Add an option for pair-wise stereo panning

4 files changed, 81 insertions, 26 deletions

diff --git a/Alc/ALc.c b/Alc/ALc.c
index 01fc8a34..fd44ed28 100644
--- a/Alc/ALc.c
+++ b/Alc/ALc.c
@@ -1972,8 +1972,8 @@ static ALCenum UpdateDeviceParams(ALCdevice *device, const ALCint *attrList)
     }
 
     device->Hrtf = NULL;
-    device->Hrtf_Mode = DisabledHrtf;
     al_string_clear(&device->Hrtf_Name);
+    device->Render_Mode = NormalRender;
     if(device->FmtChans != DevFmtStereo)
     {
         if(hrtf_appreq == Hrtf_Enable)
@@ -1982,7 +1982,7 @@ static ALCenum UpdateDeviceParams(ALCdevice *device, const ALCint *attrList)
     else
     {
         bool headphones = device->IsHeadphones;
-        enum HrtfMode hrtf_mode = FullHrtf;
+        enum RenderMode render_mode = HrtfRender;
         ALCenum hrtf_status = device->Hrtf_Status;
         const char *mode;
         int bs2blevel;
@@ -2003,9 +2003,9 @@ static ALCenum UpdateDeviceParams(ALCdevice *device, const ALCint *attrList)
             if(ConfigValueStr(al_string_get_cstr(device->DeviceName), NULL, "hrtf-mode", &mode))
             {
                 if(strcasecmp(mode, "full") == 0)
-                    hrtf_mode = FullHrtf;
+                    render_mode = HrtfRender;
                 else if(strcasecmp(mode, "basic") == 0)
-                    hrtf_mode = BasicHrtf;
+                    render_mode = NormalRender;
                 else
                     ERR("Unexpected hrtf-mode: %s\n", mode);
             }
@@ -2068,8 +2068,8 @@ static ALCenum UpdateDeviceParams(ALCdevice *device, const ALCint *attrList)
         }
         if(device->Hrtf)
         {
-            device->Hrtf_Mode = hrtf_mode;
             device->Hrtf_Status = hrtf_status;
+            device->Render_Mode = render_mode;
             TRACE("HRTF enabled, \"%s\"\n", al_string_get_cstr(device->Hrtf_Name));
         }
         else
@@ -2084,14 +2084,30 @@ static ALCenum UpdateDeviceParams(ALCdevice *device, const ALCint *attrList)
             {
                 device->Bs2b = al_calloc(16, sizeof(*device->Bs2b));
                 bs2b_set_params(device->Bs2b, bs2blevel, device->Frequency);
+                device->Render_Mode = StereoPair;
                 TRACE("BS2B enabled\n");
             }
             else
             {
                 TRACE("BS2B disabled\n");
-            }
 
-            device->Uhj_Encoder = al_calloc(16, sizeof(Uhj2Encoder));
+                render_mode = NormalRender;
+                if(ConfigValueStr(al_string_get_cstr(device->DeviceName), NULL, "stereo-panning", &mode))
+                {
+                    if(strcasecmp(mode, "paired") == 0)
+                        render_mode = StereoPair;
+                    else if(strcasecmp(mode, "uhj") != 0)
+                        ERR("Unexpected stereo-panning: %s\n", mode);
+                }
+                device->Render_Mode = render_mode;
+                if(render_mode == NormalRender)
+                {
+                    device->Uhj_Encoder = al_calloc(16, sizeof(Uhj2Encoder));
+                    TRACE("UHJ enabled\n");
+                }
+                else
+                    TRACE("UHJ disabled\n");
+            }
         }
     }
 
@@ -3342,7 +3358,7 @@ ALC_API ALCdevice* ALC_APIENTRY alcOpenDevice(const ALCchar *deviceName)
     device->Uhj_Encoder = NULL;
     VECTOR_INIT(device->Hrtf_List);
     AL_STRING_INIT(device->Hrtf_Name);
-    device->Hrtf_Mode = DisabledHrtf;
+    device->Render_Mode = NormalRender;
     AL_STRING_INIT(device->DeviceName);
     device->DryBuffer = NULL;
 
