Video capture class. More...

#include <govideocapture.h>

Public Types
enum	ColourMode { RGB24, YUV422P, YUV420P, GREY }

Public Member Functions
	goVideoCapture (const char *devname, goSize_t width, goSize_t height)

bool	setDevice (const char *name)
	Set device file name. More...

void	setFileDescriptor (int fd)
	Set file discriptor of an already open device. More...

int	getFileDescriptor () const
	Get file descriptor for open device. More...

bool	setCaptureSize (goSize_t width, goSize_t height)
	Set capture frame size. More...

goSize_t	getCaptureWidth () const
	Capture frame width. More...

goSize_t	getCaptureHeight () const
	Capture frame height. More...

void	setColourMode (enum ColourMode vm)
	Sets the colour mode. More...

enum ColourMode	getColourMode () const
	Get the colour mode this object is currently set to. More...

bool	open ()
	Open the device. More...

void	close ()
	Close the open device.

bool	grab (goSignal3DBase< void > &signal, const int *rgb_channels)
	Grab a frame from the open device. More...

bool	grab (goSignal3D< void > &signal, const int *rgb_channels)
	Convenience method. More...

bool	grab (void *buffer, goSize_t size)
	Grab a frame from the open device. More...

bool	checkCapture () const
	Check if video capture is available by the open device. More...

bool	setSettings ()
	Store settings from this object to the open device. More...

void	getSettings ()
	Get settings from device and store them internally. It is a good idea to call this after opening a device. It is also called by setFileDescriptor(). This method calls getCapabilities() and getCaptureWindow().

void	getValidRanges ()
	Get valid ranges for brightnes etc. More...

void	setBrightness (double b)

double	getBrightness () const

void	setHue (double b)

double	getHue () const

void	setColour (double b)

double	getColour () const

void	setContrast (double b)

double	getContrast () const

void	setWhiteness (double b)

double	getWhiteness () const

void	printImageProperties (goString &ret)

Public Member Functions inherited from goObjectBase
	goObjectBase ()
	Constructor.

virtual	~goObjectBase ()
	Destructor. More...

const char *	getClassName () const
	Returns the class name. More...

int	getClassID () const

virtual goSize_t	memoryUsage () const
	Returns the size of this object or some measure of its memory consumption. More...

void	setObjectName (const char *name)
	Set name string for an object. More...

void	setObjectName (const goString &name)
	Set name string for an object. More...

const goString &	getObjectName () const
	Get the object name. More...

virtual bool	writeObjectFile (FILE *) const
	Write object to a file. More...

virtual bool	readObjectFile (FILE *)
	Read object from a file. More...

void	connectObject (goObjectBase *object)
	Connects an object to this object. More...

void	disconnectObject (const goObjectBase *object)
	Disconnects an object from this object.

virtual bool	callObjectMethod (int methodID, goObjectMethodParameters *param=NULL)
	Call an object method by identifier. More...

virtual bool	queueObjectMethod (int methodID, goObjectMethodParameters *param=NULL, bool blocking=false)
	Enqueue a method call to an internal list of methods. More...

bool	callQueuedMethods ()
	Call all queued methods. More...

Protected Member Functions
void	getCapabilities ()
	Gets device capabilities and stores them internally. Called, amongst others, by getSettings().

void	getCaptureWindow ()
	Get the size of the capture frame from the device and store it internally. It can be retrieved with getCapture[Width\|Height]().

Protected Member Functions inherited from goObjectBase
void	setClassID (int id)
	Sets the class name.

void	printClassMessage (const char *msg)
	Sets the class name. More...

void	printClassMessage (goString &msg)
	Prints an informational message to the calling console. More...

void	sendObjectMessage (int messageID, void *data=NULL)
	Sends a message to all connected objects.

void	sendObjectMessage (goObjectBase object, int messageID, void data=NULL)
	Sends a message to a specific object.

virtual void	receiveObjectMessage (const goObjectMessage &message)
	Receive a message. More...

Detailed Description

Video capture class.

This class allows video capture, currently only from video4linux (version 1) devices. Version 2 will follow when the drivers for our cameras support it and there is need.

Note: Please report when a camera/driver works witht this class, it's fairly new and my first time using v4l.; Currently only supports video4linux devices under Linux. No Windows support.

Author: Christian Gosch

Examples: videocapture/videocapture.cpp.

Member Function Documentation

◆ checkCapture()

bool goVideoCapture::checkCapture ( ) const

Check if video capture is available by the open device.

