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projectm/src/libprojectM/Renderer/BeatDetect.cpp
2022-05-29 15:49:14 +02:00

100 lines
3.0 KiB
C++
Executable File

/**
* projectM -- Milkdrop-esque visualisation SDK
* Copyright (C)2003-2004 projectM Team
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
* See 'LICENSE.txt' included within this release
*
*/
/**
* Takes sound data from wherever and returns beat detection values
* Uses statistical Energy-Based methods. Very simple
*
* Some stuff was taken from Frederic Patin's beat-detection article,
* you'll find it online
*/
#include <numeric>
#include <stdio.h>
#include <stdlib.h>
#include "wipemalloc.h"
#include "BeatDetect.hpp"
#include "PCM.hpp"
#include <algorithm>
#include <cmath>
BeatDetect::BeatDetect(Pcm& _pcm)
: pcm(_pcm)
{
}
void BeatDetect::Reset()
{
this->treb = 0;
this->mid = 0;
this->bass = 0;
this->trebAtt = 0;
this->midAtt = 0;
this->bassAtt = 0;
this->volAtt = 0;
this->volOld = 0;
}
void BeatDetect::CalculateBeatStatistics()
{
volOld = vol;
std::array<float, fftLength> vdataL{};
std::array<float, fftLength> vdataR{};
pcm.GetSpectrum(vdataL.data(), CHANNEL_0, fftLength);
pcm.GetSpectrum(vdataR.data(), CHANNEL_1, fftLength);
auto const intensityBetween =
[&vdataL, &vdataR](size_t const from, size_t const to) {
return std::accumulate(&vdataL[from], &vdataL[to], 0.f) +
std::accumulate(&vdataR[from], &vdataR[to], 0.f);
};
auto const& updateBand =
[](float& band, float& bandAtt, LowPassFilter& bandSmoothed, float const bandIntensity) {
bandSmoothed.Update(bandIntensity);
band = bandIntensity / std::max(0.0001f, bandSmoothed.Get());
bandAtt = .6f * bandAtt + .4f * band;
bandAtt = std::min(bandAtt, 100.f);
band = std::min(band, 100.f);
};
static_assert(fftLength >= 256, "fftLength too small");
std::array<size_t, 4> constexpr ranges{0, 3, 23, 255};
float const bassIntensity = intensityBetween(ranges[0], ranges[1]);
updateBand(bass, bassAtt, bassSmoothed, bassIntensity);
float const midIntensity = intensityBetween(ranges[1], ranges[2]);
updateBand(mid, midAtt, midSmoothed, midIntensity);
float const trebIntensity = intensityBetween(ranges[2], ranges[3]);
updateBand(treb, trebAtt, trebSmoothed, trebIntensity);
float const volIntensity = bassIntensity + midIntensity + trebIntensity;
updateBand(vol, volAtt, volSmoothed, volIntensity);
}