Use an 8-channel cube for HRTF's virtual format.

There were phase issues caused by applying HRTF directly to the B-Format
channels, since the HRIR delays were all averaged which removed the inter-aural
time-delay, which in turn removed significant spatial information.

4 files changed, 46 insertions, 122 deletions

diff --git a/Alc/ALu.c b/Alc/ALu.c
index b36e2248..d4dac1ab 100644
--- a/Alc/ALu.c
+++ b/Alc/ALu.c
@@ -100,14 +100,14 @@ extern inline void aluMatrixdSet(aluMatrixd *matrix,
                                  ALdouble m30, ALdouble m31, ALdouble m32, ALdouble m33);
 
 
-/* NOTE: HRTF is set up a bit special in the device. By default, the device's
- * DryBuffer, NumChannels, ChannelName, and Channel fields correspond to the
- * output mixing format, and the DryBuffer is then converted and written to the
- * backend's audio buffer.
+/* NOTE: HRTF is set up a bit special in the device. By default, without HRTF,
+ * the device's DryBuffer, NumChannels, ChannelName, and Channel fields
+ * correspond to the output format, and the DryBuffer is then converted and
+ * written to the backend's audio buffer.
  *
- * With HRTF, these fields correspond to a virtual format (typically B-Format),
- * and the actual output is stored in DryBuffer[NumChannels] for the left
- * channel and DryBuffer[NumChannels+1] for the right. As a final output step,
+ * With HRTF, these fields correspond to a virtual format, and the actual
+ * output is stored in DryBuffer[NumChannels] for the left channel and
+ * DryBuffer[NumChannels+1] for the right. As a final output step,
  * the virtual channels will have HRTF applied and written to the actual
  * output. Things like effects and B-Format decoding will want to write to the
  * virtual channels so that they can be mixed with HRTF in full 3D.
diff --git a/Alc/hrtf.c b/Alc/hrtf.c
index c4cacf87..e4052f52 100644
--- a/Alc/hrtf.c
+++ b/Alc/hrtf.c
@@ -181,108 +181,6 @@ void GetLerpedHrtfCoeffs(const struct Hrtf *Hrtf, ALfloat elevation, ALfloat azi
     }
 }
 
