QMediaRecorder Class

The QMediaRecorder class is used for encoding and recording a capture session. More...

Header:	#include <QMediaRecorder>
CMake:	find_package(Qt6 COMPONENTS Multimedia REQUIRED) target_link_libraries(mytarget PRIVATE Qt6::Multimedia)
qmake:	QT += multimedia
Instantiated By:	MediaRecorder
Inherits:	QObject

• List of all members, including inherited members

Public Types

enum	EncodingMode { ConstantQualityEncoding, ConstantBitRateEncoding, AverageBitRateEncoding, TwoPassEncoding }
enum	Error { NoError, ResourceError, FormatError, OutOfSpaceError, LocationNotWritable }
enum	Quality { VeryLowQuality, LowQuality, NormalQuality, HighQuality, VeryHighQuality }
enum	RecorderState { StoppedState, RecordingState, PausedState }

Properties

• actualLocation : const QUrl
• duration : const qint64
• outputLocation : QUrl
• recorderState : const QMediaRecorder::RecorderState

Public Functions

	QMediaRecorder(QObject *parent = nullptr)
virtual	~QMediaRecorder()
QUrl	actualLocation() const
int	audioBitRate() const
int	audioChannelCount() const
int	audioSampleRate() const
qint64	duration() const
QMediaRecorder::EncodingMode	encodingMode() const
QMediaRecorder::Error	error() const
QString	errorString() const
bool	isAvailable() const
QMediaFormat	mediaFormat() const
QMediaMetaData	metaData() const
QUrl	outputLocation() const
QMediaRecorder::Quality	quality() const
QMediaRecorder::RecorderState	recorderState() const
void	setAudioBitRate(int bitRate)
void	setAudioChannelCount(int channels)
void	setAudioSampleRate(int sampleRate)
void	setEncodingMode(QMediaRecorder::EncodingMode mode)
void	setMediaFormat(const QMediaFormat &format)
void	setMetaData(const QMediaMetaData &metaData)
void	setOutputLocation(const QUrl &location)
void	setQuality(QMediaRecorder::Quality quality)
void	setVideoBitRate(int bitRate)
void	setVideoFrameRate(qreal frameRate)
void	setVideoResolution(const QSize &size)
void	setVideoResolution(int width, int height)
int	videoBitRate() const
qreal	videoFrameRate() const
QSize	videoResolution() const

Public Slots

void	pause()
void	record()
void	stop()

Signals

void	actualLocationChanged(const QUrl &location)
void	durationChanged(qint64 duration)
void	errorChanged()
void	errorOccurred(QMediaRecorder::Error error, const QString &errorString)
void	mediaFormatChanged()
void	metaDataChanged()
void	recorderStateChanged(QMediaRecorder::RecorderState state)

Detailed Description

The QMediaRecorder class is a class for encoding and recording media generated in a QMediaCaptureSession.

QMediaCaptureSession session;
QAudioInput audioInput;
session.setAudioInput(&input);
QMediaRecorder recorder;
session.setMediaRecorder(&recorder);
recorder.setQuality(QMediaRecorder::HighQuality);
recorder.setOutputLocation(QUrl::fromLocalFile("test.mp3"));
recorder.record();

Member Type Documentation

enum QMediaRecorder::EncodingMode

Enumerates encoding modes.

Constant	Value	Description
QMediaRecorder::ConstantQualityEncoding	0	Encoding will aim to have a constant quality, adjusting bitrate to fit.
QMediaRecorder::ConstantBitRateEncoding	1	Encoding will use a constant bit rate, adjust quality to fit.
QMediaRecorder::AverageBitRateEncoding	2	Encoding will try to keep an average bitrate setting, but will use more or less as needed.
QMediaRecorder::TwoPassEncoding	3	The media will first be processed to determine the characteristics, and then processed a second time allocating more bits to the areas that need it.

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.
QMediaRecorder::LocationNotWritable	4	The output location is not writable.

enum QMediaRecorder::Quality

Enumerates quality encoding levels.

Constant	Value
QMediaRecorder::VeryLowQuality	0
QMediaRecorder::LowQuality	1
QMediaRecorder::NormalQuality	2
QMediaRecorder::HighQuality	3
QMediaRecorder::VeryHighQuality	4

enum QMediaRecorder::RecorderState

Constant	Value	Description
QMediaRecorder::StoppedState	0	The recorder is not active.
QMediaRecorder::RecordingState	1	The recording is requested.
QMediaRecorder::PausedState	2	The recorder is paused.

Member Function Documentation

QMediaRecorder::QMediaRecorder(QObject *parent = nullptr)

Constructs a media recorder which records the media produced by a microphone and camera. The media recorder is a child of parent.

