The QAudioInput class provides an interface for receiving audio data from an audio input device. More...

Inheritance diagram for QAudioInput:

Public Signals
void	notify ()

void	stateChanged (QAudio::State state)

Public Signals inherited from QObject
void	destroyed (QObject *obj=nullptr)

void	objectNameChanged (const QString &objectName)

Public Methods
	QAudioInput (const QAudioDeviceInfo &audioDeviceInfo, const QAudioFormat &format=QAudioFormat (), QObject *parent=nullptr)

	QAudioInput (const QAudioFormat &format=QAudioFormat (), QObject *parent=nullptr)

	~QAudioInput ()

int	bufferSize () const

int	bytesReady () const

qint64	elapsedUSecs () const

QAudio::Error	error () const

QAudioFormat	format () const

int	notifyInterval () const

int	periodSize () const

qint64	processedUSecs () const

void	reset ()

void	resume ()

void	setBufferSize (int bytes)

void	setNotifyInterval (int milliSeconds)

void	setVolume (qreal volume)

QIODevice *	start ()

void	start (QIODevice *device)

QAudio::State	state () const

void	stop ()

void	suspend ()

qreal	volume () const

Public Methods inherited from QObject
	QObject (QObject *parent=nullptr)

	~QObject ()

bool	blockSignals (bool block)

const QList< QObject * > &	children () const

bool	connect (const QObject *sender, const QString &signalMethod, const QString &location, const QString &slotMethod, Qt::ConnectionType type=Qt::AutoConnection)

bool	connect (const QObject *sender, const QString &signalMethod, const QString &slotMethod, Qt::ConnectionType type=Qt::AutoConnection)

bool	disconnect (const QObject *receiver, const QString &slotMethod=QString ()) const

bool	disconnect (const QString &signalMethod, const QString &location, const QObject *receiver=nullptr, const QString &slotMethod=QString ()) const

bool	disconnect (const QString &signalMethod=QString (), const QObject *receiver=nullptr, const QString &slotMethod=QString ()) const

void	dumpObjectInfo ()

void	dumpObjectTree ()

QList< QString >	dynamicPropertyNames () const

virtual bool	event (QEvent *event)

virtual bool	eventFilter (QObject watched, QEvent event)

template<typename T >
T	findChild (const QString &childName=QString ()) const

template<class T >
QList< T >	findChildren (const QRegularExpression &regExp, Qt::FindChildOptions options=Qt::FindChildrenRecursively) const

template<class T >
QList< T >	findChildren (const QString &childName=QString (), Qt::FindChildOptions options=Qt::FindChildrenRecursively) const

bool	inherits (const QString &className) const

void	installEventFilter (QObject *filterObj)

bool	isWidgetType () const

bool	isWindowType () const

void	killTimer (int id)

const QMetaObject *	metaObject () const

void	moveToThread (QThread *targetThread)

QString	objectName () const

QObject *	parent () const

template<class T = QVariant>
T	property (const QString &name) const

void	removeEventFilter (QObject *obj)

void	setObjectName (const QString &name)

void	setParent (QObject *parent)

bool	setProperty (const QString &name, const QVariant &value)

bool	signalsBlocked () const

int	startTimer (int interval, Qt::TimerType timerType=Qt::CoarseTimer)

QThread *	thread () const

Additional Inherited Members
Public Slots inherited from QObject
void	deleteLater ()

Static Public Methods inherited from QObject
static bool	connect (const QObject sender, const QMetaMethod &signalMethod, const QObject receiver, const QMetaMethod &slotMethod, Qt::ConnectionType type=Qt::AutoConnection)

static bool	connect (const QObject sender, const QString &signalMethod, const QObject receiver, const QString &slotMethod, Qt::ConnectionType type=Qt::AutoConnection, const QString &location=QString ())

static bool	connect (const QObject sender, const QString &signalMethod, const QString &location, const QObject receiver, const QString &slotMethod, Qt::ConnectionType type=Qt::AutoConnection)

template<class Sender , class SignalClass , class... SignalArgs, class Receiver , class SlotClass , class... SlotArgs, class SlotReturn >
static bool	connect (const Sender sender, void (SignalClass::signalMethod)(SignalArgs...), const Receiver receiver, SlotReturn (SlotClass::slotMethod)(SlotArgs...), Qt::ConnectionType type=Qt::AutoConnection)

template<class Sender , class SignalClass , class... SignalArgs, class Receiver , class T >
static bool	connect (const Sender sender, void (SignalClass::signalMethod)(SignalArgs...), const Receiver *receiver, T slotLambda, Qt::ConnectionType type=Qt::AutoConnection)

