QMediaRecorder Class

The QMediaRecorder class is used for the recording of media content. More...

Header:	#include <QMediaRecorder>
qmake:	QT += multimedia
Inherits:	QObject and QMediaBindableInterface
Inherited By:	QAudioRecorder

• List of all members, including inherited members

Public Types

enum	Error { NoError, ResourceError, FormatError, OutOfSpaceError }
enum	State { StoppedState, RecordingState, PausedState }
enum	Status { UnavailableStatus, UnloadedStatus, LoadingStatus, LoadedStatus, StartingStatus, …, FinalizingStatus }

Properties

actualLocation : const QUrl duration : const qint64 metaDataAvailable : const bool metaDataWritable : const bool muted : bool

outputLocation : QUrl state : const QMediaRecorder::State status : const QMediaRecorder::Status volume : qreal

Public Functions

	QMediaRecorder(QMediaObject *mediaObject, QObject *parent = nullptr)
virtual	~QMediaRecorder()
QUrl	actualLocation() const
QString	audioCodecDescription(const QString &codec) const
QAudioEncoderSettings	audioSettings() const
QMultimedia::AvailabilityStatus	availability() const
QStringList	availableMetaData() const
QString	containerDescription(const QString &format) const
QString	containerFormat() const
qint64	duration() const
QMediaRecorder::Error	error() const
QString	errorString() const
bool	isAvailable() const
bool	isMetaDataAvailable() const
bool	isMetaDataWritable() const
bool	isMuted() const
QVariant	metaData(const QString &key) const
QUrl	outputLocation() const
void	setAudioSettings(const QAudioEncoderSettings &settings)
void	setContainerFormat(const QString &container)
void	setEncodingSettings(const QAudioEncoderSettings &audio, const QVideoEncoderSettings &video = QVideoEncoderSettings(), const QString &container = QString())
void	setMetaData(const QString &key, const QVariant &value)
bool	setOutputLocation(const QUrl &location)
void	setVideoSettings(const QVideoEncoderSettings &settings)
QMediaRecorder::State	state() const
QMediaRecorder::Status	status() const
QStringList	supportedAudioCodecs() const
QList<int>	supportedAudioSampleRates(const QAudioEncoderSettings &settings = QAudioEncoderSettings(), bool *continuous = nullptr) const
QStringList	supportedContainers() const
QList<qreal>	supportedFrameRates(const QVideoEncoderSettings &settings = QVideoEncoderSettings(), bool *continuous = nullptr) const
QList<QSize>	supportedResolutions(const QVideoEncoderSettings &settings = QVideoEncoderSettings(), bool *continuous = nullptr) const
QStringList	supportedVideoCodecs() const
QString	videoCodecDescription(const QString &codec) const
QVideoEncoderSettings	videoSettings() const
qreal	volume() const

Reimplemented Public Functions

virtual QMediaObject *

mediaObject() const override

Public Slots

void	pause()
void	record()
void	setMuted(bool muted)
void	setVolume(qreal volume)
void	stop()

Signals

void	actualLocationChanged(const QUrl &location)
void	availabilityChanged(QMultimedia::AvailabilityStatus availability)
void	availabilityChanged(bool available)
void	durationChanged(qint64 duration)
void	error(QMediaRecorder::Error error)
void	metaDataAvailableChanged(bool available)
void	metaDataChanged(const QString &key, const QVariant &value)
void	metaDataChanged()
void	metaDataWritableChanged(bool writable)
void	mutedChanged(bool muted)
void	stateChanged(QMediaRecorder::State state)
void	statusChanged(QMediaRecorder::Status status)
void	volumeChanged(qreal volume)

Detailed Description

The QMediaRecorder class is a high level media recording class. It's not intended to be used alone but for accessing the media recording functions of other media objects, like QRadioTuner, or QCamera.

recorder = new QMediaRecorder(camera);

QAudioEncoderSettings audioSettings;
audioSettings.setCodec("audio/amr");
audioSettings.setQuality(QMultimedia::HighQuality);

recorder->setAudioSettings(audioSettings);

recorder->setOutputLocation(QUrl::fromLocalFile(fileName));
recorder->record();

See also QAudioRecorder.

