Fix 5.1 surround sound

Apparently, 5.1 surround sound is supposed to use the "side" channels, not the
back channels, and we've been wrong this whole time. That means the "5.1 Side"
is actually the correct 5.1 setup, and using the back channels is anomalous.

Additionally, this means the 5.1 buffer format should also use the the side
channels instead of the back channels.

A final note: the 5.1 mixing coefficients are changed so both use the original
5.1 surround sound set (with the surround channels at +/-110 degrees). So the
only difference now between 5.1 "side" and 5.1 "back" is the channel labels.

7 files changed, 38 insertions, 33 deletions

diff --git a/Alc/backends/coreaudio.c b/Alc/backends/coreaudio.c
index d7cc6e9c..b38cc4ee 100644
--- a/Alc/backends/coreaudio.c
+++ b/Alc/backends/coreaudio.c
@@ -519,7 +519,7 @@ static ALCenum ca_open_capture(ALCdevice *device, const ALCchar *deviceName)
 
         case DevFmtQuad:
         case DevFmtX51:
-        case DevFmtX51Side:
+        case DevFmtX51Rear:
         case DevFmtX61:
         case DevFmtX71:
             ERR("%s not supported\n", DevFmtChannelsString(device->FmtChans));
diff --git a/Alc/backends/dsound.c b/Alc/backends/dsound.c
index 14f1a1c0..378c0798 100644
--- a/Alc/backends/dsound.c
+++ b/Alc/backends/dsound.c
@@ -43,6 +43,9 @@
 #ifndef DSSPEAKER_5POINT1
 #   define DSSPEAKER_5POINT1          0x00000006
 #endif
+#ifndef DSSPEAKER_5POINT1_BACK
+#   define DSSPEAKER_5POINT1_BACK     0x00000006
+#endif
 #ifndef DSSPEAKER_7POINT1
 #   define DSSPEAKER_7POINT1          0x00000007
 #endif
@@ -450,8 +453,10 @@ static ALCboolean ALCdsoundPlayback_reset(ALCdsoundPlayback *self)
                 device->FmtChans = DevFmtStereo;
             else if(speakers == DSSPEAKER_QUAD)
                 device->FmtChans = DevFmtQuad;
-            else if(speakers == DSSPEAKER_5POINT1 || speakers == DSSPEAKER_5POINT1_SURROUND)
+            else if(speakers == DSSPEAKER_5POINT1_SURROUND)
                 device->FmtChans = DevFmtX51;
+            else if(speakers == DSSPEAKER_5POINT1_BACK)
+                device->FmtChans = DevFmtX51Rear;
             else if(speakers == DSSPEAKER_7POINT1 || speakers == DSSPEAKER_7POINT1_SURROUND)
                 device->FmtChans = DevFmtX71;
             else
@@ -478,16 +483,16 @@ static ALCboolean ALCdsoundPlayback_reset(ALCdsoundPlayback *self)
                                            SPEAKER_FRONT_RIGHT |
                                            SPEAKER_FRONT_CENTER |
                                            SPEAKER_LOW_FREQUENCY |
-                                           SPEAKER_BACK_LEFT |
-                                           SPEAKER_BACK_RIGHT;
+                                           SPEAKER_SIDE_LEFT |
+                                           SPEAKER_SIDE_RIGHT;
                 break;
-            case DevFmtX51Side:
+            case DevFmtX51Rear:
                 OutputType.dwChannelMask = SPEAKER_FRONT_LEFT |
                                            SPEAKER_FRONT_RIGHT |
