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QuickTime files use matrices to describe spatial information about many objects, such as tracks within a movie.
A transformation matrix defines how to map points from one coordinate space into another coordinate space. By modifiying the contents of a transformation matrix, you can perform several standard graphics display operations, including translation, rotation, and scaling. The matrix used to accomplish twodimensional transformations is described mathematically by a 3by3 matrix.
All values in the matrix are 32bit fixedpoint numbers divided as 16.16, except for the {u, v, w} column, which contains 32bit fixedpoint numbers divided as 2.30. Figure 41 depicts how QuickTime uses matrices to transform displayed objects.
Figure 41 How display matrices are used in QuickTime
Figure 42 Applying the transform
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Last updated: 20010301
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