Use an alternate virtual layout for Ambisonic HRTF decoding

This uses 16 channels, an 8-channel octagon + 8-channel cube, which should
improve horizontal resolution without affecting vertical too much.

3 files changed, 76 insertions, 48 deletions

diff --git a/Alc/hrtf.c b/Alc/hrtf.c
index d1cfe6b0..cf211470 100644
--- a/Alc/hrtf.c
+++ b/Alc/hrtf.c
@@ -194,7 +194,7 @@ void GetHrtfCoeffs(const struct Hrtf *Hrtf, ALfloat elevation, ALfloat azimuth,
 }
 
 
-void BuildBFormatHrtf(const struct Hrtf *Hrtf, DirectHrtfState *state, ALsizei NumChannels, const ALfloat (*restrict AmbiPoints)[2], const ALfloat (*restrict AmbiMatrix)[2][MAX_AMBI_COEFFS], ALsizei AmbiCount)
+void BuildBFormatHrtf(const struct Hrtf *Hrtf, DirectHrtfState *state, ALsizei NumChannels, const ALfloat (*restrict AmbiPoints)[2], const ALfloat (*restrict AmbiMatrix)[MAX_AMBI_COEFFS], ALsizei AmbiCount, const ALfloat *restrict AmbiOrderHFGain)
 {
 /* Set this to 2 for dual-band HRTF processing. May require a higher quality
  * band-splitter, or better calculation of the new IR length to deal with the
@@ -248,12 +248,13 @@ void BuildBFormatHrtf(const struct Hrtf *Hrtf, DirectHrtfState *state, ALsizei N
         {
             for(i = 0;i < NumChannels;++i)
             {
+                ALfloat hfgain = AmbiOrderHFGain[(ALsizei)floor(sqrt(i))];
                 ALsizei lidx = ldelay, ridx = rdelay;
                 ALsizei j = 0;
                 while(lidx < HRIR_LENGTH && ridx < HRIR_LENGTH && j < Hrtf->irSize)
                 {
-                    state->Chan[i].Coeffs[lidx++][0] += fir[j][0] * AmbiMatrix[c][0][i];
-                    state->Chan[i].Coeffs[ridx++][1] += fir[j][1] * AmbiMatrix[c][0][i];
+                    state->Chan[i].Coeffs[lidx++][0] += fir[j][0] * AmbiMatrix[c][i] * hfgain;
+                    state->Chan[i].Coeffs[ridx++][1] += fir[j][1] * AmbiMatrix[c][i] * hfgain;
                     j++;
                 }
             }
@@ -269,12 +270,15 @@ void BuildBFormatHrtf(const struct Hrtf *Hrtf, DirectHrtfState *state, ALsizei N
             /* Apply left ear response with delay. */
             for(i = 0;i < NumChannels;++i)
             {
+                ALfloat hfgain = AmbiOrderHFGain[(ALsizei)floor(sqrt(i))];
                 for(b = 0;b < NUM_BANDS;b++)
                 {
                     ALsizei lidx = ldelay;
                     ALsizei j = 0;
                     while(lidx < HRIR_LENGTH)
-                        state->Chan[i].Coeffs[lidx++][0] += temps[b][j++] * AmbiMatrix[c][b][i];
+                        state->Chan[i].Coeffs[lidx++][0] += temps[b][j++] * AmbiMatrix[c][i] *
+                                                            hfgain;
+                    hfgain = 1.0f;
                 }
             }
 
@@ -287,12 +291,15 @@ void BuildBFormatHrtf(const struct Hrtf *Hrtf, DirectHrtfState *state, ALsizei N
             /* Apply right ear response with delay. */
             for(i = 0;i < NumChannels;++i)
             {
+                ALfloat hfgain = AmbiOrderHFGain[(ALsizei)floor(sqrt(i))];
                 for(b = 0;b < NUM_BANDS;b++)
                 {
                     ALsizei ridx = rdelay;
                     ALsizei j = 0;
                     while(ridx < HRIR_LENGTH)
-                        state->Chan[i].Coeffs[ridx++][1] += temps[b][j++] * AmbiMatrix[c][b][i];
+                        state->Chan[i].Coeffs[ridx++][1] += temps[b][j++] * AmbiMatrix[c][i] *
+                                                            hfgain;
+                    hfgain = 1.0f;
                 }
             }
         }
diff --git a/Alc/hrtf.h b/Alc/hrtf.h
index aaee4a8d..b041c911 100644
--- a/Alc/hrtf.h
+++ b/Alc/hrtf.h
@@ -79,6 +79,6 @@ void GetHrtfCoeffs(const struct Hrtf *Hrtf, ALfloat elevation, ALfloat azimuth,
  * virtual speaker positions and HF/LF matrices for decoding to them. The
  * returned coefficients are ordered and scaled according to the matrices.