Member Type Documentation

enum QMediaRecorder::Error

Constant	Value	Description
QMediaRecorder::NoError	0	No Errors.
QMediaRecorder::ResourceError	1	Device is not ready or not available.
QMediaRecorder::FormatError	2	Current format is not supported.
QMediaRecorder::OutOfSpaceError	3	No space left on device.

enum QMediaRecorder::State

Constant	Value	Description
QMediaRecorder::StoppedState	0	The recorder is not active. If this is the state after recording then the actual created recording has finished being written to the final location and is ready on all platforms except on Android. On Android, due to platform limitations, there is no way to be certain that the recording has finished writing to the final location.
QMediaRecorder::RecordingState	1	The recording is requested.
QMediaRecorder::PausedState	2	The recorder is paused.

enum QMediaRecorder::Status

Constant	Value	Description
QMediaRecorder::UnavailableStatus	0	The recorder is not available or not supported by connected media object.
QMediaRecorder::UnloadedStatus	1	The recorder is avilable but not loaded.
QMediaRecorder::LoadingStatus	2	The recorder is initializing.
QMediaRecorder::LoadedStatus	3	The recorder is initialized and ready to record media.
QMediaRecorder::StartingStatus	4	Recording is requested but not active yet.
QMediaRecorder::RecordingStatus	5	Recording is active.
QMediaRecorder::PausedStatus	6	Recording is paused.
QMediaRecorder::FinalizingStatus	7	Recording is stopped with media being finalized.

Member Function Documentation

QMediaRecorder::QMediaRecorder(QMediaObject *mediaObject, QObject *parent = nullptr)

Constructs a media recorder which records the media produced by mediaObject.

The parent is passed to QMediaObject.

[signal] void QMediaRecorder::actualLocationChanged(const QUrl &location)

Signals that the actual location of the recorded media has changed. This signal is usually emitted when recording starts.

Note: Notifier signal for property actualLocation.

[signal] void QMediaRecorder::availabilityChanged(QMultimedia::AvailabilityStatus availability)

Signals that the service availability has changed to availability.

Note: Signal availabilityChanged is overloaded in this class. To connect to this signal by using the function pointer syntax, Qt provides a convenient helper for obtaining the function pointer as shown in this example:

connect(mediaRecorder, QOverload<QMultimedia::AvailabilityStatus>::of(&QMediaRecorder::availabilityChanged),
    [=](QMultimedia::AvailabilityStatus availability){ /* ... */ });

[signal] void QMediaRecorder::availabilityChanged(bool available)

Signals that the media recorder is now available (if available is true), or not.

Note: Signal availabilityChanged is overloaded in this class. To connect to this signal by using the function pointer syntax, Qt provides a convenient helper for obtaining the function pointer as shown in this example:

connect(mediaRecorder, QOverload<bool>::of(&QMediaRecorder::availabilityChanged),
    [=](bool available){ /* ... */ });

[signal] void QMediaRecorder::durationChanged(qint64 duration)

Signals that the duration of the recorded media has changed.

Note: Notifier signal for property duration.

[signal] void QMediaRecorder::error(QMediaRecorder::Error error)

Signals that an error has occurred.

Note: Signal error is overloaded in this class. To connect to this signal by using the function pointer syntax, Qt provides a convenient helper for obtaining the function pointer as shown in this example:

connect(mediaRecorder, QOverload<QMediaRecorder::Error>::of(&QMediaRecorder::error),
    [=](QMediaRecorder::Error error){ /* ... */ });

[signal] void QMediaRecorder::metaDataAvailableChanged(bool available)

Signals that the available state of a media object's meta-data has changed.

Note: Notifier signal for property metaDataAvailable.

