Joint cosine transforming and quantizing device and joint inverse quantizing and inverse cosine transforming device

摘要

Each of the discrete cosine transforming (DCT) unit of a joint cosine transforming and quantizing device, and the inverse discrete cosine transforming (IDCT) unit of a joint inverse quantizing and inverse cosine transforming device includes a multiplication operation unit that is implemented in a look-up table device having a look-up table and an output multiplexer. The look-up table has a number of data fields, each of which contains products associated with a respective one of a corresponding number of coefficients used in multiplication-involving stages of a DCT or IDCT fast algorithm. The look-up table further has a number of outputs corresponding respectively to the data fields, and can be addressed in order to output the products, that correspond to the address data and that are stored in the data fields, at the outputs of the look-up table. The output multiplexer has data inputs connected to the outputs of the look-up table, and is operable so as to select one of the data inputs thereof and provide data at the selected one of the data inputs thereof to a data output of the output multiplexer.