Encoder, decoder, encoding method, and decoding method

An encoder which encodes a video, the encoder comprising:

• circuitry;
• and
• memory coupled to the circuitry, wherein
• using the memory, the circuitry:
• obtains at least two items of prediction information for a first partition included in the video;
• derives at least one template from a plurality of neighboring samples which neighbor the first partition;
• calculates at least two costs, using the at least one template and the at least two items of prediction information;
• using the at least two costs, (i) determines a first direction which is substantially perpendicular to a second direction in which a second partition is opposed to a third partition in the first partition and (ii) assigns one of the at least two items of prediction information to the second partition, and another of the at least two items of prediction information to the third partition split;
• and
• encodes the first partition according to the at least one splitting direction and the at least two items of prediction information.