-/* Calculates HRTF coefficients for B-Format channels (only up to first-order).
- * Note that these will decode a B-Format output mix, which uses FuMa ordering
- * and scaling, not N3D!
- */
-void GetBFormatHrtfCoeffs(const struct Hrtf *Hrtf, ALfloat (*coeffs_list[4])[2], ALuint *delay_list[4])
-{
-    ALuint elev_idx, azi_idx;
-    ALfloat scale;
-    ALuint i, c;
-
-    for(c = 0;c < 4;c++)
-    {
-        ALfloat (*coeffs)[2] = coeffs_list[c];
-        ALuint *delay = delay_list[c];
-
-        for(i = 0;i < Hrtf->irSize;i++)
-        {
-            coeffs[i][0] = 0.0f;
-            coeffs[i][1] = 0.0f;
-        }
-        delay[0] = 0;
-        delay[1] = 0;
-    }
-
-    /* NOTE: HRTF coefficients are generated by combining all the HRIRs in the
-     * dataset, with each entry scaled according to how much it contributes to
-     * the given B-Format channel based on its direction (including negative
-     * contributions!).
-     */
-    scale = 0.0f;
-    for(elev_idx = 0;elev_idx < Hrtf->evCount;elev_idx++)
-    {
-        ALfloat elev = (ALfloat)elev_idx/(ALfloat)(Hrtf->evCount-1)*F_PI - F_PI_2;
-        ALuint evoffset = Hrtf->evOffset[elev_idx];
-        ALuint azcount = Hrtf->azCount[elev_idx];
-
-        scale += (ALfloat)azcount;
-
-        for(azi_idx = 0;azi_idx < azcount;azi_idx++)
-        {
-            ALuint lidx, ridx;
-            ALfloat ambi_coeffs[4];
-            ALfloat az, gain;
-            ALfloat x, y, z;
-
-            lidx = evoffset + azi_idx;
-            ridx = evoffset + ((azcount-azi_idx) % azcount);
-
-            az = (ALfloat)azi_idx / (ALfloat)azcount * F_TAU;
-            if(az > F_PI) az -= F_TAU;
-
-            x = cosf(-az) * cosf(elev);
-            y = sinf(-az) * cosf(elev);
-            z = sinf(elev);
-
-            ambi_coeffs[0] = 1.414213562f;
-            ambi_coeffs[1] = x;
-            ambi_coeffs[2] = y;
-            ambi_coeffs[3] = z;
-
-            for(c = 0;c < 4;c++)
-            {
-                ALfloat (*coeffs)[2] = coeffs_list[c];
-                ALuint *delay = delay_list[c];
-
-                /* NOTE: Always include the total delay average since the
-                 * channels need to have matching delays. */
-                delay[0] += Hrtf->delays[lidx];
-                delay[1] += Hrtf->delays[ridx];
-
-                gain = ambi_coeffs[c];
-                if(!(fabsf(gain) > GAIN_SILENCE_THRESHOLD))
-                    continue;
-
-                for(i = 0;i < Hrtf->irSize;i++)
-                {
-                    coeffs[i][0] += Hrtf->coeffs[lidx*Hrtf->irSize + i]*(1.0f/32767.0f) * gain;
-                    coeffs[i][1] += Hrtf->coeffs[ridx*Hrtf->irSize + i]*(1.0f/32767.0f) * gain;
-                }
-            }
-        }
-    }
-
-    scale = 1.0f/scale;
-
-    for(c = 0;c < 4;c++)
-    {
-        ALfloat (*coeffs)[2] = coeffs_list[c];
-        ALuint *delay = delay_list[c];
-
-        for(i = 0;i < Hrtf->irSize;i++)
-        {
-            coeffs[i][0] *= scale;
-            coeffs[i][1] *= scale;
-        }
-        delay[0] = minu((ALuint)((ALfloat)delay[0] * scale), HRTF_HISTORY_LENGTH-1);
-        delay[0] <<= HRTFDELAY_BITS;
-        delay[1] = minu((ALuint)((ALfloat)delay[1] * scale), HRTF_HISTORY_LENGTH-1);
-        delay[1] <<= HRTFDELAY_BITS;
-    }
-}
-
 
 static struct Hrtf *LoadHrtf00(FILE *f)
 {
diff --git a/Alc/hrtf.h b/Alc/hrtf.h
index 794d6abc..86016ae6 100644
--- a/Alc/hrtf.h
+++ b/Alc/hrtf.h
@@ -34,6 +34,5 @@ ALuint GetHrtfSampleRate(const struct Hrtf *Hrtf);
 ALuint GetHrtfIrSize(const struct Hrtf *Hrtf);
 
 void GetLerpedHrtfCoeffs(const struct Hrtf *Hrtf, ALfloat elevation, ALfloat azimuth, ALfloat dirfact, ALfloat gain, ALfloat (*coeffs)[2], ALuint *delays);
-void GetBFormatHrtfCoeffs(const struct Hrtf *Hrtf, ALfloat (*coeffs_list[4])[2], ALuint *delay_list[4]);
 
 #endif /* ALC_HRTF_H */
diff --git a/Alc/panning.c b/Alc/panning.c
index 5013ec16..9f1e87d7 100644
--- a/Alc/panning.c
+++ b/Alc/panning.c
@@ -184,6 +184,15 @@ DECL_CONST static inline const char *GetLabelFromChannel(enum Channel channel)
         case SideLeft: return "side-left";
         case SideRight: return "side-right";
 
