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QVideoSurfaceFormat Class Reference
[QtMultimedia module]

The QVideoSurfaceFormat class specifies the stream format of a video presentation surface. More...

 #include <QVideoSurfaceFormat>

This class is not part of the Qt GUI Framework Edition.

This class was introduced in Qt 4.6.


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.

ConstantValueDescription
QVideoSurfaceFormat::TopToBottom0Scan lines are arranged from the top of the frame to the bottom.
QVideoSurfaceFormat::BottomToTop1Scan lines are arranged from the bottom of the frame to the top.

enum QVideoSurfaceFormat::YCbCrColorSpace

Enumerates the Y'CbCr color space of video frames.

ConstantValueDescription
QVideoSurfaceFormat::YCbCr_Undefined0No color space is specified.
QVideoSurfaceFormat::YCbCr_BT6011A 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_BT7092A Y'CbCr color space defined by ITU-R BT.709 with the same values range as YCbCr_BT601. Used for HDTV.
QVideoSurfaceFormat::YCbCr_xvYCC6013The 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 wider colors range.
QVideoSurfaceFormat::YCbCr_xvYCC7094The BT.709 color space with the value range extended to 0 to 255.
QVideoSurfaceFormat::YCbCr_JPEG5The 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 size 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 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.

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 a video format, and false if they are the same.

QVideoSurfaceFormat & QVideoSurfaceFormat::operator= ( const QVideoSurfaceFormat & other )

Assigns the values of other to a video stream description.

bool QVideoSurfaceFormat::operator== ( const QVideoSurfaceFormat & other ) const

Returns true if other is the same as a video format, and false if they are the different.


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Qt 4.6.3