@@ -3787,7 +3803,7 @@ ALC_API ALCdevice* ALC_APIENTRY alcLoopbackOpenDeviceSOFT(const ALCchar *deviceN
     AL_STRING_INIT(device->Hrtf_Name);
     device->Bs2b = NULL;
     device->Uhj_Encoder = NULL;
-    device->Hrtf_Mode = DisabledHrtf;
+    device->Render_Mode = NormalRender;
     AL_STRING_INIT(device->DeviceName);
     device->DryBuffer = NULL;
 
diff --git a/Alc/ALu.c b/Alc/ALu.c
index 41d9a3fb..38a4ef71 100644
--- a/Alc/ALu.c
+++ b/Alc/ALu.c
@@ -577,9 +577,9 @@ ALvoid CalcNonAttnSourceParams(ALvoice *voice, const ALsource *ALSource, const A
         {
             if(Device->Hrtf || Device->Uhj_Encoder)
             {
-                /* DirectChannels with HRTF enabled. Skip the virtual channels
-                 * and write FrontLeft and FrontRight inputs to the first and
-                 * second outputs.
+                /* DirectChannels with HRTF or UHJ enabled. Skip the virtual
+                 * channels and write FrontLeft and FrontRight inputs to the
+                 * first and second outputs.
                  */
                 voice->Direct.OutBuffer += voice->Direct.OutChannels;
                 voice->Direct.OutChannels = 2;
@@ -627,7 +627,7 @@ ALvoid CalcNonAttnSourceParams(ALvoice *voice, const ALsource *ALSource, const A
 
             voice->IsHrtf = AL_FALSE;
         }
-        else if(Device->Hrtf_Mode == FullHrtf)
+        else if(Device->Render_Mode == HrtfRender)
         {
             /* Full HRTF rendering. Skip the virtual channels and render each
              * input channel to the real outputs.
@@ -686,7 +686,7 @@ ALvoid CalcNonAttnSourceParams(ALvoice *voice, const ALsource *ALSource, const A
         }
         else
         {
-            /* Basic or no HRTF rendering. Use normal panning to the output. */
+            /* Non-HRTF rendering. Use normal panning to the output. */
             for(c = 0;c < num_channels;c++)
             {
                 /* Special-case LFE */
@@ -707,9 +707,24 @@ ALvoid CalcNonAttnSourceParams(ALvoice *voice, const ALsource *ALSource, const A
                     continue;
                 }
 
-                CalcAngleCoeffs(chans[c].angle, chans[c].elevation, coeffs);
+                if(Device->Render_Mode == StereoPair)
+                {
+                    /* Clamp X so it remains within 30 degrees of 0 or 180 degree azimuth. */
+                    ALfloat x = sinf(chans[c].angle) * cosf(chans[c].elevation);
+                    coeffs[0] = clampf(-x, -0.5f, 0.5f) + 0.5;
+                    voice->Direct.Gains[c].Target[0] = coeffs[0] * DryGain;
+                    voice->Direct.Gains[c].Target[1] = (1.0f-coeffs[0]) * DryGain;
+                    for(j = 2;j < MAX_OUTPUT_CHANNELS;j++)
+                        voice->Direct.Gains[c].Target[j] = 0.0f;
 
-                ComputePanningGains(Device->AmbiCoeffs, Device->NumChannels, coeffs, DryGain, voice->Direct.Gains[c].Target);
+                    CalcAngleCoeffs(chans[c].angle, chans[c].elevation, coeffs);
+                }
+                else
+                {
+                    CalcAngleCoeffs(chans[c].angle, chans[c].elevation, coeffs);
+                    ComputePanningGains(Device->AmbiCoeffs, Device->NumChannels, coeffs, DryGain,
+                                        voice->Direct.Gains[c].Target);
+                }
 
                 for(i = 0;i < NumSends;i++)
                 {
@@ -1105,7 +1120,7 @@ ALvoid CalcSourceParams(ALvoice *voice, const ALsource *ALSource, const ALCconte
         BufferListItem = BufferListItem->next;
     }
 
