increase accuracy of fades.

1 files changed, 28 insertions, 23 deletions

diff --git a/libs/ardour/audioregion.cc b/libs/ardour/audioregion.cc
index dca38e17d3..dd198db3b4 100644
--- a/libs/ardour/audioregion.cc
+++ b/libs/ardour/audioregion.cc
@@ -991,6 +991,8 @@ AudioRegion::set_fade_in (FadeShape shape, framecnt_t len)
 	_fade_in->clear ();
 	_inverse_fade_in->clear ();
 
+	const int num_steps = min((framecnt_t)256, max ((framecnt_t) 16, len / 512));
+
 	switch (shape) {
 	case FadeLinear:
 		_fade_in->fast_simple_add (0.0, VERY_SMALL_SIGNAL);
@@ -999,15 +1001,15 @@ AudioRegion::set_fade_in (FadeShape shape, framecnt_t len)
 		break;
 
 	case FadeFast:
-		generate_db_fade (_fade_in.val(), len, 10, -60);
+		generate_db_fade (_fade_in.val(), len, num_steps, -60);
 		reverse_curve (c1, _fade_in.val());
 		_fade_in->copy_events (*c1);
 		generate_inverse_power_curve (_inverse_fade_in.val(), _fade_in.val());
 		break;
 
 	case FadeSlow:
-		generate_db_fade (c1, len, 10, -1);  // start off with a slow fade
-		generate_db_fade (c2, len, 10, -80); // end with a fast fade
+		generate_db_fade (c1, len, num_steps, -1);  // start off with a slow fade
+		generate_db_fade (c2, len, num_steps, -80); // end with a fast fade
 		merge_curves (_fade_in.val(), c1, c2);
 		reverse_curve (c3, _fade_in.val());
 		_fade_in->copy_events (*c3);
@@ -1016,9 +1018,9 @@ AudioRegion::set_fade_in (FadeShape shape, framecnt_t len)
 
 	case FadeConstantPower:
 		_fade_in->fast_simple_add (0.0, VERY_SMALL_SIGNAL);
-		for (int i = 1; i < 9; ++i) {
-			float dist = (float) i/10.f;
-			_fade_in->fast_simple_add (len*dist, sin (dist*M_PI/2.f));
+		for (int i = 1; i < num_steps; ++i) {
+			const float dist = i / (num_steps + 1.f);
+			_fade_in->fast_simple_add (len * dist, sin (dist * M_PI / 2.0));
 		}
 		_fade_in->fast_simple_add (len, 1.0);
 		reverse_curve (_inverse_fade_in.val(), _fade_in.val());
@@ -1027,15 +1029,16 @@ AudioRegion::set_fade_in (FadeShape shape, framecnt_t len)
 	case FadeSymmetric:
 		//start with a nearly linear cuve
 		_fade_in->fast_simple_add (0, 1);
-		_fade_in->fast_simple_add (0.5*len, 0.6);
+		_fade_in->fast_simple_add (0.5 * len, 0.6);
 		//now generate a fade-out curve by successively applying a gain drop
-		const float breakpoint = 0.7;  //linear for first 70%
-		for (int i = 2; i < 9; i++) {
-			float coeff = (1.0-breakpoint);
+		const double breakpoint = 0.7;  //linear for first 70%
+		for (int i = 2; i < num_steps; i++) {
+			const double offset = 1.0 - breakpoint;
+			float coeff = 1.0 - breakpoint;
 			for (int j = 0; j < i; j++) {
 				coeff *= 0.5;  //6dB drop per step
 			}
-			_fade_in->fast_simple_add (len* (breakpoint+((1.0-breakpoint)*(double)i/9.0)), coeff);
+			_fade_in->fast_simple_add (len * (breakpoint + (offset * (double)i / (double)num_steps)), coeff);
 		}
 		_fade_in->fast_simple_add (len, VERY_SMALL_SIGNAL);
 		reverse_curve (c3, _fade_in.val());
@@ -1070,6 +1073,8 @@ AudioRegion::set_fade_out (FadeShape shape, framecnt_t len)
 	_fade_out->clear ();
 	_inverse_fade_out->clear ();
 
+	const int num_steps = min((framecnt_t)256, max ((framecnt_t) 16, len / 512));
+
 	switch (shape) {
 	case FadeLinear:
 		_fade_out->fast_simple_add (0.0, 1.0);
@@ -1078,13 +1083,13 @@ AudioRegion::set_fade_out (FadeShape shape, framecnt_t len)
 		break;
 		
 	case FadeFast: 
-		generate_db_fade (_fade_out.val(), len, 10, -60);
+		generate_db_fade (_fade_out.val(), len, num_steps, -60);
 		generate_inverse_power_curve (_inverse_fade_out.val(), _fade_out.val());
 		break;
 		
 	case FadeSlow: 
-		generate_db_fade (c1, len, 10, -1);  //start off with a slow fade
-		generate_db_fade (c2, len, 10, -80);  //end with a fast fade
+		generate_db_fade (c1, len, num_steps, -1);  //start off with a slow fade
+		generate_db_fade (c2, len, num_steps, -80);  //end with a fast fade
 		merge_curves (_fade_out.val(), c1, c2);
 		generate_inverse_power_curve (_inverse_fade_out.val(), _fade_out.val());
 		break;
@@ -1093,9 +1098,9 @@ AudioRegion::set_fade_out (FadeShape shape, framecnt_t len)
 		//constant-power fades use a sin/cos relationship
 		//the cutoff is abrupt but it has the benefit of being symmetrical
 		_fade_out->fast_simple_add (0.0, 1.0);
-		for (int i = 1; i < 9; i++ ) {
-			float dist = (float)i/10.0;
-			_fade_out->fast_simple_add ((len * dist), cos(dist*M_PI/2));
+		for (int i = 1; i < num_steps; ++i) {
+			const float dist = i / (num_steps + 1.f);
+			_fade_out->fast_simple_add (len * dist, cos (dist * M_PI / 2.0));
 		}
 		_fade_out->fast_simple_add (len, VERY_SMALL_SIGNAL);
 		reverse_curve (_inverse_fade_out.val(), _fade_out.val());
@@ -1104,17 +1109,17 @@ AudioRegion::set_fade_out (FadeShape shape, framecnt_t len)
 	case FadeSymmetric:
 		//start with a nearly linear cuve
 		_fade_out->fast_simple_add (0, 1);
-		_fade_out->fast_simple_add (0.5*len, 0.6);
+		_fade_out->fast_simple_add (0.5 * len, 0.6);
 
 		//now generate a fade-out curve by successively applying a gain drop
-		const float breakpoint = 0.7;  //linear for first 70%
-		const int num_steps = 9;
+		const double breakpoint = 0.7;  //linear for first 70%
 		for (int i = 2; i < num_steps; i++) {
-			float coeff = (1.0-breakpoint);
+			const double offset = 1.0 - breakpoint;
+			float coeff = 1.0 - breakpoint;
 			for (int j = 0; j < i; j++) {
-				coeff *= 0.5;  //6dB drop per step
+				coeff *= 0.5;  // 6dB drop per step
 			}
-			_fade_out->fast_simple_add (len* (breakpoint+((1.0-breakpoint)*(double)i/(double)num_steps)), coeff);
+			_fade_out->fast_simple_add (len * (breakpoint + (offset * (double)i / (double)num_steps)), coeff);
 		}
 		_fade_out->fast_simple_add (len, VERY_SMALL_SIGNAL);
 		reverse_curve (_inverse_fade_out.val(), _fade_out.val());