Merge pull request #317 from FluidSynth/balance

Add support for balance control (CC 8)

include/fluidsynth/gen.h

@@ -100,6 +100,7 @@ enum fluid_gen_type {
    * modulator. */
   GEN_PITCH,			/**< Pitch @note Not a real SoundFont generator */
 
+  GEN_CUSTOM_BALANCE,          /**< Balance @note Not a real SoundFont generator */
   /* non-standard generator for an additional custom high- or low-pass filter */
   GEN_CUSTOM_FILTERFC,		/**< Custom filter cutoff frequency */
   GEN_CUSTOM_FILTERQ,		/**< Custom filter Q */

src/synth/fluid_chan.c

@@ -118,7 +118,9 @@ fluid_channel_init_ctrl(fluid_channel_t* chan, int is_all_ctrl_off)
         continue;
       }
       if (i == BANK_SELECT_MSB || i == BANK_SELECT_LSB || i == VOLUME_MSB || 
-          i == VOLUME_LSB || i == PAN_MSB || i == PAN_LSB) {
+          i == VOLUME_LSB || i == PAN_MSB || i == PAN_LSB ||
+          i == BALANCE_MSB || i == BALANCE_LSB
+          ) {
         continue;
       }
 
@@ -165,6 +167,10 @@ fluid_channel_init_ctrl(fluid_channel_t* chan, int is_all_ctrl_off)
     fluid_channel_set_cc (chan, PAN_MSB, 64);
     fluid_channel_set_cc (chan, PAN_LSB, 0);
 
+    /* Balance (MSB & LSB) */
+    fluid_channel_set_cc (chan, BALANCE_MSB, 64);
+    fluid_channel_set_cc (chan, BALANCE_LSB, 0);
+
     /* Reverb */
     /* fluid_channel_set_cc (chan, EFFECTS_DEPTH1, 40); */
     /* Note: although XG standard specifies the default amount of reverb to 

src/synth/fluid_gen.c

@@ -86,6 +86,7 @@ static const fluid_gen_info_t fluid_gen_info[] = {
         { GEN_EXCLUSIVECLASS,         0,     0,       0.0f,      0.0f,       0.0f },
         { GEN_OVERRIDEROOTKEY,        1,     0,       0.0f,    127.0f,      -1.0f },
         { GEN_PITCH,                  1,     0,       0.0f,    127.0f,       0.0f },
+        { GEN_CUSTOM_BALANCE,         1,     0,    -960.0f,    960.0f,       0.0f },
         { GEN_CUSTOM_FILTERFC,        1,     2,       0.0f,  22050.0f,       0.0f },
         { GEN_CUSTOM_FILTERQ,         1,     1,       0.0f,    960.0f,       0.0f }
 };

src/synth/fluid_mod.c

@@ -172,7 +172,26 @@ fluid_mod_get_source_value(const unsigned char mod_src,
     
     if (mod_flags & FLUID_MOD_CC)
     {
-        val = fluid_channel_get_cc(chan, mod_src);
+        /* From MIDI Recommended Practice (RP-036) Default Pan Formula:
+         * "Since MIDI controller values range from 0 to 127, the exact center
+         * of the range, 63.5, cannot be represented. Therefore, the effective
+         * range for CC#10 is modified to be 1 to 127, and values 0 and 1 both
+         * pan hard left. The recommended method is to subtract 1 from the 
+         * value of CC#10, and saturate the result to be non-negative."
+         *
+         * We treat the balance control in exactly the same way, as the same
+         * problem applies here as well.
+         */
+        if (mod_src == PAN_MSB || mod_src == BALANCE_MSB) {
+            *range = 126;
+            val = fluid_channel_get_cc(chan, mod_src) - 1;
+            if (val < 0) {
+                val = 0;
+            }
+        }
+        else {
+            val = fluid_channel_get_cc(chan, mod_src);
+        }
     }
     else
     {
@@ -523,6 +542,7 @@ void fluid_dump_modulator(fluid_mod_t * mod){
       case GEN_CHORUSSEND: printf("Chorus send"); break;
       case GEN_REVERBSEND: printf("Reverb send"); break;
       case GEN_PAN: printf("pan"); break;
+      case GEN_CUSTOM_BALANCE: printf("balance"); break;
       case GEN_ATTENUATION: printf("att"); break;
       default: printf("dest %i",dest);
   }; /* switch dest */