                                            SPEAKER_FRONT_CENTER |
                                            SPEAKER_LOW_FREQUENCY |
-                                           SPEAKER_SIDE_LEFT |
-                                           SPEAKER_SIDE_RIGHT;
+                                           SPEAKER_BACK_LEFT |
+                                           SPEAKER_BACK_RIGHT;
                 break;
             case DevFmtX61:
                 OutputType.dwChannelMask = SPEAKER_FRONT_LEFT |
@@ -745,16 +750,16 @@ static ALCenum ALCdsoundCapture_open(ALCdsoundCapture *self, const ALCchar *devi
                                           SPEAKER_FRONT_RIGHT |
                                           SPEAKER_FRONT_CENTER |
                                           SPEAKER_LOW_FREQUENCY |
-                                          SPEAKER_BACK_LEFT |
-                                          SPEAKER_BACK_RIGHT;
+                                          SPEAKER_SIDE_LEFT |
+                                          SPEAKER_SIDE_RIGHT;
                 break;
-            case DevFmtX51Side:
+            case DevFmtX51Rear:
                 InputType.dwChannelMask = SPEAKER_FRONT_LEFT |
                                           SPEAKER_FRONT_RIGHT |
                                           SPEAKER_FRONT_CENTER |
                                           SPEAKER_LOW_FREQUENCY |
-                                          SPEAKER_SIDE_LEFT |
-                                          SPEAKER_SIDE_RIGHT;
+                                          SPEAKER_BACK_LEFT |
+                                          SPEAKER_BACK_RIGHT;
                 break;
             case DevFmtX61:
                 InputType.dwChannelMask = SPEAKER_FRONT_LEFT |
diff --git a/Alc/backends/mmdevapi.c b/Alc/backends/mmdevapi.c
index 7dcdb819..e79122af 100644
--- a/Alc/backends/mmdevapi.c
+++ b/Alc/backends/mmdevapi.c
@@ -55,8 +55,8 @@ DEFINE_DEVPROPKEY(DEVPKEY_Device_FriendlyName, 0xa45c254e, 0xdf1c, 0x4efd, 0x80,
 #define MONO SPEAKER_FRONT_CENTER
 #define STEREO (SPEAKER_FRONT_LEFT|SPEAKER_FRONT_RIGHT)
 #define QUAD (SPEAKER_FRONT_LEFT|SPEAKER_FRONT_RIGHT|SPEAKER_BACK_LEFT|SPEAKER_BACK_RIGHT)
-#define X5DOT1 (SPEAKER_FRONT_LEFT|SPEAKER_FRONT_RIGHT|SPEAKER_FRONT_CENTER|SPEAKER_LOW_FREQUENCY|SPEAKER_BACK_LEFT|SPEAKER_BACK_RIGHT)
-#define X5DOT1SIDE (SPEAKER_FRONT_LEFT|SPEAKER_FRONT_RIGHT|SPEAKER_FRONT_CENTER|SPEAKER_LOW_FREQUENCY|SPEAKER_SIDE_LEFT|SPEAKER_SIDE_RIGHT)
+#define X5DOT1 (SPEAKER_FRONT_LEFT|SPEAKER_FRONT_RIGHT|SPEAKER_FRONT_CENTER|SPEAKER_LOW_FREQUENCY|SPEAKER_SIDE_LEFT|SPEAKER_SIDE_RIGHT)
+#define X5DOT1REAR (SPEAKER_FRONT_LEFT|SPEAKER_FRONT_RIGHT|SPEAKER_FRONT_CENTER|SPEAKER_LOW_FREQUENCY|SPEAKER_BACK_LEFT|SPEAKER_BACK_RIGHT)
 #define X6DOT1 (SPEAKER_FRONT_LEFT|SPEAKER_FRONT_RIGHT|SPEAKER_FRONT_CENTER|SPEAKER_LOW_FREQUENCY|SPEAKER_BACK_CENTER|SPEAKER_SIDE_LEFT|SPEAKER_SIDE_RIGHT)
 #define X7DOT1 (SPEAKER_FRONT_LEFT|SPEAKER_FRONT_RIGHT|SPEAKER_FRONT_CENTER|SPEAKER_LOW_FREQUENCY|SPEAKER_BACK_LEFT|SPEAKER_BACK_RIGHT|SPEAKER_SIDE_LEFT|SPEAKER_SIDE_RIGHT)
 
