QVideoSurfaceFormat Class
The QVideoSurfaceFormat class specifies the stream format of a video presentation surface. More...
Header: | #include <QVideoSurfaceFormat> |
qmake: | QT += multimedia |
Public Types
enum | Direction { TopToBottom, BottomToTop } |
enum | YCbCrColorSpace { YCbCr_Undefined, YCbCr_BT601, YCbCr_BT709, YCbCr_xvYCC601, YCbCr_xvYCC709, YCbCr_JPEG } |
Public Functions
QVideoSurfaceFormat() | |
QVideoSurfaceFormat(const QSize &size, QVideoFrame::PixelFormat format, QAbstractVideoBuffer::HandleType type = QAbstractVideoBuffer::NoHandle) | |
QVideoSurfaceFormat(const QVideoSurfaceFormat &other) | |
~QVideoSurfaceFormat() | |
int | frameHeight() const |
qreal | frameRate() const |
QSize | frameSize() const |
int | frameWidth() const |
QAbstractVideoBuffer::HandleType | handleType() const |
bool | isValid() const |
QSize | pixelAspectRatio() const |
QVideoFrame::PixelFormat | pixelFormat() const |
QVariant | property(const char *name) const |
QList<QByteArray> | propertyNames() const |
Direction | scanLineDirection() const |
void | setFrameRate(qreal rate) |
void | setFrameSize(const QSize &size) |
void | setFrameSize(int width, int height) |
void | setPixelAspectRatio(const QSize &ratio) |
void | setPixelAspectRatio(int horizontal, int vertical) |
void | setProperty(const char *name, const QVariant &value) |
void | setScanLineDirection(Direction direction) |
void | setViewport(const QRect &viewport) |
void | setYCbCrColorSpace(YCbCrColorSpace space) |
QSize | sizeHint() const |
QRect | viewport() const |
YCbCrColorSpace | yCbCrColorSpace() const |
bool | operator!=(const QVideoSurfaceFormat &other) const |
QVideoSurfaceFormat & | operator=(const QVideoSurfaceFormat &other) |
bool | operator==(const QVideoSurfaceFormat &other) const |
Detailed Description
The QVideoSurfaceFormat class specifies the stream format of a video presentation surface.
A video surface presents a stream of video frames. The surface's format describes the type of the frames and determines how they should be presented.
The core properties of a video stream required to setup a video surface are the pixel format given by pixelFormat(), and the frame dimensions given by frameSize().
If the surface is to present frames using a frame's handle a surface format will also include a handle type which is given by the handleType() function.
The region of a frame that is actually displayed on a video surface is given by the viewport(). A stream may have a viewport less than the entire region of a frame to allow for videos smaller than the nearest optimal size of a video frame. For example the width of a frame may be extended so that the start of each scan line is eight byte aligned.
Other common properties are the pixelAspectRatio(), scanLineDirection(), and frameRate(). Additionally a stream may have some additional type specific properties which are listed by the dynamicPropertyNames() function and can be accessed using the property(), and setProperty() functions.
Member Type Documentation
enum QVideoSurfaceFormat::Direction
Enumerates the layout direction of video scan lines.
Constant | Value | Description |
---|---|---|
QVideoSurfaceFormat::TopToBottom |
0 |
Scan lines are arranged from the top of the frame to the bottom. |
QVideoSurfaceFormat::BottomToTop |
1 |
Scan lines are arranged from the bottom of the frame to the top. |
enum QVideoSurfaceFormat::YCbCrColorSpace
Enumerates the Y'CbCr color space of video frames.
Constant | Value | Description |
---|---|---|
QVideoSurfaceFormat::YCbCr_Undefined |
0 |
No color space is specified. |
QVideoSurfaceFormat::YCbCr_BT601 |
1 |
A Y'CbCr color space defined by ITU-R recommendation BT.601 with Y value range from 16 to 235, and Cb/Cr range from 16 to 240. Used in standard definition video. |
QVideoSurfaceFormat::YCbCr_BT709 |
2 |
A Y'CbCr color space defined by ITU-R BT.709 with the same values range as YCbCr_BT601. Used for HDTV. |
QVideoSurfaceFormat::YCbCr_xvYCC601 |
3 |
The BT.601 color space with the value range extended to 0 to 255. It is backward compatibile with BT.601 and uses values outside BT.601 range to represent a wider range of colors. |
QVideoSurfaceFormat::YCbCr_xvYCC709 |
4 |
The BT.709 color space with the value range extended to 0 to 255. |
QVideoSurfaceFormat::YCbCr_JPEG |
5 |
The full range Y'CbCr color space used in JPEG files. |
Member Function Documentation
QVideoSurfaceFormat::QVideoSurfaceFormat()
Constructs a null video stream format.
