Controlling quantization parameters based on code amount

A code amount control device 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, comprising:

• quantization means for quantizing the sample value data in units of the second block using quantization parameters that are predetermined;
• estimation means for estimating, on a unit basis of the second block, an amount of code data which results from encoding the sample value data quantized by said quantization means;
• and
• control means for controlling the quantization parameters in units of the first block in accordance with an output from said estimation means.

A code amount control method comprising:

• an input step of inputting information data in predetermined units;
• a code amount estimation step of estimating a code amount in each of a plurality of stages including a final stage;
• a calculation step of obtaining a calculation result based on a target code amount and the estimated code amount, for each stage of said code amount estimation step;
• an updating step of updating a short code amount and an excess code amount based on the calculation result of said calculation step;
• and
• a control step of controlling quantization parameters used upon encoding in accordance with the short code amount and the excess amount obtained at the final stage of said code amount estimation step.

A code amount control method 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, comprising:

• a quantization step of quantizing the sample value data in units of the second block using quantization parameters that are predetermined;
• an estimation step of estimating, on a unit basis of the second block, a code amount of data which results from encoding the sample value data quantized in said quantization step;
• and
• a control step of controlling the quantization parameters in units of the first block in accordance with an output of said estimation step.

An apparatus for predicting and finely adjusting a quantization parameter, comprising:

• input means for inputting information data;
• block forming means for dividing the information data into blocks, each block comprising a plurality of the information data;
• prediction means for predicting, on the unit basis of m blocks of the information data, an initial value for a quantization parameter, wherein the quantization parameter is to be used for quantizing the information data so as to obtain code data from the quantized information data whose code amount is within a predetermined amount, and wherein m is an integer;
• and
• adjustment means for finely adjusting the initial value, on the unit basis of n blocks of the information data wherein n is an integer and 1<n<m, to provide the quantization parameter.

A method for predicting and finely adjusting a quantization parameter, comprising the steps of:

• inputting information data;
• dividing the information data into blocks, each block comprising a plurality of the information data;
• predicting, on the unit basis of m blocks of the information data, an initial value for a quantization parameter, wherein the quantization parameter is to be used for quantizing the information data so as to obtain code data from the quantized information data whose code amount is within a predetermined amount, and wherein m is an integer;
• and
• finely adjusting the initial value, on the unit basis of n blocks of the information data wherein n is an integer and 1<n<m, to provide the quantization parameter.