@@ -800,8 +800,8 @@ static HRESULT ALCmmdevPlayback_resetProxy(ALCmmdevPlayback *self)
             device->FmtChans = DevFmtQuad;
         else if(OutputType.Format.nChannels == 6 && OutputType.dwChannelMask == X5DOT1)
             device->FmtChans = DevFmtX51;
-        else if(OutputType.Format.nChannels == 6 && OutputType.dwChannelMask == X5DOT1SIDE)
-            device->FmtChans = DevFmtX51Side;
+        else if(OutputType.Format.nChannels == 6 && OutputType.dwChannelMask == X5DOT1REAR)
+            device->FmtChans = DevFmtX51Rear;
         else if(OutputType.Format.nChannels == 7 && OutputType.dwChannelMask == X6DOT1)
             device->FmtChans = DevFmtX61;
         else if(OutputType.Format.nChannels == 8 && OutputType.dwChannelMask == X7DOT1)
@@ -828,9 +828,9 @@ static HRESULT ALCmmdevPlayback_resetProxy(ALCmmdevPlayback *self)
             OutputType.Format.nChannels = 6;
             OutputType.dwChannelMask = X5DOT1;
             break;
-        case DevFmtX51Side:
+        case DevFmtX51Rear:
             OutputType.Format.nChannels = 6;
-            OutputType.dwChannelMask = X5DOT1SIDE;
+            OutputType.dwChannelMask = X5DOT1REAR;
             break;
         case DevFmtX61:
             OutputType.Format.nChannels = 7;
@@ -911,8 +911,8 @@ static HRESULT ALCmmdevPlayback_resetProxy(ALCmmdevPlayback *self)
             device->FmtChans = DevFmtQuad;
         else if(OutputType.Format.nChannels == 6 && OutputType.dwChannelMask == X5DOT1)
             device->FmtChans = DevFmtX51;
-        else if(OutputType.Format.nChannels == 6 && OutputType.dwChannelMask == X5DOT1SIDE)
-            device->FmtChans = DevFmtX51Side;
+        else if(OutputType.Format.nChannels == 6 && OutputType.dwChannelMask == X5DOT1REAR)
+            device->FmtChans = DevFmtX51Rear;
         else if(OutputType.Format.nChannels == 7 && OutputType.dwChannelMask == X6DOT1)
             device->FmtChans = DevFmtX61;
         else if(OutputType.Format.nChannels == 8 && OutputType.dwChannelMask == X7DOT1)
diff --git a/Alc/backends/opensl.c b/Alc/backends/opensl.c
index 2547f4b4..6a022753 100644
--- a/Alc/backends/opensl.c
+++ b/Alc/backends/opensl.c
@@ -67,7 +67,10 @@ static SLuint32 GetChannelMask(enum DevFmtChannels chans)
                                 SL_SPEAKER_BACK_LEFT|SL_SPEAKER_BACK_RIGHT;
         case DevFmtX51: return SL_SPEAKER_FRONT_LEFT|SL_SPEAKER_FRONT_RIGHT|
                                SL_SPEAKER_FRONT_CENTER|SL_SPEAKER_LOW_FREQUENCY|
-                               SL_SPEAKER_BACK_LEFT|SL_SPEAKER_BACK_RIGHT;
+                               SL_SPEAKER_SIDE_LEFT|SL_SPEAKER_SIDE_RIGHT;
+        case DevFmtX51Rear: return SL_SPEAKER_FRONT_LEFT|SL_SPEAKER_FRONT_RIGHT|
+                                   SL_SPEAKER_FRONT_CENTER|SL_SPEAKER_LOW_FREQUENCY|
+                                   SL_SPEAKER_BACK_LEFT|SL_SPEAKER_BACK_RIGHT;
         case DevFmtX61: return SL_SPEAKER_FRONT_LEFT|SL_SPEAKER_FRONT_RIGHT|
                                SL_SPEAKER_FRONT_CENTER|SL_SPEAKER_LOW_FREQUENCY|
                                SL_SPEAKER_BACK_CENTER|
@@ -76,9 +79,6 @@ static SLuint32 GetChannelMask(enum DevFmtChannels chans)
                                SL_SPEAKER_FRONT_CENTER|SL_SPEAKER_LOW_FREQUENCY|
                                SL_SPEAKER_BACK_LEFT|SL_SPEAKER_BACK_RIGHT|