[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::durationChanged(qint64 duration)

Signals that the duration of the recorded media has changed.

Note: Notifier signal for property duration.

[signal] void QMediaRecorder::errorOccurred(QMediaRecorder::Error error, const QString &errorString)

Signals that an error has occurred, with errorString containing a description of the error.

[signal] void QMediaRecorder::metaDataChanged()

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

If multiple meta-data elements are changed metaDataChanged() is emitted once.

Note: Notifier signal for property metaData.

[slot] void QMediaRecorder::pause()

Pauses recording.

The recorder state is changed to QMediaRecorder::PausedState.

Depending on the platform, pausing recording may be not supported. In this case the recorder state is unchanged.

[slot] void QMediaRecorder::record()

Start recording.

While the recorder state is changed immediately to c{QMediaRecorder::RecordingState}, recording may start asynchronously.

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

[signal] void QMediaRecorder::recorderStateChanged(QMediaRecorder::RecorderState state)

Signals that a media recorder's state has changed.

Note: Notifier signal for property recorderState.

[slot] void QMediaRecorder::stop()

Stops recording.

The recorder state is changed to QMediaRecorder::StoppedState.

[virtual] QMediaRecorder::~QMediaRecorder()

Destroys a media recorder object.

int QMediaRecorder::audioBitRate() const

Returns the bit rate of the compressed audio stream in bits per second.

See also setAudioBitRate().

int QMediaRecorder::audioChannelCount() const

Returns the number of audio channels.

See also setAudioChannelCount().

int QMediaRecorder::audioSampleRate() const

Returns the audio sample rate in Hz.

See also setAudioSampleRate().

QMediaRecorder::EncodingMode QMediaRecorder::encodingMode() const

Returns the encoding mode.

See also setEncodingMode() and EncodingMode.

QMediaRecorder::Error QMediaRecorder::error() const

Returns the current error state.

Note: Getter function for property error.

See also errorString().

QString QMediaRecorder::errorString() const

Returns a string describing the current error state.

Note: Getter function for property errorString.

See also error().

bool QMediaRecorder::isAvailable() const

Returns true if media recorder service ready to use.

QMediaMetaData QMediaRecorder::metaData() const

Returns the metaData associated with the recording.

Note: Getter function for property metaData.

See also setMetaData().

QMediaRecorder::RecorderState QMediaRecorder::recorderState() const

Returns the current media recorder state.

Note: Getter function for property recorderState.

See also QMediaRecorder::RecorderState.

void QMediaRecorder::setAudioBitRate(int bitRate)

Sets the audio bitRate in bits per second.

See also audioBitRate().

void QMediaRecorder::setAudioChannelCount(int channels)

Sets the number of audio channels.

A value of -1 indicates the recorder should make an optimal choice based on what is available from the audio source and the limitations of the codec.

See also audioChannelCount().

void QMediaRecorder::setAudioSampleRate(int sampleRate)

Sets the audio sampleRate in Hz.

A value of -1 indicates the recorder should make an optimal choice based on what is available from the audio source, and the limitations of the codec.

See also audioSampleRate().

void QMediaRecorder::setEncodingMode(QMediaRecorder::EncodingMode mode)

Sets the encoding mode setting.

If ConstantQualityEncoding is set, the quality encoding parameter is used and bit rates are ignored, otherwise the bitrates are used.

See also encodingMode() and EncodingMode.

void QMediaRecorder::setMetaData(const QMediaMetaData &metaData)

Sets the meta data to metaData.

Note: Setter function for property metaData.

See also metaData().

void QMediaRecorder::setVideoBitRate(int bitRate)

Sets the video bitRate in bits per second.

See also videoBitRate().

void QMediaRecorder::setVideoFrameRate(qreal frameRate)

Sets the video frameRate.

A value of 0 indicates the recorder should make an optimal choice based on what is available from the video source and the limitations of the codec.

See also videoFrameRate().

void QMediaRecorder::setVideoResolution(const QSize &size)

Sets the resolution of the encoded video to size.

Pass an empty QSize to make the recorder choose an optimal resolution based on what is available from the video source and the limitations of the codec.

See also videoResolution().

void QMediaRecorder::setVideoResolution(int width, int height)

Sets the width and height of the resolution of the encoded video.

This is an overloaded function.

int QMediaRecorder::videoBitRate() const

Returns the bit rate of the compressed video stream in bits per second.

See also setVideoBitRate().

qreal QMediaRecorder::videoFrameRate() const

Returns the video frame rate.

See also setVideoFrameRate().

QSize QMediaRecorder::videoResolution() const

Returns the resolution of the encoded video.

See also setVideoResolution().