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wavetable morph interpolation discontinuity #7778

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merged 2 commits into from
Sep 5, 2024
Merged

wavetable morph interpolation discontinuity #7778

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59311a9
morph interpolation
blancoberg Aug 29, 2024
7924276
update acording to comments
blancoberg Aug 29, 2024
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51 changes: 19 additions & 32 deletions src/common/dsp/oscillators/WavetableOscillator.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -62,10 +62,12 @@ void WavetableOscillator::init(float pitch, bool is_display, bool nonzero_init_d

n_unison = limit_range(oscdata->p[wt_unison_voices].val.i, 1, MAX_UNISON);

isOneShot = 0;
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Since this is a bool you can use the constant true and false for better readability here

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isOneShot is actually not used anymore. I added it because it was used as a check in convolute(), but I realised later that it wasn't needed. I forgot to remove it.
Should I remove it or just change it to a bool?

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If it is completely unused it can be removed.

if (oscdata->wt.flags & wtf_is_sample)
{
sampleloop = n_unison;
n_unison = 1;
isOneShot = 1;
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And here

}

if (is_display)
Expand All @@ -89,7 +91,8 @@ void WavetableOscillator::init(float pitch, bool is_display, bool nonzero_init_d

float intpart;
shape *= ((float)oscdata->wt.n_tables - 1.f + nointerp) * 0.99999f;
tableipol = modff(shape, &intpart);
tableipol = shape;
modff(shape, &intpart);
tableid = limit_range((int)intpart, 0, std::max((int)oscdata->wt.n_tables - 2 + nointerp, 0));
last_tableipol = tableipol;
last_tableid = tableid;
Expand Down Expand Up @@ -194,7 +197,7 @@ void WavetableOscillator::convolute(int voice, bool FM, bool stereo)
if (oscdata->wt.flags & wtf_is_sample)
{
tableid++;
if (tableid > oscdata->wt.n_tables - 3 + nointerp)
if (tableid > oscdata->wt.n_tables - 4)
{
if (sampleloop < 7)
sampleloop--;
Expand All @@ -205,11 +208,14 @@ void WavetableOscillator::convolute(int voice, bool FM, bool stereo)
}
else
{
tableid = oscdata->wt.n_tables - 2 + nointerp;
tableid = oscdata->wt.n_tables - 1;
oscstate[voice] = 100000000000.f; // rather large number
return;
}
}

tableipol = tableid;
last_tableipol = tableid;
}

int ts = oscdata->wt.size;
Expand Down Expand Up @@ -297,15 +303,16 @@ void WavetableOscillator::convolute(int voice, bool FM, bool stereo)
float newlevel;

// in Continuous Morph mode tblip_ipol gives us position between current and next frame
// when not in Continuous Morph mode, we don't interpolate so this position should be zero
float lipol = (1 - nointerp) * tblip_ipol;
int tempTableId = floor(tblip_ipol);
float interpolationProc = (tblip_ipol - tempTableId) * (1 - nointerp);

// that 1 - nointerp makes sure we don't read the table off memory, keeps us bounded
// and since it gets multiplied by lipol, in morph mode ends up being zero - no sweat!
newlevel = distort_level(
(oscdata->wt.TableF32WeakPointers[mipmap[voice]][tableid][state[voice]] * (1.f - lipol)) +
(oscdata->wt.TableF32WeakPointers[mipmap[voice]][tableid + 1 - nointerp][state[voice]] *
lipol));
(oscdata->wt.TableF32WeakPointers[mipmap[voice]][tempTableId][state[voice]] *
(1.f - interpolationProc)) +
(oscdata->wt.TableF32WeakPointers[mipmap[voice]][tempTableId + 1 - nointerp][state[voice]] *
interpolationProc));

g = newlevel - last_level[voice];
last_level[voice] = newlevel;
Expand Down Expand Up @@ -427,8 +434,8 @@ void WavetableOscillator::process_block(float pitch0, float drift, bool stereo,
}
else if (oscdata->wt.flags & wtf_is_sample)
{
tableipol = 0.f;
last_tableipol = 0.f;
tableipol = tableid;
last_tableipol = tableid;
}
else
{
Expand All @@ -438,29 +445,9 @@ void WavetableOscillator::process_block(float pitch0, float drift, bool stereo,
float shape = l_shape.v;
float intpart;
shape *= ((float)oscdata->wt.n_tables - 1.f + nointerp) * 0.99999f;
tableipol = modff(shape, &intpart);
tableipol = shape;
modff(shape, &intpart);
tableid = limit_range((int)intpart, 0, (int)oscdata->wt.n_tables - 2 + nointerp);

if (tableid > last_tableid)
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Why was this code removed?

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This is the logic for the old morph interpolation. It has to be removed for the new one to work.

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In that case please comment it out instead of removing it, since this code will have to remain here in order for the option switch to work.

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@blancoberg blancoberg Aug 29, 2024 •
edited
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In that case please comment it out instead of removing it, since this code will have to remain here in order for the option switch to work.

ok, but you you told me the opposite about my last pr that I should just remove instead of commenting out, since there is a git history :)

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The difference is that we know we'll need this code soon. :) Leaving commented-out code blocks hanging around indefinitely is what we want to avoid.

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got it. I'll change it to a comment

{
if (last_tableipol != 1.f)
{
tableid = last_tableid;
tableipol = 1.f;
}
else
last_tableipol = 0.0f;
}
else if (tableid < last_tableid)
{
if (last_tableipol != 0.f)
{
tableid = last_tableid;
tableipol = 0.f;
}
else
last_tableipol = 1.0f;
}
}

if (FM)
Expand Down
1 change: 1 addition & 0 deletions src/common/dsp/oscillators/WavetableOscillator.h
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Expand Up @@ -72,6 +72,7 @@ class WavetableOscillator : public AbstractBlitOscillator
int nointerp;
float FMmul_inv;
int sampleloop;
bool isOneShot;
};

#endif // SURGE_SRC_COMMON_DSP_OSCILLATORS_WAVETABLEOSCILLATOR_H
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