How to save recordings to *.wav? - qt

Question

I trying to change my code to save recordings to wav-files. Later i have to import this to MATLAB.
Its works to save like .*pcm or.*wav. But I want play it with (example VLC Player) external player.
QAudioFormat format;
Conf values;
format.setSampleRate(values.getSampRate());
format.setChannelCount(values.getChannel());
format.setSampleSize(values.getSampSize());
format.setCodec(values.getCodec());
format.setByteOrder(QAudioFormat::LittleEndian);
format.setSampleType(QAudioFormat::SignedInt);
in config-file i have configuration:
samp_rate=88200
channel=1
samp_size=24
codec=Audio/PCM
byte_order=QAudioFormat::LittleEndian
sample_type=QAudioFormat::SignedInt
Saving file looks:
m_audio->startrecording(fn+".pcm");
I changed pcm to wav - file will be recorded, but I cant open it with VLC (just import to Audacity with manual input of sample Rate, ByteOrder). Its because of RAW-data? how can able to save my recording like wav-file included sample-size, sampl-rate ...?
Audio.cpp
// ************************************************************************************************
// Audio-Class
// ************************************************************************************************
#include "Audio.h"
#include "Conf.h"
#include "Measure.h"
// ************************************************************************************************
Audio::Audio(Conf *conf)
{
m_conf = conf;
AudioRecord();
}
// ************************************************************************************************
//Initialization and signal-slot connection
void Audio::AudioRecord()
{
QAudioFormat format;
Conf values;
format.setSampleRate(values.getSampRate());
format.setChannelCount(values.getChannel());
format.setSampleSize(values.getSampSize());
format.setCodec(values.getCodec());
format.setByteOrder(QAudioFormat::LittleEndian);
format.setSampleType(QAudioFormat::SignedInt);
QAudioDeviceInfo info = QAudioDeviceInfo::defaultInputDevice();
if (!info.isFormatSupported(format))
{
qWarning() << "Default format not supported";
format = info.nearestFormat(format);
}
m_audio = new QAudioInput(format, this);
connect(m_audio, SIGNAL(stateChanged(QAudio::State)), this, SLOT(handleStateChanged(QAudio::State)));
}
// ************************************************************************************************
//Start recording method
void Audio::startrecording(QString rec_file_path)
{
m_file.setFileName(rec_file_path);
m_file.open(QIODevice::WriteOnly);
m_audio->start(&m_file);
}
// ************************************************************************************************
//Stop recording
void Audio::stoprecording()
{
m_audio->stop();
m_file.close();
}
// ************************************************************************************************
//Recording DEBUG output
void Audio::handleStateChanged(QAudio::State newState)
{
switch (newState)
{
case QAudio::StoppedState:
if (m_audio->error() != QAudio::NoError)
{
qDebug() << "Error!!";
} else
{
qDebug() << "Finished recording";
}
break;
case QAudio::ActiveState:
qDebug() << "Started recording";
break;
default:
break;
}
}
// ************************************************************************************************
Audio.h
// ************************************************************************************************
// Audio-HEADER-file
// ************************************************************************************************
#ifndef AUDIO_H
#define AUDIO_H
// ************************************************************************************************
// Includes
#include <QDebug>
#include <QObject>
#include "Conf.h"
#include <QAudioInput>
#include <QDateTime>
#include <QTimer>
// ************************************************************************************************
// Define
#define SAVE_AUDIO_PATH "/home/nikitajarocky/workspace/QT/UART_PC/IO/"
// ************************************************************************************************
// Class variables and methods
class Audio : public QObject
{
Q_OBJECT
public:
explicit Audio(Conf *conf);
void start(QString file_name);
void stop();
void startrecording(QString);
void stoprecording();
signals:
public slots:
void handleStateChanged(QAudio::State);
void AudioRecord();
private:
Conf *m_conf;
Conf *m_samp_rate;
QAudioInput *m_audio;
QFile m_file;
};
// ************************************************************************************************
#endif // AUDIO_H

Answer 1

A much simpler approach is use QAudioRecorder, it handles the writing of the header and also handles the audio capture.
It saves you from big changes, if your goal is only recording.
See the example:
audio.h:
#ifndef AUDIO_H
#define AUDIO_H
#include <QtCore>
#include <QtMultimedia>
class Audio : public QObject
{
Q_OBJECT
public:
explicit Audio(QObject *parent = nullptr);
~Audio();
public slots:
QStringList audioInputs();
bool record(const QString &path, const QString &audio_input = QString());
void stop();
private:
QAudioRecorder *m_recorder;
};
#endif // AUDIO_H
audio.cpp:
#include "audio.h"
Audio::Audio(QObject *parent) : QObject(parent)
{
m_recorder = new QAudioRecorder(this);
}
Audio::~Audio()
{
stop();
}
QStringList Audio::audioInputs()
{
return m_recorder->audioInputs();
}
bool Audio::record(const QString &path, const QString &audio_input)
{
QAudioEncoderSettings audio_settings;
audio_settings.setCodec("audio/pcm");
audio_settings.setChannelCount(1);
audio_settings.setSampleRate(44100);
m_recorder->setEncodingSettings(audio_settings);
m_recorder->setOutputLocation(path);
m_recorder->setAudioInput(audio_input);
m_recorder->record();
if (m_recorder->state() == QAudioRecorder::RecordingState)
{
qDebug() << "Recording...";
return true;
}
else
{
qDebug() << qPrintable(m_recorder->errorString());
return false;
}
}
void Audio::stop()
{
if (m_recorder->state() == QAudioRecorder::RecordingState)
{
m_recorder->stop();
qDebug() << "Recording stopped";
}
else
{
qDebug() << "Nothing to stop";
}
}
Usage example (recording 5 seconds):
#include <QtCore>
#include "audio.h"
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
Audio audio;
audio.record("file.wav");
QTimer::singleShot(5 * 1000, &audio, &Audio::stop);
return a.exec();
}