Que: How to play PCM data in Qt?

santa1367

Explanation: I have character array and I want paly it by using Qt.
I am using following code. But its playing something garbage voice.

My_Audio.h

#ifndef MYAUDIO
#define MYAUDIO

#endif // MYAUDIO


#include <QDebug>
#include <QIODevice>
#include <QAudioInput>
#include <QAudioOutput>
#include <QCoreApplication>
#include <QWidget>

//#define SAMPLE_RATE 22050
#define SAMPLE_RATE 22050
#define CHANNELS 1
#define SAMPLE_SIZE 16

#define SAMPLE_TYPE SignedInt

const float DurationSeconds = 0.1;
const int ToneFrequencyHz = 4000;
const int DataFrequencyHz = 44100;
const int BufferSize   = 131072;

class myAudio
{
 // Q_OBJECT

public:
    QAudioOutput *audioOut;
    QAudioInput  *audioIn;
    QWidget *parent;


    myAudio(QWidget *parent);
   ~myAudio(){}
   void fillBuffer();
    QAudioFormat formatIn,formatOut;
    QByteArray buff;
     QAudioDeviceInfo deviceinfo;
    QIODevice*            auIObuffer;     // IODevice to connect to m_AudioOutput
    signed short   aubuffer[BufferSize];     // Audio circular buffer
    int                      readpointer;           // Pointer to the portion of the audio buffer
                                                 // to be read.
    int                      writepointer;

public slots:
    void write();
};

My_Audio.cpp

#include "myAudio.h"
#include <QDebug>
#include <windows.h>
#include <qmath.h>
#include <qEndian.h>
#include <QFile>

myAudio::myAudio(QWidget *parent)
{
   formatOut.setSampleRate(SAMPLE_RATE);
   formatOut.setChannelCount(CHANNELS);
   formatOut.setSampleSize(SAMPLE_SIZE);
   formatOut.setCodec("audio/pcm");
   formatOut.setByteOrder(QAudioFormat::LittleEndian);
   formatOut.setSampleType(QAudioFormat::SAMPLE_TYPE);

//print out the output device setup parameters

   deviceinfo = QAudioDeviceInfo::defaultOutputDevice(); // Device info = default

   if(!deviceinfo.isFormatSupported(formatOut))
   {
       qDebug() << "\nformat specifieed not supported";
   }

      audioOut=0;
      audioOut = new QAudioOutput(deviceinfo, formatOut, parent);
      audioOut->setNotifyInterval(10);
      audioOut->setBufferSize(131072); //in bytes
      QObject::connect(audioOut, SIGNAL(notify()), parent, SLOT(write()));
   //auIObuffer->open(QIODevice::ReadOnly);
      auIObuffer = audioOut->start();


//   print out the device specifications
    foreach(const QAudioDeviceInfo &deviceInfo, QAudioDeviceInfo::availableDevices(QAudio::AudioOutput))
        {
        qDebug() << "\nSuported output devices";
        qDebug() << "Device name: "             << deviceInfo.deviceName();
        qDebug() << "Supported channel count: "   << deviceInfo.supportedChannelCounts();
        qDebug() << "Supported Codec: "           << deviceInfo.supportedCodecs();
        qDebug() << "Supported byte order: "      << deviceInfo.supportedByteOrders();
        qDebug() << "Supported Sample Rate: "     << deviceInfo.supportedSampleRates();
        qDebug() << "Supported Sample Size: "     << deviceInfo.supportedSampleSizes();
        qDebug() << "Supported Sample Type: "     << deviceInfo.supportedSampleTypes();
        qDebug() << "Preferred Device settings:"  << deviceInfo.preferredFormat();
        }

     for (int sample=0; sample<BufferSize; sample++) {
          signed short value=0;
          if ((sample>20000) && (sample<20000+(DurationSeconds*DataFrequencyHz))){
            float time = (float) sample/DataFrequencyHz ;
            float x = qSin(2 * M_PI *ToneFrequencyHz* time);
            value = static_cast<signed short>(x * 32767);
          }
          aubuffer[sample] = value;
     }
     writepointer=0;
     readpointer=0;
     write();
}

void myAudio::write()
{
   int emptyBytes = audioOut->bytesFree(); // Check how many empty bytes are in the device buffer
   int periodSize = audioOut->periodSize(); // Check the ideal chunk size, in bytes
   int chunks = emptyBytes/periodSize;
   char *data = "#Dis";	// referring to “This” 
       auIObuffer->write((const char*) data, periodSize);
}

MainWindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
   Q_OBJECT

public:
   explicit MainWindow(QWidget *parent = 0);
   ~MainWindow();

private slots:
   void on_pushButton_clicked();

private:
   Ui::MainWindow *ui;
};

#endif // MAINWINDOW_H

MainWindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "myaudio.h"
myAudio *m;
MainWindow::MainWindow(QWidget *parent) :
   QMainWindow(parent),
   ui(new Ui::MainWindow)
{
   ui->setupUi(this);

m = new myAudio(parent);

}

MainWindow::~MainWindow()
{
   delete ui;
}

void MainWindow::on_pushButton_clicked()
{
   m->write();
}

Main.cpp

#include "mainwindow.h"
#include <QApplication>

int main(int argc, char *argv[])
{
   QApplication a(argc, argv);
   MainWindow w;
   w.show();

   return a.exec();
}

ProjectName.Pro

QT       += core gui
QT += multimedia widgets
greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = ProjectName
TEMPLATE = app
CONFIG   -= app_bundle

SOURCES += main.cpp\
       mainwindow.cpp \
   myaudio.cpp

HEADERS  += mainwindow.h \
   myaudio.h

FORMS    += mainwindow.ui

Please help me on this.

santa1367

It worked.

Was doing mistake by providing actually speech content to write buffer api.
Instead of speech content, actual PCM data need to be given.
And Thanks to @Chris Kawa for editing post to make it more readable

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Que: How to play PCM data in Qt?