INTER-FRAME BAND COMPRESSION SIGNAL SWITCHING CIRCUIT

摘要

PURPOSE: To attain a switched image of high quality by outputting only the valid signal for which an intra-frame coding processing is performed once without outputting the image by a difference signal when plural inter-frame band compression signals are switched. CONSTITUTION: When an inter-frame coding processing is executed, both of switches 24 and 25 are turned on. Therefore, the signal corresponding to the difference of an input video signal and the video signal before the one frame is obtained from a subtraction circuit 12. This difference signal is inputted in a DCT circuit 14, the signal is converted from a time base area to a frequency axis area and the signal is quantized in a quantization circuit 15. Because the difference signal and the video signal are added in an addition circuit 21 and are inputted in a frame delay circuit 22, the predictive video signal predicting the input video signal to be the base for preparing the difference signal is prepared and is inputted. By continuously outputting the valid block of the signal for which the intra-frame processing is performed once as a matter of practice the excellent image quality is obtained at the time of switching signals.