predictive quantization parameter of the second block regardless of the position of the third block or the fourth block, or both the third and fourth blocks, with respect to the boundary of the first block, and wherein (b) when the size of the second block is smaller than the size specified in the extracted size information to derive a predictive quantization parameter and the second block is a block other than the block located at the left top corner within the block of the size specified in the extracted size information to derive a predictive quantization parameter, the predictive quantization parameter deriving unit uses as the predictive quantization parameter of the second block the predictive quantization parameter derived in the block located at the left top corner within the block of the size specified in the extracted size information to derive a predictive quantization parameter that includes the second block.