  */
-void BuildBFormatHrtf(const struct Hrtf *Hrtf, DirectHrtfState *state, ALsizei NumChannels, const ALfloat (*restrict AmbiPoints)[2], const ALfloat (*restrict AmbiMatrix)[2][MAX_AMBI_COEFFS], ALsizei AmbiCount);
+void BuildBFormatHrtf(const struct Hrtf *Hrtf, DirectHrtfState *state, ALsizei NumChannels, const ALfloat (*restrict AmbiPoints)[2], const ALfloat (*restrict AmbiMatrix)[MAX_AMBI_COEFFS], ALsizei AmbiCount, const ALfloat *restrict AmbiOrderHFGain);
 
 #endif /* ALC_HRTF_H */
diff --git a/Alc/panning.c b/Alc/panning.c
index eaeb2646..e368c946 100644
--- a/Alc/panning.c
+++ b/Alc/panning.c
@@ -870,59 +870,79 @@ static void InitHrtfPanning(ALCdevice *device)
 {
     /* NOTE: azimuth goes clockwise. */
     static const ALfloat AmbiPoints[][2] = {
-        { DEG2RAD( 90.0f), DEG2RAD(   0.0f) },
         { DEG2RAD( 35.0f), DEG2RAD( -45.0f) },
-        { DEG2RAD( 35.0f), DEG2RAD(  45.0f) },
-        { DEG2RAD( 35.0f), DEG2RAD( 135.0f) },
         { DEG2RAD( 35.0f), DEG2RAD(-135.0f) },
+        { DEG2RAD( 35.0f), DEG2RAD( 135.0f) },
+        { DEG2RAD( 35.0f), DEG2RAD(  45.0f) },
         { DEG2RAD(  0.0f), DEG2RAD(   0.0f) },
-        { DEG2RAD(  0.0f), DEG2RAD(  90.0f) },
-        { DEG2RAD(  0.0f), DEG2RAD( 180.0f) },
+        { DEG2RAD(  0.0f), DEG2RAD( -45.0f) },
         { DEG2RAD(  0.0f), DEG2RAD( -90.0f) },
+        { DEG2RAD(  0.0f), DEG2RAD(-135.0f) },
+        { DEG2RAD(  0.0f), DEG2RAD( 180.0f) },
+        { DEG2RAD(  0.0f), DEG2RAD( 135.0f) },
+        { DEG2RAD(  0.0f), DEG2RAD(  90.0f) },
+        { DEG2RAD(  0.0f), DEG2RAD(  45.0f) },
         { DEG2RAD(-35.0f), DEG2RAD( -45.0f) },
-        { DEG2RAD(-35.0f), DEG2RAD(  45.0f) },
-        { DEG2RAD(-35.0f), DEG2RAD( 135.0f) },
         { DEG2RAD(-35.0f), DEG2RAD(-135.0f) },
-        { DEG2RAD(-90.0f), DEG2RAD(   0.0f) },
+        { DEG2RAD(-35.0f), DEG2RAD( 135.0f) },
+        { DEG2RAD(-35.0f), DEG2RAD(  45.0f) },
+    };
+    static const ALfloat AmbiMatrixFOA[][MAX_AMBI_COEFFS] = {
+        { 6.25000000e-002f,  5.00000000e-002f,  1.25000000e-001f,  5.00000000e-002f },
+        { 6.25000000e-002f,  5.00000000e-002f,  1.25000000e-001f, -5.00000000e-002f },
+        { 6.25000000e-002f, -5.00000000e-002f,  1.25000000e-001f, -5.00000000e-002f },
+        { 6.25000000e-002f, -5.00000000e-002f,  1.25000000e-001f,  5.00000000e-002f },
+        { 6.25000000e-002f,  0.00000000e+000f,  0.00000000e+000f,  8.66025404e-002f },
+        { 6.25000000e-002f,  6.12372435e-002f,  0.00000000e+000f,  6.12372435e-002f },
+        { 6.25000000e-002f,  8.66025404e-002f,  0.00000000e+000f,  0.00000000e+000f },
