Implement a crossfeed config option

Alc/ALc.c

@@ -32,6 +32,7 @@
 #include "alThunk.h"
 #include "alSource.h"
 #include "alExtension.h"
+#include "bs2b.h"
 
 ///////////////////////////////////////////////////////
 // DEBUG INFORMATION
@@ -329,6 +330,8 @@ ALCvoid ProcessContext(ALCcontext *pContext)
 */
 static ALvoid InitContext(ALCcontext *pContext)
 {
+    int level;
+
     //Initialise listener
     pContext->Listener.Gain = 1.0f;
     pContext->Listener.Position[0] = 0.0f;
@@ -361,6 +364,14 @@ static ALvoid InitContext(ALCcontext *pContext)
     pContext->lNumMonoSources = pContext->Device->MaxNoOfSources - pContext->lNumStereoSources;
 
     strcpy(pContext->ExtensionList, "AL_EXT_EXPONENT_DISTANCE AL_EXT_FLOAT32 AL_EXT_IMA4 AL_EXT_LINEAR_DISTANCE AL_EXT_MCFORMATS AL_EXT_OFFSET");
+
+    level = GetConfigValueInt(NULL, "cf_level", 0);
+    if(level > 0 && level <= 6)
+    {
+        pContext->bs2b = calloc(1, sizeof(*pContext->bs2b));
+        bs2b_set_srate(pContext->bs2b, pContext->Frequency);
+        bs2b_set_level(pContext->bs2b, level);
+    }
 }
 
 
@@ -394,6 +405,9 @@ static ALCvoid ExitContext(ALCcontext *pContext)
     //Invalidate context
     pContext->LastError = AL_NO_ERROR;
     pContext->InUse = AL_FALSE;
+
+    free(pContext->bs2b);
+    pContext->bs2b = NULL;
 }
 
 ///////////////////////////////////////////////////////

openalrc.sample

@@ -23,6 +23,17 @@ format = AL_FORMAT_STEREO16  # Sets the output format. Can be one of:
                              # AL_FORMAT_71CHN16  (16-bit 7.1 output)
                              # Default is AL_FORMAT_STEREO16
 
+cf_level = 0  # Sets the crossfeed level for stereo output. Valid values are:
+              # 0 - No crossfeed
+              # 1 - Low crossfeed
+              # 2 - Middle crossfeed
+              # 3 - High crossfeed (virtual speakers are closer to itself)
+              # 4 - Low easy crossfeed
+              # 5 - Middle easy crossfeed
+              # 6 - High easy crossfeed
+              # Default is 0. Users of headphones may want to try various
+              # settings. Has no effect on non-stereo modes.
+
 frequency = 44100  # Sets the output frequency. Default is 44100
 
 refresh = 0  # Sets the number of frames-per-update. Default is calculated as