Qt音频文件像大胆一样挥动

Question

我必须管理电影和音频文件，我需要像大胆一样渲染声音的波形。但我只是找到了实时渲染的例子。我想渲染所有文件而不播放它。预期结果：我的实际结果：使用Qt我试图使用QAudioDecoder打开我的文件并得到一个QAudioBuffer但我没有找到将所有数据转换为wave的算法。我也尝试用Qt Spectrum Example来看，但这并不是一件容易理解的事情，它仍然是实时的。

我的track.h：

#ifndef TRACK_H
#define TRACK_H

#include <QWidget>
#include <QAudioBuffer>

class QAudioDecoder;

class Track : public QWidget
{
    Q_OBJECT    
public:
    Track(QWidget *parent = Q_NULLPTR);
    ~Track();
    void setSource(const QString &fileName);

public slots:
    void setBuffer();

protected:
    void paintEvent(QPaintEvent *e) override;

private:
    int pointDistance(const QPoint& a, const QPoint& b);
    QAudioDecoder *decoder;
    QAudioBuffer buffer;
    QByteArray byteArr;    
};    
#endif // TRACK_H

我的track.cpp：

#include "track.h"

#include <QPaintEvent>
#include <QPainter>
#include <QAudioDecoder>

Track::Track(QWidget *parent)
    : QWidget(parent)
    , decoder(new QAudioDecoder(this))
{
    setMinimumHeight(50);

    connect(decoder, SIGNAL(bufferReady()), this, SLOT(setBuffer()));
    connect(decoder, SIGNAL(finished()), this, SLOT(update()));
}

Track::~Track()
{
    delete decoder;
}

void Track::setSource(const QString &fileName)
{
    byteArr.clear();
    decoder->setSourceFilename(fileName);
    decoder->start();
}

void Track::setBuffer()
{
    buffer = decoder->read();
    byteArr.append(buffer.constData<char>(), buffer.byteCount());
}

void Track::paintEvent(QPaintEvent *e)
{
    QWidget::paintEvent(e);

    int w = width(), h = height();
    QBrush backgroundBrush(Qt::white);
    QPainter painter(this);
    painter.fillRect(0, 0, w, h, backgroundBrush);

    painter.drawLine(0, h/2, w, h/2);
    if (!byteArr.isEmpty()){
        QPen pen(QColor(Qt::blue));
        painter.setPen(pen);
        int length = byteArr.size();
        int samplesPerPixel = length/w;
        int idx=0;
        for (int i=0; i<w; i++){
            QLine line;
            int higher = 0;
            for (int j=0; j<samplesPerPixel && idx+1<length; j++){
                const QPoint a(i, byteArr.at(idx)+(h/2));
                const QPoint b(i, byteArr.at(idx+1)+(h/2));
                if (higher < pointDistance(a, b))
                    line = QLine(a, b);
                idx++;
            }
            painter.drawLine(line);
        }
    }
}

int Track::pointDistance(const QPoint &a, const QPoint &b)
{
    int ret = 0;
    ret = sqrt(pow(b.x()-a.x(), 2) + pow(b.y()-a.y(), 2));
    return ret;
}