MOVING IMAGE CODING APPARATUS, CODE AMOUNT CONTROL METHOD, AND STORAGE MEDIUM

摘要

A moving image coding apparatus, a code amount control method, and a code amount control program enable appropriate code amount control to be performed in units shorter than frames. The moving image coding apparatus includes a coding unit, a quantization parameter determination unit, and a target code amount setting unit. The target code amount setting unit designates the number of macroblocks and sets a target code amount as a code amount to be allocated to the designated number of macroblocks. The quantization parameter determination unit calculates, for each macroblock, a quantization parameter to be used in quantization of a current macroblock based on a sum of absolute transformed differences SATD used in a motion estimate process. The moving image coding apparatus performs quantization using the calculated quantization parameter value.

主权项

1. A moving image coding apparatus that codes a moving image signal for forming a frame image including a plurality of macroblocks, and controls an amount of code to be generated in coding the moving image signal, the apparatus comprising:
a target code amount setting unit configured to designate the number of macroblocks and set a target code amount as a code amount to be allocated to the designated number of macroblocks; a quantization parameter determination unit configured to determine a quantization parameter value to be used in quantization performed in coding the moving image signal; and a coding unit configured to code the moving image signal and perform quantization with respect to the moving image signal using the quantization parameter value determined by the quantization parameter determination unit, wherein the coding unit includes a storage unit configured to store at least one previous frame image, and a motion estimate unit configured to obtain a difference image by extracting a reference frame image from the at least one previous frame image stored in the storage unit and calculating a difference between a current macroblock that is a processing target macroblock and an image region of the reference frame image having the same size as the current macroblock, obtain a sum of absolute transformed differences of the obtained difference image, and calculate a motion vector based on the obtained sum of absolute transformed differences, and the quantization parameter determination unit determines the quantization parameter value based on the sum of absolute transformed differences for the current macroblock obtained by the motion estimate unit.