src/synth/fluid_synth.c

@@ -138,6 +138,7 @@ static fluid_mod_t default_expr_mod;           /* SF2.01 section 8.4.7  */
 static fluid_mod_t default_reverb_mod;         /* SF2.01 section 8.4.8  */
 static fluid_mod_t default_chorus_mod;         /* SF2.01 section 8.4.9  */
 static fluid_mod_t default_pitch_bend_mod;     /* SF2.01 section 8.4.10 */
+static fluid_mod_t custom_balance_mod;         /* Non-standard modulator */
 
 
 /* reverb presets */
@@ -405,6 +406,19 @@ fluid_synth_init(void)
 		       );
   fluid_mod_set_dest(&default_pitch_bend_mod, GEN_PITCH);                 /* Destination: Initial pitch */
   fluid_mod_set_amount(&default_pitch_bend_mod, 12700.0);                 /* Amount: 12700 cents */
+
+
+  /* Non-standard MIDI continuous controller 8 to channel stereo balance */
+  fluid_mod_set_source1(&custom_balance_mod, BALANCE_MSB, /* Index=8 */
+		       FLUID_MOD_CC                              /* CC=1 */
+		       | FLUID_MOD_CONCAVE                       /* type=1 */
+		       | FLUID_MOD_BIPOLAR                       /* P=1 */
+		       | FLUID_MOD_POSITIVE                      /* D=0 */
+		       );
+  fluid_mod_set_source2(&custom_balance_mod, 0, 0);
+  fluid_mod_set_dest(&custom_balance_mod, GEN_CUSTOM_BALANCE);                  /* Destination: stereo balance */
+  /* Amount: 96 dB of attenuation (on the opposite channel) */
+  fluid_mod_set_amount(&custom_balance_mod, 960.0);
 }
 
 static FLUID_INLINE unsigned int fluid_synth_get_ticks(fluid_synth_t* synth)
@@ -672,7 +686,7 @@ new_fluid_synth(fluid_settings_t *settings)
   fluid_synth_add_default_mod(synth, &default_reverb_mod, FLUID_SYNTH_ADD);
   fluid_synth_add_default_mod(synth, &default_chorus_mod, FLUID_SYNTH_ADD);
   fluid_synth_add_default_mod(synth, &default_pitch_bend_mod, FLUID_SYNTH_ADD);
-
+  fluid_synth_add_default_mod(synth, &custom_balance_mod, FLUID_SYNTH_ADD);
 
   /* Create and initialize the Fx unit.*/
   fluid_settings_getint(settings, "synth.ladspa.active", &with_ladspa);

src/synth/fluid_voice.c

@@ -545,8 +545,9 @@ fluid_voice_calculate_runtime_synthesis_parameters(fluid_voice_t* voice)
     /* GEN_FINETUNE             [1]                        #52  */
     GEN_OVERRIDEROOTKEY,                 /*                #58  */
     GEN_PITCH,                           /*                ---  */
+    GEN_CUSTOM_BALANCE,                  /*                ---  */
     GEN_CUSTOM_FILTERFC,                 /*                ---  */
-    GEN_CUSTOM_FILTERQ,                  /*                ---  */
+    GEN_CUSTOM_FILTERQ                   /*                ---  */
   };
 
   /* When the voice is made ready for the synthesis process, a lot of
@@ -696,14 +697,20 @@ fluid_voice_update_param(fluid_voice_t* voice, int gen)
   switch (gen) {
 
   case GEN_PAN:
-    /* range checking is done in the fluid_pan function */
+  case GEN_CUSTOM_BALANCE:
-    voice->pan = x;
+    /* range checking is done in the fluid_pan and fluid_balance functions */
-    
+    voice->pan = fluid_voice_gen_value(voice, GEN_PAN);
+    voice->balance = fluid_voice_gen_value(voice, GEN_CUSTOM_BALANCE);
+
     /* left amp */
-    UPDATE_RVOICE_BUFFERS2(fluid_rvoice_buffers_set_amp, 0, fluid_voice_calculate_gain_amplitude(voice, fluid_pan(x, 1)));
+    UPDATE_RVOICE_BUFFERS2(fluid_rvoice_buffers_set_amp, 0,
+            fluid_voice_calculate_gain_amplitude(voice,
+                fluid_pan(voice->pan, 1) * fluid_balance(voice->balance, 1)));
     
