| 摘要 |
PURPOSE:To converge a quantization step size to an optimum value in response to a change in the picture by decreasing the quantization step size more than a preceding frame quantization step size when a power of a picture data obtained by the inter-frame coding. CONSTITUTION:A quantization control unit 36 decreases a quantization step size QNT to a 1/2 of a preceding frame-quantization step size PQNT used in the preceding frame when a macro block power MBP obtained by the inter- frame coding is smaller than a prescribed threshold level. Then the quantization control unit discriminates whether or not the preset QNT is smaller than the lower limit 1. When smaller, the QNT is set again to the lower limit 1. When the QNT is not smaller than 1, the value is set as the QNT without resetting. When a picture with less movement is sent, the quantization control unit 36 applies table quantization processing while the quantization step size QNT is converged to the lower limit. |