                                SL_SPEAKER_SIDE_LEFT|SL_SPEAKER_SIDE_RIGHT;
-        case DevFmtX51Side: return SL_SPEAKER_FRONT_LEFT|SL_SPEAKER_FRONT_RIGHT|
-                                   SL_SPEAKER_FRONT_CENTER|SL_SPEAKER_LOW_FREQUENCY|
-                                   SL_SPEAKER_SIDE_LEFT|SL_SPEAKER_SIDE_RIGHT;
     }
     return 0;
 }
diff --git a/Alc/backends/pulseaudio.c b/Alc/backends/pulseaudio.c
index a8fb64fb..a90e06c1 100644
--- a/Alc/backends/pulseaudio.c
+++ b/Alc/backends/pulseaudio.c
@@ -671,10 +671,10 @@ static void ALCpulsePlayback_sinkInfoCallback(pa_context *UNUSED(context), const
           DevFmtX71 },
         { "front-left,front-right,front-center,lfe,rear-center,side-left,side-right",
           DevFmtX61 },
-        { "front-left,front-right,front-center,lfe,rear-left,rear-right",
-          DevFmtX51 },
         { "front-left,front-right,front-center,lfe,side-left,side-right",
-          DevFmtX51Side },
+          DevFmtX51 },
+        { "front-left,front-right,front-center,lfe,rear-left,rear-right",
+          DevFmtX51Rear },
         { "front-left,front-right,rear-left,rear-right", DevFmtQuad },
         { "front-left,front-right", DevFmtStereo },
         { "mono", DevFmtMono },
@@ -994,11 +994,11 @@ static ALCboolean ALCpulsePlayback_reset(ALCpulsePlayback *self)
             mapname = "front-left,front-right,rear-left,rear-right";
             break;
         case DevFmtX51:
-            mapname = "front-left,front-right,front-center,lfe,rear-left,rear-right";
-            break;
-        case DevFmtX51Side:
             mapname = "front-left,front-right,front-center,lfe,side-left,side-right";
             break;
+        case DevFmtX51Rear:
+            mapname = "front-left,front-right,front-center,lfe,rear-left,rear-right";
+            break;
         case DevFmtX61:
             mapname = "front-left,front-right,front-center,lfe,rear-center,side-left,side-right";
             break;
diff --git a/Alc/backends/wave.c b/Alc/backends/wave.c
index 5bfdf72c..6999f0cb 100644
--- a/Alc/backends/wave.c
+++ b/Alc/backends/wave.c
@@ -260,8 +260,8 @@ static ALCboolean ALCwaveBackend_reset(ALCwaveBackend *self)
         case DevFmtMono:   chanmask = 0x04; break;
         case DevFmtStereo: chanmask = 0x01 | 0x02; break;
         case DevFmtQuad:   chanmask = 0x01 | 0x02 | 0x10 | 0x20; break;
-        case DevFmtX51Side: chanmask = 0x01 | 0x02 | 0x04 | 0x08 | 0x200 | 0x400; break;
-        case DevFmtX51: chanmask = 0x01 | 0x02 | 0x04 | 0x08 | 0x010 | 0x020; break;
+        case DevFmtX51: chanmask = 0x01 | 0x02 | 0x04 | 0x08 | 0x200 | 0x400; break;
+        case DevFmtX51Rear: chanmask = 0x01 | 0x02 | 0x04 | 0x08 | 0x010 | 0x020; break;
         case DevFmtX61: chanmask = 0x01 | 0x02 | 0x04 | 0x08 | 0x100 | 0x200 | 0x400; break;
         case DevFmtX71: chanmask = 0x01 | 0x02 | 0x04 | 0x08 | 0x010 | 0x020 | 0x200 | 0x400; break;
     }
diff --git a/Alc/backends/winmm.c b/Alc/backends/winmm.c
index 1e557883..74d3f858 100644
--- a/Alc/backends/winmm.c
+++ b/Alc/backends/winmm.c
@@ -558,7 +558,7 @@ static ALCenum ALCwinmmCapture_open(ALCwinmmCapture *self, const ALCchar *name)
 
         case DevFmtQuad:
         case DevFmtX51:
-        case DevFmtX51Side:
+        case DevFmtX51Rear:
         case DevFmtX61:
         case DevFmtX71:
             return ALC_INVALID_ENUM;