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fixed number of steps for symmetric fades:

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Extra steps are all below -20dB vs inverse signal being over -2dB.
linear interpolation -6dB steps is sufficient for the tail.
This commit is contained in:
Robin Gareus 2014-05-29 21:03:46 +02:00
parent be575b7945
commit 1cfdad6ffb
1 changed files with 6 additions and 11 deletions
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17
libs/ardour/audioregion.cc
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@ -1032,11 +1032,9 @@ AudioRegion::set_fade_in (FadeShape shape, framecnt_t len)
_fade_in->fast_simple_add (0.5 * len, 0.6);
//now generate a fade-out curve by successively applying a gain drop
const double breakpoint = 0.7; //linear for first 70%
for (int i = max(2, (int)ceil(num_steps / 9.0)); i < num_steps; i++) {
const double offset = 1.0 - breakpoint;
float coeff = 1.0 - breakpoint;
coeff *= powf(0.5, i * 9.0 / (double)num_steps); // -6dB per step for 7 steps
_fade_in->fast_simple_add (len * (breakpoint + (offset * (double)i / (double)num_steps)), coeff);
for (int i = 2; i < 9; ++i) {
const float coeff = (1.f - breakpoint) * powf (0.5, i);
_fade_in->fast_simple_add (len * (breakpoint + ((1.0 - breakpoint) * (double)i / 9.0)), coeff);
}
_fade_in->fast_simple_add (len, VERY_SMALL_SIGNAL);
reverse_curve (c3, _fade_in.val());
@ -1108,14 +1106,11 @@ AudioRegion::set_fade_out (FadeShape shape, framecnt_t len)
//start with a nearly linear cuve
_fade_out->fast_simple_add (0, 1);
_fade_out->fast_simple_add (0.5 * len, 0.6);
//now generate a fade-out curve by successively applying a gain drop
const double breakpoint = 0.7; //linear for first 70%
for (int i = max(2, (int)ceil(num_steps / 9.0)); i < num_steps; i++) {
const double offset = 1.0 - breakpoint;
float coeff = 1.0 - breakpoint;
coeff *= powf(0.5, i * 9.0 / (double)num_steps); // -6dB per step for 7 steps
_fade_out->fast_simple_add (len * (breakpoint + (offset * (double)i / (double)num_steps)), coeff);
for (int i = 2; i < 9; ++i) {
const float coeff = (1.f - breakpoint) * powf (0.5, i);
_fade_out->fast_simple_add (len * (breakpoint + ((1.0 - breakpoint) * (double)i / 9.0)), coeff);
}
_fade_out->fast_simple_add (len, VERY_SMALL_SIGNAL);
reverse_curve (_inverse_fade_out.val(), _fade_out.val());