`
`[Claim 1]
`
`An encoder, comprising:
`
`circuitry; and
`
`memory connected to the circuitry,
`
`wherein the circuitry, in operation,
`
`determines a mode to be applied to a block from a
`
`plurality of merge modes based on a width of the block and a height
`
`of the block,
`
`10
`
`when the mode determined is a first mode, stores ina
`
`bitstream an index indicating a distance and an angle that define two
`
`partitions in the block, and encodes the block using the first mode,
`
`and
`
`15
`
`the width is at least 8 times as much as the height or (ii) the height
`
`disables storing of the index in the bitstream when (i)
`
`is at least 8 times as much as the width.
`
`[Claim 2]
`
`The encoder according to claim 1, wherein
`
`20
`
`the circuitry disables the storing of the index in the bitstream
`
`when (i) the width is 64 pixels and the height is 8 pixels or (ii) the
`
`width is 8 pixels and the height is 64 pixels.
`
`[Claim 3]
`
`25
`
`The encoder according to claim 1, wherein
`
`a line that determines shapes of the two partitions in the block
`
`is defined by the distance and the angle,
`
`the distance is a distance between a center of the block and
`
`the line, and
`
`30
`
`the angle is an angle related to the line.
`
`[Claim 4]
`
`A decoder, comprising:
`
`circuitry; and
`
`35
`
`memory connected to the circuitry,
`- 160 -
`
`
`
`wherein the circuitry, in operation,
`
`determines a mode to be applied to a block from a
`
`plurality of merge modes based on a width of the block and a height
`
`of the block,
`
`when the mode determined is a first mode, obtains from
`
`a bitstream an index indicating a distance and an angle that define
`
`two partitions in the block, and decodes the block using the first
`
`mode, and
`
`10
`
`(i) the width is at least 8 times as much as the height or (ii) the
`
`disables obtaining of the index from the bitstream when
`
`height is at least 8 times as much as the width.
`
`[Claim 5]
`
`The decoder according to claim 4, wherein
`
`15
`
`the circuitry disables the obtaining of the index from the
`
`bitstream when (i) the width is 64 pixels and the height is 8 pixels or
`
`(ii) the width is 8 pixels and the height is 64 pixels.
`
`[Claim 6]
`
`20
`
`The decoder according to claim 4, wherein
`
`a line that determines shapes of the two partitions in the block
`
`is defined by the distance and the angle,
`
`the distance is a distance between a center of the block and
`
`the line, and
`
`25
`
`the angle is an angle related to the line.
`
`[Claim 7]
`
`An encoding method, comprising:
`
`determining a mode to be applied to a block from a plurality of
`
`30
`
`merge modes based on a width of the block and a height of the block;
`
`when the mode determined is a
`
`first mode, storing in a
`
`bitstream an index indicating a distance and an angle that define two
`
`partitions in the block, and encoding the block using the first mode;
`
`and
`
`35
`
`disabling the storing of the index in the bitstream when (i) the
`- 161 -
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`
`
`width is at least 8 times as much as the height or (ii) the height is at
`
`least 8 times as much as the width.
`
`[Claim 8]
`
`A decoding method, comprising:
`
`determining a mode to be applied to a block from a plurality of
`
`merge modes based on a width of the block and a height of the block;
`
`when the mode determined is a first mode, obtaining from a
`
`bitstream an index indicating a distance and an angle that define two
`
`10
`
`partitions in the block, and decoding the block using the first mode;
`
`and
`
`disabling the obtaining of the index from the bitstream when
`
`(i) the width is at least 8 times as much as the height or (ii) the
`
`height is at least 8 times as much as the width.
`
`15
`
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