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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