QVideoFrame

PyQt5.QtMultimedia.QVideoFrame

Description

The QVideoFrame class represents a frame of video data.

A QVideoFrame encapsulates the pixel data of a video frame, and information about the frame.

Video frames can come from several places - decoded QMediaPlayer, a QCamera, or generated programmatically. The way pixels are described in these frames can vary greatly, and some pixel formats offer greater compression opportunities at the expense of ease of use.

The pixel contents of a video frame can be mapped to memory using the map() function. While mapped, the video data can accessed using the bits() function, which returns a pointer to a buffer. The total size of this buffer is given by the mappedBytes() function, and the size of each line is given by bytesPerLine(). The return value of the handle() function may also be used to access frame data using the internal buffer’s native APIs (for example - an OpenGL texture handle).

A video frame can also have timestamp information associated with it. These timestamps can be used by an implementation of QAbstractVideoSurface to determine when to start and stop displaying the frame, but not all surfaces might respect this setting.

The video pixel data in a QVideoFrame is encapsulated in a QAbstractVideoBuffer. A QVideoFrame may be constructed from any buffer type by subclassing the QAbstractVideoBuffer class.

Note: Since video frames can be expensive to copy, QVideoFrame is explicitly shared, so any change made to a video frame will also apply to any copies.

Enums

FieldType

Specifies the field an interlaced video frame belongs to.

Member	Value	Description
BottomField	2	The frame contains a bottom field.
InterlacedFrame	3	The frame contains a merged top and bottom field.
ProgressiveFrame	0	The frame is not interlaced.
TopField	1	The frame contains a top field.

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PixelFormat

Enumerates video data types.

Member	Value	Description
Format_ABGR32	TODO	TODO
Format_AdobeDng	TODO	The frame is stored using raw Adobe Digital Negative (DNG) format.
Format_ARGB32	1	The frame is stored using a 32-bit ARGB format (0xAARRGGBB). This is equivalent to Format_ARGB32.
Format_ARGB32_Premultiplied	2	The frame stored using a premultiplied 32-bit ARGB format (0xAARRGGBB). This is equivalent to Format_ARGB32_Premultiplied.
Format_ARGB8565_Premultiplied	7	The frame is stored using a 24-bit premultiplied ARGB format (8-5-6-5).
Format_AYUV444	15	The frame is stored using a packed 32-bit AYUV format (0xAAYYUUVV).
Format_AYUV444_Premultiplied	16	The frame is stored using a packed premultiplied 32-bit AYUV format (0xAAYYUUVV).
Format_BGR24	11	The frame is stored using a 24-bit BGR format (0xBBGGRR).
Format_BGR32	10	The frame is stored using a 32-bit BGR format (0xBBGGRRff).
Format_BGR555	13	The frame is stored using a 16-bit BGR format (5-5-5).
Format_BGR565	12	The frame is stored using a 16-bit BGR format (5-6-5).
Format_BGRA32	8	The frame is stored using a 32-bit BGRA format (0xBBGGRRAA).
Format_BGRA32_Premultiplied	9	The frame is stored using a premultiplied 32bit BGRA format.
Format_BGRA5658_Premultiplied	14	The frame is stored using a 24-bit premultiplied BGRA format (5-6-5-8).
Format_CameraRaw	TODO	The frame is stored using a device specific camera raw format.
Format_IMC1	24	The frame is stored using an 8-bit per component planar YUV format with the U and V planes horizontally and vertically sub-sampled. This is similar to the type, except that the bytes per line of the U and V planes are padded out to the same stride as the Y plane.
Format_IMC2	25	The frame is stored using an 8-bit per component planar YUV format with the U and V planes horizontally and vertically sub-sampled. This is similar to the type, except that the lines of the U and V planes are interleaved, i.e. each line of U data is followed by a line of V data creating a single line of the same stride as the Y data.
Format_IMC3	26	The frame is stored using an 8-bit per component planar YVU format with the V and U planes horizontally and vertically sub-sampled. This is similar to the type, except that the bytes per line of the V and U planes are padded out to the same stride as the Y plane.
Format_IMC4	27	The frame is stored using an 8-bit per component planar YVU format with the V and U planes horizontally and vertically sub-sampled. This is similar to the type, except that the lines of the V and U planes are interleaved, i.e. each line of V data is followed by a line of U data creating a single line of the same stride as the Y data.
Format_Invalid	0	The frame is invalid.
Format_Jpeg	TODO	The frame is stored in compressed Jpeg format.
Format_NV12	22	The frame is stored using an 8-bit per component semi-planar YUV format with a Y plane (Y) followed by a horizontally and vertically sub-sampled, packed UV plane (U-V).
Format_NV21	23	The frame is stored using an 8-bit per component semi-planar YUV format with a Y plane (Y) followed by a horizontally and vertically sub-sampled, packed VU plane (V-U).
Format_RGB24	4	The frame is stored using a 24-bit RGB format (8-8-8). This is equivalent to Format_RGB888
Format_RGB32	3	The frame stored using a 32-bit RGB format (0xffRRGGBB). This is equivalent to Format_RGB32
Format_RGB555	6	The frame is stored using a 16-bit RGB format (5-5-5). This is equivalent to Format_RGB555.
Format_RGB565	5	The frame is stored using a 16-bit RGB format (5-6-5). This is equivalent to Format_RGB16.
Format_User	1000	Start value for user defined pixel formats.
Format_UYVY	20	The frame is stored using an 8-bit per component packed YUV format with the U and V planes horizontally sub-sampled (U-Y-V-Y), i.e. two horizontally adjacent pixels are stored as a 32-bit macropixel which has a Y value for each pixel and common U and V values.
Format_Y16	29	The frame is stored using a 16-bit linear greyscale format. Little endian.
Format_Y8	28	The frame is stored using an 8-bit greyscale format.
Format_YUV420P	18	The frame is stored using an 8-bit per component planar YUV format with the U and V planes horizontally and vertically sub-sampled, i.e. the height and width of the U and V planes are half that of the Y plane.
Format_YUV422P	TODO	TODO
Format_YUV444	17	The frame is stored using a 24-bit packed YUV format (8-8-8).
Format_YUYV	21	The frame is stored using an 8-bit per component packed YUV format with the U and V planes horizontally sub-sampled (Y-U-Y-V), i.e. two horizontally adjacent pixels are stored as a 32-bit macropixel which has a Y value for each pixel and common U and V values.
Format_YV12	19	The frame is stored using an 8-bit per component planar YVU format with the V and U planes horizontally and vertically sub-sampled, i.e. the height and width of the V and U planes are half that of the Y plane.

