Motion picture encoding device and motion picture decoding device

A motion picture encoding method for making an inter-field motion compensation prediction and for executing an encoding process on a motion picture signal, wherein each frame has two fields and a number of pixels of a chrominance vertical component is different than a number of pixels of a luminance vertical component, the motion picture encoding method comprising:

• generating a chrominance motion vector from a luminance motion vector based on an equation represented as
• MVCy=MVy/2−0.25
• when a reference field is a bottom field and a coding field is a top field so that the generated chrominance motion vector and the luminance motion vector are thereby parallel, wherein
• MVy represents the luminance motion vector which indicates a vertical direction movement of a luminance pixel of a field, and
• MVCy represents the chrominance motion vector which indicates a vertical direction movement of a chrominance pixel of the field image.

A motion picture encoding method for making an inter-field motion compensation prediction and for executing an encoding process on a motion picture signal, wherein each frame has two fields and a number of pixels of a chrominance vertical component is different than a number of pixels of a luminance vertical component, the motion picture encoding method comprising:

• generating a chrominance motion vector from a luminance motion vector which depends on whether each of a reference field and a coding field is a top field or a bottom field,
• based on a first calculation when both the reference and coding fields are top fields or are bottom fields,
• based on a second calculation when the reference field is a top field and the coding field is a bottom field, and
• based on a third calculation when the reference field is a bottom field and the coding field is a top field.