| 摘要 |
PURPOSE:To shorten refreshing cycle, to improve resistance to transmission errors and to evade the degradation of the entire encoding efficiency by shortening screen set-up time at the time of scene conversion when a power source is applied on a decoder side. CONSTITUTION:Picture signals from an input terminal 11 are supplied to a screen position detection circuit 27 and to what area of a screen respective blocks to be supplied to a DCT circuit 13 for which an encoding processing is to be performed are equivalent within one frame is detected. In this case, the screen is divided into a center part A, a middle part B and a peripheral part C, a binary counter 28 is counted up when it is judged that the block for which the encoding processing is to be performed is included in the center part A, a quaternary counter 29 is counted up when it is judged that it is included in the middle part B and an octanary counter 30 is counted up when it is judged that it is included in the peripheral part C respectively. In an encoding mode control circuit 31, based on the detected result of the circuit 27 and the count values of the counters 28 to 30, switches 24 and 25 are turned ON or OFF. |
