[openal] a new panning matrix ChannelMap?

[Ben Simons]

Hi,

I'd like to add another format, beyond 7.1, and have forked openal-soft
v1.6 from github.
The new format is essentially 22 channels, but it's not Hamasaki 22.2.

I have an RME Fireface UFX. A linux connection to it allows 22 channels.
Speakers set up in a 360-degree ring.

Looking at Alc/panning.c the co-efs in aluInitPanning() appear to be a
matrix,
but I can't quite decode it. Have tried plotting them, but basically get
0,0,0 positions.
ie: I'm looking at the ChannelMaps.

Alc/panning.c line 319 onwards

MonoCfg[1] = {{ FrontCenter, { { 1.4142f }, { 1.4142f } } }

heh. looks like sqrt(2). Hmmm. Whereas:

X71Cfg[7] = {
        { FrontLeft,   { { 0.167065f,  0.200583f,  0.172695f, 0.0f,
0.0f, 0.0f, 0.0f,  0.029855f,  0.186407f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f,
-0.039241f,  0.068910f }, { 0.167065f,  0.153519f,  0.132175f, 0.0f } } },
        { FrontRight,  { { 0.167065f,  0.200583f, -0.172695f, 0.0f,
0.0f, 0.0f, 0.0f,  0.029855f, -0.186407f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f,
-0.039241f, -0.068910f }, { 0.167065f,  0.153519f, -0.132175f, 0.0f } } },
        { FrontCenter, { { 0.109403f,  0.179490f,  0.000000f, 0.0f,
0.0f, 0.0f, 0.0f,  0.142031f,  0.000000f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 
0.072024f,  0.000000f }, { 0.109403f,  0.137375f,  0.000000f, 0.0f } } },
        { BackLeft,    { { 0.224752f, -0.295009f,  0.170325f, 0.0f,
0.0f, 0.0f, 0.0f,  0.105349f, -0.182473f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 
0.000000f,  0.065799f }, { 0.224752f, -0.225790f,  0.130361f, 0.0f } } },
        { BackRight,   { { 0.224752f, -0.295009f, -0.170325f, 0.0f,
0.0f, 0.0f, 0.0f,  0.105349f,  0.182473f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 
0.000000f, -0.065799f }, { 0.224752f, -0.225790f, -0.130361f, 0.0f } } },
        { SideLeft,    { { 0.224739f,  0.000000f,  0.340644f, 0.0f,
0.0f, 0.0f, 0.0f, -0.210697f,  0.000000f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 
0.000000f, -0.065795f }, { 0.224739f,  0.000000f,  0.260717f, 0.0f } } },
        { SideRight,   { { 0.224739f,  0.000000f, -0.340644f, 0.0f,
0.0f, 0.0f, 0.0f, -0.210697f,  0.000000f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 
0.000000f,  0.065795f }, { 0.224739f,  0.000000f, -0.260717f, 0.0f } } },
    }

Now "FrontLeft" also has 2 braced sets. The first set looks like a 4x4
matrix, the the 2nd is 4 floats.
Is the first a transform matrix?

Could someone pls describe/doc this section - including the transform
order (Scale,Rot,Trans? XYZ?)

thanks,
ben.

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