Methods

__init__()

Constructs a null video frame.

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__init__(QImage)

Constructs a video frame from an image.

Note: This will construct an invalid video frame if there is no frame type equivalent to the image format.

See also

pixelFormatFromImageFormat().

---

__init__(QVideoFrame)

Constructs a shallow copy of other. Since QVideoFrame is explicitly shared, these two instances will reflect the same frame.

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__init__(QAbstractVideoBuffer, QSize, PixelFormat)

Constructs a video frame from a buffer with the given pixel format and size in pixels.

Note: This doesn’t increment the reference count of the video buffer.

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__init__(int, QSize, int, PixelFormat)

Constructs a video frame of the given pixel format and size in pixels.

The bytesPerLine (stride) is the length of each scan line in bytes, and bytes is the total number of bytes that must be allocated for the frame.

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availableMetaData() → Dict[str, Any]

TODO

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bits() → sip.voidptr

Returns a pointer to the start of the frame data buffer.

This value is only valid while the frame data is map().

Changes made to data accessed via this pointer (when mapped with write access) are only guaranteed to have been persisted when unmap() is called and when the buffer has been mapped for writing.

See also

map(), mappedBytes(), bytesPerLine().

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bits(int) → sip.voidptr

TODO

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buffer() → QAbstractVideoBuffer

TODO

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bytesPerLine() → int

Returns the number of bytes in a scan line.

Note: For planar formats this is the bytes per line of the first plane only. The bytes per line of subsequent planes should be calculated as per the frame PixelFormat.

This value is only valid while the frame data is map().

See also

bits(), map(), mappedBytes().

---

bytesPerLine(int) → int

TODO

---

endTime() → int

Returns the presentation time (in microseconds) when a frame should stop being displayed.

An invalid time is represented as -1.

See also

setEndTime().

---

__eq__(QVideoFrame) → bool

TODO

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fieldType() → FieldType

Returns the field an interlaced video frame belongs to.

If the video is not interlaced this will return WholeFrame.

See also

setFieldType().

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handle() → Any

Returns a type specific handle to a video frame’s buffer.

For an OpenGL texture this would be the texture ID.

