QMediaRecorder 类用于编码和录制捕获会话。 更多...
| 头: |
#include <QMediaRecorder>
|
| CMake: |
find_package(Qt6 REQUIRED COMPONENTS Multimedia)
target_link_libraries(mytarget PRIVATE Qt6::Multimedia)
|
| qmake: |
QT += multimedia
|
| 在 QML: | MediaRecorder |
| 继承: | QObject |
| 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 } |
|
|
| QMediaRecorder (QObject * parent = nullptr) | |
| virtual | ~QMediaRecorder () override |
| QUrl | actualLocation () const |
| void | addMetaData (const QMediaMetaData & metaData ) |
| int | audioBitRate () const |
| int | audioChannelCount () const |
| int | audioSampleRate () const |
| bool | autoStop () const |
| QMediaCaptureSession * | captureSession () const |
| qint64 | duration () const |
| QMediaRecorder::EncodingMode | encodingMode () const |
| QMediaRecorder::Error | error () const |
| QString | errorString () const |
| bool | isAvailable () const |
| QMediaFormat | mediaFormat () const |
| QMediaMetaData | metaData () const |
| QIODevice * | outputDevice () 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 | setAutoStop (bool autoStop ) |
| void | setEncodingMode (QMediaRecorder::EncodingMode mode ) |
| void | setMediaFormat (const QMediaFormat & format ) |
| void | setMetaData (const QMediaMetaData & metaData ) |
| void | setOutputDevice (QIODevice * device ) |
| 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 |
| void | pause () |
| void | record () |
| void | stop () |
| void | actualLocationChanged (const QUrl & location ) |
| void | audioBitRateChanged () |
| void | audioChannelCountChanged () |
| void | audioSampleRateChanged () |
| void | autoStopChanged () |
| void | durationChanged (qint64 duration ) |
| void | encoderSettingsChanged () |
| void | encodingModeChanged () |
| void | errorChanged () |
| void | errorOccurred (QMediaRecorder::Error error , const QString & errorString ) |
| void | mediaFormatChanged () |
| void | metaDataChanged () |
| void | qualityChanged () |
| void | recorderStateChanged (QMediaRecorder::RecorderState state ) |
| void | videoBitRateChanged () |
| void | videoFrameRateChanged () |
| void | videoResolutionChanged () |
Use the QMediaRecorder class to encode and record media generated in QMediaCaptureSession . You can generate:
To record media, connect a generator to a corresponding media capture session.
Performance of video encoding and recording is limited by the hardware, the operating system, the installed graphic drivers, and the input video format. If
QCamera
,
QScreenCapture
,或
QWindowCapture
produces video frames faster than
QMediaRecorder
can encode and record them, the recorder may drop some frames. This is likely to occur if the input frame resolution is high, 4K for example, and hardware-accelerated encoding is unavailable. If you generate input video via
QVideoFrameInput
, the method
QVideoFrameInput::sendVideoFrame
will do nothing and return
false
whenever this limitation is reached and the internal frame queue is full. Rely on the signal
QVideoFrameInput::readyToSendVideoFrame
to know when the recorder is ready to receive new frames again. If you cannot change the rate of video frame generation and dropping frames is undesirable, we recommend implementing your own frame queue on top of
QVideoFrameInput
, considering the memory limitations of the hardware.
QMediaCaptureSession session; QAudioInput audioInput; session.setAudioInput(&input); QMediaRecorder recorder; session.setRecorder(&recorder); recorder.setQuality(QMediaRecorder::HighQuality); recorder.setOutputLocation(QUrl::fromLocalFile("test.mp3")); recorder.record();
枚举编码模式。
| 常量 | 值 | 描述 |
|---|---|---|
QMediaRecorder::ConstantQualityEncoding
|
0
|
编码的目标是拥有常量品质,调节比特率以拟合。 |
QMediaRecorder::ConstantBitRateEncoding
|
1
|
编码将使用常量比特率,调节品质以拟合。 |
QMediaRecorder::AverageBitRateEncoding
|
2
|
编码将试着保持平均比特率设置,但会根据需要使用更多 (或更少)。 |
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. |
| 常量 | 值 | 描述 |
|---|---|---|
QMediaRecorder::NoError
|
0
|
没有错误。 |
QMediaRecorder::ResourceError
|
1
|
设备未就绪 (或不可用)。 |
QMediaRecorder::FormatError
|
2
|
不支持当前格式。 |
QMediaRecorder::OutOfSpaceError
|
3
|
设备没有剩余空间。 |
QMediaRecorder::LocationNotWritable
|
4
|
输出位置不可写。 |
枚举品质编码级别。
| 常量 | 值 |
|---|---|
QMediaRecorder::VeryLowQuality
|
0
|
QMediaRecorder::LowQuality
|
1
|
QMediaRecorder::NormalQuality
|
2
|
QMediaRecorder::HighQuality
|
3
|
QMediaRecorder::VeryHighQuality
|
4
|
| 常量 | 值 | 描述 |
|---|---|---|
QMediaRecorder::StoppedState
|
0
|
录制器不活动。 |
QMediaRecorder::RecordingState
|
1
|
请求录制。 |
QMediaRecorder::PausedState
|
2
|
录制器暂停。 |
[read-only]
actualLocation
: const
QUrl
此特性保持最后媒体内容的实际位置。
The actual location is reset when a new
outputLocation
or a non-null
outputDevice
is assigned. When
record
() is invoked and
outputDevice
is
null
or not writable, the recorder generates the actual location basing on the following rules.
outputLocation
is empty, a directory, or a file without an extension, the recorder generates the appropriate extension based on the selected media format and system MIME types.
outputLocation
is a directory, the recorder generates a new file name within it.
outputLocation
is empty, the recorder generates a new file name in the system-specific directory for audio or video.
recorderStateChanged(RecordingState)
.
访问函数:
| QUrl | actualLocation () const |
通知程序信号:
| void | actualLocationChanged (const QUrl & location ) |
This property controls whether the media recorder stops automatically when all media inputs have reported the end of the stream or have been deactivated.
The end of the stream is reported by sending an empty media frame, which you can send explicitly via QVideoFrameInput or QAudioBufferInput .
Video inputs, specificly,
QCamera
,
QScreenCapture
and
QWindowCapture
, can be deactivated via the function
setActive
.
默认为
false
.
QMediaRecorder::autoStop is only supported with the FFmpeg backend.
访问函数:
| bool | autoStop () const |
| void | setAutoStop (bool autoStop ) |
通知程序信号:
| void | autoStopChanged () |
另请参阅 QCamera , QScreenCapture ,和 QWindowCapture .
[read-only]
duration
: const
qint64
此特性保持录制媒体的持续时间 (以毫秒为单位)。
访问函数:
| qint64 | duration () const |
通知程序信号:
| void | durationChanged (qint64 duration ) |
[read-only]
error
: const
QMediaRecorder::Error
返回当前错误状态。
访问函数:
| QMediaRecorder::Error | error () const |
通知程序信号:
| void | errorChanged () |
另请参阅 errorString ().
[read-only]
errorString
: const
QString
返回描述当前错误状态的字符串。
访问函数:
| QString | errorString () const |
通知程序信号:
| void | errorChanged () |
另请参阅 error ().
This property holds the current QMediaFormat of the recorder.
The value of this property may change when invoking record (). If this happens, the mediaFormatChanged() signal will be emitted. This will always happen if the QMediaFormat::audioCodec or QMediaFormat::fileFormat properties are set to unspecified. If a video source ( QCamera , QScreenCapture ,或 QVideoFrameInput ) is connected to the QMediaCaptureSession , QMediaFormat::videoCodec must also be specified. The QMediaFormat::audioCodec and QMediaFormat::videoCodec property values may also change if the media backend does not support the selected file format or codec.
The
QMediaFormat::fileFormat
property value may also change to an
audio
only format if a video format was requested, but
QMediaCaptureSession
does not have a video source connected. For example, if
QMediaFormat::fileFormat
被设为
QMediaFormat::MPEG4
, it may be changed to
QMediaFormat::Mpeg4Audio
.
Applications can determine if
mediaFormat
will change before recording starts by calling the
QMediaFormat::isSupported
() function. When recording without any video inputs,
record
() will not be changed the
QMediaFormat
if the following is true:
true
When recording with video input,
mediaFormat
will not be changed if the following is true:
true
注意: The QMediaRecorder does not take the file name extension from the outputLocation property into account when determining the QMediaFormat::fileFormat , and will not adjust the extension of the outputLocation QUrl to match the selected file format if an extension is specified. Applications should therefore make sure to set the QMediaRecorder::mediaFormat::fileFormat to match the file extension, or not specify a file extension. If no file extension is specified, the actualLocation file extension will be updated to match the file format used for recording.