-    if(Device->Hrtf_Mode == FullHrtf)
+    if(Device->Render_Mode == HrtfRender)
     {
         /* Full HRTF rendering. Skip the virtual channels and render to the
          * real outputs.
@@ -1170,7 +1185,7 @@ ALvoid CalcSourceParams(ALvoice *voice, const ALsource *ALSource, const ALCconte
     }
     else
     {
-        /* Basic or no HRTF rendering. Use normal panning to the output. */
+        /* Non-HRTF rendering. */
         ALfloat dir[3] = { 0.0f, 0.0f, -1.0f };
         ALfloat radius = ALSource->Radius;
         ALfloat coeffs[MAX_AMBI_COEFFS];
@@ -1193,10 +1208,24 @@ ALvoid CalcSourceParams(ALvoice *voice, const ALsource *ALSource, const ALCconte
             dir[1] *= dirfact;
             dir[2] *= dirfact;
         }
-        CalcDirectionCoeffs(dir, coeffs);
 
-        ComputePanningGains(Device->AmbiCoeffs, Device->NumChannels, coeffs, DryGain,
-                            voice->Direct.Gains[0].Target);
+        if(Device->Render_Mode == StereoPair)
+        {
+            /* Clamp X so it remains within 30 degrees of 0 or 180 degree azimuth. */
+            coeffs[0] = clampf(-dir[0], -0.5f, 0.5f) + 0.5;
+            voice->Direct.Gains[0].Target[0] = coeffs[0] * DryGain;
+            voice->Direct.Gains[0].Target[1] = (1.0f-coeffs[0]) * DryGain;
+            for(i = 2;i < MAX_OUTPUT_CHANNELS;i++)
+                voice->Direct.Gains[0].Target[i] = 0.0f;
+
+            CalcDirectionCoeffs(dir, coeffs);
+        }
+        else
+        {
+            CalcDirectionCoeffs(dir, coeffs);
+            ComputePanningGains(Device->AmbiCoeffs, Device->NumChannels, coeffs, DryGain,
+                                voice->Direct.Gains[0].Target);
+        }
 
         for(i = 0;i < NumSends;i++)
         {
diff --git a/OpenAL32/Include/alMain.h b/OpenAL32/Include/alMain.h
index f9532727..8c75cb83 100644
--- a/OpenAL32/Include/alMain.h
+++ b/OpenAL32/Include/alMain.h
@@ -387,10 +387,10 @@ enum DeviceType {
 };
 
 
-enum HrtfMode {
-    DisabledHrtf,
-    BasicHrtf,
-    FullHrtf
+enum RenderMode {
+    NormalRender,
+    StereoPair,
+    HrtfRender
 };
 
 
@@ -465,7 +465,6 @@ struct ALCdevice_struct
     al_string Hrtf_Name;
     const struct Hrtf *Hrtf;
     ALCenum Hrtf_Status;
-    enum HrtfMode Hrtf_Mode;
     HrtfState Hrtf_State[MAX_OUTPUT_CHANNELS];
     HrtfParams Hrtf_Params[MAX_OUTPUT_CHANNELS];
     ALuint Hrtf_Offset;
@@ -476,6 +475,9 @@ struct ALCdevice_struct
     // Stereo-to-binaural filter
     struct bs2b *Bs2b;
 
+    /* Rendering mode. */
+    enum RenderMode Render_Mode;
+
     // Device flags
     ALuint Flags;
 
diff --git a/alsoftrc.sample b/alsoftrc.sample
index 7d73b7c6..255f82d0 100644
--- a/alsoftrc.sample
+++ b/alsoftrc.sample
@@ -86,6 +86,14 @@
 #  Valid settings are auto, speakers, and headphones.
 #stereo-mode = auto
 
+## stereo-panning:
+#  Specifies the panning method for non-HRTF stereo output. uhj (default)
+#  creates stereo-compatible two-channel UHJ output, which encodes some
+#  surround sound information, while paired uses standard pair-wise panning
+#  between -30 and +30 degrees. If crossfeed filters are used, uhj panning is
+#  disabled.
+#stereo-panning = uhj
+
 ## hrtf:
 #  Controls HRTF processing. These filters provide better spatialization of
 #  sounds while using headphones, but do require a bit more CPU power. The