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

Public Types

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

Properties

  • 1 property inherited from QObject

Public Functions

QMediaRecorder(QMediaObject *mediaObject, QObject *parent = Q_NULLPTR)
~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
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)
State state() const
Status status() const
QStringList supportedAudioCodecs() const
QList<int> supportedAudioSampleRates(const QAudioEncoderSettings &settings = QAudioEncoderSettings(), bool *continuous = Q_NULLPTR) const
QStringList supportedContainers() const
QList<qreal> supportedFrameRates(const QVideoEncoderSettings &settings = QVideoEncoderSettings(), bool *continuous = Q_NULLPTR) const
QList<QSize> supportedResolutions(const QVideoEncoderSettings &settings = QVideoEncoderSettings(), bool *continuous = Q_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()
  • 1 public slot inherited from QObject

Signals

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

Additional Inherited Members

Detailed Description

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

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

ConstantValueDescription
QMediaRecorder::NoError0No Errors.
QMediaRecorder::ResourceError1Device is not ready or not available.
QMediaRecorder::FormatError2Current format is not supported.
QMediaRecorder::OutOfSpaceError3No space left on device.

enum QMediaRecorder::State

ConstantValueDescription
QMediaRecorder::StoppedState0The 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::RecordingState1The recording is requested.
QMediaRecorder::PausedState2The recorder is paused.

enum QMediaRecorder::Status

ConstantValueDescription
QMediaRecorder::UnavailableStatus0The recorder is not available or not supported by connected media object.
QMediaRecorder::UnloadedStatus1The recorder is avilable but not loaded.
QMediaRecorder::LoadingStatus2The recorder is initializing.
QMediaRecorder::LoadedStatus3The recorder is initialized and ready to record media.
QMediaRecorder::StartingStatus4Recording is requested but not active yet.
QMediaRecorder::RecordingStatus5Recording is active.
QMediaRecorder::PausedStatus6Recording is paused.
QMediaRecorder::FinalizingStatus7Recording is stopped with media being finalized.

Property Documentation

actualLocation : const QUrl

This property holds the actual location of the last media content.

The actual location is usually available after recording starts, and reset when new location is set or new recording starts.

Access functions:

QUrl actualLocation() const

Notifier signal:

void actualLocationChanged(const QUrl &location)

duration : const qint64

This property holds the recorded media duration in milliseconds.

Access functions:

qint64 duration() const

Notifier signal:

void durationChanged(qint64 duration)

metaDataAvailable : const bool

This property holds whether access to a media object's meta-data is available.

If this is true there is meta-data available, otherwise there is no meta-data available.

Access functions:

bool isMetaDataAvailable() const

Notifier signal:

void metaDataAvailableChanged(bool available)

metaDataWritable : const bool

This property holds whether a media object's meta-data is writable.

If this is true the meta-data is writable, otherwise the meta-data is read-only.

Access functions:

bool isMetaDataWritable() const

Notifier signal:

void metaDataWritableChanged(bool writable)

muted : bool

This property holds whether a recording audio stream is muted.

Access functions:

bool isMuted() const
void setMuted(bool muted)

Notifier signal:

void mutedChanged(bool muted)

outputLocation : QUrl

This property holds the destination location of media content.

Setting the location can fail, for example when the service supports only local file system locations but a network URL was passed. If the service does not support media recording this setting the output location will always fail.

The location can be relative or empty; in this case the recorder uses the system specific place and file naming scheme. After recording has stated, QMediaRecorder::outputLocation() returns the actual output location.

Access functions:

QUrl outputLocation() const
bool setOutputLocation(const QUrl &location)

state : const QMediaRecorder::State

This property holds the current state of the media recorder.

The state property represents the user request and is changed synchronously during record(), pause() or stop() calls. Recorder state may also change asynchronously when recording fails.

Access functions:

State state() const

Notifier signal:

void stateChanged(QMediaRecorder::State state)

status : const QMediaRecorder::Status

This property holds the current status of the media recorder.

The status is changed asynchronously and represents the actual status of media recorder.

Access functions:

Status status() const

Notifier signal:

void statusChanged(QMediaRecorder::Status status)

volume : qreal

This property holds the current recording audio volume.

The volume is scaled linearly from 0.0 (silence) to 1.0 (full volume). Values outside this range will be clamped.

The default volume is 1.0.

UI volume controls should usually be scaled nonlinearly. For example, using a logarithmic scale will produce linear changes in perceived loudness, which is what a user would normally expect from a volume control. See QAudio::convertVolume() for more details.

Access functions:

qreal volume() const
void setVolume(qreal volume)

Notifier signal:

void volumeChanged(qreal volume)

Member Function Documentation

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

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

The parent is passed to QMediaObject.

QMediaRecorder::~QMediaRecorder()

Destroys a media recorder object.

[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.

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().

[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 one using the function pointer syntax, you must specify the signal type in a static cast, as shown in this example:

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

[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 one using the function pointer syntax, you must specify the signal type in a static cast, as shown in this example:

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

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().

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

Signals that the duration of the recorded media has changed.

Note: Notifier signal for property duration.

Error QMediaRecorder::error() const

Returns the current error state.

See also errorString().

[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 one using the function pointer syntax, you must specify the signal type in a static cast, as shown in this example:

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

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

Reimplemented from QMediaBindableInterface::mediaObject().

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().

[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()

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 one using the function pointer syntax, you must specify the signal type in a static cast, as shown in this example:

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

[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 one using the function pointer syntax, you must specify the signal type in a static cast, as shown in this example:

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

[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.

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().

State QMediaRecorder::state() const

Returns the current media recorder state.

Note: Getter function for property state.

See also QMediaRecorder::State.

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

Signals that a media recorder's state has changed.

Note: Notifier signal for property state.

Status QMediaRecorder::status() const

Returns the current media recorder status.

Note: Getter function for property status.

See also QMediaRecorder::Status.

[slot] void QMediaRecorder::stop()

Stop recording.

The recorder state is changed to QMediaRecorder::StoppedState.

QStringList QMediaRecorder::supportedAudioCodecs() const

Returns a list of supported audio codecs.

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

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