v4l2capture.h File Reference

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Detailed Description

set of functions to grab frames from v4l2 device

This is a very light wrapper to v4l2 interface. It uses MMAP transfer method only and doesn't do any copying, just passing assigned buffers filled by driver. It's intention was to easily access device without need to prepate all those structures for ioctl's.

To use it, first create FRAMEGRABBER2 object by fg2_createFrameGrabber

Authors

Marcin Rudowski

Definition in file v4l2capture.h.

#include <stdio.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/ioctl.h>
#include <linux/fs.h>
#include <linux/kernel.h>
#include <asm/types.h>
#include <linux/videodev.h>

Go to the source code of this file.

Classes
struct	my_buffer
struct	FRAMEGRABBER2
Defines
#define	FG_DEFAULT_DEVICE   "/dev/video0"
#define	FG_DEFAULT_WIDTH   640
#define	FG_DEFAULT_HEIGHT   480
#define	FG_SOURCE_TV   0
#define	FG_SOURCE_COMPOSITE   1
#define	FG_SOURCE_SVIDEO   2
Functions
FRAMEGRABBER2 *	fg2_createFrameGrabber ()
void	fg2_delete (FRAMEGRABBER2 **fg)
int	fg2_open (FRAMEGRABBER2 *fg, const char *dev)
int	fg2_startCapture (FRAMEGRABBER2 *fg)
int	fg2_stopCapture (FRAMEGRABBER2 *fg)
my_buffer *	getFrameBuffer (FRAMEGRABBER2 *fg)
void	giveBackFrameBuffer (FRAMEGRABBER2 *fg, struct my_buffer *mBuff)
int	fg2_get_source_count (FRAMEGRABBER2 *fg)
int	fg2_get_source_id (FRAMEGRABBER2 *fg)
const char *	fg2_get_source_name (FRAMEGRABBER2 *fg)
const char *	fg2_get_id_source_name (FRAMEGRABBER2 *fg, int src)
const char *	fg2_get_device_name (FRAMEGRABBER2 *fg)
int	fg2_set_source (FRAMEGRABBER2 *fg, int src, const char *strSrc)
int	fg2_countControls (FRAMEGRABBER2 *fg)
int	fg2_setControlValueI (FRAMEGRABBER2 *fg, int id, double val)
int	fg2_setControlValue (FRAMEGRABBER2 *fg, const char *id, double val)
double	fg2_getControlValueI (FRAMEGRABBER2 *fg, int id)
double	fg2_getControlValue (FRAMEGRABBER2 *fg, const char *id)
const char *	fg2_getControlName (FRAMEGRABBER2 *fg, int id)
int	fg2_set_source_norm (FRAMEGRABBER2 *fg, v4l2_std_id norm)
int	fg2_setPixelSettings (FRAMEGRABBER2 *fg, int width, int height, unsigned int fmt, enum v4l2_field fld, int depth)

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Function Documentation

int fg2_countControls (  FRAMEGRABBER2 *  fg  )

Returns number of found controls Definition at line 464 of file v4l2capture.c. References FRAMEGRABBER2::numOfCtls.

FRAMEGRABBER2* fg2_createFrameGrabber (   )

Create device handler (just fill structure) Returns: new device handler Definition at line 90 of file v4l2capture.c. References FRAMEGRABBER2::altField, FRAMEGRABBER2::buffers, FRAMEGRABBER2::controls, FRAMEGRABBER2::cur_frame, FRAMEGRABBER2::device, FRAMEGRABBER2::fd, FRAMEGRABBER2::field, FRAMEGRABBER2::height, FRAMEGRABBER2::isCapturing, FRAMEGRABBER2::n_buffers, FRAMEGRABBER2::numOfCtls, FRAMEGRABBER2::numOfIn, FRAMEGRABBER2::pix_fmt, FRAMEGRABBER2::source, FRAMEGRABBER2::sources, and FRAMEGRABBER2::width.

void fg2_delete (  FRAMEGRABBER2 **  fg  )

delete completely fg handler (including whatever is needed to close device) Parameters: fg  Definition at line 126 of file v4l2capture.c.

const char* fg2_get_device_name (  FRAMEGRABBER2 *  fg  )

Name of device Definition at line 409 of file v4l2capture.c. References FRAMEGRABBER2::caps.

const char* fg2_get_id_source_name (  FRAMEGRABBER2 *  fg, int  src )

Name of given source identified by id Definition at line 395 of file v4l2capture.c. References FRAMEGRABBER2::numOfIn, and FRAMEGRABBER2::sources.

int fg2_get_source_count (  FRAMEGRABBER2 *  fg  )

Returns number of found inputs Definition at line 364 of file v4l2capture.c. References FRAMEGRABBER2::numOfIn.

