Moving picture coding method and moving picture decoding method using a determination whether or not a reference block has two reference motion vectors that refer forward in display order with respect to a current picture

A moving picture coding method of coding a current picture to be coded which is included in a moving picture, said moving picture coding method comprising:

• selecting a first reference picture from among all reference pictures, the first reference picture temporally preceding the current picture in a display order and including a reference block having a first reference motion vector and a second motion vector, the all reference pictures being included in at least one of a first reference picture list and a second reference picture list;
• deriving at least one candidate motion vector of the current picture using at least one of the first reference motion vector and the second reference motion vector, and adding the at least one candidate motion vector into a candidate list;
• and
• coding the current picture using at least one motion vector selected from the candidate list,
• wherein said deriving and adding includes:
• deriving, when the all reference pictures are determined to temporally precede the current picture in the display order, two candidate motion vectors of the current picture from the first reference motion vector and the second reference motion vector, respectively, by scaling the first reference motion vector and the second reference motion vector;
• and
• deriving, when the all reference pictures are determined to include a reference picture temporally preceding the current picture in the display order and a reference picture temporally preceded by the current picture in the display order, one candidate motion vector from one of the first reference motion vector and the second reference motion vector.

A moving picture coding apparatus that codes a current picture to be coded which is included in a moving picture, said moving picture coding apparatus comprising:

• a selecting unit configured to select a first reference picture from among all reference pictures, the first reference picture temporally preceding the current picture in a display order and including a reference block having a first reference motion vector and a second motion vector, the all reference pictures being included in at least one of a first reference picture list and a second reference picture list;
• a candidate deriving unit configured to derive at least one candidate motion vector of the current picture using at least one of the first reference motion vector and the second reference motion vector, and add the at least one candidate motion vector into a candidate list;
• and
• a coding unit configured to code the current picture using at least one motion vector selected from the candidate list,
• wherein said candidate deriving unit is configured to:
• derive, when the all reference pictures are determined to temporally precede the current picture in the display order, two candidate motion vectors of the current picture from the first reference motion vector and the second reference motion vector, respectively, by scaling the first reference motion vector and the second reference motion vector;
• and
• derive, when the all reference pictures are determined to include a reference picture temporally preceding the current picture in the display order and a reference picture temporally preceded by the current picture in the display order, one candidate motion vector from one of the first reference motion vector and the second reference motion vector.

A moving picture coding apparatus that codes a current picture to be coded which is included in a moving picture, said moving picture coding apparatus comprising:

• one or more processors;
• and
• storage coupled to the one or more processors,
• wherein said one or more processors are configured to execute, using said storage:
• selecting a first reference picture from among all reference pictures, the first reference picture temporally preceding the current picture in a display order and including a reference block having a first reference motion vector and a second motion vector, the all reference pictures being included in at least one of a first reference picture list and a second reference picture list;
• deriving at least one candidate motion vector of the current picture using at least one of the first reference motion vector and the second reference motion vector, and adding the at least one candidate motion vector into a candidate list;
• and
• coding the current picture using at least one motion vector selected from the candidate list, and
• said deriving and adding includes:
• deriving, when the all reference pictures are determined to temporally precede the current picture in the display order, two candidate motion vectors of the current picture from the first reference motion vector and the second reference motion vector, respectively, by scaling the first reference motion vector and the second reference motion vector;
• and
• deriving, when the all reference pictures are determined to include a reference picture temporally preceding the current picture in the display order and a reference picture temporally preceded by the current picture in the display order, one candidate motion vector from one of the first reference motion vector and the second reference motion vector.