QAbstractVideoSurface

PyQt5.QtMultimedia.QAbstractVideoSurface

Inherits from QObject.

Description

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. You can subclass this interface to receive video frames from sources like QMediaPlayer or QCamera to perform your own processing.

A video surface presents a continuous stream of identically formatted QVideoFrame instances, where the format of each frame is compatible with a stream format supplied when starting a presentation. Each frame may have timestamp information that can be used by the surface to decide when to display that frame.

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. In addition, a video surface may hold a reference to a video frame until the endTime() has passed. The stop() function will disable a surface and release any video buffers it holds references to.

Implementing a subclass of QAbstractVideoSurface

When implementing a subclass of this interface, there are only a handful of functions to implement, broken down into two classes:

• Format related

• Presentation related

For format related functionality, you just have to describe the pixel formats that you support (and the nearestFormat() function). For presentation related functionality, you have to implement the present() function, and the start() and stop() functions.

Note: You must call the base class implementation of start() and stop() in your implementation.

Enums

Error

This enum describes the errors that may be returned by the error() function.

Member	Value	Description
IncorrectFormatError	2	A video frame was not compatible with the format of the surface.
NoError	0	No error occurred.
ResourceError	4	The surface could not allocate some resource.
StoppedError	3	The surface has not been started.
UnsupportedFormatError	1	A video format was not supported.

Methods

__init__(parent: QObject = None)

Constructs a video surface with the given parent.

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error() → Error

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.

See also

setError().

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isActive() → bool

Indicates whether a video surface has been started.

Returns true if the surface has been started, and false otherwise.

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isFormatSupported(QVideoSurfaceFormat) → bool

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.

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nativeResolution() → QSize

See also

setNativeResolution().

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nearestFormat(QVideoSurfaceFormat) → QVideoSurfaceFormat

Returns a supported video surface format that is similar to format.

A similar surface format is one that has the same pixelFormat() and handleType() but may differ in some of the other properties. For example, if there are restrictions on the frameSize() 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.

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present(QVideoFrame) → bool

TODO

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setError(Error)

Sets the value of error() to error.

This can be called by implementors of this interface to communicate what the most recent error was.

See also

error().

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setNativeResolution(QSize)

Set the video surface native resolution.

This function can be called by implementors of this interface to specify to frame producers what the native resolution of this surface is.

See also

nativeResolution().

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start(QVideoSurfaceFormat) → bool

Starts a video surface presenting format frames.

Returns true if the surface was started, and false if an error occurred.

Note: You must call the base class implementation of at the end of your implementation.

See also

isActive(), stop().

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stop()

Stops a video surface presenting frames and releases any resources acquired in start().

Note: You must call the base class implementation of at the start of your implementation.

See also

isActive(), start().

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supportedPixelFormats(type: HandleType = NoHandle) → List[PixelFormat]

TODO

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surfaceFormat() → QVideoSurfaceFormat

Returns the format of a video surface.

Signals

activeChanged(bool)

TODO

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nativeResolutionChanged(QSize)

TODO

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supportedFormatsChanged()

TODO

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surfaceFormatChanged(QVideoSurfaceFormat)

TODO