From ee35eecb548db2c9f2ddfdf30d7f6782d5898412 Mon Sep 17 00:00:00 2001
From: curt <curt>
Date: Sun, 25 Aug 2002 23:27:00 +0000
Subject: [PATCH] Erik Hofman:

I removed some pending random code and I also fixed a
small cosmetic glitch where dt_play was cleared before it was printed.

Curt: Erik changed the sound update intervale and I further I tweaked it.
The issue is that if we put too much into the sound buffer, then we can't react
quick enough to sounds like tire squeek that need to be synced with the visuals
and the action.  We put too little into the sound buffer and we risk the
audio dropping out for moment if a frame takes longer to draw than the amount
of audio in the buffer.
---
 src/Main/main.cxx      | 18 ++++++++++++++++--
 src/Sound/fg_sound.cxx | 12 +++++-------
 src/Sound/fg_sound.hxx |  1 -
 3 files changed, 21 insertions(+), 10 deletions(-)

diff --git a/src/Main/main.cxx b/src/Main/main.cxx
index 52a488382..2e1df4a68 100644
--- a/src/Main/main.cxx
+++ b/src/Main/main.cxx
@@ -861,6 +861,11 @@ static const double alt_adjust_m = alt_adjust_ft * SG_FEET_TO_METER;
 static void fgMainLoop( void ) {
 
     // Update the elapsed time.
+    static bool first_time = true;
+    if ( first_time ) {
+        last_time_stamp.stamp();
+        first_time = false;
+    }
     current_time_stamp.stamp();
     delta_time_sec = double(current_time_stamp - last_time_stamp) / 1000000.0;
     last_time_stamp = current_time_stamp;
@@ -1082,8 +1087,17 @@ static void fgMainLoop( void ) {
 #ifdef ENABLE_AUDIO_SUPPORT
     if ( fgGetBool("/sim/sound/audible")
            && globals->get_soundmgr()->is_working() ) {
-	globals->get_fx()->update(1); // FIXME: use dt
-	globals->get_soundmgr()->update(1); // FIXME: use dt
+        static double dt = 0.0;
+        static double sound_update_rate = 0.05;
+
+        dt += delta_time_sec;
+
+	// Updating four times a second should be enough
+        if ( dt >= sound_update_rate ) {
+	    globals->get_fx()->update( dt );
+	    globals->get_soundmgr()->update( dt );
+            dt = 0.0;
+        }
     }
 #endif
 
diff --git a/src/Sound/fg_sound.cxx b/src/Sound/fg_sound.cxx
index ccd8075e0..28ebafb70 100644
--- a/src/Sound/fg_sound.cxx
+++ b/src/Sound/fg_sound.cxx
@@ -136,8 +136,6 @@ FGSound::init(SGPropertyNode *node)
          volume.intern = &_dt_play;
       else if (!strcmp(intern_str, "dt_stop"))
          volume.intern = &_dt_stop;
-      else if (!strcmp(intern_str, "random"))
-         volume.intern = &_random;
 
       if ((volume.factor = kids[i]->getDoubleValue("factor", 1.0)) != 0.0)
          if (volume.factor < 0.0) {
@@ -271,16 +269,16 @@ FGSound::update (double dt)
       )
    {
 
-      _active = false;
-      _dt_stop += dt;
-      _dt_play = 0.0;
-
       if (_sample->is_playing()) {
          SG_LOG(SG_GENERAL, SG_INFO, "Stopping audio after " << _dt_play
                                       << " sec: " << _name );
          _sample->stop( _mgr->get_scheduler() );
       }
 
+      _active = false;
+      _dt_stop += dt;
+      _dt_play = 0.0;
+
       return;
 
    }
@@ -302,7 +300,7 @@ FGSound::update (double dt)
    }
 
    //
-   // Update playtime, cache the current value and feed the random number
+   // Update playing time and cache the current value.
    //
     _dt_play += dt;
    _prev_value = curr_value;
diff --git a/src/Sound/fg_sound.hxx b/src/Sound/fg_sound.hxx
index fb871d2cb..f6c21b80b 100644
--- a/src/Sound/fg_sound.hxx
+++ b/src/Sound/fg_sound.hxx
@@ -81,7 +81,6 @@ private:
   string _name;
   int _mode;
   double _prev_value;
-  double _random;
   double _dt_play;
   double _dt_stop;
 
-- 
2.39.5