Webcam library declarations. More...

#include <assert.h>

Data Structures
struct	_Control
	An internal control description associated with a device. More...

struct	_ControlList
	Base structure that contains a list of controls and associated data. More...

struct	_Device
	Internal device information. More...

struct	_DeviceList
	Base structure that contains a list of devices and associated data. More...

struct	_Handle
	Information associated with a device handle. More...

struct	_HandleList
	Base structure that contains an array of device handles and associated data. More...

Macros
#define	USE_UVCVIDEO
	Whether private controls of the Linux UVC driver should be used or not.

#define	ENABLE_UVCVIDEO_DYNCTRL
	Whether to compile in support functions for the Linux UVC driver's dynamic controls. More...

#define	USE_LOGITECH_DYNCTRL
	Whether to include the automatically generated Logitech dynamic controls header file. More...

#define	ENABLE_V4L2_ADVANCED_CONTROL_ENUMERATION
	Whether to include support for raw controls. More...

#define	DYNCTRL_IGNORE_EEXIST_AFTER_PASS1
	Ignore EEXIST errors for the UVCIOC_CTRL_ADD and UVCIOC_CTRL_MAP ioctls for all but the first device. More...

#define	MAX_HANDLES 32
	The maximum number (plus 1) of handles libwebcam supports.

#define	DISABLE_LOCKING 1
	Debug option to disable locking.

#define	DEBUG_LOCKING 1
	Debug option to add verbosity to locking and unlocking.

#define	UNKNOWN_CONTROL_NAME "Unknown control"
	The name used for controls whose name could not be retrieved.

#define	CONTROL_IO_ERROR_RETRIES 2
	Number of retries for failed V4L2 ioctl requests. More...

#define	GUID_SIZE 16
	Size of a GUID in bytes.

#define	GET_HANDLE(handle) (handle_list.handles[(handle)])
	Returns the given handle structure.

#define	HANDLE_OPEN(handle) ((handle) < MAX_HANDLES && GET_HANDLE(handle).open)
	Returns true if the given handle is open (valid or invalid)

#define	HANDLE_VALID(handle) (HANDLE_OPEN(handle) && GET_HANDLE(handle).device)
	Returns true if the given handle is open and valid.

#define	V4L2_MENU_CTRL_MAX_NAME_SIZE sizeof(((struct v4l2_querymenu *)NULL)->name)
	Returns the maximum number of characters that a menu-type control choice can have in V4L2. More...

#define	MAKE_FOURCC(c1, c2, c3, c4) (unsigned int)((long)c1 \| (long)c2 << 8 \| (long)c3 << 16 \| (long)c4 << 24)
	Converts the given characters into a FourCC code.

#define	GUID_FORMAT "%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x"
	Format string to print a GUID byte array with printf.

#define	GUID_ARGS(guid)
	Argument macro to print a GUID byte array with printf. More...

Typedefs
typedef struct _Control	Control
	An internal control description associated with a device.

typedef struct _ControlList	ControlList
	Base structure that contains a list of controls and associated data.

typedef struct _Device	Device
	Internal device information.

typedef struct _DeviceList	DeviceList
	Base structure that contains a list of devices and associated data.

typedef struct _Handle	Handle
	Information associated with a device handle. More...

typedef struct _HandleList	HandleList
	Base structure that contains an array of device handles and associated data.

Functions
void	print_error (char *format,...)

int	open_v4l2_device (char *device_name)
	Open the V4L2 device node with the given name. More...

static CResult	lock_mutex (pthread_mutex_t *mutex)
	Acquire a mutex. More...

static void	unlock_mutex (pthread_mutex_t *mutex)
	Release a mutex. More...

static void	copy_string_to_buffer (char *target, char source, void buffer, unsigned int offset)
	Copies a variable-length string to the part of an enumeration buffer that is reserved for dynamic data. More...

Variables
int	initialized
	A flag indicating whether the library was initialized.

HandleList	handle_list
	The fixed size list of file handles.

Detailed Description

Webcam library declarations.

Macro Definition Documentation

#define CONTROL_IO_ERROR_RETRIES 2

Number of retries for failed V4L2 ioctl requests.

This is a workaround for faulty devices.

