QVideoFrame ¶

概要 ¶

详细描述 ¶

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

Video frames can come from several places - decoded media ， camera , 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 类。

注意

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.

class QVideoFrame ¶

QVideoFrame(buffer, size, format)

QVideoFrame(image)

QVideoFrame(other)

QVideoFrame(bytes, size, bytesPerLine, format)

param bytes

int

param format

PixelFormat

param bytesPerLine

int

param image

QImage

param size

QSize

param buffer

QAbstractVideoBuffer

param other

QVideoFrame

构造 null 视频帧。

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

注意

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

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

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.

PySide2.QtMultimedia.QVideoFrame. FieldType ¶

Specifies the field an interlaced video frame belongs to.

常量	描述
QVideoFrame.ProgressiveFrame	The frame is not interlaced.
QVideoFrame.TopField	The frame contains a top field.
QVideoFrame.BottomField	The frame contains a bottom field.
QVideoFrame.InterlacedFrame	The frame contains a merged top and bottom field.

PySide2.QtMultimedia.QVideoFrame. PixelFormat ¶

枚举视频数据类型。

常量	描述
QVideoFrame.Format_Invalid	帧是无效的。
QVideoFrame.Format_ARGB32	The frame is stored using a 32-bit ARGB format (0xAARRGGBB). This is equivalent to Format_ARGB32 .
QVideoFrame.Format_ARGB32_Premultiplied	The frame stored using a premultiplied 32-bit ARGB format (0xAARRGGBB). This is equivalent to Format_ARGB32_Premultiplied .
QVideoFrame.Format_RGB32	The frame stored using a 32-bit RGB format (0xffRRGGBB). This is equivalent to Format_RGB32
QVideoFrame.Format_RGB24	The frame is stored using a 24-bit RGB format (8-8-8). This is equivalent to Format_RGB888
QVideoFrame.Format_RGB565	The frame is stored using a 16-bit RGB format (5-6-5). This is equivalent to Format_RGB16 .
QVideoFrame.Format_RGB555	The frame is stored using a 16-bit RGB format (5-5-5). This is equivalent to Format_RGB555 .
QVideoFrame.Format_ARGB8565_Premultiplied	The frame is stored using a 24-bit premultiplied ARGB format (8-5-6-5).
QVideoFrame.Format_BGRA32	The frame is stored using a 32-bit BGRA format (0xBBGGRRAA).
QVideoFrame.Format_BGRA32_Premultiplied	The frame is stored using a premultiplied 32bit BGRA format.
QVideoFrame.Format_ABGR32	The frame is stored using a 32-bit ABGR format (0xAABBGGRR).
QVideoFrame.Format_BGR32	The frame is stored using a 32-bit BGR format (0xBBGGRRff).
QVideoFrame.Format_BGR24	The frame is stored using a 24-bit BGR format (0xBBGGRR).
QVideoFrame.Format_BGR565	帧使用 16 位 BGR 格式 (5-6-5) 存储。
QVideoFrame.Format_BGR555	帧使用 16 位 BGR 格式 (5-5-5) 存储。
QVideoFrame.Format_BGRA5658_Premultiplied	The frame is stored using a 24-bit premultiplied BGRA format (5-6-5-8).
QVideoFrame.Format_AYUV444	The frame is stored using a packed 32-bit AYUV format (0xAAYYUUVV).
QVideoFrame.Format_AYUV444_Premultiplied	The frame is stored using a packed premultiplied 32-bit AYUV format (0xAAYYUUVV).
QVideoFrame.Format_YUV444	The frame is stored using a 24-bit packed YUV format (8-8-8).
QVideoFrame.Format_YUV420P	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.
QVideoFrame.Format_YUV422P	The frame is stored using an 8-bit per component planar YUV format with the U and V planes horizontally sub-sampled, i.e. the width of the U and V planes are half that of the Y plane, and height of U and V planes is the same as Y.
QVideoFrame.Format_YV12	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.
QVideoFrame.Format_UYVY	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.
QVideoFrame.Format_YUYV	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.
QVideoFrame.Format_NV12	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).
QVideoFrame.Format_NV21	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).
QVideoFrame.Format_IMC1	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.
QVideoFrame.Format_IMC2	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.
QVideoFrame.Format_IMC3	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.
QVideoFrame.Format_IMC4	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.
QVideoFrame.Format_Y8	The frame is stored using an 8-bit greyscale format.
QVideoFrame.Format_Y16	The frame is stored using a 16-bit linear greyscale format. Little endian.
QVideoFrame.Format_Jpeg	The frame is stored in compressed Jpeg format.
QVideoFrame.Format_CameraRaw	The frame is stored using a device specific camera raw format.
QVideoFrame.Format_AdobeDng	The frame is stored using raw Adobe Digital Negative (DNG) format.
QVideoFrame.Format_User	用户定义像素格式的起始值。

