Patent ID: 9484008
Filing Date: 2016-11-01
CPC Classification: G10H,H04S

Claim Text:
1. An apparatus for down-mixing an m-channel audio signal into a n-channel audio signal, where m is an integer for which holds m>n and n is an integer for which holds n≧2, comprising inputs for receiving the m-channel digital audio signal, a down-mixing circuit for converting the m-channel audio signal into the n-channel stereo audio signal, outputs for supplying the n-channel stereo audio signal to a plurality of loudspeakers, wherein said down-mixing circuit comprises first and second signal pre-processing units for pre-processing a front-center surround signal component of the m-channel audio signal prior to down-mixing the m-channel audio signal into the n-channel audio signal, the pre-processing steps on the front-center surround signal component being equivalent to first and second pre-filtering functions H1 and H2 respectively, which first and second filtering functions H1 and H2 at least substantially satisfy the following formula: where H(c−re) and H(c−le) are frequency characteristics of transmission paths between the position of the front-center loudspeaker and the positions of the right ear and left ear, respectively, of the listener, in an m-channel surround reproduction situation, and H(fr−re) is a frequency characteristic of a transmission path between the position of the front-right loudspeaker and the position of the right ear of the listener, in an n-channel stereo reproduction situation, and H(fl−le) is the frequency characteristic of the transmission path between the position of the front-left loudspeaker and the position of the left ear of the listener, in an n-channel reproduction situation, the down-mixing circuit further comprises a first signal combination unit for combining a right channel signal component with the front-center channel signal component pre-filtered by said first pre-filtering function, and comprises a second signal combination unit for combining a left channel signal component with the front-center channel signal component pre-filtered by said second pre-filtering function.