vidl_v4l2_device Class Reference

#include <vidl_v4l2_device.h>

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 devide is opened, a 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 a unknown format (the first one valid for the driver).
See also:
vidl_v4l2_devices

Definition at line 50 of file vidl_v4l2_device.h.


Public Member Functions
	vidl_v4l2_device (const char *file)
	Constructor.
	~vidl_v4l2_device ()
void	reset ()
	Reset the device to a initial state.
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 .
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	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 ()
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
bool	try_formats ()
	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
buffer *	buffers
unsigned int	n_buffers
int	last_buffer
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_
Classes
struct	buffer

Constructor & Destructor Documentation

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

vidl_v4l2_device::vidl_v4l2_device ( const char * file )

Constructor.

Parameters:

file

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

Definition at line 100 of file vidl_v4l2_device.cxx.

vidl_v4l2_device::~vidl_v4l2_device ( )

Definition at line 141 of file vidl_v4l2_device.cxx.

Member Function Documentation

void vidl_v4l2_device::update_controls ( ) [private]

Definition at line 55 of file vidl_v4l2_device.cxx.

bool vidl_v4l2_device::open ( ) [private]

Definition at line 181 of file vidl_v4l2_device.cxx.

bool vidl_v4l2_device::initialize_device ( ) [private]

Definition at line 213 of file vidl_v4l2_device.cxx.

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

Definition at line 339 of file vidl_v4l2_device.cxx.

bool vidl_v4l2_device::uninit_mmap ( ) [private]

Definition at line 539 of file vidl_v4l2_device.cxx.

bool vidl_v4l2_device::close ( ) [private]

Definition at line 552 of file vidl_v4l2_device.cxx.

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

Definition at line 81 of file vidl_v4l2_device.h.

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

Definition at line 82 of file vidl_v4l2_device.h.

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

Definition at line 83 of file vidl_v4l2_device.h.

bool vidl_v4l2_device::try_formats ( ) [private]

Definition at line 250 of file vidl_v4l2_device.cxx.

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

void vidl_v4l2_device::reset ( )

Reset the device to a initial state.

Definition at line 153 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 102 of file vidl_v4l2_device.h.

vcl_string vidl_v4l2_device::card_name ( ) const [inline]

Friendly name of the device.

Definition at line 104 of file vidl_v4l2_device.h.

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

Number of inputs in device.

Definition at line 106 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 562 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 112 of file vidl_v4l2_device.h.

bool vidl_v4l2_device::set_input ( unsigned int i )

Select input i.

Returns:: if successful

Definition at line 577 of file vidl_v4l2_device.cxx.

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

Select a new format.

Device try automatically different formats (

See also:: try_formats()). Then this function could be ignored if you don't mind the format. Usually, user wants a concrete pixel format or, simply, change width and height.

Parameters:

	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

Returns:: if successful

See also:: format_is_set

Definition at line 281 of file vidl_v4l2_device.cxx.

bool vidl_v4l2_device::format_is_set ( ) const [inline]

Return if the format is set.

Normally, a format is automatically selected of 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 130 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 135 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 143 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 147 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 151 of file vidl_v4l2_device.h.

void vidl_v4l2_device::reset_controls ( )

Reset controls to default.

Definition at line 90 of file vidl_v4l2_device.cxx.

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 160 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 funcionality.

Parameters:

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

Returns:: pointer to control

See also:: n_controls

Definition at line 166 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 funcionality.

Parameters: