| 摘要 |
<p>PURPOSE: To reduce block errors based on transmission characteristic degradation by dividing block data after DCT transformation and quantization into plural frequency bands and adding error correction codes corresponding to the frequency bands. CONSTITUTION: Digital picture data supplied to an input terminal 11 are transformed to frequency axis areas in a DCT circuit 13 for the respective blocks of 8×8 picture elements divided in a blocking circuit 12 and a DCT coefficient composed of 64 samples is obtained. After the quantization is performed in a quantization circuit 14, division into the plural frequency bands is performed in a dividing circuit 24 and a convolution encoding process and an encoding process for error detection and correction 251, 252,... corresponding to the frequency bands are performed at every frequency band. In this case, for instance, the frequency bands are divided into three section which are a low band, a middle band and a high band and the error correction codes are added by the encoding rate of 1/2 to the low band, by the encoding rate of 3/4 to the middle band and by the encoding rate of 7/8 to the high band. A mixing circuit 26 assembles the data to the original block and they are passed through a parameter addition circuit 16 and sent out to a transmission line.</p> |
