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| #### 18.2 Prediction Subblocks {#h-18-02} |
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| The prediction calculation for each subblock is then as follows. |
| Temporarily disregarding the fractional part of the motion vector |
| (that is, rounding "up" or "left" by right-shifting each component |
| 3 bits with sign propagation) and adding the origin (upper left |
| position) of the (16x16 luma or 8x8 chroma) current macroblock gives |
| us an origin in the Y, U, or V plane of the predictor frame (either |
| the golden frame or previous frame). |
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| Considering that origin to be the upper left corner of a (luma or |
| chroma) macroblock, we need to specify the relative positions of the |
| pixels associated to that subblock, that is, any pixels that might be |
| involved in the sub-pixel interpolation processes for the subblock. |
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