访问函数:
| QMediaFormat | mediaFormat () const |
| void | setMediaFormat (const QMediaFormat & format ) |
通知程序信号:
| void | mediaFormatChanged () |
另请参阅 QMediaFormat::isSupported () 和 actualLocation .
返回录制关联的 metaData。
访问函数:
| QMediaMetaData | metaData () const |
| void | setMetaData (const QMediaMetaData & metaData ) |
通知程序信号:
| void | metaDataChanged () |
此特性保持媒体内容的目的地位置。
Setting the location can fail, for example when the service supports only local file system locations but a network URL was passed. If the operation fails, the errorOccured() signal is emitted.
The output location is ignored if a writable
outputDevice
has been assigned to the recorder. This behavior may change in the future, so we recommend setting only one output, either
outputLocation
or
outputDevice
.
The output location can be empty, a directory, or a file. The path to a directory or file can be relative or absolute. The record () method generates the actual location according to the specified output location and system-specific settings. Refer to the actualLocation property description for details.
访问函数:
| QUrl | outputLocation () const |
| void | setOutputLocation (const QUrl & location ) |
另请参阅 actualLocation and outputDevice ().
返回录制品质。
访问函数:
| QMediaRecorder::Quality | quality () const |
| void | setQuality (QMediaRecorder::Quality quality ) |
通知程序信号:
| void | qualityChanged () |
[read-only]
recorderState
: const
QMediaRecorder::RecorderState
此特性保持媒体录制器的当前状态。
The state property represents the user request and is changed synchronously during record (), pause () 或 stop () calls. Recorder state may also change asynchronously when recording fails.
访问函数:
| QMediaRecorder::RecorderState | recorderState () const |
通知程序信号:
| void | recorderStateChanged (QMediaRecorder::RecorderState state ) |
Constructs a media recorder. The media recorder is a child of parent .
[override virtual noexcept]
QMediaRecorder::
~QMediaRecorder
()
销毁媒体录制器对象。
[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.
注意: 通知程序信号对于特性 actualLocation .
添加 metaData 到录制媒体。
Returns the bit rate of the compressed audio stream in bits per second.
注意: getter 函数对于特性 audioBitRate。
另请参阅 setAudioBitRate ().
[signal]
void
QMediaRecorder::
audioBitRateChanged
()
Signals when the recording audio bit rate changes.
注意: 通知程序信号对于特性 audioBitRate .
Returns the number of audio channels.
注意: Getter function for property audioChannelCount.
另请参阅 setAudioChannelCount ().
[signal]
void
QMediaRecorder::
audioChannelCountChanged
()
Signals when the recording audio channel count changes.
注意: 通知程序信号对于特性 audioChannelCount .
Returns the audio sample rate in Hz.
注意: Getter function for property audioSampleRate.
另请参阅 setAudioSampleRate ().
[signal]
void
QMediaRecorder::
audioSampleRateChanged
()
Signals when the recording audio sample rate changes.
注意: 通知程序信号对于特性 audioSampleRate .
Returns the media capture session.
[signal]
void
QMediaRecorder::
durationChanged
(
qint64
duration
)
发射信号,当 duration of the recorded media has changed.
注意: 通知程序信号对于特性 duration .
[signal]
void
QMediaRecorder::
encoderSettingsChanged
()
Signals when the encoder settings change.
Returns the encoding mode.
注意: Getter function for property encodingMode.
另请参阅 setEncodingMode () 和 EncodingMode .
[signal]
void
QMediaRecorder::
encodingModeChanged
()
Signals when the encoding mode changes.
注意: 通知程序信号对于特性 encodingMode .
[signal]
void
QMediaRecorder::
errorOccurred
(
QMediaRecorder::Error
error
, const
QString
&
errorString
)
发射信号,当 error has occurred, with errorString containing a description of the error.
返回
true
if media recorder service ready to use.
[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.
注意: 通知程序信号对于特性 metaData .
Returns the output IO device for media content.
另请参阅 setOutputDevice ().
[slot]
void
QMediaRecorder::
pause
()
暂停录制。
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.
[signal]
void
QMediaRecorder::
qualityChanged
()
Signals when the recording quality changes.
注意: 通知程序信号对于特性 quality .
[slot]
void
QMediaRecorder::
record
()
Starts recording.