+        { 6.25000000e-002f,  6.12372435e-002f,  0.00000000e+000f, -6.12372435e-002f },
+        { 6.25000000e-002f,  0.00000000e+000f,  0.00000000e+000f, -8.66025404e-002f },
+        { 6.25000000e-002f, -6.12372435e-002f,  0.00000000e+000f, -6.12372435e-002f },
+        { 6.25000000e-002f, -8.66025404e-002f,  0.00000000e+000f,  0.00000000e+000f },
+        { 6.25000000e-002f, -6.12372435e-002f,  0.00000000e+000f,  6.12372435e-002f },
+        { 6.25000000e-002f,  5.00000000e-002f, -1.25000000e-001f,  5.00000000e-002f },
+        { 6.25000000e-002f,  5.00000000e-002f, -1.25000000e-001f, -5.00000000e-002f },
+        { 6.25000000e-002f, -5.00000000e-002f, -1.25000000e-001f, -5.00000000e-002f },
+        { 6.25000000e-002f, -5.00000000e-002f, -1.25000000e-001f,  5.00000000e-002f },
+    }, AmbiMatrixHOA[][MAX_AMBI_COEFFS] = {
+        { 6.25000000e-002f,  5.00000000e-002f,  1.25000000e-001f,  5.00000000e-002f,  4.55645099e-002f,  9.68245837e-002f,  0.00000000e+000f,  9.68245837e-002f,  0.00000000e+000f },
+        { 6.25000000e-002f,  5.00000000e-002f,  1.25000000e-001f, -5.00000000e-002f, -4.55645099e-002f,  9.68245837e-002f,  0.00000000e+000f, -9.68245837e-002f,  0.00000000e+000f },
+        { 6.25000000e-002f, -5.00000000e-002f,  1.25000000e-001f, -5.00000000e-002f,  4.55645099e-002f, -9.68245837e-002f,  0.00000000e+000f, -9.68245837e-002f,  0.00000000e+000f },
+        { 6.25000000e-002f, -5.00000000e-002f,  1.25000000e-001f,  5.00000000e-002f, -4.55645099e-002f, -9.68245837e-002f,  0.00000000e+000f,  9.68245837e-002f,  0.00000000e+000f },
+        { 6.25000000e-002f,  0.00000000e+000f,  0.00000000e+000f,  8.66025404e-002f,  0.00000000e+000f,  0.00000000e+000f,  0.00000000e+000f,  0.00000000e+000f,  1.29099445e-001f },
+        { 6.25000000e-002f,  6.12372435e-002f,  0.00000000e+000f,  6.12372435e-002f,  6.83467648e-002f,  0.00000000e+000f,  0.00000000e+000f,  0.00000000e+000f,  0.00000000e+000f },
+        { 6.25000000e-002f,  8.66025404e-002f,  0.00000000e+000f,  0.00000000e+000f,  0.00000000e+000f,  0.00000000e+000f,  0.00000000e+000f,  0.00000000e+000f, -1.29099445e-001f },
+        { 6.25000000e-002f,  6.12372435e-002f,  0.00000000e+000f, -6.12372435e-002f, -6.83467648e-002f,  0.00000000e+000f,  0.00000000e+000f,  0.00000000e+000f,  0.00000000e+000f },
+        { 6.25000000e-002f,  0.00000000e+000f,  0.00000000e+000f, -8.66025404e-002f,  0.00000000e+000f,  0.00000000e+000f,  0.00000000e+000f,  0.00000000e+000f,  1.29099445e-001f },
+        { 6.25000000e-002f, -6.12372435e-002f,  0.00000000e+000f, -6.12372435e-002f,  6.83467648e-002f,  0.00000000e+000f,  0.00000000e+000f,  0.00000000e+000f,  0.00000000e+000f },