     /* right amp */
-    UPDATE_RVOICE_BUFFERS2(fluid_rvoice_buffers_set_amp, 1, fluid_voice_calculate_gain_amplitude(voice, fluid_pan(x, 0)));
+    UPDATE_RVOICE_BUFFERS2(fluid_rvoice_buffers_set_amp, 1,
+        fluid_voice_calculate_gain_amplitude(voice,
+                fluid_pan(voice->pan, 0) * fluid_balance(voice->balance, 0)));
     break;
 
   case GEN_ATTENUATION:
@@ -1594,8 +1601,10 @@ int fluid_voice_set_gain(fluid_voice_t* voice, fluid_real_t gain)
   }
 
   voice->synth_gain = gain;
-  left = fluid_voice_calculate_gain_amplitude(voice, fluid_pan(voice->pan, 1));
+  left = fluid_voice_calculate_gain_amplitude(voice,
-  right = fluid_voice_calculate_gain_amplitude(voice, fluid_pan(voice->pan, 0));
+          fluid_pan(voice->pan, 1) * fluid_balance(voice->balance, 1));
+  right = fluid_voice_calculate_gain_amplitude(voice,
+          fluid_pan(voice->pan, 0) * fluid_balance(voice->balance, 0));
   reverb = fluid_voice_calculate_gain_amplitude(voice, voice->reverb_send);
   chorus = fluid_voice_calculate_gain_amplitude(voice, voice->chorus_send);
 

src/synth/fluid_voice.h

@@ -92,6 +92,9 @@ struct _fluid_voice_t
 	/* pan */
 	fluid_real_t pan;
 
+    /* balance */
+    fluid_real_t balance;
+
 	/* reverb */
 	fluid_real_t reverb_send;
 

src/utils/fluid_conv.c

@@ -252,15 +252,45 @@ fluid_pan(fluid_real_t c, int left)
   if (left) {
     c = -c;
   }
-  if (c < -500) {
+  if (c <= -500) {
     return (fluid_real_t) 0.0;
-  } else if (c > 500) {
+  } else if (c >= 500) {
     return (fluid_real_t) 1.0;
   } else {
     return fluid_pan_tab[(int) (c + 500)];
   }
 }
 
+/*
+ * Return the amount of attenuation based on the balance for the specified
+ * channel. If balance is negative (turned toward left channel, only the right
+ * channel is attenuated. If balance is positive, only the left channel is
+ * attenuated.
+ *
+ * @params balance left/right balance, range [-960;960] in absolute centibels
+ * @return amount of attenuation [0.0;1.0]
+ */
+fluid_real_t fluid_balance(fluid_real_t balance, int left)
+{
+    /* This is the most common case */
+    if (balance == 0)
+    {
+        return 1.0f;
+    }
+
+    if ((left && balance < 0) || (!left && balance > 0))
+    {
+        return 1.0f;
+    }
+
+    if (balance < 0)
+    {
+        balance = -balance;
+    }
+
+    return fluid_cb2amp(balance);
+}
+
 /*
  * fluid_concave
  */

src/utils/fluid_conv.h

@@ -40,6 +40,7 @@ fluid_real_t fluid_tc2sec_release(fluid_real_t tc);
 fluid_real_t fluid_act2hz(fluid_real_t c);
 fluid_real_t fluid_hz2ct(fluid_real_t c);
 fluid_real_t fluid_pan(fluid_real_t c, int left);
+fluid_real_t fluid_balance(fluid_real_t balance, int left);
 fluid_real_t fluid_concave(fluid_real_t val);
 fluid_real_t fluid_convex(fluid_real_t val);