[signal] void QMediaRecorder::metaDataChanged(const QString &key, const QVariant &value)

Signal the changes of one meta-data element value with the given key.

Note: Signal metaDataChanged is overloaded in this class. To connect to this signal by using the function pointer syntax, Qt provides a convenient helper for obtaining the function pointer as shown in this example:

connect(mediaRecorder, QOverload<const QString &, const QVariant &>::of(&QMediaRecorder::metaDataChanged),
    [=](const QString &key, const QVariant &value){ /* ... */ });

[signal] void QMediaRecorder::metaDataChanged()

Signals that a media object's meta-data has changed.

If multiple meta-data elements are changed, metaDataChanged(const QString &key, const QVariant &value) signal is emitted for each of them with metaDataChanged() changed emitted once.

Note: Signal metaDataChanged is overloaded in this class. To connect to this signal by using the function pointer syntax, Qt provides a convenient helper for obtaining the function pointer as shown in this example:

connect(mediaRecorder, QOverload<>::of(&QMediaRecorder::metaDataChanged),
    [=](){ /* ... */ });

[signal] void QMediaRecorder::metaDataWritableChanged(bool writable)

Signals that the writable state of a media object's meta-data has changed.

Note: Notifier signal for property metaDataWritable.

[signal] void QMediaRecorder::mutedChanged(bool muted)

Signals that the muted state has changed. If true the recording is being muted.

Note: Notifier signal for property muted.

[slot] void QMediaRecorder::pause()

Pause recording.

The recorder state is changed to QMediaRecorder::PausedState.

Depending on platform recording pause may be not supported, in this case the recorder state stays unchanged.

[slot] void QMediaRecorder::record()

Start recording.

While the recorder state is changed immediately to QMediaRecorder::RecordingState, recording may start asynchronously, with statusChanged(QMediaRecorder::RecordingStatus) signal emitted when recording starts.

If recording fails error() signal is emitted with recorder state being reset back to QMediaRecorder::StoppedState.

[signal] void QMediaRecorder::stateChanged(QMediaRecorder::State state)

Signals that a media recorder's state has changed.

Note: Notifier signal for property state.

[slot] void QMediaRecorder::stop()

Stop recording.

The recorder state is changed to QMediaRecorder::StoppedState.

[virtual] QMediaRecorder::~QMediaRecorder()

Destroys a media recorder object.

QString QMediaRecorder::audioCodecDescription(const QString &codec) const

Returns a description of an audio codec.

QAudioEncoderSettings QMediaRecorder::audioSettings() const

Returns the audio encoder settings being used.

See also setAudioSettings() and setEncodingSettings().

QMultimedia::AvailabilityStatus QMediaRecorder::availability() const

Returns the availability of this functionality.

See also availabilityChanged().

QStringList QMediaRecorder::availableMetaData() const

Returns a list of keys there is meta-data available for.

QString QMediaRecorder::containerDescription(const QString &format) const

Returns a description of a container format.

QString QMediaRecorder::containerFormat() const

Returns the selected container format.

See also setContainerFormat().

QMediaRecorder::Error QMediaRecorder::error() const

Returns the current error state.

See also errorString().

QString QMediaRecorder::errorString() const

Returns a string describing the current error state.

See also error().

bool QMediaRecorder::isAvailable() const

Returns true if media recorder service ready to use.

See also availabilityChanged().

[override virtual] QMediaObject *QMediaRecorder::mediaObject() const

Reimplements: QMediaBindableInterface::mediaObject() const.

Returns the QMediaObject instance that this QMediaRecorder is bound too, or 0 otherwise.

QVariant QMediaRecorder::metaData(const QString &key) const

Returns the value associated with a meta-data key.

See also setMetaData().

void QMediaRecorder::setAudioSettings(const QAudioEncoderSettings &settings)

Sets the audio encoder settings.

If some parameters are not specified, or null settings are passed, the encoder will choose default encoding parameters, depending on media source properties.

