Add fade in/out option to the content audio tab (#1026).

1 files changed, 15 insertions, 0 deletions

diff --git a/src/lib/maths_util.h b/src/lib/maths_util.h
index 8adefbbc4..24c4b547f 100644
--- a/src/lib/maths_util.h
+++ b/src/lib/maths_util.h
@@ -30,6 +30,21 @@
 extern double db_to_linear (double db);
 extern double linear_to_db (double linear);
 
+/** @return linear gain according to a logarithmic curve, for fading in.
+ *  t < 0:       linear gain of 0
+ *  0 >= t >= 1: logarithmic fade in curve
+ *  t > 1:       linear gain of 1
+ */
+extern float logarithmic_fade_in_curve (float t);
+
+
+/** @return linear gain according to a logarithmic curve, for fading out.
+ *  t > 1:       linear gain of 0
+ *  0 >= t >= 1: logarithmic fade out curve
+ *  t < 0:       linear gain of 1
+ */
+extern float logarithmic_fade_out_curve (float t);
+
 
 template <class T>
 T clamp (T val, T minimum, T maximum)