[tebasuna51]

Downmix -down2 and simple stereo for all standard channel configuration.

If exist the parameter -mixlfe add:
FL' = ... + 0.7071 x LFE
FR' = ... + 0.7071 x LFE

2.1
    Stereo
        FL' = FL
        FR' = FR

2/1 or 2/1.1
    Stereo
        FL' = FL + 0.7071 x BC
        FR' = FR + 0.7071 x BC
    Dpl
        FL' = FL + 0.7071 x BC
        FR' = FR - 0.7071 x BC

2/2 or 2/2.1
    Stereo
        FL' = FL + BL
        FR' = FR + BR
    Dpl
        FL' = FL + 0.8660 x BL + 0.5000 x BR
        FR' = FR - 0.5000 x BL - 0.8660 x BR

3/0 or 3/0.1
    Stereo
        FL' = FL + 0.7071 x FC
        FR' = FR + 0.7071 x FC

3/1 or 3/1.1
    Stereo
        FL' = FL + 0.7071 x FC + 0.7071 x BC
        FR' = FR + 0.7071 x FC + 0.7071 x BC
    Dpl
        FL' = FL + 0.7071 x FC + 0.7071 x BC
        FR' = FR + 0.7071 x FC - 0.7071 x BC

3/2 or 3/2.1
    Stereo
        FL' = FL + 0.7071 x FC + BL
        FR' = FR + 0.7071 x FC + BR
    Dpl
        FL' = FL + 0.7071 x FC + 0.8660 x BL + 0.5000 x BR
        FR' = FR + 0.7071 x FC - 0.5000 x BL - 0.8660 x BR

3/2/1 or 3/2/1.1
    Stereo
        FL' = FL + 0.7071 x FC + BL + 0.7071 x BC
        FR' = FR + 0.7071 x FC + BR + 0.7071 x BC
    Dpl
        FL' = FL + 0.7071 x FC + 0.8660 x BL + 0.5000 x BR + 0.7071 x BC
        FR' = FR + 0.7071 x FC - 0.5000 x BL - 0.8660 x BR - 0.7071 x BC

3/2/2 or 3/2/2.1
    Stereo
        FL' = FL + 0.7071 x FC + BL + SL
        FR' = FR + 0.7071 x FC + BR + SR
    Dpl
        FL' = FL + 0.7071 x FC + 0.8660 x (BL + SL) + 0.5000 x (BR + SR)
        FR' = FR + 0.7071 x FC - 0.5000 x (BL + SL) - 0.8660 x (BR + SR)