Qt 5.9 | Qt Multimedia | C++ Classes | QMediaRecorder

Qt 5.9.4 Reference Documentation

# QMediaRecorder Class

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

Header: | #include <QMediaRecorder>
qmake: | QT += multimedia
Inherits: | QMediaBindableInterface and
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, ..., 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 = 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

- 1 public function inherited from QMediaBindableInterface

## Public Slots

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

## 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

- 1 protected function inherited from QMediaBindableInterface

## 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

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.

## 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().