| 摘要 |
PURPOSE:To surely control data quantity within a constant value with frame unit, etc., by coding control information representing by what method feedback control is performed with the same method as variable length encoding for an orthogonal transform coefficient, and transmitting it to a decoder side. CONSTITUTION:An accumulation value K outputted from a data quantity accumulator 31 is supplied to a quantization step shifter 32, and is converted to quantization step shift quantity DSq. The feedback control is applied to a predictive error for data quantity, and is controlled in detail in block unit. The control information required to be transmitted to the decoder side represents shift quantity in a quantization step that is the result of the feedback control. The data quantity can be remarkably reduced by performing runlength-coding on a part remaining unchanged. Since rough control can be performed in feedforward control, picture quality can be prevented from being remarkably fluctuated by the feedback control in block unit, and the capacity of a variable length buffer for data output can be also reduced. |
