| 摘要 |
A method for down-mixing of a m-channel audio signal (L, R, C, Ls, Rs, Rss, Lss) into a n-channel audio signal (Ro, Lo, Rso, Lso), where m is an integer for which holds m>n and n is an integer for which holds n≧2, including the step of generating one of the n-channel audio signals of one side (right or left) of a listener (Ro, Lo, Rso, Lso), by a combination of: a first term including a signal component (R, L, Rs, Ls) of the m-channel audio signal of the same side only, and a second term dependent of m, including one or more of further signal components of the m-channel audio signal (C, Ls, Rs, Rss, Lss) of the same side only, multiplied by at least one respective filtering function (H1, H2, H3, H4, H5, H6, H7, H8), said filtering function being dependent on: a frequency characteristic of the transmission path between the position of the loudspeaker of the respective signal component of the further m-channel audio signal, and a position of the right ear or left ear, respectively, of a listener in an m-channel reproduction situation, and a frequency characteristic of the transmission path between the position of a loudspeaker of the said one of the n-channel audio down-mixed signals, (Ro, Lo, Rso, Lso), and a position of the right ear or left ear, respectively, of a listener in an n-channel reproduction situation. |
| 主权项 |
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:
H(c−re)=H1*H(fr−re), andH(c−le)=H2*H(fl−le) 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. |
