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Added a time resolution slider #127

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Added a time resolution slider #127

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hansvi
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@hansvi hansvi commented Apr 13, 2017

Increasing time resolution by narrowing the fft window function. The window function now is a Kaiser bessel function.

Also, I removed some variables that were not used.. They are just commented out, so please review this and if there is a reason for this, please let me know.

plotview.cpp Outdated
@@ -382,20 +382,27 @@ void PlotView::setFFTAndZoom(int size, int zoom)

void PlotView::setPowerMin(int power)
{
powerMin = power;
// HVI_REVIEW: Not needed? powerMin = power;
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It does look like these are unused and should be removed. I'd prefer that as a separate commit that just deletes the lines, rather than commenting them out

plotview.cpp Outdated
{
if (spectrogramPlot != nullptr)
spectrogramPlot->setTimeResolution(resolution);
// updateView(true);
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This shouldn't be commented out, it should just be deleted

timeResolutionSlider = new QSlider(Qt::Horizontal, widget);
timeResolutionSlider->setRange(0, 99);
layout->addRow(new QLabel(tr("Time resolution:")), timeResolutionSlider);

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Minor nit, but I'd prefer this to be just under the zoom slider - it makes sense to group FFT size/zoom/resolution together.

int windowSize = fftSize - zeroCount;
for (int i = 0; i < windowSize; i++) {
float term = float(2*i - windowSize + 1) / windowSize;
window[i] = bessel(beta * sqrt(1.0 - term * term)) / denominator;
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Currently I notice that the spectrogram shifts to the right as you increase the time resolution slider. To stop that happening, I think that the non-zero values should be centered in the window, rather than left-aligned.

@miek
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miek commented Apr 14, 2017

This is looking like a nice feature, thanks for submitting and let me know what you think about the proposed changes.

@hansvi
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hansvi commented Apr 15, 2017

I will be making the changes you requested.

@hansvi
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hansvi commented Apr 15, 2017

I've been doing my own improvements in the meantime: I now use the liquid-dsp implementation of the kaiser window, and I made the beta parameter configurable as it is also handy to be able to tune the fft window shape.

@hansvi
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hansvi commented Jun 4, 2017

Hey miek,
Can you take another look at the changes? I think the changes should be done.

Base automatically changed from master to main March 1, 2021 15:37
@catkira
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catkira commented Oct 18, 2022

ping
is this repo still active?

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3 participants