+        { 6.25000000e-002f, -8.66025404e-002f,  0.00000000e+000f,  0.00000000e+000f,  0.00000000e+000f,  0.00000000e+000f,  0.00000000e+000f,  0.00000000e+000f, -1.29099445e-001f },
+        { 6.25000000e-002f, -6.12372435e-002f,  0.00000000e+000f,  6.12372435e-002f, -6.83467648e-002f,  0.00000000e+000f,  0.00000000e+000f,  0.00000000e+000f,  0.00000000e+000f },
+        { 6.25000000e-002f,  5.00000000e-002f, -1.25000000e-001f,  5.00000000e-002f,  4.55645099e-002f, -9.68245837e-002f,  0.00000000e+000f, -9.68245837e-002f,  0.00000000e+000f },
+        { 6.25000000e-002f,  5.00000000e-002f, -1.25000000e-001f, -5.00000000e-002f, -4.55645099e-002f, -9.68245837e-002f,  0.00000000e+000f,  9.68245837e-002f,  0.00000000e+000f },
+        { 6.25000000e-002f, -5.00000000e-002f, -1.25000000e-001f, -5.00000000e-002f,  4.55645099e-002f,  9.68245837e-002f,  0.00000000e+000f,  9.68245837e-002f,  0.00000000e+000f },
+        { 6.25000000e-002f, -5.00000000e-002f, -1.25000000e-001f,  5.00000000e-002f, -4.55645099e-002f,  9.68245837e-002f,  0.00000000e+000f, -9.68245837e-002f,  0.00000000e+000f },
     };
-    static const ALfloat AmbiMatrixFOA[][2][MAX_AMBI_COEFFS] = {
-        { { 1.88982237e-001f,  0.00000000e+000f,  1.90399923e-001f,  0.00000000e+000f }, { 7.14285714e-002f,  0.00000000e+000f,  1.24646009e-001f,  0.00000000e+000f } },
-        { { 1.88982237e-001f,  1.09057783e-001f,  1.09208910e-001f,  1.09057783e-001f }, { 7.14285714e-002f,  7.13950780e-002f,  7.14940135e-002f,  7.13950780e-002f } },
-        { { 1.88982237e-001f, -1.09057783e-001f,  1.09208910e-001f,  1.09057783e-001f }, { 7.14285714e-002f, -7.13950780e-002f,  7.14940135e-002f,  7.13950780e-002f } },
-        { { 1.88982237e-001f, -1.09057783e-001f,  1.09208910e-001f, -1.09057783e-001f }, { 7.14285714e-002f, -7.13950780e-002f,  7.14940135e-002f, -7.13950780e-002f } },
-        { { 1.88982237e-001f,  1.09057783e-001f,  1.09208910e-001f, -1.09057783e-001f }, { 7.14285714e-002f,  7.13950780e-002f,  7.14940135e-002f, -7.13950780e-002f } },
-        { { 1.88982237e-001f,  0.00000000e+000f,  0.00000000e+000f,  1.88281281e-001f }, { 7.14285714e-002f,  0.00000000e+000f,  0.00000000e+000f,  1.23259031e-001f } },
-        { { 1.88982237e-001f, -1.88281281e-001f,  0.00000000e+000f,  0.00000000e+000f }, { 7.14285714e-002f, -1.23259031e-001f,  0.00000000e+000f,  0.00000000e+000f } },
-        { { 1.88982237e-001f,  0.00000000e+000f,  0.00000000e+000f, -1.88281281e-001f }, { 7.14285714e-002f,  0.00000000e+000f,  0.00000000e+000f, -1.23259031e-001f } },
