| 摘要 |
PURPOSE:To improve the compression efficiency by giving an input signal to an LPF, in which the signal is divided into a high frequency component and a low frequency component and applying optimum quantity to each of them. CONSTITUTION:Picture data 100 outputted from a frame processing circuit 32 are inputted into an LPF 80, from which picture data 101 are outputted and data 102 being an output of an interleave circuit 81 receiving the data 101 are fed to an MUX 85 and a subtractor 83. Furthermore, the data 100 are fed to the subtractor 83 as data 103 via the circuit 82. Subtracted data 104 are fed to the MUX 85 via a block delay circuit 84. The MUX 85 gives the data 102, 104 sequentially to a DCT 33 as data 105 and its output is fed to a data rate matching circuit 63 via a block activity calculation circuit 60, an activity calculation circuit 61 and a frame delay circuit 62. The circuit 63 calculates a ratio of frame activity to a delay signal in each block to form an optimum offset signal of quantization tables 36, 86. As a result, the data 105 are subjected to optimum quantization. |
