Combined filter for MPEG and Dolby AC3 audio decoder

摘要

Opening a combined filter for MPEG and Dolby AC3 audio decoders. The combined filter of the present invention comprises a first mux, a second mux, a first ram, a second ram, a ROM table, a butterfly module, an address generator, a state machine and a third mux. The first and second muxes multiplex the MPEG bitstream and the AC-3 bitstream and perform a function of determining whether the FFT module is written to the RAM or accepts another input according to the status of completion of the FFT module. The first RAM and the second RAM temporarily store the transform coefficients received as inputs and store the intermediate results of each calculation. The ROM table provides the table coefficients to the butterfly module. The butterfly module is a basic butterfly module that performs FFT. The address generator generates the addresses of the first and second rams in which the input and output samples are stored and the appropriate address of the butterfly module for performing the FFT. The state machine is used to control each module and is connected to the entire module. The third mux outputs a time domain sample.;Therefore, according to the present invention, even though the combined filter is used and a decoder integrated with hardware units is used, it is possible to reproduce both the signals encoded by the two audio compression algorithms, thereby increasing the efficiency and the added value.