-        { { 1.88982237e-001f,  1.88281281e-001f,  0.00000000e+000f,  0.00000000e+000f }, { 7.14285714e-002f,  1.23259031e-001f,  0.00000000e+000f,  0.00000000e+000f } },
-        { { 1.88982237e-001f,  1.09057783e-001f, -1.09208910e-001f,  1.09057783e-001f }, { 7.14285714e-002f,  7.13950780e-002f, -7.14940135e-002f,  7.13950780e-002f } },
-        { { 1.88982237e-001f, -1.09057783e-001f, -1.09208910e-001f,  1.09057783e-001f }, { 7.14285714e-002f, -7.13950780e-002f, -7.14940135e-002f,  7.13950780e-002f } },
-        { { 1.88982237e-001f, -1.09057783e-001f, -1.09208910e-001f, -1.09057783e-001f }, { 7.14285714e-002f, -7.13950780e-002f, -7.14940135e-002f, -7.13950780e-002f } },
-        { { 1.88982237e-001f,  1.09057783e-001f, -1.09208910e-001f, -1.09057783e-001f }, { 7.14285714e-002f,  7.13950780e-002f, -7.14940135e-002f, -7.13950780e-002f } },
-        { { 1.88982237e-001f,  0.00000000e+000f, -1.90399923e-001f,  0.00000000e+000f }, { 7.14285714e-002f,  0.00000000e+000f, -1.24646009e-001f,  0.00000000e+000f } }
-    }, AmbiMatrixHOA[][2][MAX_AMBI_COEFFS] = {
-        { { 1.43315266e-001f,  0.00000000e+000f,  1.90399923e-001f,  0.00000000e+000f,  0.00000000e+000f,  0.00000000e+000f,  1.18020996e-001f,  0.00000000e+000f,  0.00000000e+000f }, { 7.26741039e-002f,  0.00000000e+000f,  1.24646009e-001f,  0.00000000e+000f,  0.00000000e+000f,  0.00000000e+000f,  1.49618920e-001f,  0.00000000e+000f,  0.00000000e+000f } },
-        { { 1.40852210e-001f,  1.09057783e-001f,  1.09208910e-001f,  1.09057783e-001f,  7.58818830e-002f,  7.66295578e-002f, -3.28314629e-004f,  7.66295578e-002f,  0.00000000e+000f }, { 7.14251066e-002f,  7.13950780e-002f,  7.14940135e-002f,  7.13950780e-002f,  9.61978444e-002f,  9.71456952e-002f, -4.16214759e-004f,  9.71456952e-002f,  0.00000000e+000f } },
-        { { 1.40852210e-001f, -1.09057783e-001f,  1.09208910e-001f,  1.09057783e-001f, -7.58818830e-002f, -7.66295578e-002f, -3.28314629e-004f,  7.66295578e-002f,  0.00000000e+000f }, { 7.14251066e-002f, -7.13950780e-002f,  7.14940135e-002f,  7.13950780e-002f, -9.61978444e-002f, -9.71456952e-002f, -4.16214759e-004f,  9.71456952e-002f,  0.00000000e+000f } },
-        { { 1.40852210e-001f, -1.09057783e-001f,  1.09208910e-001f, -1.09057783e-001f,  7.58818830e-002f, -7.66295578e-002f, -3.28314629e-004f, -7.66295578e-002f,  0.00000000e+000f }, { 7.14251066e-002f, -7.13950780e-002f,  7.14940135e-002f, -7.13950780e-002f,  9.61978444e-002f, -9.71456952e-002f, -4.16214759e-004f, -9.71456952e-002f,  0.00000000e+000f } },
