Moving picture coding method and moving picture coding device

Abstract

A moving picture is provided which can prevent image quality deterioration due to drops in motion vector prediction accuracy in temporal direct mode coding, and compress a moving image with great efficiency.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects, advantages and features of the invention will become apparent from the following description thereof taken in conjunction with the accompanying drawings that illustrate a specific embodiment of the invention. In the Drawings:

FIG. 1 is a schematic diagram which shows the prediction generation method for the motion vector in temporal direct mode;

FIG. 2 is a schematic diagram which shows the prediction generation method for the motion vector in spatial direct mode;

FIG. 3 is a diagram which shows an example of a telecine conversion (2-3 conversion);

FIG. 4 is a diagram which shows an example of temporal direct mode motion vector prediction for the moving picture on which the telecine conversion (2-3 conversion) has been performed;

FIG. 5 is a diagram which shows an example of temporal direct mode motion vector prediction for the moving picture on which the telecine conversion (2-3 conversion) has been performed;

FIG. 6 is a block diagram which shows the structure of the moving picture coding device according to the first embodiment of the present invention;

FIG. 7 is a diagram which shows diagram (a) in which a sequence of the pictures is shown and a diagram (b) which shows the inputted sequence re-arranged into a new sequence;

FIG. 8 is a flowchart which shows an operation for determining whether temporal direct mode is used or not by the method 1 in a temporal direct mode disabling assessment unit;

FIG. 9 is a block diagram which shows the structure of the moving picture coding device according to the second embodiment of the present invention;

FIG. 10 is a flowchart which shows an operation for determining whether temporal direct mode is used or not by a method 2 in the temporal direct mode disabling assessment unit;

FIG. 11 is a block diagram which shows the structure of the moving picture coding device according to the third embodiment of the present invention;

FIG. 12 is a flowchart which shows an operation for determining whether temporal direct mode is used or not by a method 3 in the temporal direct mode disabling assessment unit;

FIG. 13 is a block diagram which shows the structure of the moving picture coding device according to the fourth embodiment of the present invention;

FIG. 14 is a flowchart which shows an operation for determining whether temporal direct mode is used or not by a combination of the method 2 and the method 3 in the temporal direct mode disabling assessment unit; and

FIG. 15 is an explanatory diagram of a recording medium that stores a program for realizing the moving picture coding method according to the first to fourth embodiments via a computer system.

Claims

1. A moving picture coding method which codes a moving picture that includes a B picture on which predictive coding is performed by referencing plural coded pictures which are temporally located before or after the B picture, said moving picture coding method comprising: predicting and generating a motion vector for a target block by referencing a motion vector of a coded picture that is temporally nearby, as a direct mode processing for the B picture; andassessing whether use of the temporal direct mode should be disabled according to a condition for a moving picture to be coded,wherein, in said assessing, predictive coding is performed on the moving picture to be coded using a process other than said predicting and generating, when use of the temporal direct mode is disabled.

2. The moving picture coding method according to claim 1, wherein referencing a motion vector of a coded block located in a spatial periphery of the target block and predicting and generating a motion vector for the target block as a direct mode for the B picture is included in the process other than said predicting and generating, andin said assessing, the predictive coding is performed on the moving picture to be coded using said predicting and generating when use of the temporal direct mode is disabled.

3. The moving picture coding method according to claim 1, wherein in said assessing, it is assessed that use of the temporal direct mode should be disabled when it is assessed that the time intervals of pictures which compose the moving picture to be coded are not fixed.

4. The moving picture coding method according to claim 1, wherein in said assessing, it is assessed that use of the temporal direct mode should be disabled when it is assessed that a picture-display time interval conversion has been performed on the moving picture to be coded.

5. The moving picture coding method according to claim 1, wherein in said assessing, it is assessed that use of the temporal direct mode should be disabled when it is assessed that the coded picture used as a reference for the motion vector in the temporal direct mode is an I picture on which intra-picture predictive coding is to be performed.

6. The moving picture coding method according to claim 1, wherein in said assessing, it is assessed whether or not one of at least two of the following cases applies:when it is assessed that the time intervals for the pictures which compose the moving picture to be coded are not fixed;when it is assessed that a picture-display time interval conversion has been performed on the moving picture to be coded; andwhen it is assessed that the coded picture that is used as a reference for the motion vector in the temporal direct mode is an I picture on which intra-picture predictive coding is performed, andin the case where one of at least two of the cases applies, it is assessed that use of the temporal direct mode should be disabled.

7. A moving picture coding device which codes a moving picture that includes a B picture on which predictive coding is performed by referencing plural coded pictures which are temporally located before or after the B picture, said moving picture coding device comprising: a temporal direct mode processing unit operable to predict and generate a motion vector for a target block by referencing a motion vector of a coded picture that is temporally nearby, as a direct mode processing for the B picture; anda temporal direct mode disabling assessment unit operable to assess whether use of the temporal direct mode should be disabled according to a condition for the moving picture to be coded,wherein, in said temporal direct mode assessment unit, predictive coding is performed on the moving picture to be coded using a unit other than said temporal direct mode processing unit, when use of the temporal direct mode is disabled.

8. A program for a moving picture coding method which codes a moving picture that includes a B picture on which predictive coding is performed by referencing plural coded pictures which are temporally located before or after the B picture, said program being stored on a computer-readable medium and causing a computer to execute: predicting and generating a motion vector for a target block by referencing a motion vector of a coded picture that is temporally nearby, as a direct mode processing for the B picture; andassessing whether use of the temporal direct mode should be disabled according to a condition for the moving picture to be coded,wherein, in said assessing, predictive coding is performed on the moving picture to be coded using a process other than said predicting and generating, when use of the temporal direct mode is disabled.

9. An integrated circuit in which the units, which are included in a moving picture coding device which codes a moving picture that includes a B picture on which predictive coding is performed by referencing plural coded pictures which are temporally located before or after the B picture, are integrated, the units being: a temporal direct mode processing unit operable to predict and generate a motion vector for a target block by referencing a motion vector of a coded picture that is temporally near, as a direct mode processing for the B picture; anda temporal direct mode disabling assessment unit operable to assess whether use of the temporal direct mode should be disabled according to a condition for the moving picture to be coded,wherein, in said temporal direct mode assessment unit, predictive coding is performed on the moving picture to be coded using a unit other than said temporal direct mode processing unit, when use of the temporal direct mode is disabled.