+        case UpperFrontLeft: return "upper-front-left";
+        case UpperFrontRight: return "upper-front-right";
+        case UpperBackLeft: return "upper-back-left";
+        case UpperBackRight: return "upper-back-right";
+        case LowerFrontLeft: return "lower-front-left";
+        case LowerFrontRight: return "lower-front-right";
+        case LowerBackLeft: return "lower-back-left";
+        case LowerBackRight: return "lower-back-right";
+
         case BFormatW: return "bformat-w";
         case BFormatX: return "bformat-x";
         case BFormatY: return "bformat-y";
@@ -466,6 +475,15 @@ ALvoid aluInitPanning(ALCdevice *device)
         { 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 } },
         { 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 } },
         { 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 } },
+    }, Cube8Cfg[8] = {
+        { UpperFrontLeft,  { 0.176776695f,  0.072168784f,  0.072168784f,  0.072168784f } },
+        { UpperFrontRight, { 0.176776695f,  0.072168784f, -0.072168784f,  0.072168784f } },
+        { UpperBackLeft,   { 0.176776695f, -0.072168784f,  0.072168784f,  0.072168784f } },
+        { UpperBackRight,  { 0.176776695f, -0.072168784f, -0.072168784f,  0.072168784f } },
+        { LowerFrontLeft,  { 0.176776695f,  0.072168784f,  0.072168784f, -0.072168784f } },
+        { LowerFrontRight, { 0.176776695f,  0.072168784f, -0.072168784f, -0.072168784f } },
+        { LowerBackLeft,   { 0.176776695f, -0.072168784f,  0.072168784f, -0.072168784f } },
+        { LowerBackRight,  { 0.176776695f, -0.072168784f, -0.072168784f, -0.072168784f } },
     }, BFormat3D[4] = {
         { BFormatW, { 1.0f, 0.0f, 0.0f, 0.0f } },
         { BFormatX, { 0.0f, 1.0f, 0.0f, 0.0f } },
@@ -482,13 +500,25 @@ ALvoid aluInitPanning(ALCdevice *device)
 
     if(device->Hrtf)
     {
-        ALfloat (*coeffs_list[4])[2];
-        ALuint *delay_list[4];
+        static const struct {
+            enum Channel Channel;
+            ALfloat Angle;
+            ALfloat Elevation;
+        } CubeInfo[8] = {
+            { UpperFrontLeft,  DEG2RAD( -45.0f), DEG2RAD( 45.0f) },
+            { UpperFrontRight, DEG2RAD(  45.0f), DEG2RAD( 45.0f) },
+            { UpperBackLeft,   DEG2RAD(-135.0f), DEG2RAD( 45.0f) },
+            { UpperBackRight,  DEG2RAD( 135.0f), DEG2RAD( 45.0f) },
+            { LowerFrontLeft,  DEG2RAD( -45.0f), DEG2RAD(-45.0f) },
+            { LowerFrontRight, DEG2RAD(  45.0f), DEG2RAD(-45.0f) },
+            { LowerBackLeft,   DEG2RAD(-135.0f), DEG2RAD(-45.0f) },
+            { LowerBackRight,  DEG2RAD( 135.0f), DEG2RAD(-45.0f) },
+        };
         ALuint i;
 
-        count = COUNTOF(BFormat3D);
-        chanmap = BFormat3D;
-        ambiscale = 1.0f;
+        count = COUNTOF(Cube8Cfg);
+        chanmap = Cube8Cfg;
+        ambiscale = FIRST_ORDER_SCALE;
 
         for(i = 0;i < count;i++)
             device->ChannelName[i] = chanmap[i].ChanName;
@@ -498,15 +528,12 @@ ALvoid aluInitPanning(ALCdevice *device)
                       &device->NumChannels, AL_TRUE);
         device->AmbiScale = ambiscale;
 
-        for(i = 0;i < 4;++i)
+        for(i = 0;i < device->NumChannels;i++)
         {
-            static const enum Channel inputs[4] = { BFormatW, BFormatX, BFormatY, BFormatZ };
-            int chan = GetChannelIdxByName(device, inputs[i]);
-            coeffs_list[i] = device->Hrtf_Params[chan].Coeffs;
-            delay_list[i] = device->Hrtf_Params[chan].Delay;
+            int chan = GetChannelIdxByName(device, CubeInfo[i].Channel);
+            GetLerpedHrtfCoeffs(device->Hrtf, CubeInfo[i].Elevation, CubeInfo[i].Angle, 1.0f, 1.0f,
+                                device->Hrtf_Params[chan].Coeffs, device->Hrtf_Params[chan].Delay);
         }
-        GetBFormatHrtfCoeffs(device->Hrtf, coeffs_list, delay_list);
-
         return;
     }