Index: libaf/af_pan.c
===================================================================
--- libaf/af_pan.c	（版本 23556）
+++ libaf/af_pan.c	（工作副本）
@@ -111,7 +111,31 @@
   case AF_CONTROL_PAN_NOUT | AF_CONTROL_GET:
     *(int*)arg = af->data->nch;
     return AF_OK;
+  case AF_CONTROL_PAN_BALANCE | AF_CONTROL_SET:{
+    float val = *(float*)arg;
+    if (s->nch)
+      return AF_ERROR;
+    if (af->data->nch >= 2) {
+      s->level[0][0] = min(1.f, 1.f - val);
+      s->level[0][1] = max(0.f, val);
+      s->level[1][0] = max(0.f, -val);
+      s->level[1][1] = min(1.f, 1.f + val);
+    }
+    return AF_OK;
   }
+  case AF_CONTROL_PAN_BALANCE | AF_CONTROL_GET:
+    if (s->nch)
+      return AF_ERROR;
+    if (af->data->nch < 2)
+      *(float*)arg = 0.f;
+    else if (s->level[0][1])
+      *(float*)arg = s->level[0][1];
+    else if (s->level[1][0])
+      *(float*)arg = -s->level[1][0];
+    else
+      *(float*)arg = 0.f;
+    return AF_OK;
+  }
   return AF_UNKNOWN;
 }
 
Index: libaf/control.h
===================================================================
--- libaf/control.h	（版本 23556）
+++ libaf/control.h	（工作副本）
@@ -193,6 +193,8 @@
 // Number of outputs from pan, arg is int*
 #define AF_CONTROL_PAN_NOUT	 	0x00001B00 | AF_CONTROL_FILTER_SPECIFIC
  
+// Number of outputs from pan, arg is float*
+#define AF_CONTROL_PAN_BALANCE	 	0x00002500 | AF_CONTROL_FILTER_SPECIFIC
 
 // Set equalizer gain, arg is a control_ext with a float* 
 #define AF_CONTROL_EQUALIZER_GAIN 	0x00001C00 | AF_CONTROL_FILTER_SPECIFIC