avoid voice_count becomming negative

bug around fluid_voice_off(), fixes issue #151

fluidsynth/src/synth/fluid_synth.c

@@ -800,8 +800,18 @@ delete_fluid_synth(fluid_synth_t* synth)
         continue;
       fluid_voice_unlock_rvoice(voice);
       fluid_voice_overflow_rvoice_finished(voice); 
-      if (fluid_voice_is_playing(voice))
+      if (fluid_voice_is_playing(voice)) {
-	fluid_voice_off(voice);
+        fluid_voice_off(voice);
+        /* If we only use fluid_voice_off(voice) it will trigger a delayed 
+         * fluid_voice_stop(voice) via fluid_synth_check_finished_voices().
+         * But here, we are deleting the fluid_synth_t instance so
+         * fluid_voice_stop() will be never triggered resulting in 
+         * SoundFont data never unloaded (i.e a serious memory leak).
+         * So, fluid_voice_stop() must be explicitly called to insure 
+         * unloading SoundFont data
+         */
+        fluid_voice_stop(voice);
+     }
     }
   }
 
@@ -2812,7 +2822,7 @@ fluid_synth_check_finished_voices(fluid_synth_t* synth)
     for (j=0; j < synth->polyphony; j++) {
       if (synth->voice[j]->rvoice == fv) {
         fluid_voice_unlock_rvoice(synth->voice[j]);
-        fluid_voice_off(synth->voice[j]);
+        fluid_voice_stop(synth->voice[j]);
         break;
       }
       else if (synth->voice[j]->overflow_rvoice == fv) {

fluidsynth/src/synth/fluid_voice.c

@@ -1277,21 +1277,30 @@ void fluid_voice_overflow_rvoice_finished(fluid_voice_t* voice)
   fluid_sample_null_ptr(&voice->overflow_rvoice->dsp.sample);
 }
 
-
 /*
  * fluid_voice_off
+ * 
+ * Force the voice into finished stage. Useful anywhere a voice
+ * needs to be cancelled from MIDI API.
+ */
+void fluid_voice_off(fluid_voice_t* voice)
+{
+  UPDATE_RVOICE0(fluid_rvoice_voiceoff); /* request to finish the voice */
+}
+
+/*
+ * fluid_voice_stop
  *
  * Purpose:
  * Turns off a voice, meaning that it is not processed
  * anymore by the DSP loop.
  */
-int
+void
-fluid_voice_off(fluid_voice_t* voice)
+fluid_voice_stop(fluid_voice_t* voice)
 {
   fluid_profile(FLUID_PROF_VOICE_RELEASE, voice->ref);
 
   voice->chan = NO_CHANNEL;
-  UPDATE_RVOICE0(fluid_rvoice_voiceoff);
   
   if (voice->can_access_rvoice)
     fluid_sample_null_ptr(&voice->rvoice->dsp.sample);
@@ -1304,8 +1313,6 @@ fluid_voice_off(fluid_voice_t* voice)
 
   /* Decrement voice count */
   voice->channel->synth->active_voice_count--;
-
-  return FLUID_OK;
 }
 
 /**

fluidsynth/src/synth/fluid_voice.h

@@ -143,15 +143,10 @@ int fluid_voice_set_output_rate(fluid_voice_t* voice, fluid_real_t value);
     function.*/
 void fluid_voice_update_param(fluid_voice_t* voice, int gen);
 
-/**  fluid_voice_release
- Force the voice into release stage. Usefuf anywhere a voice
- needs to be damped even if pedals (sustain sostenuto) are depressed.
- See fluid_synth_damp_voices_LOCAL(), fluid_synth_damp_voices_by_sostenuto_LOCAL,
- fluid_voice_noteoff(), fluid_synth_stop_LOCAL().
-*/
 void fluid_voice_release(fluid_voice_t* voice);
 int fluid_voice_noteoff(fluid_voice_t* voice);
-int fluid_voice_off(fluid_voice_t* voice);
+void fluid_voice_off(fluid_voice_t* voice);
+void fluid_voice_stop(fluid_voice_t* voice);
 void fluid_voice_overflow_rvoice_finished(fluid_voice_t* voice);
 void fluid_voice_mix (fluid_voice_t *voice, int count, fluid_real_t* dsp_buf,
 		 fluid_real_t* left_buf, fluid_real_t* right_buf,