PySide2.QtMultimedia.QVideoFrame. availableMetaData ( ) ¶

返回类型

返回关联此帧的任何额外元数据。

PySide2.QtMultimedia.QVideoFrame. bits ( ) ¶

返回类型

uchar

返回指向帧数据缓冲起始的指针。

此值才有效当帧数据为 mapped .

若缓冲未采用读取访问被映射，此缓冲的内容将被初始为未被初始化。

另请参阅

map() mappedBytes() bytesPerLine()

PySide2.QtMultimedia.QVideoFrame. buffer ( ) ¶

返回类型

QAbstractVideoBuffer

返回底层视频缓冲或 null 若没有。

PySide2.QtMultimedia.QVideoFrame. bytesPerLine ( plane ) ¶

参数

plane – int

返回类型

int

Returns the number of bytes in a scan line of a plane .

此值才有效当帧数据为 mapped .

另请参阅

bits() map() mappedBytes() planeCount()

PySide2.QtMultimedia.QVideoFrame. bytesPerLine ( ) ¶

返回类型

int

返回扫描行字节数。

注意

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 pixel format .

此值才有效当帧数据为 mapped .

另请参阅

bits() map() mappedBytes()

PySide2.QtMultimedia.QVideoFrame. endTime ( ) ¶

返回类型

qint64

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

无效时间表示为 -1。

另请参阅

setEndTime()

PySide2.QtMultimedia.QVideoFrame. fieldType ( ) ¶

返回类型

FieldType

Returns the field an interlaced video frame belongs to.

If the video is not interlaced this will return WholeFrame.

另请参阅

setFieldType()

PySide2.QtMultimedia.QVideoFrame. handle ( ) ¶

返回类型

object

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

对于 OpenGL 纹理，这将是纹理 ID。

另请参阅

handle()

PySide2.QtMultimedia.QVideoFrame. handleType ( ) ¶

返回类型

HandleType

Returns the type of a video frame’s handle.

PySide2.QtMultimedia.QVideoFrame. height ( ) ¶

返回类型

int

返回视频帧的高度。

PySide2.QtMultimedia.QVideoFrame. image ( ) ¶

返回类型

QImage

基于像素格式将当前视频帧转换成图像。

static PySide2.QtMultimedia.QVideoFrame. imageFormatFromPixelFormat ( format ) ¶

参数

format – PixelFormat

返回类型

格式

返回图像格式等效视频帧像素 format 。若没有等效格式 Format_Invalid 被返回取而代之。

注意

通常 QImage 没有 YUV 格式。

PySide2.QtMultimedia.QVideoFrame. isMapped ( ) ¶

返回类型

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.

另请参阅

mapMode() MapMode

PySide2.QtMultimedia.QVideoFrame. isReadable ( ) ¶

返回类型

bool

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

这是方便的校验函数若 MapMode contains the WriteOnly 标志。

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

另请参阅

mapMode() MapMode

PySide2.QtMultimedia.QVideoFrame. isValid ( ) ¶

返回类型

bool

标识视频帧是否有效。

无效帧没有关联它的视频缓冲。

返回 true 若帧有效，和 false 若帧无效。

PySide2.QtMultimedia.QVideoFrame. isWritable ( ) ¶

返回类型

bool

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

这是方便的校验函数若 MapMode contains the WriteOnly 标志。

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

注意

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.

另请参阅

mapMode() MapMode

PySide2.QtMultimedia.QVideoFrame. map ( mode ) ¶

参数

mode – MapMode

返回类型

bool

把视频帧的内容映射到系统 (CPU 可寻址) 内存。

在某些情况下，视频帧数据可能被存储在视频内存或其它不可访问内存中，因此有必要映射帧在访问像素数据之前。这可能涉及围绕内容的拷贝，因此，应避免映射和取消映射 (除非要求)。

映射 mode 指示映射内存内容是否应读取自和/或写入帧。若映射模式包括 QAbstractVideoBuffer::ReadOnly 标志将采用视频帧内容填充映射内存当初始映射时。若映射模式包括 QAbstractVideoBuffer::WriteOnly 标志可能将修改映射内存内容写回到帧当取消映射时。

当映射时，可以直接访问视频帧内容透过指针返回通过 bits() 函数。

当访问数据不再需要时，确保调用 unmap() function to release the mapped memory and possibly update the video frame contents.