Referenced by refresh_control_list().

#define DYNCTRL_IGNORE_EEXIST_AFTER_PASS1

Ignore EEXIST errors for the UVCIOC_CTRL_ADD and UVCIOC_CTRL_MAP ioctls for all but the first device.

This is required if the driver uses global controls instead of per-device controls.

Referenced by process_control(), and process_mapping().

#define ENABLE_UVCVIDEO_DYNCTRL

Whether to compile in support functions for the Linux UVC driver's dynamic controls.

#define ENABLE_V4L2_ADVANCED_CONTROL_ENUMERATION

Whether to include support for raw controls.

Note that this requires V4L2_CTRL_TYPE_STRING to be available (i.e. V4L2 >= 2.6.32). This is disabled by default but CMake enables it if it finds V4L2_CTRL_TYPE_STRING. Whether to use the V4L2_CTRL_FLAG_NEXT_CTRL flag when enumerating V4L2 controls

#define GUID_ARGS ( guid )

Value:

(guid)[3],  (guid)[2],  (guid)[1],  (guid)[0], \
        (guid)[5],  (guid)[4], \
        (guid)[7],  (guid)[6], \
        (guid)[8],  (guid)[9], \
        (guid)[10], (guid)[11], (guid)[12], \
        (guid)[13], (guid)[14], (guid)[15]

Argument macro to print a GUID byte array with printf.

Referenced by process_control().

#define USE_LOGITECH_DYNCTRL

Whether to include the automatically generated Logitech dynamic controls header file.

#define V4L2_MENU_CTRL_MAX_NAME_SIZE sizeof(((struct v4l2_querymenu *)NULL)->name)

Returns the maximum number of characters that a menu-type control choice can have in V4L2.

Referenced by create_control_choices().

Typedef Documentation

typedef struct _Handle Handle

Information associated with a device handle.

Note that a handle can have three different states:

Closed/free: The device handle is not being used by an application.
Valid: The device handle is open by an application and points to a valid device.
Invalid: The device handle is open by an application but does not point to a (valid) device anymore. This happens when a device is removed from the system but there are still open handles around. An "open" handle can be both valid or invalid.

Function Documentation

static void copy_string_to_buffer	(	char **	target,
		char *	source,
		void *	buffer,
		unsigned int *	offset
	)

inlinestatic

Copies a variable-length string to the part of an enumeration buffer that is reserved for dynamic data.

This function is used by the enumeration functions.

Referenced by c_enum_devices(), c_enum_pixel_formats(), and c_get_device_info().

static CResult lock_mutex ( pthread_mutex_t * mutex )

inlinestatic

Acquire a mutex.

This function is identical to pthread_mutex_lock except that it has different return values and supports some debug flags.

Returns: C_SUCCESS if the mutex was successfully acquired C_SYNC_ERROR if an error occured while trying to acquire the mutex

References C_SUCCESS, and C_SYNC_ERROR.

Referenced by c_cleanup(), c_enum_controls(), c_enum_devices(), clear_control_list(), close_handle(), create_handle(), delete_device(), refresh_control_list(), and refresh_device_list().

int open_v4l2_device ( char * device_name )

Open the V4L2 device node with the given name.

Parameters

device_name A device name as accepted by c_open_device()

Returns

0 if the device could not be opened
a device handle > 0 on success

References C_INVALID_ARG.

Referenced by add_control_mappings(), c_enum_frame_intervals(), c_enum_frame_sizes(), c_enum_pixel_formats(), read_v4l2_control(), refresh_control_list(), refresh_device_details(), and write_v4l2_control().

static void unlock_mutex ( pthread_mutex_t * mutex )

inlinestatic

Release a mutex.

This function is identical to pthread_mutex_unlock except that it has different return values and supports some debug flags.

Returns: C_SUCCESS if the mutex was successfully released C_SYNC_ERROR if an error occured while trying to release the mutex

Referenced by c_cleanup(), c_enum_controls(), c_enum_devices(), clear_control_list(), close_handle(), create_handle(), delete_device(), refresh_control_list(), and refresh_device_list().

Data Structures

Macros

Typedefs

Functions

Variables

Detailed Description

Macro Definition Documentation

Typedef Documentation

Function Documentation