| 摘要 |
PURPOSE:To adaptively control the generation quantity of encoded information and the quality of reproduced picture in frame unit in a wide range by adaptively selecting and switching turning-on/off operations of plural encoder and decoders in accordance with the number of times of encoding of each frame. CONSTITUTION:In the first stage of encoding, an input signal vector 1 passes a subtractor 2 as it is and is outputted as a residual signal vector 3. A switch 4 turns on only an average value encoder and decoder 6 by a control signal 22 from an encoding control part 21. In the second stage of encoding, a decoded vector in the preceding stage is subtracted from the vector 1 to obtain the vector 3 by the subtractor 2, and the switch 4 turns on the encoder and decoder 6 and a normalized vector quantization encoder and decoder 7 by the signal 22. In the third stage of encoding, the vector 3 is obtained from the subtracter 2 similarly to the second stage, and the switch 4 turns on only a sample value encoder and decoder 5 by the signal 22. Even a rough picture is reproduced in the first stage, and a picture whose quality is higher than that of the preceding stage is reproduced in the second stage, and a picture whose quality is higher than that of the preceding stage is reproduced in the third stage. |
