[PATCH 1/2] dsound: Revised 5.1 to stereo downmix

[Nikola Pavlica]

Signed-off-by: Nikola Pavlica 
---
 dlls/dsound/dsound_convert.c | 24 +++++++++++-------------
 1 file changed, 11 insertions(+), 13 deletions(-)

diff --git a/dlls/dsound/dsound_convert.c b/dlls/dsound/dsound_convert.c
index 26dbb3220a..0da9823298 100644
--- a/dlls/dsound/dsound_convert.c
+++ b/dlls/dsound/dsound_convert.c
@@ -216,39 +216,37 @@ void put_stereo2surround51(const IDirectSoundBufferImpl *dsb, DWORD pos, DWORD c

void put_surround512stereo(const IDirectSoundBufferImpl *dsb, DWORD pos, DWORD channel, float value)
 {
-    /* based on pulseaudio's downmix algorithm */
+    /* based on analyzing a recording of a dsound downmix */
     switch(channel){

-    case 4: /* back left */
-        value *= 0.056f; /* (1/9) / (sum of left volumes) */
+    case 4: /* surround left */
+        value *= 0.24f;
         dsb->put_aux(dsb, pos, 0, value);
         break;

case 0: /* front left */
-        value *= 0.503f; /* 1 / (sum of left volumes) */
+        value *= 1.0f; 
         dsb->put_aux(dsb, pos, 0, value);
         break;

-    case 5: /* back right */
-        value *= 0.056f; /* (1/9) / (sum of right volumes) */
+    case 5: /* surround right */
+        value *= 0.24f;
         dsb->put_aux(dsb, pos, 1, value);
         break;

case 1: /* front right */
-        value *= 0.503f; /* 1 / (sum of right volumes) */
+        value *= 1.0f;
         dsb->put_aux(dsb, pos, 1, value);
         break;

-    case 2: /* front centre */
-        value *= 0.252f; /* 0.5 / (sum of left/right volumes) */
+    case 2: /* centre */
+        value *= 0.7;
         dsb->put_aux(dsb, pos, 0, value);
         dsb->put_aux(dsb, pos, 1, value);
         break;

-    case 3: /* LFE */
-        value *= 0.189f; /* 0.375 / (sum of left/right volumes) */
-        dsb->put_aux(dsb, pos, 0, value);
-        dsb->put_aux(dsb, pos, 1, value);
+    case 3:
+        /* LFE is totally ignored in dsound when downmixing to 2 channels */
         break;
     }
 }