int fg2_get_source_id (  FRAMEGRABBER2 *  fg  )

Current source id Definition at line 372 of file v4l2capture.c. References FRAMEGRABBER2::fd.

const char* fg2_get_source_name (  FRAMEGRABBER2 *  fg  )

Current source name Definition at line 387 of file v4l2capture.c.

double fg2_getControlValue (  FRAMEGRABBER2 *  fg, const char *  id )

Gets current control value. <0 means error. Control is identified by its name Definition at line 560 of file v4l2capture.c. References FRAMEGRABBER2::controls, and FRAMEGRABBER2::numOfCtls.

double fg2_getControlValueI (  FRAMEGRABBER2 *  fg, int  id )

Gets current control value. <0 means error. Control is identified by id in local table Definition at line 531 of file v4l2capture.c. References FRAMEGRABBER2::controls, FRAMEGRABBER2::fd, and FRAMEGRABBER2::numOfCtls.

int fg2_open (  FRAMEGRABBER2 *  fg, const char *  dev )

open device and discover capabilities and inputs. To capture from device You need to use fg2_startCapture first. Earlier You can set source and size. Parameters: fg  framegrabber handler dev  pathc to /dev/videoX file Returns: error status Definition at line 140 of file v4l2capture.c. References FRAMEGRABBER2::caps, FRAMEGRABBER2::cur_frame, FRAMEGRABBER2::device, FRAMEGRABBER2::fd, FG_DEFAULT_DEVICE, and FRAMEGRABBER2::numOfIn.

int fg2_set_source (  FRAMEGRABBER2 *  fg, int  srcNo, const char *  strSrc )

Select input source. if src<0, then strSrc is used to compare with known sources Returns: error status Definition at line 419 of file v4l2capture.c. References FRAMEGRABBER2::fd, FRAMEGRABBER2::numOfIn, FRAMEGRABBER2::source, and FRAMEGRABBER2::sources.

int fg2_set_source_norm (  FRAMEGRABBER2 *  fg, v4l2_std_id  norm )

pal, ntsc, secam, etc. Definition at line 586 of file v4l2capture.c. References FRAMEGRABBER2::fd.

int fg2_setControlValue (  FRAMEGRABBER2 *  fg, const char *  id, double  val )

Sets new value to control. Val is in 0.0-1.0 range. Values <0 means use default Control is identified by its name Definition at line 516 of file v4l2capture.c. References FRAMEGRABBER2::controls, and FRAMEGRABBER2::numOfCtls.

int fg2_setControlValueI (  FRAMEGRABBER2 *  fg, int  id, double  val )

Sets new value to control. Val is in 0.0-1.0 range. Values <0 means use default Control is identified by id in local table Definition at line 473 of file v4l2capture.c. References FRAMEGRABBER2::controls, FRAMEGRABBER2::fd, and FRAMEGRABBER2::numOfCtls.

int fg2_setPixelSettings (  FRAMEGRABBER2 *  fg, int  width, int  height, unsigned int  fmt, enum v4l2_field  fld, int  dpth )

Tries to apply given frame settings Definition at line 603 of file v4l2capture.c. References FRAMEGRABBER2::depth, FRAMEGRABBER2::field, FRAMEGRABBER2::height, FRAMEGRABBER2::pix_fmt, and FRAMEGRABBER2::width.

int fg2_startCapture (  FRAMEGRABBER2 *  fg  )

Turn capture stream on. You need to use it by hand after opening, or stopping Returns: error status Definition at line 217 of file v4l2capture.c. References FRAMEGRABBER2::fd, and FRAMEGRABBER2::isCapturing.

int fg2_stopCapture (  FRAMEGRABBER2 *  fg  )

Turn capture stream of. You need to use it by hand when changing format or size of frame. Only controls doesn't need stopping Returns: error status Definition at line 268 of file v4l2capture.c. References FRAMEGRABBER2::fd, and FRAMEGRABBER2::isCapturing.

struct my_buffer* getFrameBuffer (  FRAMEGRABBER2 *  fg  )

light capture interface, gives live data without any memcpy (just after dequeueing) Parameters: fg  framegrabber struct Returns: bufer struct (dont change it, just read) Definition at line 300 of file v4l2capture.c. References FRAMEGRABBER2::altField, my_buffer::buf, FRAMEGRABBER2::buffers, FRAMEGRABBER2::fd, and FRAMEGRABBER2::n_buffers.

void giveBackFrameBuffer (  FRAMEGRABBER2 *  fg, struct my_buffer *  mBuff )

This is opposite to getFrameBuffer. It Queues used buffer to the driver. Parameters: fg  framegrabber handler mBuff  earlier received buffer with image and its state Definition at line 347 of file v4l2capture.c. References my_buffer::buf, and FRAMEGRABBER2::fd.

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