static bool	disconnect (const QObject sender, const QMetaMethod &signalMethod, const QObject receiver, const QMetaMethod &slotMethod)

static bool	disconnect (const QObject sender, const QString &signalMethod, const QObject receiver, const QString &slotMethod)

static bool	disconnect (const QObject sender, const QString &signalMethod, const QString &location, const QObject receiver, const QString &slotMethod)

static bool	disconnect (const QObject sender, std::nullptr_t, const QObject receiver, std::nullptr_t)

template<class Sender , class SignalClass , class... SignalArgs, class Receiver , class SlotClass , class... SlotArgs, class SlotReturn >
static bool	disconnect (const Sender sender, void (SignalClass::signalMethod)(SignalArgs...), const Receiver receiver, SlotReturn (SlotClass::slotMethod)(SlotArgs...))

template<class Sender , class SignalClass , class... SignalArgs, class Receiver >
static bool	disconnect (const Sender sender, void (SignalClass::signalMethod)(SignalArgs...), const Receiver *receiver, std::nullptr_t slotMethod=nullptr)

template<class Sender , class SignalClass , class... SignalArgs, class Receiver , class T >
static bool	disconnect (const Sender sender, void (SignalClass::signalMethod)(SignalArgs...), const Receiver *receiver, T slotMethod)

static QMetaObject &	staticMetaObject ()

static QString	tr (const char text, const char comment=nullptr, std::optional< int > numArg=std::optional< int >())

Protected Methods inherited from QObject
virtual void	childEvent (QChildEvent *event)

virtual void	connectNotify (const QMetaMethod &signalMethod) const

virtual void	customEvent (QEvent *event)

virtual void	disconnectNotify (const QMetaMethod &signalMethod) const

bool	isSignalConnected (const QMetaMethod &signalMethod) const

int	receivers (const QString &signal) const

QObject *	sender () const

int	senderSignalIndex () const

virtual void	timerEvent (QTimerEvent *event)

Properties inherited from QObject
	objectName

Related Functions inherited from QObject
T	qobject_cast (QObject *object)

	QObjectList

Detailed Description

The QAudioInput class provides an interface for receiving audio data from an audio input device.

An audio input can be constructed with the system's default audio input device. It is also possible to create a QAudioInput with a specific QAudioDeviceInfo. When creating the audio input the QAudioFormat should be specified. Starting up the QAudioInput is simply a matter of calling start() with a QIODevice opened for writing.

The following code shows how to record to a file. This will start recording if the format specified is supported by the input device (you can check this with QAudioDeviceInfo::isFormatSupported(). In case there are any issues use the error() function to check what went wrong.

QFile outputFile;               // class member
QAudioInput *audioInput;        // class member
 
void startRecording() {
   outputFile.setFileName("/tmp/test.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, this);
   QTimer::singleShot(3000, this, SLOT(stopRecording()));
 
   audioInput->start(&outputFile);
   // Records audio for 3000ms
}

The code to stop recording is placed in the stopRecording() slot.

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

At any point in time, QAudioInput will be in one of four states: active, suspended, stopped, or idle. These states are specified by the QAudio::State enum. You can request a state change directly through suspend(), resume(), stop(), reset(), and start(). The current state is reported by state(). QAudioOutput will also signal you when the state changes (stateChanged()).

QAudioInput provides several ways of measuring the time that has passed since the start() of the recording. The processedUSecs() function returns the length of the stream in microseconds written, i.e., it leaves out the times the audio input was suspended or idle. The elapsedUSecs() function returns the time elapsed since start() was called regardless of which states the QAudioInput has been in.

If an error should occur, you can fetch its reason with error(). The possible error reasons are described by the QAudio::Error> enum. The QAudioInput will enter the StoppedState when an error is encountered. Connect to the stateChanged() signal to handle the error:

void stateChanged(QAudio::State newState) {
   switch(newState) {
 
      case QAudio::StoppedState:
         if (audioInput->error() != QAudio::NoError) {
            // Perform error handling
         } else {
 
         }
 
         break;
   }
}

See also: QAudioOutput, QAudioDeviceInfo

Constructor & Destructor Documentation

QAudioInput::QAudioInput	(	const QAudioFormat &	format = `QAudioFormat()`,
		QObject *	parent = `nullptr`
	)

explicit

Construct a new audio input and attach it to parent. The default audio input device is used with the output format parameters.

QAudioInput::QAudioInput	(	const QAudioDeviceInfo &	audioDeviceInfo,
		const QAudioFormat &	format = `QAudioFormat()`,
		QObject *	parent = `nullptr`
	)

explicit

Construct a new audio input and attach it to parent. The device referenced by audioDeviceInfo is used with the input format parameters.

