A class for handle a video device. More...

#include <vidl_v4l2_device.h>

Classes
struct	buffer
Public Member Functions
	vidl_v4l2_device (const char *file)
	Constructor.
	~vidl_v4l2_device ()
vcl_string	device_file () const
	Name of the associated file device (same as constructor).
vcl_string	card_name () const
	Friendly name of the device.
unsigned int	n_inputs () const
	Number of inputs in device.
unsigned int	current_input () const
	Inputs been used (0 to ninputs-1).
const vidl_v4l2_input &	input (int i) const
	Return input number i (0 ..\ ninputs-1).
bool	set_input (unsigned int i)
	Select input i.
bool	set_v4l2_format (unsigned int fourcode, int width, int height, double fps=0.0)
	Select a new format.
bool	try_formats (int width=640, int height=480)
	Try several formats implemented in vidl.
bool	format_is_set () const
	Return if the format is set.
unsigned int	get_v4l2_format () const
	Get pixel format of type of compression.
int	get_width () const
	Return Image width in pixels.
int	get_height () const
	Return Image height in pixels.
double	get_frame_rate () const
	Return Current frame rate.
void	reset_controls ()
	Reset controls to default.
int	n_controls () const
	Get number of controls.
vidl_v4l2_control *	get_control (int i) const
	Get control.
vidl_v4l2_control *	get_control_id (int id) const
	Get control from driver id.
vidl_v4l2_control_integer *	get_control_integer_id (int id) const
	Get control from driver id.
vidl_v4l2_control_menu *	get_control_menu_id (int id) const
	Get control from driver id.
vidl_v4l2_control_boolean *	get_control_boolean_id (int id) const
	Get control from driver id.
vidl_v4l2_control_button *	get_control_button_id (int id) const
	Get control from driver id.
bool	start_capturing ()
	Start capturing.
bool	is_capturing () const
	Return if device is capturing.
bool	stop_capturing ()
	Stop capturing.
bool	read_frame ()
	Read next frame.
bool	set_number_of_buffers (unsigned int nb)
	Set numbers of buffers.
unsigned int	get_number_of_buffers () const
	Get numbers of buffers.
void *	current_buffer () const
	Return the last used buffer.
unsigned int	current_buffer_length () const
	Return length of the last used buffer.
void *	ibuffer (unsigned int i) const
	Return buffer number i.
unsigned int	sequence () const
bool	time_available () const
	Return if driver has time associated to the captured frame.
v4l2_timecode	time () const
	Time from last frame.
	operator safe_bool () const
	Cast to bool is true if video device is working ok.
bool	operator! () const
	Return false if video device is not working ok.
vcl_string	get_error () const
	Return last error if device is in a bad state. Empty if ok.
void	ref ()
	Increment reference count.
void	unref ()
	Decrement reference count.
int	ref_count () const
	Number of objects referring to this data.
Private Member Functions
void	update_controls ()
void	reset ()
bool	open ()
bool	initialize_device ()
bool	init_mmap (int reqbuf)
bool	uninit_mmap ()
bool	close ()
bool	is_open () const
bool	is_prepared_for_capturing () const
bool	good () const
	vidl_v4l2_device (const vidl_v4l2_device &)
vidl_v4l2_device &	operator= (const vidl_v4l2_device &)
Private Attributes
	VCL_SAFE_BOOL_DEFINE
int	fd
unsigned int	pre_nbuffers
struct buffer *	buffers
unsigned int	n_buffers
int	last_buffer
struct v4l2_format	fmt
double	frame_rate
vcl_string	dev_name_
vcl_string	card_name_
vcl_string	last_error
bool	capturing
vcl_vector< vidl_v4l2_input >	inputs_
vcl_vector< vidl_v4l2_control * >	controls_
int	ref_count_

Detailed Description

A class for handle a video device.

This class is designed to be vidl independent, although it is very easy to create a vidl istream from it. It has not been fully tested, although it has been proven to capture images from multiple webcams with a single buffer (default) and has worked properly. Generally, the steps to be made for a capture are as follows:

Select input
Select format
Select number of buffers.
Start capturing
Stop capturing When a device is opened, an input and format are selected by default (see vidl_v4l2_device::try_formats function). Then if you start capturing, you will probably get 640x480 frames, from input 0, using just one buffer with an unknown format (the first one valid for the driver).
See also:
vidl_v4l2_devices

Definition at line 57 of file vidl_v4l2_device.h.

Constructor & Destructor Documentation

vidl_v4l2_device::vidl_v4l2_device ( const vidl_v4l2_device & ) [private]

vidl_v4l2_device::vidl_v4l2_device ( const char * file )

Constructor.

After construction, device is closed (device is not busy). You can use device as a boolean expression to test if device is ok.

Parameters:

file	device name (for example, "/dev/video")
file	device name (for example, "/dev/video")

Definition at line 103 of file vidl_v4l2_device.cxx.

vidl_v4l2_device::~vidl_v4l2_device ( )

Definition at line 145 of file vidl_v4l2_device.cxx.

