MeeGo 1.2 Harmattan Developer Documentation Develop for the Nokia N9

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QVideoFrame Class Reference

The QVideoFrame class provides a representation of a frame of video data. More...

 #include <QVideoFrame>

This class was introduced in Qt Mobility 1.0.

Public Types

enum FieldType { ProgressiveFrame, TopField, BottomField, InterlacedFrame }
enum PixelFormat { Format_Invalid, Format_ARGB32, Format_ARGB32_Premultiplied, Format_RGB32, ..., Format_User }

Public Functions

QVideoFrame ()
QVideoFrame ( QAbstractVideoBuffer * buffer, const QSize & size, PixelFormat format )
QVideoFrame ( int bytes, const QSize & size, int bytesPerLine, PixelFormat format )
QVideoFrame ( const QImage & image )
QVideoFrame ( const QVideoFrame & other )
~QVideoFrame ()
uchar * bits ()
const uchar * bits () const
int bytesPerLine () const
qint64 endTime () const
FieldType fieldType () const
QVariant handle () const
QAbstractVideoBuffer::HandleType handleType () const
int height () const
bool isMapped () const
bool isReadable () const
bool isValid () const
bool isWritable () const
bool map ( QAbstractVideoBuffer::MapMode mode )
QAbstractVideoBuffer::MapMode mapMode () const
int mappedBytes () const
PixelFormat pixelFormat () const
void setEndTime ( qint64 time )
void setFieldType ( FieldType field )
void setStartTime ( qint64 time )
QSize size () const
qint64 startTime () const
void unmap ()
int width () const
QVideoFrame & operator= ( const QVideoFrame & other )

Static Public Members

QImage::Format imageFormatFromPixelFormat ( PixelFormat format )
PixelFormat pixelFormatFromImageFormat ( QImage::Format format )

Detailed Description

The QVideoFrame class provides a representation of a frame of video data.

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

The 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 which is given by the mappedBytes(), and the size of each line is given by bytesPerLine(). The return value of the handle() function may be used to access frame data using the internal buffer's native APIs.

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

Note: QVideoFrame is explicitly shared, any change made to video frame will also apply to any copies.

Member Type Documentation

enum QVideoFrame::FieldType

Specifies the field an interlaced video frame belongs to.

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

enum QVideoFrame::PixelFormat

Enumerates video data types.

Constant Value Description
QVideoFrame::Format_Invalid 0 The frame is invalid.
QVideoFrame::Format_ARGB32 1 The frame is stored using a 32-bit ARGB format (0xAARRGGBB). This is equivalent to QImage::Format_ARGB32.
QVideoFrame::Format_ARGB32_Premultiplied 2 The frame stored using a premultiplied 32-bit ARGB format (0xAARRGGBB). This is equivalent to QImage::Format_ARGB32_Premultiplied.
QVideoFrame::Format_RGB32 3 The frame stored using a 32-bit RGB format (0xffRRGGBB). This is equivalent to QImage::Format_RGB32
QVideoFrame::Format_RGB24 4 The frame is stored using a 24-bit RGB format (8-8-8). This is equivalent to QImage::Format_RGB888
QVideoFrame::Format_RGB565 5 The frame is stored using a 16-bit RGB format (5-6-5). This is equivalent to QImage::Format_RGB16.
QVideoFrame::Format_RGB555 6 The frame is stored using a 16-bit RGB format (5-5-5). This is equivalent to QImage::Format_RGB555.
QVideoFrame::Format_ARGB8565_Premultiplied 7 The frame is stored using a 24-bit premultiplied ARGB format (8-6-6-5).
QVideoFrame::Format_BGRA32 8 The frame is stored using a 32-bit ARGB format (0xBBGGRRAA).
QVideoFrame::Format_BGRA32_Premultiplied 9 The frame is stored using a premultiplied 32bit BGRA format.
QVideoFrame::Format_BGR32 10 The frame is stored using a 32-bit BGR format (0xBBGGRRff).
QVideoFrame::Format_BGR24 11 The frame is stored using a 24-bit BGR format (0xBBGGRR).
QVideoFrame::Format_BGR565 12 The frame is stored using a 16-bit BGR format (5-6-5).
QVideoFrame::Format_BGR555 13 The frame is stored using a 16-bit BGR format (5-5-5).
QVideoFrame::Format_BGRA5658_Premultiplied 14 The frame is stored using a 24-bit premultiplied BGRA format (5-6-5-8).
QVideoFrame::Format_AYUV444 15 The frame is stored using a packed 32-bit AYUV format (0xAAYYUUVV).
QVideoFrame::Format_AYUV444_Premultiplied 16 The frame is stored using a packed premultiplied 32-bit AYUV format (0xAAYYUUVV).
QVideoFrame::Format_YUV444 17 The frame is stored using a 24-bit packed YUV format (8-8-8).
QVideoFrame::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.
QVideoFrame::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.
QVideoFrame::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.
QVideoFrame::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.
QVideoFrame::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).
QVideoFrame::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).
QVideoFrame::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 Format_YUV420P 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 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 Format_YUV420P 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 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 Format_YV12 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 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 Format_YV12 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 28 The frame is stored using an 8-bit greyscale format.
QVideoFrame::Format_Y16 29 The frame is stored using a 16-bit linear greyscale format. Little endian.
QVideoFrame::Format_Jpeg 30 The frame is stored in compressed Jpeg format.
QVideoFrame::Format_CameraRaw 31 The frame is stored using device specific camera raw format.
QVideoFrame::Format_AdobeDng 32 The frame is stored using raw Adobe Digital Negative (DNG) format.
QVideoFrame::Format_User 1000 Start value for user defined pixel formats.

