| 摘要 |
PURPOSE:To efficiently control the transmission rate without increasing the code volume by sending the code of coefficients till the transmission code volume exceeds a set value and forcibly stopping to send the code for remaining coefficients. CONSTITUTION:The code volume on the way of scanning is successively calculated in a rate calculating circuit 108 and is inputted to a variable length code encoding control circuit 109 as a momentary rate Rp and an average rate Rh. Rate set values rh (average) and rp (peak) are preliminarily given to the circuit 109, and a control signal Cp or Ch is sent if the average value or the peak value exceeds them. In the case of Rp>rp, a variable length code encoding part 107 regards remaining coefficients as 0 to terminate encoding of the block. In the case of Rh>rh, an EOB code is forcibly inserted after a two-dimensional code to abandon the remaining code, and encoding of the block is terminated. Thus, an influence of the visual degradation in picture quality is less because abandoned coefficients are on the high frequency component side. |
