| 摘要 |
<p>PURPOSE:To make the error coefficient data 0, and to decode the coefficient data which are not erroneous with respect to a valid block resulting from deciding the validity/invalidity of the block including the error coefficient data. CONSTITUTION:The coefficient data and an error flag are outputted from a variable-length code decoder 47 in order of a zigzag scanning. A counter 52 counts the number of pieces of the coefficient data which are not erroneous by each block. The count value is compared with a threshold value by a comparator circuit 54. A threshold value generating circuit 53 receives an activity code AT to indicate the precision of the picture of the block, and generates a threshold value corresponding to the precision. When the number of pieces of the coefficient data which are not erroneous is more than the threshold value, the valid block is decided. Then, the coefficient data which are erroneous are forcedly turned to 0 in the valid block by a control signal CONT from the comparator circuit 54. Afterwards, the coefficient data are inverse- transformed by an inverse DCT circuit 50.</p> |
