US Patent 7408851 Pseudo multi-channel play-back apparatus

Compressed audio data for 5.1 channels stored in the DVD-ROM 11A is read by the AC-3 decoder 12 of a pseudo multi-channel stereo play-back apparatus and, after expansion, stored temporarily in a buffer 13, channel by channel. Among stored audio data stored in the buffer 13, audio data for left and right channels and for a front center channel are then subjected to the phase transformation. Audio data for left and right front channels are mixed with the phase transformed audio data by first and second mixing circuits 21 and 22 and mixed audio data are converted into analog audio signals by first and second D/A converters. The apparatus is capable of pseudo reproduction of the multi-channel audio signals stored in a recording medium such as a DVD-ROM by two channel play-back with an excellent sound effect which is not obtainable by usual two-channel play-back systems.