| Modified discrete cosine transform: Definition and Links by Encyclopedian.com |

| | The modified **discrete** **cosine** **transform** (MDCT) is a frequency **transform** based on the type-IV **discrete** **cosine** **transform** (DCT-IV), with the additional property of being lapped: it is designed to be performed on consecutive blocks of a larger dataset, where subsequent blocks are 50% overlapped. |

| | As a lapped **transform**, the MDCT is a bit unusual compared to other frequency **transforms** in that it has half as many outputs as inputs (instead of the same number). |

| | In principle, x and y could have different window functions, and the window function could also change from one block to the next (especially for the case where data blocks of different sizes are combined), but for simplicity we consider the common case of identical window functions for equal-sized blocks. |

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