QAudioInput::~QAudioInput ( )

Destroy this audio input.

Method Documentation

int QAudioInput::bufferSize ( ) const

Returns the audio buffer size in milliseconds.

If called before start(), returns platform default value. If called before start() but setBufferSize() was called prior, returns value set by setBufferSize(). If called after start(), returns the actual buffer size being used. This may not be what was set previously by setBufferSize().

See also: setBufferSize()

int QAudioInput::bytesReady ( ) const

Returns the amount of audio data available to read in bytes.

The returned value is only valid while in QAudio::ActiveState or QAudio::IdleState state, otherwise returns zero.

qint64 QAudioInput::elapsedUSecs ( ) const

Returns the microseconds since start() was called, including time in Idle and Suspend states.

QAudio::Error QAudioInput::error ( ) const

Returns the error state.

QAudioFormat QAudioInput::format ( ) const

Returns the QAudioFormat being used.

void QAudioInput::notify ( )

signal

This signal is emitted when x ms of audio data has been processed the interval set by setNotifyInterval(x).

int QAudioInput::notifyInterval ( ) const

Returns the notify interval in milliseconds.

See also: setNotifyInterval()

int QAudioInput::periodSize ( ) const

Returns the period size in bytes.

qint64 QAudioInput::processedUSecs ( ) const

Returns the amount of audio data processed since start() was called in microseconds.

void QAudioInput::reset ( )

Drops all audio data in the buffers, resets buffers to zero.

void QAudioInput::resume ( )

Resumes processing audio data after a suspend().

Sets error() to QAudio::NoError. Sets state() to QAudio::ActiveState if you previously called start(QIODevice*). Sets state() to QAudio::IdleState if you previously called start(). emits stateChanged() signal.

void QAudioInput::setBufferSize ( int bytes )

Sets the audio buffer size to bytes.

The method can be called anytime before start() is called. After start() has been called, this method has no effect. The actual buffer size may be rounded up. Calling bufferSize() after start() has been called will return the calculated buffer.

See also: bufferSize()

void QAudioInput::setNotifyInterval ( int milliSeconds )

Sets the interval for notify() signal to be emitted. This is based on the milliSeconds of audio data processed not on clock time. The minimum resolution of the timer is platform specific and values should be checked with notifyInterval() to confirm actual value being used.

See also: notifyInterval()

void QAudioInput::setVolume ( qreal volume )

Sets the value of the property to volume.

QIODevice * QAudioInput::start ( )

Returns a pointer to a new QIODevice that will be used to handle the data transfer. This QIODevice can be used to read() audio data directly. You will typically connect to the readyRead() signal, and read from the device in the slot you connect to. QAudioInput keeps ownership of the device.

If able to access the systems audio device the state() is set to QAudio::IdleState, error() is set to QAudio::NoError and the stateChanged() signal is emitted.

If a problem occurs during this process the error() is set to QAudio::OpenError, the state() is set to QAudio::StoppedState, and the stateChanged signal is emitted.

See also: QIODevice

void QAudioInput::start ( QIODevice * device )

Uses the device as the QIODevice to transfer data. Passing a QIODevice allows the data to be transferred without any extra code. All that is required is to open the QIODevice. QAudioInput does not take ownership of device.

The QAudioInput will write to the device when new data is available. You can subclass QIODevice and reimplement writeData() if you wish to access the data. If you simply want to save data to a file, you can pass a QFile to this function.

If able to successfully get audio data from the systems audio device the state() is set to either QAudio::ActiveState or QAudio::IdleState, error() is set to QAudio::NoError and the stateChanged() signal is emitted.

If a problem occurs during this process the error() is set to QAudio::OpenError, the state() is set to QAudio::StoppedState, and the stateChanged signal is emitted.

See also: QIODevice

QAudio::State QAudioInput::state ( ) const

Returns the state of audio processing.

void QAudioInput::stateChanged ( QAudio::State state )

signal

This signal is emitted when the device state has changed.

void QAudioInput::stop ( )

Stops the audio input, detaching from the system resource. Sets error() to QAudio::NoError, state() to QAudio::StoppedState and then emits the stateChanged() signal.

void QAudioInput::suspend ( )

Stops processing audio data, preserving buffered audio data. Sets error() to QAudio::NoError, state() to QAudio::SuspendedState, and emits the stateChanged() signal.

qreal QAudioInput::volume ( ) const

Returns the value of the property.

Public Signals

Public Methods

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

Method Documentation