Virtual playback method for surround-sound in multi-channel three-dimensional space

A virtual reproduction method for a multichannel spatial surround sound in a three-dimensional space, the method comprising:

• the following steps:
• step 1:
• arranging four loudspeakers at directions of left-front, right-front in a horizontal plane and at directions of left-front-up, right-front-up on an elevation plane with an elevation angle of 30°±15° respectively, wherein the elevation angle is measured from a listening position on the horizontal plane;
• step 2:
• inputting M non-front and non-back channel signals E1, E2, . . . EM of an original spatial surround sound in a horizontal layer, and a front channel signal EM+1 and a back channel signal EM+2 if the front channel signal EM+1 and a back channel signal EM+2 exist, wherein M is an even number;
• and numbering M channel signals according to a rule that an odd number represents a left half-space channel and an even number represents a symmetric right half-space channel;
• step 3:
• inputting M′ non-front and non-back channel signals E′1, E′2, . . . E′M′ of the original spatial surround sound in an upper layer, and a front channel signal E′M′+1 and a back channel signal E′M′+2 if the front channel signal E′M′+1 and the back channel signal E′M′+2 exist wherein M′ is an even number;
• and numbering M′ channel signals according to a rule that an odd number represents a left half-space channel and an even number represents a symmetric right half-space channel;
• step 4:
• for the M channel signals of the horizontal layer, carrying out a sum and difference operation on each left half-space channel signal and each symmetric right half-space channel signal to obtain M/2 sum signals (E1+E2), (E3+E4), . . . (EM−1+EM) of the horizontal layer and M/2 difference signals (E1−E2), (E3−E4), . . . (EM−1−EM) of the horizontal layer;
• step 5:
• for the M′ channel signals of the upper layer, carrying out a sum and difference operation on each left half-space channel signal and each symmetric right half-space channel signal to obtain M′/2 sum signals (E′1+E′2), (E′3+E′4), . . . (E′M′−1+E′M′+1) of the upper layer and M′/2 difference signals (E′1−E′2), (E′3−E′4), . . . (E′M′−1−E′M′) of the upper layer;
• step 6:
• filtering the M/2 sum signals of the horizontal layer with M/2 virtual reproduction signal processing functions Σ1,2, Σ3,4, . . . ΣM−1,M respectively and summing the signals, and then adding the front and back channel signals ΣM+1 and EM+2, if the front and back channel signals EM+1 and EM+2 exist, to obtain a total sum signal ESUM=Σ1,2 (E1+E2)+Σ3,4(E3+E4), . . . +ΣM−1,M(EM+EM+1)+EM+1+EM+2 of the horizontal layer;
• step 7:
• filtering the M/2 difference signals of the horizontal layer with M/2 virtual reproduction signal processing functions Δ1,2, Δ3,4 . . . ΔM−1,M respectively and then summing the signals to obtain a total difference signal EDIF=Δ1,2 (E1−E2)+Δ3,4 (E3−E4), . . . ΔM−1,M (EM−1−EM) of the horizontal layer;
• step 8:
• filtering the M′/2 sum signals of the upper layer with M′/2 virtual reproduction signal processing functions Σ′1,2, Σ′3,4, . . . Σ′M′−1,M′ respectively and summing the signals, and then adding the possible front and back channel signals EM′+1 and EM′+2 to obtain a total sum signal E′SUM=Σ′1,2 (E′1+E′2)+Σ′3,4(E′3+E′4), . . . +Σ′M′−1,M′ (E′M′+E′M′+1)+E′M′+1+E′M′+2 of the upper layer;
• step 9:
• filtering the M′/2 difference signals of the upper layer with M′/2 virtual reproduction signal processing functions Δ′1,2, Δ′3,4, . . . Δ′M−1,M respectively and then summing the signals to obtain a total difference signal E′DIF=Δ′1,2 (E′1−E′2)+Δ′3,4 (E′3−E′4), . . . +Δ′M′−1,M′ (E′M′−E′M′+1) of the upper layer;
• step 10:
• carrying out a sum and difference operation on the total sum signal ESUM and the total difference signal EDIF of the horizontal layer, attenuating them to respectively obtain reproduced signals for actual loudspeakers at left-front and right-front directions in the horizontal plane, and feeding the signals to corresponding actual loudspeakers for reproduction;
• and
• step 11:
• carrying out a sum and difference operation on the total sum signal E′SUM and the total difference signal E′DIF of the upper layer, attenuating them to respectively obtain reproduction signals of actual loudspeakers at left-front-up and right-front-up directions, and feeding the signals to corresponding actual loudspeakers for reproduction.