QT使用C读取音频文件并绘制图像

需要使用Qt的QAudioDecoder类来读取音频文件，并使用QCustomPlot类来绘制图像。

首先，需要在.pro文件中添加以下代码：

QT += multimedia
QT += multimediawidgets
QT += widgets

然后，在头文件中添加以下代码：

#include <QAudioDecoder>
#include <QCustomPlot>

接下来，需要创建一个QAudioDecoder对象，并连接相应的信号槽，以获取音频数据和元数据：

QAudioDecoder *decoder = new QAudioDecoder(this);
connect(decoder, SIGNAL(bufferReady()), this, SLOT(handleBufferReady()));
connect(decoder, SIGNAL(finished()), this, SLOT(handleFinished()));
connect(decoder, SIGNAL(error(QAudioDecoder::Error)), this, SLOT(handleError(QAudioDecoder::Error)));

在handleBufferReady()槽中，可以获取音频数据并将其存储在QVector<double>对象中：

QAudioBuffer buffer = decoder->read();
const qint16 *data = buffer.constData<qint16>();
int sampleCount = buffer.sampleCount();
for (int i = 0; i < sampleCount; i++) {
double value = (double)data[i] / 32768.0;
audioData.append(value);
}

最后，可以使用QCustomPlot类来绘制音频波形图：

QCustomPlot *plot = new QCustomPlot(this);
plot->addGraph();
plot->graph(0)->setData(xData, audioData);
plot->xAxis->setLabel("Time");
plot->yAxis->setLabel("Amplitude");
plot->rescaleAxes();
plot->replot();

完整代码示例：

#include <QAudioDecoder>
#include <QCustomPlot>

class MainWindow : public QMainWindow
{
Q_OBJECT

public:
MainWindow(QWidget *parent = nullptr)
: QMainWindow(parent)
{
QAudioDecoder *decoder = new QAudioDecoder(this);
connect(decoder, SIGNAL(bufferReady()), this, SLOT(handleBufferReady()));
connect(decoder, SIGNAL(finished()), this, SLOT(handleFinished()));
connect(decoder, SIGNAL(error(QAudioDecoder::Error)), this, SLOT(handleError(QAudioDecoder::Error)));
decoder->setSourceFilename("audio.wav");
decoder->start();

QCustomPlot *plot = new QCustomPlot(this);
plot->addGraph();
plot->xAxis->setLabel("Time");
plot->yAxis->setLabel("Amplitude");
plot->rescaleAxes();
setCentralWidget(plot);
}

private slots:
void handleBufferReady()
{
QAudioBuffer buffer = decoder->read();
const qint16 *data = buffer.constData<qint16>();
int sampleCount = buffer.sampleCount();
for (int i = 0; i < sampleCount; i++) {
double value = (double)data[i] / 32768.0;
audioData.append(value);
}
plot->graph(0)->setData(xData, audioData);
plot->rescaleAxes();
plot->replot();
}

void handleFinished()
{
// TODO: handle finished decoding
}

void handleError(QAudioDecoder::Error error)
{
// TODO: handle decoding error
}

private:
QAudioDecoder *decoder;
QVector<double> audioData;
QVector<double> xData;
QCustomPlot *plot;
};