Returns: True if capture is available, false otherwise.

◆ getCaptureHeight()

goSize_t goVideoCapture::getCaptureHeight ( ) const

Capture frame height.

Returns: Frame height in pixels.

◆ getCaptureWidth()

goSize_t goVideoCapture::getCaptureWidth ( ) const

Capture frame width.

Returns: Frame width in pixels.

◆ getColourMode()

enum goVideoCapture::ColourMode goVideoCapture::getColourMode ( ) const

Get the colour mode this object is currently set to.

Returns: The colour mode enumerator.

◆ getFileDescriptor()

int goVideoCapture::getFileDescriptor ( ) const

Get file descriptor for open device.

Returns: File descriptor. Negative means no device is open.

◆ getValidRanges()

void goVideoCapture::getValidRanges ( )

Get valid ranges for brightnes etc.

Todo:: Does not work yet. a) doesn't find the real maximum value the way it works now, b) gets invalid argument all the time.

◆ grab() [1/3]

bool goVideoCapture::grab	(	goSignal3D< void > &	target,
		const int *	rgb_channels
	)

Convenience method.

Calls grab (goSignal3DBase<void>&), changing type and size of target if necessary.

Parameters

target	Target containing the image if return value is true.
rgb_channels	Contains 3 integers, each denoting the channel number in target for r, g, and b respectively.

Returns: True if successful, false otherwise.

◆ grab() [2/3]

bool goVideoCapture::grab	(	goSignal3DBase< void > &	target,
		const int *	rgb_channels
	)

Grab a frame from the open device.

Parameters

target	Target. Must currently be linear in memory (block size == signal size), of type GO_UINT8 and must have 3 channels if the colour mode is RGB24.
rgb_channels	Contains 3 integers, each denoting the channel number in target for r, g, and b respectively.

Returns: True if successful, false otherwise.

Examples: videocapture/videocapture.cpp.

◆ grab() [3/3]

bool goVideoCapture::grab	(	void *	target,
		goSize_t	sz
	)

Grab a frame from the open device.

Note: No data conversion is done. The data is as-is from the video device.

Parameters

target	Target pointer to memory of size sz bytes.
sz	Maximum of sz bytes is read from the open device.

Returns: True if successful, false otherwise.

◆ open()

bool goVideoCapture::open ( )

Open the device.

See also: setDevice()

Returns: True if successful, false otherwise.

Examples: videocapture/videocapture.cpp.

◆ setCaptureSize()

bool goVideoCapture::setCaptureSize	(	goSize_t	width,
		goSize_t	height
	)

Set capture frame size.

Parameters

width	Width in pixels.
height	Height in pixels.

Returns: True if successful, false otherwise.

Examples: videocapture/videocapture.cpp.

◆ setColourMode()

void goVideoCapture::setColourMode ( enum ColourMode vm )

Sets the colour mode.

Note: Care should be taken when forcing a colour mode and setting it with setSettings(). Apparently some devices don't support most colour modes or I'm not using the v4l interface right. Either way, it didn't work with my cameras. So just use the format provided by the camera for now.

Parameters

m	Colour mode enumerator.

◆ setDevice()

bool goVideoCapture::setDevice ( const char * name )

Set device file name.

Parameters

name	Device file name, e.g. "/dev/video0"

Returns: True if successful, false otherwise.

Examples: videocapture/videocapture.cpp.

◆ setFileDescriptor()

void goVideoCapture::setFileDescriptor ( int fd )

Set file discriptor of an already open device.

Sets the descriptor and automatically reads settings from the device to update the settings stored in the goVideoCapture object.

Parameters

fd	File descriptor.

◆ setSettings()

bool goVideoCapture::setSettings ( )

Store settings from this object to the open device.

Returns: True if successful, false otherwise. Also check the logfile.

Examples: videocapture/videocapture.cpp.

The documentation for this class was generated from the following files:

govideocapture.h
govideocapture.cpp

Public Types

Public Member Functions

Protected Member Functions

Detailed Description

Member Function Documentation

◆ checkCapture()

◆ getCaptureHeight()

◆ getCaptureWidth()

◆ getColourMode()

◆ getFileDescriptor()

◆ getValidRanges()

◆ grab() [1/3]

◆ grab() [2/3]

◆ grab() [3/3]

◆ open()

◆ setCaptureSize()

◆ setColourMode()

◆ setDevice()

◆ setFileDescriptor()

◆ setSettings()