若视频帧已映射在只读模式下，以只读模式多次映射它 (且取消映射它相应次数) 是准许的。在所有其它情况下，有必要先取消帧映射，在映射第二次之前。

注意

作为只读的写入映射内存是未定义的，并可能导致共享数据改变或崩溃。

返回 true 若帧被映射到内存按给定 mode 和 false 否则。

另请参阅

unmap() mapMode() bits()

PySide2.QtMultimedia.QVideoFrame. mapMode ( ) ¶

返回类型

MapMode

返回将视频帧映射到系统内存中的模式。

另请参阅

map() MapMode

PySide2.QtMultimedia.QVideoFrame. mappedBytes ( ) ¶

返回类型

int

返回由映射帧数据所占据的字节数。

此值才有效当帧数据为 mapped .

另请参阅

map()

PySide2.QtMultimedia.QVideoFrame. metaData ( key ) ¶

参数

key – unicode

返回类型

object

返回此帧的任何元数据为给定 key .

This might include frame specific information from a camera, or subtitles from a decoded video stream.

See the documentation for the relevant video frame producer for further information about available metadata.

另请参阅

setMetaData()

PySide2.QtMultimedia.QVideoFrame. __ne__ ( other ) ¶

参数

other – QVideoFrame

返回类型

bool

返回 true 若此 QVideoFrame and other 不反射相同帧。

PySide2.QtMultimedia.QVideoFrame. __eq__ ( other ) ¶

参数

other – QVideoFrame

返回类型

bool

返回 true 若此 QVideoFrame and other 反射相同帧。

PySide2.QtMultimedia.QVideoFrame. pixelFormat ( ) ¶

返回类型

PixelFormat

返回视频帧的颜色格式。

static PySide2.QtMultimedia.QVideoFrame. pixelFormatFromImageFormat ( format ) ¶

参数

format – 格式

返回类型

PixelFormat

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

注意

通常 QImage 没有 YUV 格式。

PySide2.QtMultimedia.QVideoFrame. planeCount ( ) ¶

返回类型

int

返回视频帧中的平面数。

此值才有效当帧数据为 mapped .

另请参阅

map()

PySide2.QtMultimedia.QVideoFrame. setEndTime ( time ) ¶

参数

time – qint64

设置呈现 time (以微秒为单位) 当帧应停止显示时。

无效时间表示为 -1。

另请参阅

endTime()

PySide2.QtMultimedia.QVideoFrame. setFieldType ( arg__1 ) ¶

参数

arg__1 – FieldType

设置 field 属于隔行扫描视频帧。

另请参阅

fieldType()

PySide2.QtMultimedia.QVideoFrame. setMetaData ( key , value ) ¶

参数

• key – unicode

• value – object

设置元数据为给定 key to value .

若 value is a null variant, any metadata for this key will be removed.

The producer of the video frame might use this to associate certain data with this frame, or for an intermediate processor to add information for a consumer of this frame.

另请参阅

metaData()

PySide2.QtMultimedia.QVideoFrame. setStartTime ( time ) ¶

参数

time – qint64

设置呈现 time (以微秒为单位) 当帧应该被初始显示时。

无效时间表示为 -1。

另请参阅

startTime()

PySide2.QtMultimedia.QVideoFrame. size ( ) ¶

返回类型

QSize

返回视频帧尺度。

PySide2.QtMultimedia.QVideoFrame. startTime ( ) ¶

返回类型

qint64

返回呈现时间 (以微秒为单位) 当帧应该被显示时。

无效时间表示为 -1。

另请参阅

setStartTime()

PySide2.QtMultimedia.QVideoFrame. unmap ( ) ¶

释放映射内存，映射通过 map() 函数。

若 MapMode 包括 WriteOnly 标志，则这会把映射内存当前内容坚持到视频帧。

should not be called if map() function failed.

另请参阅

map()

PySide2.QtMultimedia.QVideoFrame. width ( ) ¶

返回类型

int

返回视频帧的宽度。