Controlling quantization parameters based on code amount

Abstract

There is provided code amount control in which information data are input in predetermined units and a code amount is estimated in each of a plurality of stages, including a final stage. A calculation result is obtained based on a target code amount and the estimated code amount, for each stage. A short code amount and an excess code amount are updated based on the calculation result, and quantization parameters used upon encoding are controlled in accordance with the short code amount and the excess code amount obtained at the final estimation stage. Also provided is code amount control for controlling a code amount in units of second blocks, each consisting of a plurality of first blocks, each consisting of a plurality of sample value data, which discriminates quantization parameters which result in a code amount less than a predetermined amount when a second block of data is encoded using the quantization parameters. The discriminated quantization parameters are adjusted on a unit basis of the first block.