-        { { 1.40852210e-001f,  1.09057783e-001f,  1.09208910e-001f, -1.09057783e-001f, -7.58818830e-002f,  7.66295578e-002f, -3.28314629e-004f, -7.66295578e-002f,  0.00000000e+000f }, { 7.14251066e-002f,  7.13950780e-002f,  7.14940135e-002f, -7.13950780e-002f, -9.61978444e-002f,  9.71456952e-002f, -4.16214759e-004f, -9.71456952e-002f,  0.00000000e+000f } },
-        { { 1.39644596e-001f,  0.00000000e+000f,  0.00000000e+000f,  1.88281281e-001f,  0.00000000e+000f,  0.00000000e+000f, -5.83538687e-002f,  0.00000000e+000f,  1.01835015e-001f }, { 7.08127349e-002f,  0.00000000e+000f,  0.00000000e+000f,  1.23259031e-001f,  0.00000000e+000f,  0.00000000e+000f, -7.39770307e-002f,  0.00000000e+000f,  1.29099445e-001f } },
-        { { 1.39644596e-001f, -1.88281281e-001f,  0.00000000e+000f,  0.00000000e+000f,  0.00000000e+000f,  0.00000000e+000f, -5.83538687e-002f,  0.00000000e+000f, -1.01835015e-001f }, { 7.08127349e-002f, -1.23259031e-001f,  0.00000000e+000f,  0.00000000e+000f,  0.00000000e+000f,  0.00000000e+000f, -7.39770307e-002f,  0.00000000e+000f, -1.29099445e-001f } },
-        { { 1.39644596e-001f,  0.00000000e+000f,  0.00000000e+000f, -1.88281281e-001f,  0.00000000e+000f,  0.00000000e+000f, -5.83538687e-002f,  0.00000000e+000f,  1.01835015e-001f }, { 7.08127349e-002f,  0.00000000e+000f,  0.00000000e+000f, -1.23259031e-001f,  0.00000000e+000f,  0.00000000e+000f, -7.39770307e-002f,  0.00000000e+000f,  1.29099445e-001f } },
-        { { 1.39644596e-001f,  1.88281281e-001f,  0.00000000e+000f,  0.00000000e+000f,  0.00000000e+000f,  0.00000000e+000f, -5.83538687e-002f,  0.00000000e+000f, -1.01835015e-001f }, { 7.08127349e-002f,  1.23259031e-001f,  0.00000000e+000f,  0.00000000e+000f,  0.00000000e+000f,  0.00000000e+000f, -7.39770307e-002f,  0.00000000e+000f, -1.29099445e-001f } },
-        { { 1.40852210e-001f,  1.09057783e-001f, -1.09208910e-001f,  1.09057783e-001f,  7.58818830e-002f, -7.66295578e-002f, -3.28314629e-004f, -7.66295578e-002f,  0.00000000e+000f }, { 7.14251066e-002f,  7.13950780e-002f, -7.14940135e-002f,  7.13950780e-002f,  9.61978444e-002f, -9.71456952e-002f, -4.16214759e-004f, -9.71456952e-002f,  0.00000000e+000f } },
-        { { 1.40852210e-001f, -1.09057783e-001f, -1.09208910e-001f,  1.09057783e-001f, -7.58818830e-002f,  7.66295578e-002f, -3.28314629e-004f, -7.66295578e-002f,  0.00000000e+000f }, { 7.14251066e-002f, -7.13950780e-002f, -7.14940135e-002f,  7.13950780e-002f, -9.61978444e-002f,  9.71456952e-002f, -4.16214759e-004f, -9.71456952e-002f,  0.00000000e+000f } },