It's only possible to change settings when the encoder is in the QMediaEncoder::StoppedState state.

See also audioSettings(), videoSettings(), and containerFormat().

void QMediaRecorder::setContainerFormat(const QString &container)

Sets the media container format.

If the container format is not specified, the encoder will choose format, depending on media source properties and encoding settings selected.

It's only possible to change settings when the encoder is in the QMediaEncoder::StoppedState state.

See also audioSettings(), videoSettings(), and containerFormat().

void QMediaRecorder::setEncodingSettings(const QAudioEncoderSettings &audio, const QVideoEncoderSettings &video = QVideoEncoderSettings(), const QString &container = QString())

Sets the audio and video encoder settings and container format.

If some parameters are not specified, or null settings are passed, the encoder will choose default encoding parameters, depending on media source properties.

It's only possible to change settings when the encoder is in the QMediaEncoder::StoppedState state.

See also audioSettings(), videoSettings(), and containerFormat().

void QMediaRecorder::setMetaData(const QString &key, const QVariant &value)

Sets a value for a meta-data key.

Note: To ensure that meta data is set corretly, it should be set before starting the recording. Once the recording is stopped, any meta data set will be attached to the next recording.

See also metaData().

void QMediaRecorder::setVideoSettings(const QVideoEncoderSettings &settings)

Sets the video encoder settings.

If some parameters are not specified, or null settings are passed, the encoder will choose default encoding parameters, depending on media source properties.

It's only possible to change settings when the encoder is in the QMediaEncoder::StoppedState state.

See also audioSettings(), videoSettings(), and containerFormat().

QMediaRecorder::State QMediaRecorder::state() const

Returns the current media recorder state.

Note: Getter function for property state.

See also QMediaRecorder::State.

QMediaRecorder::Status QMediaRecorder::status() const

Returns the current media recorder status.

Note: Getter function for property status.

See also QMediaRecorder::Status.

QStringList QMediaRecorder::supportedAudioCodecs() const

Returns a list of supported audio codecs.

QList<int> QMediaRecorder::supportedAudioSampleRates(const QAudioEncoderSettings &settings = QAudioEncoderSettings(), bool *continuous = nullptr) const

Returns a list of supported audio sample rates.

If non null audio settings parameter is passed, the returned list is reduced to sample rates supported with partial settings applied.

This can be used to query the list of sample rates, supported by specific audio codec.

If the encoder supports arbitrary sample rates within the supported rates range, *continuous is set to true, otherwise *continuous is set to false.

QStringList QMediaRecorder::supportedContainers() const

Returns a list of supported container formats.

QList<qreal> QMediaRecorder::supportedFrameRates(const QVideoEncoderSettings &settings = QVideoEncoderSettings(), bool *continuous = nullptr) const

Returns a list of frame rates video can be encoded at.

If non null video settings parameter is passed, the returned list is reduced to frame rates supported with partial settings like video codec or resolution applied.

If the encoder supports arbitrary frame rates within the supported range, *continuous is set to true, otherwise *continuous is set to false.

See also QVideoEncoderSettings::frameRate().

QList<QSize> QMediaRecorder::supportedResolutions(const QVideoEncoderSettings &settings = QVideoEncoderSettings(), bool *continuous = nullptr) const

Returns a list of resolutions video can be encoded at.

If non null video settings parameter is passed, the returned list is reduced to resolution supported with partial settings like video codec or framerate applied.

If the encoder supports arbitrary resolutions within the supported range, *continuous is set to true, otherwise *continuous is set to false.

See also QVideoEncoderSettings::resolution().

QStringList QMediaRecorder::supportedVideoCodecs() const

Returns a list of supported video codecs.

QString QMediaRecorder::videoCodecDescription(const QString &codec) const

Returns a description of a video codec.

See also setEncodingSettings().

QVideoEncoderSettings QMediaRecorder::videoSettings() const

Returns the video encoder settings being used.

See also setVideoSettings() and setEncodingSettings().