Member Function Documentation

vcl_string vidl_v4l2_device::card_name ( ) const [inline]

Friendly name of the device.

Definition at line 114 of file vidl_v4l2_device.h.

bool vidl_v4l2_device::close ( void ) [private]

Definition at line 579 of file vidl_v4l2_device.cxx.

void* vidl_v4l2_device::current_buffer ( ) const [inline]

Return the last used buffer.

Precondition:: device is capturing

Definition at line 257 of file vidl_v4l2_device.h.

unsigned int vidl_v4l2_device::current_buffer_length ( ) const [inline]

Return length of the last used buffer.

Precondition:: device is capturing

Definition at line 263 of file vidl_v4l2_device.h.

unsigned int vidl_v4l2_device::current_input ( ) const

Inputs been used (0 to ninputs-1).

if equal to ninputs, indicates unknown

See also:: ninputs

Definition at line 599 of file vidl_v4l2_device.cxx.

vcl_string vidl_v4l2_device::device_file ( ) const [inline]

Name of the associated file device (same as constructor).

Definition at line 112 of file vidl_v4l2_device.h.

bool vidl_v4l2_device::format_is_set ( ) const [inline]

Return if the format is set.

Normally, a format is automatically selected or user call set_v4l2_format. User can use this function to know if a format is selected before calling start_capturing.

See also:: set_v4l2_format

Definition at line 149 of file vidl_v4l2_device.h.

vidl_v4l2_control* vidl_v4l2_device::get_control ( int i ) const [inline]

Get control.

The user must downcast the pointer -depending on type- to use all functionality.

Parameters:

i	indicates the control to be extracted, from 0 to n_controls-1

Returns:: pointer to control

See also:: n_controls

Definition at line 185 of file vidl_v4l2_device.h.

vidl_v4l2_control_boolean* vidl_v4l2_device::get_control_boolean_id ( int id ) const [inline]

Get control from driver id.

Parameters:

id	is control ID from v4l2 specification. For example, V4L2_CID_BRIGHTNESS

Returns:: pointer to control. Null if doesn't exist or is not of type V4L2_CTRL_TYPE_BOOLEAN

Definition at line 216 of file vidl_v4l2_device.h.

vidl_v4l2_control_button* vidl_v4l2_device::get_control_button_id ( int id ) const [inline]

Get control from driver id.

Parameters:

id	is control ID from v4l2 specification. For example, V4L2_CID_BRIGHTNESS

Returns:: pointer to control. Null if doesn't exist or is not of type V4L2_CTRL_TYPE_BUTTON

Definition at line 226 of file vidl_v4l2_device.h.

vidl_v4l2_control* vidl_v4l2_device::get_control_id ( int id ) const [inline]

Get control from driver id.

The user must downcast the pointer -depending on type- to use all functionality.

Parameters:

id	is control ID from v4l2 specification. For example, V4L2_CID_BRIGHTNESS

Returns:: pointer to control or 0 if does not exist

Definition at line 190 of file vidl_v4l2_device.h.

vidl_v4l2_control_integer* vidl_v4l2_device::get_control_integer_id ( int id ) const [inline]

Get control from driver id.

Parameters:

id	is control ID from v4l2 specification. For example, V4L2_CID_BRIGHTNESS

Returns:: pointer to control. Null if doesn't exist or is not of type V4L2_CTRL_TYPE_INTEGER

Definition at line 196 of file vidl_v4l2_device.h.

vidl_v4l2_control_menu* vidl_v4l2_device::get_control_menu_id ( int id ) const [inline]

Get control from driver id.

Parameters:

id	is control ID from v4l2 specification. For example, V4L2_CID_BRIGHTNESS

Returns:: pointer to control. Null if doesn't exist or is not of type V4L2_CTRL_TYPE_MENU

Definition at line 206 of file vidl_v4l2_device.h.

vcl_string vidl_v4l2_device::get_error ( ) const [inline]

Return last error if device is in a bad state. Empty if ok.

Definition at line 305 of file vidl_v4l2_device.h.

double vidl_v4l2_device::get_frame_rate ( ) const [inline]

Return Current frame rate.

See also:: set_v4l2_format

Definition at line 170 of file vidl_v4l2_device.h.

int vidl_v4l2_device::get_height ( ) const [inline]

Return Image height in pixels.

Note:: You can use this function to know the height selected by driver after calling set_v4l2_format

See also:: set_v4l2_format

Definition at line 166 of file vidl_v4l2_device.h.

unsigned int vidl_v4l2_device::get_number_of_buffers ( ) const [inline]

Get numbers of buffers.

Definition at line 253 of file vidl_v4l2_device.h.

unsigned int vidl_v4l2_device::get_v4l2_format ( ) const [inline]

Get pixel format of type of compression.

Returns:: the four character code which is being used by driver(see v4l2 specification and vidl_pixel_format.h) or 0 if not set

See also:: set_v4l2_format

Definition at line 154 of file vidl_v4l2_device.h.

int vidl_v4l2_device::get_width ( ) const [inline]

Return Image width in pixels.