QVideoSurfaceFormat::QVideoSurfaceFormat(const QSize &size, QVideoFrame::PixelFormat format, QAbstractVideoBuffer::HandleType type = QAbstractVideoBuffer::NoHandle)
Contructs a description of stream which receives stream of type buffers with given frame size and pixel format.
QVideoSurfaceFormat::QVideoSurfaceFormat(const QVideoSurfaceFormat &other)
Constructs a copy of other.
QVideoSurfaceFormat::~QVideoSurfaceFormat()
Destroys a video stream description.
int QVideoSurfaceFormat::frameHeight() const
Returns the height of frame in a video stream.
qreal QVideoSurfaceFormat::frameRate() const
Returns the frame rate of a video stream in frames per second.
See also setFrameRate().
QSize QVideoSurfaceFormat::frameSize() const
Returns the dimensions of frames in a video stream.
See also setFrameSize(), frameWidth(), and frameHeight().
int QVideoSurfaceFormat::frameWidth() const
Returns the width of frames in a video stream.
See also frameSize() and frameHeight().
QAbstractVideoBuffer::HandleType QVideoSurfaceFormat::handleType() const
Returns the type of handle the surface uses to present the frame data.
If the handle type is QAbstractVideoBuffer::NoHandle
, buffers with any handle type are valid provided they can be mapped with the QAbstractVideoBuffer::ReadOnly flag. If the handleType() is not QAbstractVideoBuffer::NoHandle then the handle type of the buffer must be the same as that of the surface format.
bool QVideoSurfaceFormat::isValid() const
Identifies if a video surface format has a valid pixel format and frame size.
Returns true if the format is valid, and false otherwise.
QSize QVideoSurfaceFormat::pixelAspectRatio() const
Returns a video stream's pixel aspect ratio.
See also setPixelAspectRatio().
QVideoFrame::PixelFormat QVideoSurfaceFormat::pixelFormat() const
Returns the pixel format of frames in a video stream.
QVariant QVideoSurfaceFormat::property(const char *name) const
Returns the value of the video format's name property.
See also setProperty().
QList<QByteArray> QVideoSurfaceFormat::propertyNames() const
Returns a list of video format dynamic property names.
Direction QVideoSurfaceFormat::scanLineDirection() const
Returns the direction of scan lines.
See also setScanLineDirection().
void QVideoSurfaceFormat::setFrameRate(qreal rate)
Sets the frame rate of a video stream in frames per second.
See also frameRate().
void QVideoSurfaceFormat::setFrameSize(const QSize &size)
Sets the size of frames in a video stream to size.
This will reset the viewport() to fill the entire frame.
See also frameSize().
void QVideoSurfaceFormat::setFrameSize(int width, int height)
This is an overloaded function.
Sets the width and height of frames in a video stream.
This will reset the viewport() to fill the entire frame.
void QVideoSurfaceFormat::setPixelAspectRatio(const QSize &ratio)
Sets a video stream's pixel aspect ratio.
See also pixelAspectRatio().
void QVideoSurfaceFormat::setPixelAspectRatio(int horizontal, int vertical)
This is an overloaded function.
Sets the horizontal and vertical elements of a video stream's pixel aspect ratio.
void QVideoSurfaceFormat::setProperty(const char *name, const QVariant &value)
Sets the video format's name property to value.
Trying to set a read only property will be ignored.
See also property().
void QVideoSurfaceFormat::setScanLineDirection(Direction direction)
Sets the direction of scan lines.
See also scanLineDirection().
void QVideoSurfaceFormat::setViewport(const QRect &viewport)
Sets the viewport of a video stream to viewport.
See also viewport().
void QVideoSurfaceFormat::setYCbCrColorSpace(YCbCrColorSpace space)
Sets the Y'CbCr color space of a video stream. It is only used with raw YUV frame types.
See also yCbCrColorSpace().
QSize QVideoSurfaceFormat::sizeHint() const
Returns a suggested size in pixels for the video stream.
This is the size of the viewport scaled according to the pixel aspect ratio.
QRect QVideoSurfaceFormat::viewport() const
Returns the viewport of a video stream.
The viewport is the region of a video frame that is actually displayed.
By default the viewport covers an entire frame.
See also setViewport().
YCbCrColorSpace QVideoSurfaceFormat::yCbCrColorSpace() const
Returns the Y'CbCr color space of a video stream.
See also setYCbCrColorSpace().
bool QVideoSurfaceFormat::operator!=(const QVideoSurfaceFormat &other) const
Returns true if other is different to this video format, and false if they are the same.
QVideoSurfaceFormat &QVideoSurfaceFormat::operator=(const QVideoSurfaceFormat &other)
Assigns the values of other to this object.
bool QVideoSurfaceFormat::operator==(const QVideoSurfaceFormat &other) const
Returns true if other is the same as this video format, and false if they are different.
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Licensed under the GNU Free Documentation License, Version 1.3.
https://doc.qt.io/qt-5.9/qvideosurfaceformat.html