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Use linear fades for loop-range cross-fades

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The cross-over point of an exponential fade occurs further towards
start of the fade. This increases consistency of cross-fades moving
the cross-over point to the center of the fade.

Also looped material is likely correlated in which a linear fade
is more appropriate.
This commit is contained in:
Robin Gareus 2020-09-25 17:08:21 +02:00
parent c08298e6d8
commit 751db481a6
Signed by: rgareus
GPG Key ID: A090BCE02CF57F04
2 changed files with 20 additions and 4 deletions
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2
libs/ardour/ardour/disk_reader.h
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@ -181,7 +181,7 @@ protected:
Declicker ();
~Declicker ();
void alloc (samplecnt_t sr, bool fadein);
void alloc (samplecnt_t sr, bool fadein, bool linear);
void run (Sample* buf, samplepos_t start, samplepos_t end);
void reset (samplepos_t start, samplepos_t end, bool fadein, samplecnt_t sr);

22
libs/ardour/disk_reader.cc
View File

@ -1643,11 +1643,27 @@ DiskReader::Declicker::~Declicker ()
}
void
DiskReader::Declicker::alloc (samplecnt_t sr, bool fadein)
DiskReader::Declicker::alloc (samplecnt_t sr, bool fadein, bool linear)
{
delete[] vec;
vec = new Sample[loop_fade_length];
if (linear) {
if (fadein) {
for (samplecnt_t n = 0; n < loop_fade_length; ++n) {
vec[n] = n / (float) loop_fade_length;
}
} else {
for (samplecnt_t n = 0; n < loop_fade_length; ++n) {
vec[n] = 1.f - n / (float) loop_fade_length;
}
}
fade_length = loop_fade_length - 1;
return;
}
/* Exponential fade */
const float a = 390.f / sr; // ~ 1/100Hz for 40dB
/* build a psuedo-exponential (linear-volume) shape for the fade */
@ -1884,8 +1900,8 @@ void
DiskReader::alloc_loop_declick (samplecnt_t sr)
{
loop_fade_length = lrintf (ceil (-log (GAIN_COEFF_DELTA / 2.) / (390. / sr)));
loop_declick_in.alloc (sr, true);
loop_declick_out.alloc (sr, false);
loop_declick_in.alloc (sr, true, Config->get_loop_fade_choice () == XFadeLoop);
loop_declick_out.alloc (sr, false, Config->get_loop_fade_choice () == XFadeLoop);
}
#undef GAIN_COEFF_DELTA