A simple test app to test Phonon's Audio data out: To Compile: qmake && make , To Run: ./audiodataout /path/to/audiofile

audioclass.h

#include <QtGui>
#include <phonon/audiodataoutput.h>

class AudioClass: public QWidget{
Q_OBJECT
    QMap<Phonon::AudioDataOutput::Channel, QVector<qint16> > m_audiodata;

public  slots:
  void dataReceived(const QMap<Phonon::AudioDataOutput::Channel, QVector<qint16> >& data){
  //qDebug()<<"Hii"<<data[Phonon::AudioDataOutput::LeftChannel][512];
      m_audiodata = data;
      update();
 }
  void paintEvent(QPaintEvent *event){
//      qDebug()<<"In Paint Event";
      int w = size().width();
      int h = size().height();
      QPainter painter;
      painter.begin(this);
        painter.setBrush(Qt::white);
        //Draw A Background Rectangle
        painter.drawRect(0,0,w,h);


        //Draw the wave form
        QPainterPath leftChannelPath,rightChannelPath;

        int y = 0;
        int x = 0;
        int nSamples = m_audiodata[Phonon::AudioDataOutput::LeftChannel].size();
        for(int i =0; i < nSamples ;i++){
            //One for the left channel
            y = (m_audiodata[Phonon::AudioDataOutput::LeftChannel][i]*h)/131070 + h*0.25;
            x = (i*w)/nSamples;
            leftChannelPath.lineTo(x,y);
            //One for the right channel
            y= (m_audiodata[Phonon::AudioDataOutput::RightChannel][i]*h)/131070 + h*0.75;
            rightChannelPath.lineTo(x,y);
        }
        //Draw the Audio data
        painter.setBrush(Qt::transparent);
        painter.setPen(Qt::blue);
        painter.drawPath(leftChannelPath);
        painter.setPen(Qt::red);
        painter.drawPath(rightChannelPath);

        painter.setPen(Qt::black);
        //Draw the axes
        painter.drawLine(0,0,0,h);
        painter.drawLine(0,h*0.25,w,h*0.25);
        painter.drawLine(0,h*0.5,w,h*0.5);
        painter.drawLine(0,h*0.75,w,h*0.75);

      painter.end();
  }

};

audiodataout.pro

######################################################################
# Automatically generated by qmake (2.01a) Sat Feb 11 03:09:54 2012
######################################################################

QT += phonon
TEMPLATE = app
TARGET = 
DEPENDPATH += .
INCLUDEPATH += .

# Input
SOURCES += main.cpp
HEADERS += audioclass.h

main.cpp

#include <QtGui>
#include <phonon/audiooutput.h>
#include <phonon/audiodataoutput.h>
#include <phonon/mediaobject.h>

#include <QDebug>

#include <audioclass.h>
int main(int argc, char * argv[]) {
    QApplication app(argc, argv);
    app.setApplicationName("simpleplayer");

    Phonon::AudioOutput output(Phonon::MusicCategory, &app);
    Phonon::MediaObject media(&app);
    Phonon::AudioDataOutput dataout(&app);
    if(dataout.isValid()){
      qDebug()<<"AudioDataOutput::isValid() : True";

      Phonon::createPath(&media, &dataout);
      media.connect(&media, SIGNAL(finished()), &app, SLOT(quit()));

      Phonon::createPath(&media, &output);

      AudioClass monitor;
      media.connect( &dataout, SIGNAL(dataReady(const QMap<Phonon::AudioDataOutput::Channel, QVector<qint16> >&)), 
              &monitor, SLOT(dataReceived(const QMap<Phonon::AudioDataOutput::Channel, QVector<qint16> >&)));
      media.setCurrentSource(app.arguments().at(1));
      media.play();

      monitor.show();

      return app.exec();
    }
    else{
      qDebug() << "AudioDataOutput::isValid() : False";
      return -1;
    }
}

very good thank you!