CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National Stage entry of PCT Application No: PCT/JP2019/050103 filed Dec. 20, 2019, which claims priority to Japanese Patent Application Nos. 2018-247407 filed Dec. 28, 2018, and 2019-063065 filed Mar. 28, 2019, the contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to picture coding and decoding technology for dividing a picture into blocks and performing prediction.

BACKGROUND ART

In picture coding and decoding, a target picture is divided into blocks, each of which is a set of a prescribed number of samples, and a process is performed in units of blocks. Coding efficiency is improved by dividing a picture into appropriate blocks and appropriately setting intra picture prediction (intra prediction) and inter picture prediction (inter prediction).

In moving-picture coding/decoding, coding efficiency is improved by inter prediction for performing prediction from a coded/decoded picture. Patent Literature 1 describes technology for applying an affine transform at the time of inter prediction. It is not uncommon for an object to cause deformation such as enlargement/reduction and rotation in moving pictures and efficient coding is enabled by applying the technology of Patent Literature 1.

CITATION LIST

Patent Literature

[Patent Literature 1]

Japanese Unexamined Patent Application, First Publication No. H9-172644

SUMMARY OF INVENTION

Technical Problem

However, because the technology of Patent Literature 1 involves a picture transform, there is a problem in that the processing load is large. In view of the above problem, the present invention provides efficient coding technology with a low load.

Solution to Problem

In order to solve the above problems, a moving-picture decoding device according to an aspect of the present invention includes a spatial motion information candidate derivation unit configured to derive a spatial motion information candidate from motion information of a block neighboring a decoding target block in a space domain; a temporal motion information candidate derivation unit configured to derive a temporal motion information candidate from motion information of a block neighboring a decoding target block in a time domain; and a history-based motion information candidate derivation unit configured to derive a history-based motion information candidate from a memory for retaining motion information of a decoded block, wherein the temporal motion information candidate is compared with neither the spatial motion information candidate nor the history-based motion information candidate with respect to the motion information.

Also, a moving-picture decoding method according to another aspect of the present invention includes steps of: deriving a spatial motion information candidate from motion information of a block neighboring a decoding target block in a space domain; deriving a temporal motion information candidate from motion information of a block neighboring a decoding target block in a time domain; and deriving a history-based motion information candidate from a memory for retaining motion information of a decoded block, wherein the temporal motion information candidate is compared with neither the spatial motion information candidate nor the history-based motion information candidate with respect to the motion information.

Also, a moving-picture decoding program according to another aspect of the present invention causes a computer to execute steps of: deriving a spatial motion information candidate from motion information of a block neighboring a decoding target block in a space domain; deriving a temporal motion information candidate from motion information of a block neighboring a decoding target block in a time domain; and deriving a history-based motion information candidate from a memory for retaining motion information of a decoded block, wherein the temporal motion information candidate is compared with neither the spatial motion information candidate nor the history-based motion information candidate with respect to the motion information.

Advantageous Effects of Invention

According to the present invention, it is possible to implement a highly efficient picture coding/decoding process with a low load.