-        { { 1.40852210e-001f, -1.09057783e-001f, -1.09208910e-001f, -1.09057783e-001f,  7.58818830e-002f,  7.66295578e-002f, -3.28314629e-004f,  7.66295578e-002f,  0.00000000e+000f }, { 7.14251066e-002f, -7.13950780e-002f, -7.14940135e-002f, -7.13950780e-002f,  9.61978444e-002f,  9.71456952e-002f, -4.16214759e-004f,  9.71456952e-002f,  0.00000000e+000f } },
-        { { 1.40852210e-001f,  1.09057783e-001f, -1.09208910e-001f, -1.09057783e-001f, -7.58818830e-002f, -7.66295578e-002f, -3.28314629e-004f,  7.66295578e-002f,  0.00000000e+000f }, { 7.14251066e-002f,  7.13950780e-002f, -7.14940135e-002f, -7.13950780e-002f, -9.61978444e-002f, -9.71456952e-002f, -4.16214759e-004f,  9.71456952e-002f,  0.00000000e+000f } },
-        { { 1.43315266e-001f,  0.00000000e+000f, -1.90399923e-001f,  0.00000000e+000f,  0.00000000e+000f,  0.00000000e+000f,  1.18020996e-001f,  0.00000000e+000f,  0.00000000e+000f }, { 7.26741039e-002f,  0.00000000e+000f, -1.24646009e-001f,  0.00000000e+000f,  0.00000000e+000f,  0.00000000e+000f,  1.49618920e-001f,  0.00000000e+000f,  0.00000000e+000f } },
+    static const ALfloat AmbiOrderHFGainFOA[MAX_AMBI_ORDER+1] = {
+        2.82842712e+00, 1.63299316e+00
+    }, AmbiOrderHFGainHOA[MAX_AMBI_ORDER+1] = {
+        2.15665546e+00, 1.67053814e+00, 8.62662186e-01
     };
-    const ALfloat (*AmbiMatrix)[2][MAX_AMBI_COEFFS] = device->AmbiUp ? AmbiMatrixHOA :
-                                                                       AmbiMatrixFOA;
-    ALsizei count = device->AmbiUp ? 9 : 4;
+    const ALfloat (*restrict AmbiMatrix)[MAX_AMBI_COEFFS] = AmbiMatrixFOA;
+    const ALfloat *restrict AmbiOrderHFGain = AmbiOrderHFGainFOA;
+    ALsizei count = 4;
     ALsizei i;
 
+    static_assert(COUNTOF(AmbiPoints) == COUNTOF(AmbiMatrixFOA), "FOA Ambisonic HRTF mismatch");
+    static_assert(COUNTOF(AmbiPoints) == COUNTOF(AmbiMatrixHOA), "HOA Ambisonic HRTF mismatch");
     static_assert(COUNTOF(AmbiPoints) <= HRTF_AMBI_MAX_CHANNELS, "HRTF_AMBI_MAX_CHANNELS is too small");
 
+    if(device->AmbiUp)
+    {
+        AmbiMatrix = AmbiMatrixHOA;
+        AmbiOrderHFGain = AmbiOrderHFGainHOA;
+        count = 9;
+    }
+
     device->Hrtf = al_calloc(16, FAM_SIZE(DirectHrtfState, Chan, count));
 
     for(i = 0;i < count;i++)
@@ -956,7 +976,8 @@ static void InitHrtfPanning(ALCdevice *device)
     device->RealOut.NumChannels = ChannelsFromDevFmt(device->FmtChans, device->AmbiOrder);
 
     BuildBFormatHrtf(device->HrtfHandle,
-        device->Hrtf, device->Dry.NumChannels, AmbiPoints, AmbiMatrix, COUNTOF(AmbiPoints)
+        device->Hrtf, device->Dry.NumChannels, AmbiPoints, AmbiMatrix, COUNTOF(AmbiPoints),
+        AmbiOrderHFGain
     );
 
     InitNearFieldCtrl(device, device->HrtfHandle->distance, device->AmbiUp ? 2 : 1, true);