| 摘要 |
PURPOSE:To suppress mosquito noise by providing a multiplier, a selector circuit and a quantization section using a selected quantization width to quantize a DCT coefficient to the quantizer. CONSTITUTION:A multiplier 4 multiplies a quantization width inputted to an input terminal 1 with a constant set to a switch 3 and the constant is a positive value less than the unity depending on a coding bit rate. Moreover, a selector control circuit 6 discriminates whether or not a discrete cosine transformation(DCT) coefficient inputted from a terminal 2 is resident in an area sensitive to mosquito noise and informs the result to a selector circuit 5. When the DCT coefficient inputted from the input terminal 2 is resident in an area sensitive to mosquito noise, the circuit 5 informs an output of the multiplier 4 to a quantization section 7, and when the DCT coefficient inputted from the input terminal 2 is not resident in an area sensitive to mosquito noise, the inputted quantization width inputted from the input terminal 1 is informed to the quantization section 7. Thus, the production of mosquito noise is suppressed. |
