Moving picture encoding system

Abstract

A moving picture encoding system capable of bit rate control, by which moving pictures are encoded while maintaining high quality even when there are substantial changes in the size of objects and the characteristics of texture is provided. A predictive area calculating parameter extracting means obtains a predictive area calculating parameter to describe a function that indicates temporal variations in the area based on the history of the area data of an object. Besides, a bit number model parameter calculating means finds a bit number model parameter to describe a parameter for a bit number model used in modeling the generated bit number per unit area. A target bit number calculating means estimates a predictive value of the generated bit number for the uncoded VOPs based on the predictive area calculating parameter and the predictive bit number calculating parameter, and accordingly, allocates the remaining allocatable bits to decide a target bit number for the next VOP to be encoded. A coding means encodes the VOP according to the target bit number.

Description

BACKGROUND OF THE INVENTION [0001] The present invention relates to a moving picture encoding system, in which a moving picture is encoded with respect to each object, or a moving picture is divided into plural sections and bit allocation for encoding is decided with respect to each section, in particular, relates to improvement in bit rate control. DESCRIPTION OF THE RELATED ART [0002] In encoding moving pictures, there is a system employed by Test Model 5 (hereinafter referred to as TM-5) of MPEG-2 (Moving Picture Experts Group, Phase 2) as a coding control system, in which the target bit number of each frame is determined based on the amount of available bits, and the number of bits generated for the frame is controlled so as to approximate the target number (manuscript: “March, 1993, ISO / IEC JTC 1 / SC 29 / WG 11 / NO400”). [0003]FIG. 1 is a block diagram showing a conventional bit rate control scheme. The rate control scheme comprises a coding means 1001, a target bit rate calculatin...

AI Technical Summary

Benefits of technology

[0016] It is therefore an object of the present invention to provide a moving picture encoding system capable of bit rate control, by which moving pictures are encoded while maintaining high quality even when there are substantial changes in the size of objects and the characteristics of texture.

[0017] Besides, it is another object of the present invention to provide a moving picture encoding system capable of bit rate control, by which bit allocation is performed properly even when the frame rate varies with each object.

Problems solved by technology

However, in object-based coding such as MPEG-4, when there is a sudden increase in object's size, bit allocation is not carried out successfully toward the end of a GOV (Group Of VOP) despite the substantial increase in the amount of generated bits.

Consequently, picture quality is deteriorated, and encoding cannot be performed within the target bit number.

However, since the information is unconsidered at the point of determining the total target by expression (13), the same problems occur.

As a result, the number of bits to be allocated for other objects is reduced on the whole, which causes deterioration in the picture quality of the other objects.

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