videovisualspectrum.cpp

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// QT
#include <QPen>
 
// MythTV
#include "videovisualspectrum.h"
 
// FFmpeg
static constexpr int k_FFT_sample_length { 512 };
 
// Std
#include <algorithm>
 
VideoVisualSpectrum::VideoVisualSpectrum(AudioPlayer* Audio, MythRender* Render)
  : VideoVisual(Audio, Render),
    m_dftL(static_cast<FFTComplex*>(av_malloc(sizeof(FFTComplex) * k_FFT_sample_length))),
    m_dftR(static_cast<FFTComplex*>(av_malloc(sizeof(FFTComplex) * k_FFT_sample_length))),
    m_fftContextForward(av_fft_init(std::log2(k_FFT_sample_length), 0))
{
}
 
VideoVisualSpectrum::~VideoVisualSpectrum()
{
    av_freep(reinterpret_cast<void*>(&m_dftL));
    av_freep(reinterpret_cast<void*>(&m_dftR));
    av_fft_end(m_fftContextForward);
}
 
template<typename T> T sq(T a) { return a*a; };
 
void VideoVisualSpectrum::Draw(const QRect Area, MythPainter* Painter, QPaintDevice* Device)
{
    if (m_disabled)
        return;
 
    uint i = 0;
    {
        QMutexLocker locker(mutex());
        VisualNode* node = GetNode();
        if (Area.isEmpty() || !Painter)
            return;
 
        if (!Initialise(Area))
            return;
 
        if (node)
        {
            i = static_cast<uint>(node->m_length);
            for (auto k = 0; k < node->m_length; k++)
            {
                m_dftL[k] = (FFTComplex){ .re = (FFTSample)node->m_left[k], .im = 0 };
                if (node->m_right)
                    m_dftR[k] = (FFTComplex){ .re = (FFTSample)node->m_right[k], .im = 0 };
            }
        }
    }
 
    for (auto k = i; k < k_FFT_sample_length; k++)
    {
        m_dftL[k] = (FFTComplex){ .re = 0, .im = 0 };
        m_dftL[k] = (FFTComplex){ .re = 0, .im = 0 };
    }
    av_fft_permute(m_fftContextForward, m_dftL);
    av_fft_calc(m_fftContextForward, m_dftL);
 
    av_fft_permute(m_fftContextForward, m_dftR);
    av_fft_calc(m_fftContextForward, m_dftR);
 
    double falloff = std::clamp(((static_cast<double>(SetLastUpdate().count())) / 40.0) * m_falloff, 0.0, 2048.0);
    for (int l = 0, r = m_scale.range(); l < m_scale.range(); l++, r++)
    {
        int index = m_scale[l];
 
        // The 1D output is Hermitian symmetric (Yk = Yn-k) so Yn = Y0 etc.
        // The dft_r2c_1d plan doesn't output these redundant values
        // and furthermore they're not allocated in the ctor
        double tmp = 2 * sq(m_dftL[index].re);
        double magL = (tmp > 1.) ? (log(tmp) - 22.0) * m_scaleFactor : 0.;
 
        tmp = 2 * sq(m_dftR[index].re);
        double magR = (tmp > 1.) ? (log(tmp) - 22.0) * m_scaleFactor : 0.;
        if (magL > m_range)
            magL = 1.0;
 
        if (magL < m_magnitudes[l])
        {
            tmp = m_magnitudes[l] - falloff;
            tmp = std::max(tmp, magL);
            magL = tmp;
        }
 
        magL = std::max(magL, 1.0);
 
        if (magR > m_range)
            magR = 1.0;
 
        if (magR < m_magnitudes[r])
        {
            tmp = m_magnitudes[r] - falloff;
            tmp = std::max(tmp, magR);
            magR = tmp;
        }
 
        magR = std::max(magR, 1.0);
 
        m_magnitudes[l] = magL;
        m_magnitudes[r] = magR;
    }
 
    DrawPriv(Painter, Device);
}
 
void VideoVisualSpectrum::prepare()
{
    std::fill(m_magnitudes.begin(), m_magnitudes.end(), 0.0);
    VideoVisual::prepare();
}
 
void VideoVisualSpectrum::DrawPriv(MythPainter* Painter, QPaintDevice* Device)
{
    static const QBrush kBrush(QColor(0, 0, 200, 180));
    static const QPen   kPen(QColor(255, 255, 255, 255));
    double range = m_area.top() + (m_area.height() / 2.0);
    int count = m_scale.range();
    Painter->Begin(Device);
    for (int i = 0; i < count; i++)
    {
        m_rects[i].setTop(static_cast<int>(range - static_cast<int>(m_magnitudes[i])));
        m_rects[i].setBottom(static_cast<int>(range + static_cast<int>(m_magnitudes[i + count])));
        if (m_rects[i].height() > 4)
            Painter->DrawRect(m_rects[i], kBrush, kPen, 255);
    }
    Painter->End();
}
 
bool VideoVisualSpectrum::Initialise(const QRect Area)
{
    if (Area == m_area)
        return true;
 
    m_area = Area;
    m_barWidth = m_area.width() / m_numSamples;
    m_barWidth = std::max(m_barWidth, 6);
    m_scale.setMax(192, m_area.width() / m_barWidth);
 
    m_magnitudes.resize(m_scale.range() * 2);
    std::fill(m_magnitudes.begin(), m_magnitudes.end(), 0.0);
    InitialisePriv();
    return true;
}
 
bool VideoVisualSpectrum::InitialisePriv()
{
    m_range = m_area.height() / 2.0;
    m_rects.resize(m_scale.range());
    int y = m_area.top() + static_cast<int>(m_range);
    for (int i = 0, x = m_area.left(); i < m_rects.size(); i++, x+= m_barWidth)
        m_rects[i].setRect(x, y, m_barWidth - 1, 1);
 
    m_scaleFactor = (static_cast<double>(m_area.height()) / 2.0) / log(static_cast<double>(k_FFT_sample_length));
    m_falloff = static_cast<double>(m_area.height()) / 150.0;
 
    LOG(VB_GENERAL, LOG_INFO, DESC + QString("Initialised Spectrum with %1 bars").arg(m_scale.range()));
    return true;
}
 
static class VideoVisualSpectrumFactory : public VideoVisualFactory
{
  public:
    const QString &name() const override;
    VideoVisual *Create(AudioPlayer* Audio, MythRender* Render) const override;
    bool SupportedRenderer(RenderType /*Type*/) override { return true; }
} VideoVisualSpectrumFactory;
 
const QString& VideoVisualSpectrumFactory::name() const
{
    static QString s_name(SPECTRUM_NAME);
    return s_name;
}
 
VideoVisual* VideoVisualSpectrumFactory::Create(AudioPlayer* Audio, MythRender* Render) const
{
    return new VideoVisualSpectrum(Audio, Render);
}