The QAbstractVideoSurface class is a base class for video presentation surfaces. More...
#include <QAbstractVideoSurface>
Inherits: QObject.
This class was introduced in Qt Mobility 1.0.
| enum | Error { NoError, UnsupportedFormatError, IncorrectFormatError, StoppedError, ResourceError } |
| QAbstractVideoSurface ( QObject * parent = 0 ) | |
| ~QAbstractVideoSurface () | |
| Error | error () const |
| bool | isActive () const |
| virtual bool | isFormatSupported ( const QVideoSurfaceFormat & format ) const |
| QSize | nativeResolution () const |
| virtual QVideoSurfaceFormat | nearestFormat ( const QVideoSurfaceFormat & format ) const |
| virtual bool | present ( const QVideoFrame & frame ) = 0 |
| virtual bool | start ( const QVideoSurfaceFormat & format ) |
| virtual void | stop () |
| virtual QList<QVideoFrame::PixelFormat> | supportedPixelFormats ( QAbstractVideoBuffer::HandleType type = QAbstractVideoBuffer::NoHandle ) const = 0 |
| QVideoSurfaceFormat | surfaceFormat () const |
| void | activeChanged ( bool active ) |
| void | nativeResolutionChanged ( const QSize & resolution ) |
| void | supportedFormatsChanged () |
| void | surfaceFormatChanged ( const QVideoSurfaceFormat & format ) |
| void | setError ( Error error ) |
| void | setNativeResolution ( const QSize & resolution ) |
The QAbstractVideoSurface class is a base class for video presentation surfaces.
The QAbstractVideoSurface class defines the standard interface that video producers use to inter-operate with video presentation surfaces. It is not supposed to be instantiated directly. Instead, you should subclass it to create new video surfaces.
A video surface presents a continuous stream of identically formatted frames, where the format of each frame is compatible with a stream format supplied when starting a presentation.
A list of pixel formats a surface can present is given by the supportedPixelFormats() function, and the isFormatSupported() function will test if a video surface format is supported. If a format is not supported the nearestFormat() function may be able to suggest a similar format. For example if a surface supports fixed set of resolutions it may suggest the smallest supported resolution that contains the proposed resolution.
The start() function takes a supported format and enables a video surface. Once started a surface will begin displaying the frames it receives in the present() function. Surfaces may hold a reference to the buffer of a presented video frame until a new frame is presented or streaming is stopped. The stop() function will disable a surface and a release any video buffers it holds references to.
This enum describes the errors that may be returned by the error() function.
| Constant | Value | Description |
|---|---|---|
| QAbstractVideoSurface::NoError | 0 | No error occurred. |
| QAbstractVideoSurface::UnsupportedFormatError | 1 | A video format was not supported. |
| QAbstractVideoSurface::IncorrectFormatError | 2 | A video frame was not compatible with the format of the surface. |
| QAbstractVideoSurface::StoppedError | 3 | The surface has not been started. |
| QAbstractVideoSurface::ResourceError | 4 | The surface could not allocate some resource. |
The native resolution of video surface. This is the resolution of video frames the surface can render with optimal quality and/or performance.
The native resolution is not always known and can be changed during playback.
This property was introduced in Qt Mobility 1.1.
Access functions:
| QSize | nativeResolution () const |
Notifier signal:
| void | nativeResolutionChanged ( const QSize & resolution ) |
Constructs a video surface with the given parent.
Destroys a video surface.
Signals that the active state of a video surface has changed.
This function was introduced in Qt Mobility 1.0.
See also isActive(), start(), and stop().
Returns the last error that occurred.
If a surface fails to start(), or stops unexpectedly this function can be called to discover what error occurred.
This function was introduced in Qt Mobility 1.0.
See also setError().
Indicates whether a video surface has been started.
Returns true if the surface has been started, and false otherwise.
This function was introduced in Qt Mobility 1.0.
Tests a video surface format to determine if a surface can accept it.
Returns true if the format is supported by the surface, and false otherwise.
This function was introduced in Qt Mobility 1.0.
Signals the native resolution of video surface has changed.
This function was introduced in Qt Mobility 1.1.
Returns a supported video surface format that is similar to format.
A similar surface format is one that has the same pixel format and handle type but differs in some of the other properties. For example if there are restrictions on the frame sizes a video surface can accept it may suggest a format with a larger frame size and a viewport the size of the original frame size.
If the format is already supported it will be returned unchanged, or if there is no similar supported format an invalid format will be returned.
This function was introduced in Qt Mobility 1.0.
Presents a video frame.
Returns true if the frame was presented, and false if an error occurred.
Not all surfaces will block until the presentation of a frame has completed. Calling present() on a non-blocking surface may fail if called before the presentation of a previous frame has completed. In such cases the surface may not return to a ready state until it's had an opportunity to process events.
If present() fails for any other reason the surface will immediately enter the stopped state and an error() value will be set.
A video surface must be in the started state for present() to succeed, and the format of the video frame must be compatible with the current video surface format.
This function was introduced in Qt Mobility 1.0.
See also error().
Sets the value of error() to error.
This function was introduced in Qt Mobility 1.0.
See also error().
Set the video surface native resolution.
This function was introduced in Qt Mobility 1.1.
See also nativeResolution().
Starts a video surface presenting format frames.
Returns true if the surface was started, and false if an error occurred.
This function was introduced in Qt Mobility 1.0.
See also isActive() and stop().
Stops a video surface presenting frames and releases any resources acquired in start().
This function was introduced in Qt Mobility 1.0.
See also isActive() and start().
Signals that the set of formats supported by a video surface has changed.
This function was introduced in Qt Mobility 1.0.
See also supportedPixelFormats() and isFormatSupported().
Returns a list of pixel formats a video surface can present for a given handle type.
The pixel formats returned for the QAbstractVideoBuffer::NoHandle type are valid for any buffer that can be mapped in read-only mode.
Types that are first in the list can be assumed to be faster to render.
This function was introduced in Qt Mobility 1.0.
Returns the format of a video surface.
This function was introduced in Qt Mobility 1.0.
Signals that the configured format of a video surface has changed.
This function was introduced in Qt Mobility 1.0.
See also surfaceFormat() and start().
© 2008-2011 Nokia Corporation and/or its subsidiaries. Nokia, Qt and their respective logos are trademarks of Nokia Corporation in Finland and/or other countries worldwide.
All other trademarks are property of their respective owners. Privacy Policy
Licensees holding valid Qt Commercial licenses may use this document in accordance with the Qt Commercial License Agreement provided with the Software or, alternatively, in accordance with the terms contained in a written agreement between you and Nokia.
Alternatively, this document may be used under the terms of the GNU Free Documentation License version 1.3 as published by the Free Software Foundation.