| 摘要 |
<p>PURPOSE:To eliminate difference of picture quality from each processing unit by switching a control characteristic of a quantization table so as to reduce the difference when a generated information quantity between a processing frame and its succeeding processing frame largely differs depending on the property of an input picture signal. CONSTITUTION:A picture signal is quantized by a subtractor 2, DCT circuit 3, quantization circuit 4, inverse quantization circuit 5, adder 8, frame memory 10, motion compensation circuit 9, loop filter 7 and a motion detection circuit 11, and a variable length coding circuit 12 implements variable length coding. An output from an in-frame processing and an output from an inter-frame processing is adaptively selected and inputted to a buffer memory 13 in this system in response to a picture motion of an input picture signal. In this case, coding control circuits 21,22 output a quantization table control signal with a different characteristic are outputted in response to the data occupancy quantity of the buffer memory 13. A selection circuit 22 selects a proper control signal in response to the input picture signal to set a quantization step.</p> |
