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Bug 1830 - Zero Crossings selection may change when zero crossing not found

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The old method was overly reliant on absolute value.
Now we have penalties base on consecutive samples signs.

We'll only make a change if the overall score is good enough.
Also we try to avoid making a point selection, if we were not previously a point.
This commit is contained in:
James Crook 2018-03-23 16:27:39 +00:00
parent d94f6c9b5b
commit 4a7c4f400f
1 changed files with 23 additions and 19 deletions
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40
src/Menus.cpp
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@ -4369,6 +4369,7 @@ double AudacityProject::NearestZeroCrossing(double t0)
TrackListIterator iter(GetTracks());
Track *track = iter.First();
int nTracks = 0;
while (track) {
if (!track->GetSelected() || track->GetKind() != (Track::Wave)) {
track = iter.Next();
@ -4383,25 +4384,18 @@ double AudacityProject::NearestZeroCrossing(double t0)
one->Get((samplePtr)oneDist.get(), floatSample,
s - (int)oneWindowSize/2, oneWindowSize, fillTwo);
// Start by penalizing downward motion. We prefer upward
// zero crossings.
if (oneDist[1] - oneDist[0] < 0)
oneDist[0] = oneDist[0]*6 + (oneDist[0] > 0 ? 0.3 : -0.3);
for(size_t i=1; i<oneWindowSize; i++)
if (oneDist[i] - oneDist[i-1] < 0)
oneDist[i] = oneDist[i]*6 + (oneDist[i] > 0 ? 0.3 : -0.3);
// Taking the absolute value -- apply a tiny LPF so square waves work.
float newVal, oldVal = oneDist[0];
oneDist[0] = fabs(.75 * oneDist[0] + .25 * oneDist[1]);
for(size_t i=1; i + 1 < oneWindowSize; i++)
{
newVal = fabs(.25 * oldVal + .5 * oneDist[i] + .25 * oneDist[i+1]);
oldVal = oneDist[i];
oneDist[i] = newVal;
// Looking for actual crossings.
double prev = 2.0;
for(size_t i=0; i<oneWindowSize; i++){
float fDist = fabs( oneDist[i]); // score is absolute value
if( prev * oneDist[i] > 0 ) // both same sign? No good.
fDist = fDist + 0.4; // No good if same sign.
else if( prev > 0.0 )
fDist = fDist + 0.1; // medium penalty for downward crossing.
prev = oneDist[i];
oneDist[i] = fDist;
}
oneDist[oneWindowSize-1] = fabs(.25 * oldVal +
.75 * oneDist[oneWindowSize-1]);
// TODO: The mixed rate zero crossing code is broken,
// if oneWindowSize > windowSize we'll miss out some
@ -4415,9 +4409,10 @@ double AudacityProject::NearestZeroCrossing(double t0)
dist[i] += oneDist[j];
// Apply a small penalty for distance from the original endpoint
// We'll always prefer an upward
dist[i] += 0.1 * (abs(int(i) - int(windowSize/2))) / float(windowSize/2);
}
nTracks++;
track = iter.Next();
}
@ -4431,6 +4426,13 @@ double AudacityProject::NearestZeroCrossing(double t0)
}
}
// If we're worse than 0.2 on average, on one track, then no good.
if(( nTracks == 1 ) && ( min > (0.2*nTracks) ))
return t0;
// If we're worse than 0.6 on average, on multi-track, then no good.
if(( nTracks > 1 ) && ( min > (0.6*nTracks) ))
return t0;
return t0 + (argmin - (int)windowSize/2)/GetRate();
}
@ -4441,6 +4443,8 @@ void AudacityProject::OnZeroCrossing(const CommandContext &WXUNUSED(context) )
mViewInfo.selectedRegion.setTimes(t0, t0);
else {
const double t1 = NearestZeroCrossing(mViewInfo.selectedRegion.t1());
// Empty selection is generally not much use, so do not make it if empty.
if( fabs( t1 - t0 ) * GetRate() > 1.5 )
mViewInfo.selectedRegion.setTimes(t0, t1);
}