CODEWITHSUNDEEP
c++qtaudio
Tiina
Tiina

Reputation: 4785

Audio input example doesn't work - QAudioInput: IOError

I am a freshgirl to Qt. (C++ as well)

I saw an example from QAudioInput class reference, and in order to pass the compile I made a little change (all the difference you see from my code to the example is because of compile failed at first).

I looked up a lot on the Internet, still got nothing. And the example http://doc.qt.io/archives/qt-4.7/multimedia-audioinput-audioinput-h.html does work. And I read it carefully, nothing different except mine is to save to a file, and that one is to save to a buffer.

so, please help me with 1, what are the reasons to cause QAudioInput: IOError (I know there is problem on IO devices, but what is the problem?) 2, how could I make the code work?

Here are the code:

    //audioprocess.h
#ifndef AUDIOPROCESS_H
#define AUDIOPROCESS_H

#include <QAudioInput>
#include <QFile>
#include <QDebug>
#include <QTimer>
#include <QObject>

class audioprocess : public QObject
{
  Q_OBJECT
public:
  void startRecording();
private slots:
  void stopRecording();
private:
  QFile outputFile; // class member.
  QAudioInput *audioInput; // class member.
};

#endif // AUDIOPROCESS_H

//----------------------------------------------
//audioprocess.cpp


#include "audioprocess.h"

void audioprocess::startRecording()
{
  outputFile.setFileName("/audio_qt.raw");
  outputFile.open( QIODevice::WriteOnly | QIODevice::Truncate );

  QAudioFormat format;
  // set up the format you want, eg.
  format.setFrequency(8000);
  format.setChannels(1);
  format.setSampleSize(8);
  format.setCodec("audio/pcm");
  format.setByteOrder(QAudioFormat::LittleEndian);
  format.setSampleType(QAudioFormat::UnSignedInt);

  QAudioDeviceInfo info = QAudioDeviceInfo::defaultInputDevice();
  if (!info.isFormatSupported(format)) {
  qWarning()<<"default format not supported try to use nearest";
  format = info.nearestFormat(format);
  }

  audioInput = new QAudioInput(format,reinterpret_cast<QObject*>(this));

  QTimer::singleShot(100, reinterpret_cast<QObject*>(this), SLOT(stopRecording()));
  audioInput->start(&outputFile);
  // Records audio for 3000ms
}

void audioprocess::stopRecording()
{
  audioInput->stop();
  outputFile.close();
  delete audioInput;
}
//--------------------------------------------------------

//main.cpp
#include <QtGui/QApplication>
#include "audioprocess.h"

int main(int argc, char *argv[])
{
  QApplication a(argc, argv);
  audioprocess audiorecord;
  audiorecord.startRecording();

  return a.exec();
}

Upvotes: 1

Views: 4320

Answers (1)

Paolo Brandoli
Paolo Brandoli

Reputation: 4750

Are you sure that the application has the rights to write into the root folder (file name = "/audio_qt.raw")?

I would try to write into the user's home folder.

A quick test to check if this is really the problem is to check the return value of outputFile.open() (should return true).

Upvotes: 1

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