Use floats internally in limiter for performance reasons.

Signed-off-by: Stefan Westerfeld <stefan@space.twc.de>

src/limiter.cc

@@ -14,21 +14,21 @@ Limiter::Limiter (int n_channels, int sample_rate) :
 }
 
 void
-Limiter::set_attack (double attack_ms)
+Limiter::set_attack (float attack_ms)
 {
   look_ahead = sample_rate / 1000.0 * attack_ms;
   look_ahead = max (look_ahead, 1u);
 }
 
 void
-Limiter::set_release (double release_ms)
+Limiter::set_release (float release_ms)
 {
   release_factor = exp (log (0.5) / (sample_rate / 1000.0 * release_ms));
-  release_factor = max (release_factor, 0.5);
+  release_factor = max (release_factor, 0.5f);
 }
 
 void
-Limiter::set_ceiling (double new_ceiling)
+Limiter::set_ceiling (float new_ceiling)
 {
   ceiling = new_ceiling;
   maximum = ceiling;
@@ -58,8 +58,8 @@ Limiter::process (const vector<float>& samples)
             {
               if (int (i) - int (j) >= 0)
                 {
-                  double alpha = double (j) / look_ahead;
-                  max_buffer[i - j] = max<float> (max_buffer[i - j], channel_max * (1 - alpha) + ceiling * alpha);
+                  float alpha = float (j) / look_ahead;
+                  max_buffer[i - j] = max (max_buffer[i - j], channel_max * (1 - alpha) + ceiling * alpha);
                 }
             }
         }

src/limiter.hh

@@ -6,9 +6,9 @@
 
 class Limiter
 {
-  double ceiling        = 1;
-  double maximum        = 1;
-  double release_factor = 0;
+  float ceiling         = 1;
+  float maximum         = 1;
+  float release_factor  = 0;
   uint look_ahead       = 0;
   uint n_channels       = 0;
   uint sample_rate      = 0;
@@ -18,9 +18,9 @@ class Limiter
 public:
   Limiter (int n_channels, int sample_rate);
 
-  void set_release (double value_ms);
-  void set_attack (double value_ms);
-  void set_ceiling (double ceiling);
+  void set_release (float value_ms);
+  void set_attack (float value_ms);
+  void set_ceiling (float ceiling);
 
   std::vector<float> process (const std::vector<float>& samples);
 };