| 摘要 |
<p>PURPOSE:To reduce the deterioration in picture quality and to improve the periodic fluctuation of picture quality by inserting a refresh frame periodically to vary the quantization step between an in-frame coding and an inter-frame coding depending on the movement quantity of a frame. CONSTITUTION:A quantization circuit 16 decides a step size at quantization according to a control signal of a quantization control circuit 25. On the other hand, a quantized data is fed to a variable length coding circuit 22 and coded by, e.g. Huffman code or the like and written in a buffer memory 23. A switching signal between in-frame and inter-frame of switching control 13 and a moving vector of a moving detection circuit 21 are fed to the quantization control circuit 25 whose control signal is generated by the 3 kinds of values. Thus, since the quantization step is controlled adaptively depending on the case of in-frame and the case of inter-frame, the periodic fluctuation of picture quality is suppressed.</p> |
