Changeset 86801 in webkit

Timestamp:

May 18, 2011 4:14:25 PM (13 years ago)

Author:

crogers@google.com

Message:

2011-05-18 Chris Rogers <​crogers@google.com>

Reviewed by James Robinson.

EqualPowerPanner is not using the correct azimuth range for stereo panning
​https://bugs.webkit.org/show_bug.cgi?id=61085

No new tests since audio API is not yet implemented.

• platform/audio/EqualPowerPanner.cpp: (WebCore::EqualPowerPanner::pan):

Location:

trunk/Source/WebCore

Files:

• ChangeLog (modified) (1 diff)
• platform/audio/EqualPowerPanner.cpp (modified) (2 diffs)

trunk/Source/WebCore/ChangeLog

@@ +1 @@
+2011-05-18  Chris Rogers  <crogers@google.com>
+
+        Reviewed by James Robinson.
+
+        EqualPowerPanner is not using the correct azimuth range for stereo panning
+        https://bugs.webkit.org/show_bug.cgi?id=61085
+
+        No new tests since audio API is not yet implemented.
+
+        * platform/audio/EqualPowerPanner.cpp:
+        (WebCore::EqualPowerPanner::pan):
+
 2011-05-18  Yi Shen  <yi.4.shen@nokia.com>
 

trunk/Source/WebCore/platform/audio/EqualPowerPanner.cpp

@@ -31 +31 @@
 #include "AudioBus.h"
 #include "AudioUtilities.h"
+#include <algorithm>
 #include <wtf/MathExtras.h>
 
 // Use a 50ms smoothing / de-zippering time-constant.
 const double SmoothingTimeConstant = 0.050;
- 
+
+using namespace std;
+
 namespace WebCore {
 
@@ -68 +71 @@
         return;
 
-    // Pan smoothly from left to right with azimuth going from -30 -> +30 degrees.
-    double desiredPanPosition;
-    if (azimuth > 30.0)
-        desiredPanPosition = 1.0;
-    else if (azimuth < -30.0)
-        desiredPanPosition = 0.0;
-    else
-        desiredPanPosition = (azimuth + 30.0) / 60.0;
+    // Clamp azimuth to allowed range of -180 -> +180.
+    azimuth = max(-180.0, azimuth);
+    azimuth = min(180.0, azimuth);
+    
+    // Alias the azimuth ranges behind us to in front of us:
+    // -90 -> -180 to -90 -> 0 and 90 -> 180 to 90 -> 0
+    if (azimuth < -90)
+        azimuth = -180 - azimuth;
+    else if (azimuth > 90)
+        azimuth = 180 - azimuth;
+    
+    // Pan smoothly from left to right with azimuth going from -90 -> +90 degrees.
+    double desiredPanPosition = (azimuth + 90) / 180;
 
     double desiredGainL = 0.5 * cos(piDouble * desiredPanPosition) + 0.5;