Member Function Documentation

QVideoFrame::QVideoFrame ()

Constructs a null video frame.

QVideoFrame::QVideoFrame ( QAbstractVideoBuffer * buffer, const QSize & size, PixelFormat format )

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

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

This function was introduced in Qt Mobility 1.0.

QVideoFrame::QVideoFrame ( int bytes, const QSize & size, int bytesPerLine, PixelFormat format )

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.

This function was introduced in Qt Mobility 1.0.

QVideoFrame::QVideoFrame ( const QImage & image )

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.

This function was introduced in Qt Mobility 1.0.

See also pixelFormatFromImageFormat().

QVideoFrame::QVideoFrame ( const QVideoFrame & other )

Constructs a copy of other.

This function was introduced in Qt Mobility 1.0.

QVideoFrame::~QVideoFrame ()

Destroys a video frame.

uchar * QVideoFrame::bits ()

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

This value is only valid while the frame data is mapped.

This function was introduced in Qt Mobility 1.0.

See also map(), mappedBytes(), and bytesPerLine().

const uchar * QVideoFrame::bits () const

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

This value is only valid while the frame data is mapped.

This function was introduced in Qt Mobility 1.0.

See also map(), mappedBytes(), and bytesPerLine().

int QVideoFrame::bytesPerLine () const

Returns the number of bytes in a scan line.

Note: 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 type.

This value is only valid while the frame data is mapped.

This function was introduced in Qt Mobility 1.0.

See also bits(), map(), and mappedBytes().

qint64 QVideoFrame::endTime () const

Returns the presentation time when a frame should stop being displayed.

This function was introduced in Qt Mobility 1.0.

See also setEndTime().

FieldType QVideoFrame::fieldType () const

Returns the field an interlaced video frame belongs to.

If the video is not interlaced this will return WholeFrame.

This function was introduced in Qt Mobility 1.0.

See also setFieldType().

QVariant QVideoFrame::handle () const

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

For an OpenGL texture this would be the texture ID.

This function was introduced in Qt Mobility 1.0.

See also QAbstractVideoBuffer::handle().

QAbstractVideoBuffer::HandleType QVideoFrame::handleType () const

Returns the type of a video frame's handle.

This function was introduced in Qt Mobility 1.0.

int QVideoFrame::height () const

Returns the height of a video frame.

This function was introduced in Qt Mobility 1.0.

QImage::Format QVideoFrame::imageFormatFromPixelFormat ( PixelFormat format ) [static]

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

This function was introduced in Qt Mobility 1.0.

bool QVideoFrame::isMapped () const

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 QAbstractVideoBuffer::NotMapped.

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

This function was introduced in Qt Mobility 1.0.

See also mapMode() and QAbstractVideoBuffer::MapMode.

bool QVideoFrame::isReadable () const

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 QAbstractVideoBuffer::WriteOnly flag.

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

This function was introduced in Qt Mobility 1.0.

See also mapMode() and QAbstractVideoBuffer::MapMode.

bool QVideoFrame::isValid () const

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.

This function was introduced in Qt Mobility 1.0.

bool QVideoFrame::isWritable () const

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 QAbstractVideoBuffer::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.

This function was introduced in Qt Mobility 1.0.

See also mapMode() and QAbstractVideoBuffer::MapMode.

bool QVideoFrame::map ( QAbstractVideoBuffer::MapMode mode )

Maps the contents of a video frame to memory.

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 mapped. If the map mode inclues the QAbstractVideoBuffer::WriteOnly flag the content of the mapped memory will be persisted in 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.

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

This function was introduced in Qt Mobility 1.0.

See also unmap(), mapMode(), and bits().

QAbstractVideoBuffer::MapMode QVideoFrame::mapMode () const

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

This function was introduced in Qt Mobility 1.0.

See also map() and QAbstractVideoBuffer::MapMode.

int QVideoFrame::mappedBytes () const

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

This value is only valid while the frame data is mapped.

This function was introduced in Qt Mobility 1.0.

See also map().

PixelFormat QVideoFrame::pixelFormat () const

Returns the color format of a video frame.

This function was introduced in Qt Mobility 1.0.

PixelFormat QVideoFrame::pixelFormatFromImageFormat ( QImage::Format format ) [static]

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

This function was introduced in Qt Mobility 1.0.

void QVideoFrame::setEndTime ( qint64 time )

Sets the presentation time when a frame should stop being displayed.

This function was introduced in Qt Mobility 1.0.

See also endTime().

void QVideoFrame::setFieldType ( FieldType field )

Sets the field an interlaced video frame belongs to.

This function was introduced in Qt Mobility 1.0.

See also fieldType().

void QVideoFrame::setStartTime ( qint64 time )

Sets the presentation time when the frame should be displayed.

This function was introduced in Qt Mobility 1.0.

See also startTime().

QSize QVideoFrame::size () const

Returns the size of a video frame.

This function was introduced in Qt Mobility 1.0.

qint64 QVideoFrame::startTime () const

Returns the presentation time when the frame should be displayed.

This function was introduced in Qt Mobility 1.0.

See also setStartTime().

void QVideoFrame::unmap ()

Releases the memory mapped by the map() function.

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

This function was introduced in Qt Mobility 1.0.

See also map().

int QVideoFrame::width () const

Returns the width of a video frame.

This function was introduced in Qt Mobility 1.0.

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

Assigns the contents of other to a video frame.

This function was introduced in Qt Mobility 1.0.

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