From b659fd82a5037b2b0e49d7c2a59e86252fe16c39 Mon Sep 17 00:00:00 2001
From: jjceresa <jjc_fluid@orange.fr>
Date: Wed, 19 Dec 2018 18:12:09 +0100
Subject: [PATCH] Import modulator source src2 correctly. - When secondary
 source input (src2) is set to General   Controller 'No Controller', output
 will be forced to +1.0 at synthesis time   (see fluid_mod_get_value()).  
 That means that this source will behave unipolar only. We need to force the  
 unipolar flags to ensure the modulator will behave correctly later in  
 fluid_voice_get_lower_boundary_for_attenuation().

---
 src/sfloader/fluid_defsfont.c | 10 ++++++++++
 src/synth/fluid_mod.c         | 23 ++++++++++++++++++++++-
 2 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/src/sfloader/fluid_defsfont.c b/src/sfloader/fluid_defsfont.c
index 1931d4ee..9a8f3245 100644
--- a/src/sfloader/fluid_defsfont.c
+++ b/src/sfloader/fluid_defsfont.c
@@ -1364,6 +1364,16 @@ fluid_zone_mod_import_sfont(fluid_mod_t **mod, SFZone *sfzone)
              * Deactivate the modulator by setting the amount to 0. */
             mod_dest->amount = 0;
         }  
+        /* Note: When secondary source input (src2) is set to General Controller 'No Controller',
+           output will be forced to +1.0 at synthesis time (see fluid_mod_get_value()).
+           That means that this source will behave unipolar only. We need to force the
+           unipolar flags to ensure the modulator will behave correctly later.
+        */
+        if(((mod_dest->flags2 & FLUID_MOD_CC) == FLUID_MOD_GC) && 
+            (mod_dest->src2 == FLUID_MOD_NONE))
+        {
+            mod_dest->flags2 &= ~FLUID_MOD_BIPOLAR;
+        }
 
         /* *** Transform *** */
         /* SF2.01 only uses the 'linear' transform (0).
diff --git a/src/synth/fluid_mod.c b/src/synth/fluid_mod.c
index 9a48ed45..db59642b 100644
--- a/src/synth/fluid_mod.c
+++ b/src/synth/fluid_mod.c
@@ -364,7 +364,22 @@ fluid_mod_transform_source_value(fluid_real_t val, unsigned char mod_flags, cons
 }
 
 /*
- * fluid_mod_get_value
+ * fluid_mod_get_value.
+ * Computes and return modulator output following SF2.01
+ * (See SoundFont Modulator Controller Model Chapter 9.5).
+ *
+ * Output = Transform(Amount * Map(primary source input) * Map(secondary source input))
+ *
+ * Notes:
+ * 1)fluid_mod_get_value, ignores the Transform operator. The result is:
+ *
+ *   Output = Amount * Map(primary source input) * Map(secondary source input)
+ *
+ * 2)When primary source input (src1) is set to General Controller 'No Controller',
+ *   output is forced to 0.
+ *
+ * 3)When secondary source input (src2) is set to General Controller 'No Controller',
+ *   output is forced to +1.0 
  */
 fluid_real_t
 fluid_mod_get_value(fluid_mod_t *mod, fluid_voice_t *voice)
@@ -418,6 +433,9 @@ fluid_mod_get_value(fluid_mod_t *mod, fluid_voice_t *voice)
         /* transform the input value */
         v1 = fluid_mod_transform_source_value(v1, mod->flags1, range1);
     }
+    /* When primary source input (src1) is set to General Controller 'No Controller',
+       output is forced to 0.0
+    */
     else
     {
         return 0.0;
@@ -437,6 +455,9 @@ fluid_mod_get_value(fluid_mod_t *mod, fluid_voice_t *voice)
         /* transform the second input value */
         v2 = fluid_mod_transform_source_value(v2, mod->flags2, range2);
     }
+    /* When secondary source input (src2) is set to General Controller 'No Controller',
+       output is forced to +1.0
+    */
     else
     {
         v2 = 1.0f;