While the recorder state is changed immediately to c{ QMediaRecorder::RecordingState }, recording may start asynchronously.
若录制失败
error
() signal is emitted with recorder state being reset back to
QMediaRecorder::StoppedState
.
This method updates actualLocation according to its generation rules.
注意: On mobile devices, recording will happen in the orientation the device had when calling record and is locked for the duration of the recording. To avoid artifacts on the user interface, we recommend to keep the user interface locked to the same orientation as long as the recording is ongoing using the contentOrientation property of QWindow and unlock it again once the recording is finished.
Returns the current media recorder state.
注意: getter 函数对于特性 recorderState。
另请参阅 QMediaRecorder::RecorderState .
[signal]
void
QMediaRecorder::
recorderStateChanged
(
QMediaRecorder::RecorderState
state
)
Signals that a media recorder's state 已改变。
注意: 通知程序信号对于特性 recorderState .
设置音频 bitRate 以位每秒为单位。
注意: setter 函数对于特性 audioBitRate .
另请参阅 audioBitRate ().
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.
注意: setter 函数对于特性 audioChannelCount .
另请参阅 audioChannelCount ().
设置音频 sampleRate (以 Hz 为单位)。
值
-1
indicates the recorder should make an optimal choice based on what is available from the audio source, and the limitations of the codec.
注意: setter 函数对于特性 audioSampleRate .
另请参阅 audioSampleRate ().
设置编码 mode 设置。
若 ConstantQualityEncoding is set, the quality encoding parameter is used and bit rates are ignored, otherwise the bitrates are used.
注意: setter 函数对于特性 encodingMode .
另请参阅 encodingMode () 和 EncodingMode .
将元数据设为 metaData .
注意: To ensure that meta-data is set correctly, it should be set before starting the recording. Once the recording is started, any meta-data set will be attached to the next recording.
注意: setter 函数对于特性 metaData .
另请参阅 metaData ().
Set the output IO device for media content.
The device 必须已打开以 WriteOnly or ReadWrite modes before the recording starts.
The media recorder doesn't take ownership of the specified
device
. If the recording has been started, the device must be kept alive and open until the signal
recorderStateChanged(StoppedState)
is emitted.
This method resets
actualLocation
immediately unless the specified
device
is
null
.
If a writable output device is assigned to the recorder,
outputLocation
is ignored, and
actualLocation
is not generated when recording starts. This behavior may change in the future, so we recommend setting only one output, either
outputLocation
or
outputDevice
.
QMediaRecorder::setOutputDevice
is only supported with the FFmpeg backend.
另请参阅 outputDevice () 和 outputLocation .
设置视频 bitRate 以位每秒为单位。
注意: setter 函数对于特性 videoBitRate .
另请参阅 videoBitRate ().
设置视频 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.
注意: setter 函数对于特性 videoFrameRate .
另请参阅 videoFrameRate ().
Sets the resolution of the encoded video to size .
传递空 QSize to make the recorder choose an optimal resolution based on what is available from the video source and the limitations of the codec.
注意: setter 函数对于特性 videoResolution .
另请参阅 videoResolution ().
设置 width and height of the resolution of the encoded video.
这是重载函数。
注意: setter 函数对于特性 videoResolution .
[slot]
void
QMediaRecorder::
stop
()
The recorder will stop the recording. Processing pending video and audio data might however still take some time. The recording is finished, once the state of the media recorder changes to QMediaRecorder::StoppedState .
Returns the bit rate of the compressed video stream in bits per second.
注意: getter 函数对于特性 videoBitRate。
另请参阅 setVideoBitRate ().
[signal]
void
QMediaRecorder::
videoBitRateChanged
()
Signals when the recording video bit rate changes.
注意: 通知程序信号对于特性 videoBitRate .
返回视频帧速率。
注意: getter 函数对于特性 videoFrameRate。
另请参阅 setVideoFrameRate ().
[signal]
void
QMediaRecorder::
videoFrameRateChanged
()
Signals when the recording video frame rate changes.
注意: 通知程序信号对于特性 videoFrameRate .
Returns the resolution of the encoded video.
注意: getter 函数对于特性 videoResolution。
另请参阅 setVideoResolution ().
[signal]
void
QMediaRecorder::
videoResolutionChanged
()
Signals when the video recording resolution changes.
注意: 通知程序信号对于特性 videoResolution .