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下混等式是基于 AC-3 标准。无论信号是直接下混（例如 7.1 下混为立体声）还是分步下混（例如 7.1 下混到 5.1，然后再下混到立体声），它们的最终结果都一样。
请考虑下表，表中描述了将 5.1 输入连通到立体声输出时使用的下混等式。
采样表：将 5.1 连通到立体声
|
输入声道 |
L |
R |
|---|---|---|
|
FL |
1 |
0 |
|
FR |
0 |
1 |
|
C |
1/√2 |
1/√2 |
|
SL |
1/√2 |
0 |
|
SR |
0 |
1/√2 |
下混获得的立体声信号的左右声道是这些等式的输入值的加权和：
LOUT = FL + 1/√2 * C + 1/√2 * SL
ROUT = FR + 1/√2 * C + 1/√2 * SR
与上面公式一样，您可以计算各个下混格式的输出信号，方式是将下文下混参考表中的各个输出声道列的总计加起来：
至单声道
|
输入声道 |
C |
|---|---|
|
FL |
1/√2 |
|
FR |
1/√2 |
|
C |
1 |
|
SL |
1/2 |
|
SR |
1/2 |
|
BL |
1/2 |
|
BR |
1/2 |
|
Top |
1 |
|
HFL |
1/2 |
|
HFC |
1/√2 |
|
HFR |
1/2 |
|
HBL |
1/(2√2) |
|
HBR |
1/(2√2) |
至立体声
|
输入声道 |
L |
R |
|---|---|---|
|
FL |
1 |
0 |
|
FR |
0 |
1 |
|
C |
1/√2 |
1/√2 |
|
SL |
1/√2 |
0 |
|
SR |
0 |
1/√2 |
|
BL |
1/√2 |
0 |
|
BR |
0 |
1/√2 |
|
Top |
1/√2 |
1/√2 |
|
HFL |
1/√2 |
0 |
|
HFC |
1/2 |
1/2 |
|
HFR |
0 |
1/√2 |
|
HBL |
1/2 |
0 |
|
HBR |
0 |
1/2 |
至 3.x
|
输入声道 |
L |
R |
C |
|---|---|---|---|
|
FL |
1 |
0 |
0 |
|
FR |
0 |
1 |
0 |
|
C |
0 |
0 |
1 |
|
SL |
1/√2 |
0 |
0 |
|
SR |
0 |
1/√2 |
0 |
|
BL |
1/√2 |
0 |
0 |
|
BR |
0 |
1/√2 |
0 |
|
Top |
1/√3 |
1/√3 |
1/√3 |
|
HFL |
1/√2 |
0 |
0 |
|
HFC |
0 |
0 |
1/√2 |
|
HFR |
0 |
1/√2 |
0 |
|
HBL |
1/2 |
0 |
0 |
|
HBR |
0 |
1/2 |
0 |
至 4.x
|
输入声道 |
L |
R |
SL |
SR |
|---|---|---|---|---|
|
FL |
1 |
0 |
0 |
0 |
|
FR |
0 |
1 |
0 |
0 |
|
C |
1/√2 |
1/√2 |
0 |
0 |
|
SL |
0 |
0 |
1 |
0 |
|
SR |
0 |
0 |
0 |
1 |
|
BL |
0 |
0 |
1 |
0 |
|
BR |
0 |
0 |
0 |
1 |
|
Top |
1/2 |
1/2 |
1/2 |
1/2 |
|
HFL |
1/√2 |
0 |
0 |
0 |
|
HFC |
1/2 |
1/2 |
0 |
0 |
|
HFR |
0 |
1/√2 |
0 |
0 |
|
HBL |
0 |
0 |
1/√2 |
0 |
|
HBR |
0 |
0 |
0 |
1/√2 |
至 5.x
|
输入声道 |
L |
R |
C |
SL |
SR |
|---|---|---|---|---|---|
|
FL |
1 |
0 |
0 |
0 |
0 |
|
FR |
0 |
1 |
0 |
0 |
0 |
|
C |
0 |
0 |
1 |
0 |
0 |
|
SL |
0 |
0 |
0 |
1 |
0 |
|
SR |
0 |
0 |
0 |
0 |
1 |
|
BL |
0 |
0 |
0 |
1 |
0 |
|
BR |
0 |
0 |
0 |
0 |
1 |
|
Top |
1/√5 |
1/√5 |
1/√5 |
1/√5 |
1/√5 |
|
HFL |
1/√2 |
0 |
0 |
0 |
0 |
|
HFC |
0 |
0 |
1/√2 |
0 |
0 |
|
HFR |
0 |
1/√2 |
0 |
0 |
0 |
|
HBL |
0 |
0 |
0 |
1/√2 |
0 |
|
HBR |
0 |
0 |
0 |
0 |
1/√2 |
至 6.x
|
输入声道 |
L |
R |
SL |
SR |
BL |
BR |
|---|---|---|---|---|---|---|
|
FL |
1 |
0 |
0 |
0 |
0 |
0 |
|
FR |
0 |
1 |
0 |
0 |
0 |
0 |
|
C |
1/√2 |
1/√2 |
0 |
0 |
0 |
0 |
|
SL |
0 |
0 |
1 |
0 |
0 |
0 |
|
SR |
0 |
0 |
0 |
1 |
0 |
0 |
|
BL |
0 |
0 |
0 |
0 |
1 |
0 |
|
BR |
0 |
0 |
0 |
0 |
0 |
1 |
|
Top |
1/√6 |
1/√6 |
1/√6 |
1/√6 |
1/√6 |
1/√6 |
|
HFL |
1/√2 |
0 |
0 |
0 |
0 |
0 |
|
HFC |
1/2 |
1/2 |
0 |
0 |
0 |
0 |
|
HFR |
0 |
1/√2 |
0 |
0 |
0 |
0 |
|
HBL |
0 |
0 |
0 |
0 |
1/√2 |
0 |
|
HBR |
0 |
0 |
0 |
0 |
0 |
1/√2 |
至 7.x