See also

handle().

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handleType() → HandleType

Returns the type of a video frame’s handle.

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height() → int

Returns the height of a video frame.

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@staticmethod
imageFormatFromPixelFormat(PixelFormat) → Format

Returns an image format equivalent to a video frame pixel format. If there is no equivalent format Format_Invalid is returned instead.

Note: In general QImage does not handle YUV formats.

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isMapped() → bool

Identifies if a video frame’s contents are currently mapped to system memory.

This is a convenience function which checks that the MapMode of the frame is not equal to NotMapped.

Returns true if the contents of the video frame are mapped to system memory, and false otherwise.

See also

mapMode(), MapMode.

---

isReadable() → bool

Identifies if the mapped contents of a video frame were read from the frame when it was mapped.

This is a convenience function which checks if the MapMode contains the WriteOnly flag.

Returns true if the contents of the mapped memory were read from the video frame, and false otherwise.

See also

mapMode(), MapMode.

---

isValid() → bool

Identifies whether a video frame is valid.

An invalid frame has no video buffer associated with it.

Returns true if the frame is valid, and false if it is not.

---

isWritable() → bool

Identifies if the mapped contents of a video frame will be persisted when the frame is unmapped.

This is a convenience function which checks if the MapMode contains the WriteOnly flag.

Returns true if the video frame will be updated when unmapped, and false otherwise.

Note: The result of altering the data of a frame that is mapped in read-only mode is undefined. Depending on the buffer implementation the changes may be persisted, or worse alter a shared buffer.

See also

mapMode(), MapMode.

---

map(MapMode) → bool

Maps the contents of a video frame to system (CPU addressable) memory.

In some cases the video frame data might be stored in video memory or otherwise inaccessible memory, so it is necessary to map a frame before accessing the pixel data. This may involve copying the contents around, so avoid mapping and unmapping unless required.

The map mode indicates whether the contents of the mapped memory should be read from and/or written to the frame. If the map mode includes the QAbstractVideoBuffer::ReadOnly flag the mapped memory will be populated with the content of the video frame when initially mapped. If the map mode includes the QAbstractVideoBuffer::WriteOnly flag the content of the possibly modified mapped memory will be written back to the frame when unmapped.

While mapped the contents of a video frame can be accessed directly through the pointer returned by the bits() function.

When access to the data is no longer needed, be sure to call the unmap() function to release the mapped memory and possibly update the video frame contents.

If the video frame has been mapped in read only mode, it is permissible to map it multiple times in read only mode (and unmap it a corresponding number of times). In all other cases it is necessary to unmap the frame first before mapping a second time.

Note: Writing to memory that is mapped as read-only is undefined, and may result in changes to shared data or crashes.

Returns true if the frame was mapped to memory in the given mode and false otherwise.

See also

unmap(), mapMode(), bits().

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mapMode() → MapMode

Returns the mode a video frame was mapped to system memory in.

See also

map(), MapMode.

---

mappedBytes() → int

Returns the number of bytes occupied by the mapped frame data.

This value is only valid while the frame data is map().

See also

map().

---

metaData(str) → Any

TODO

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__ne__(QVideoFrame) → bool

TODO

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pixelFormat() → PixelFormat

Returns the color format of a video frame.

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@staticmethod
pixelFormatFromImageFormat(Format) → PixelFormat

Returns a video pixel format equivalent to an image format. If there is no equivalent format QVideoFrame::InvalidType is returned instead.

Note: In general QImage does not handle YUV formats.

---

planeCount() → int

TODO

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setEndTime(int)

Sets the presentation time (in microseconds) when a frame should stop being displayed.

An invalid time is represented as -1.

See also

endTime().

---

setFieldType(FieldType)

Sets the field an interlaced video frame belongs to.

See also

fieldType().

---

setMetaData(str, Any)

TODO

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setStartTime(int)

Sets the presentation time (in microseconds) when the frame should initially be displayed.

An invalid time is represented as -1.

See also

startTime().

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size() → QSize

Returns the dimensions of a video frame.

---

startTime() → int

Returns the presentation time (in microseconds) when the frame should be displayed.

An invalid time is represented as -1.

See also

setStartTime().

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unmap()

Releases the memory mapped by the map() function.

If the MapMode included the WriteOnly flag this will persist the current content of the mapped memory to the video frame.

should not be called if map() function failed.

See also

map().

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width() → int

Returns the width of a video frame.