Note:: You can use this function to know the width selected by driver after calling set_v4l2_format

See also:: set_v4l2_format

Definition at line 162 of file vidl_v4l2_device.h.

bool vidl_v4l2_device::good ( ) const [inline, private]

Definition at line 95 of file vidl_v4l2_device.h.

void* vidl_v4l2_device::ibuffer ( unsigned int i ) const [inline]

Return buffer number i.

Precondition:: device is capturing

See also:: get_number_of_buffers

Definition at line 270 of file vidl_v4l2_device.h.

bool vidl_v4l2_device::init_mmap ( int reqbuf ) [private]

Definition at line 365 of file vidl_v4l2_device.cxx.

bool vidl_v4l2_device::initialize_device ( ) [private]

Definition at line 226 of file vidl_v4l2_device.cxx.

const vidl_v4l2_input& vidl_v4l2_device::input ( int i ) const [inline]

Return input number i (0 ..\ ninputs-1).

Definition at line 122 of file vidl_v4l2_device.h.

bool vidl_v4l2_device::is_capturing ( ) const [inline]

Return if device is capturing.

Definition at line 239 of file vidl_v4l2_device.h.

bool vidl_v4l2_device::is_open ( ) const [inline, private]

Definition at line 93 of file vidl_v4l2_device.h.

bool vidl_v4l2_device::is_prepared_for_capturing ( ) const [inline, private]

Definition at line 94 of file vidl_v4l2_device.h.

int vidl_v4l2_device::n_controls ( ) const [inline]

Get number of controls.

Returns:: the number of detected controls (control not disabled and not inactive).

Definition at line 179 of file vidl_v4l2_device.h.

unsigned int vidl_v4l2_device::n_inputs ( ) const [inline]

Number of inputs in device.

Definition at line 116 of file vidl_v4l2_device.h.

bool vidl_v4l2_device::open ( ) [private]

Definition at line 194 of file vidl_v4l2_device.cxx.

vidl_v4l2_device::operator safe_bool ( ) const [inline]

Cast to bool is true if video device is working ok.

Definition at line 297 of file vidl_v4l2_device.h.

bool vidl_v4l2_device::operator! ( ) const [inline]

Return false if video device is not working ok.

Definition at line 301 of file vidl_v4l2_device.h.

vidl_v4l2_device& vidl_v4l2_device::operator= ( const vidl_v4l2_device & ) [private]

bool vidl_v4l2_device::read_frame ( void )

Member Data Documentation

struct buffer* vidl_v4l2_device::buffers [private]

Definition at line 68 of file vidl_v4l2_device.h.

bool vidl_v4l2_device::capturing [private]

Definition at line 77 of file vidl_v4l2_device.h.

vcl_string vidl_v4l2_device::card_name_ [private]

Definition at line 75 of file vidl_v4l2_device.h.

vcl_vector<vidl_v4l2_control *> vidl_v4l2_device::controls_ [private]

Definition at line 79 of file vidl_v4l2_device.h.

vcl_string vidl_v4l2_device::dev_name_ [private]

Definition at line 74 of file vidl_v4l2_device.h.

int vidl_v4l2_device::fd [private]

Definition at line 60 of file vidl_v4l2_device.h.

struct v4l2_format vidl_v4l2_device::fmt [private]

Definition at line 71 of file vidl_v4l2_device.h.

double vidl_v4l2_device::frame_rate [private]

Definition at line 72 of file vidl_v4l2_device.h.

vcl_vector<vidl_v4l2_input> vidl_v4l2_device::inputs_ [private]

Definition at line 78 of file vidl_v4l2_device.h.

int vidl_v4l2_device::last_buffer [private]

Definition at line 70 of file vidl_v4l2_device.h.

vcl_string vidl_v4l2_device::last_error [mutable, private]

Definition at line 76 of file vidl_v4l2_device.h.

unsigned int vidl_v4l2_device::n_buffers [private]

Definition at line 69 of file vidl_v4l2_device.h.

unsigned int vidl_v4l2_device::pre_nbuffers [private]

Definition at line 67 of file vidl_v4l2_device.h.

int vidl_v4l2_device::ref_count_ [private]

Definition at line 328 of file vidl_v4l2_device.h.

vidl_v4l2_device::VCL_SAFE_BOOL_DEFINE [private]

Definition at line 59 of file vidl_v4l2_device.h.

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

core/vidl/vidl_v4l2_device.h
core/vidl/vidl_v4l2_device.cxx

bool vidl_v4l2_device::set_v4l2_format	(	unsigned int	fourcode,
		int	width,
		int	height,
		double	fps = `0.0`
	)

bool vidl_v4l2_device::try_formats	(	int	width = `640`,
		int	height = `480`
	)

fourcode	A four character code defined in v4l2 (see v4l2 specification and vidl_pixel_format.h) indicating pixel encoding
width	can be changed by drivers to the closest possible value
height	can be changed by drivers to the closest possible value
fps	frame rate to try (not garanteed).

Classes

Public Member Functions

Private Member Functions

Private Attributes

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation