vpV4l2Grabber Class Reference

#include <vpV4l2Grabber.h>

Inheritance diagram for vpV4l2Grabber:

Public Types
enum	vpV4l2FramerateType { framerate_50fps, framerate_25fps }
enum	vpV4l2FrameFormatType { V4L2_FRAME_FORMAT, V4L2_IMAGE_FORMAT }
enum	vpV4l2PixelFormatType {   V4L2_GREY_FORMAT, V4L2_RGB24_FORMAT, V4L2_RGB32_FORMAT, V4L2_BGR24_FORMAT,   V4L2_YUYV_FORMAT, V4L2_MAX_FORMAT }

Public Member Functions
	vpV4l2Grabber ()
	vpV4l2Grabber (bool verbose)
	vpV4l2Grabber (unsigned input, unsigned scale=vpV4l2Grabber::DEFAULT_SCALE)
	vpV4l2Grabber (vpImage< unsigned char > &I, unsigned input, unsigned scale=vpV4l2Grabber::DEFAULT_SCALE)
	vpV4l2Grabber (vpImage< vpRGBa > &I, unsigned input, unsigned scale=vpV4l2Grabber::DEFAULT_SCALE)
virtual	~vpV4l2Grabber ()
void	open (vpImage< unsigned char > &I)
void	open (vpImage< vpRGBa > &I)
void	acquire (vpImage< unsigned char > &I)
void	acquire (vpImage< unsigned char > &I, const vpRect &roi)
void	acquire (vpImage< unsigned char > &I, struct timeval &timestamp, const vpRect &roi=vpRect())
void	acquire (vpImage< vpRGBa > &I)
void	acquire (vpImage< vpRGBa > &I, const vpRect &roi)
void	acquire (vpImage< vpRGBa > &I, struct timeval &timestamp, const vpRect &roi=vpRect())
bool	getField ()
vpV4l2FramerateType	getFramerate ()
vpV4l2PixelFormatType	getPixelFormat ()
vpV4l2Grabber &	operator>> (vpImage< unsigned char > &I)
vpV4l2Grabber &	operator>> (vpImage< vpRGBa > &I)
void	setVerboseMode (bool verbose)
void	setFramerate (vpV4l2FramerateType framerate)
void	setInput (unsigned input=vpV4l2Grabber::DEFAULT_INPUT)
void	setWidth (unsigned w)
void	setHeight (unsigned h)
void	setScale (unsigned scale=vpV4l2Grabber::DEFAULT_SCALE)
void	setNBuffers (unsigned nbuffers)
void	setDevice (const std::string &devname)
void	setPixelFormat (vpV4l2PixelFormatType pixelformat)
void	close ()
Inherited functionalities from vpFramegrabber
unsigned int	getHeight () const
unsigned int	getWidth () const

Public Attributes
bool	init

Static Public Attributes
static const unsigned int	DEFAULT_INPUT = 2
static const unsigned int	DEFAULT_SCALE = 2
static const __u32	MAX_INPUTS = 16
static const __u32	MAX_NORM = 16
static const __u32	MAX_FORMAT = 32
static const unsigned int	MAX_CTRL = 32
static const unsigned int	MAX_BUFFERS = 32
static const unsigned int	FRAME_SIZE = 288

Protected Attributes
unsigned int	height
unsigned int	width

Detailed Description

Class that is a wrapper over the Video4Linux2 (V4L2) driver.

Thus to be enabled, this class needs the optional V4L2 3rd party. Installation instruction are provided here https://visp.inria.fr/3rd_v4l2.

Information about Video4Linux can be found on http://linuxtv.org/v4lwiki/index.php/Main_Page

This class was tested with a Pinnacle PCTV Studio/Rave board but also with the following webcams (Logitech QuickCam Vision Pro 9000, Logitech QuickCam Orbit AF, Logitech QuickCam IM (V-USB39), Dell latitude E6400 internal webcam).

If the grabbing fail with a webcam, it means probably that you don't have the read/write permission on the /dev/video%d device. You can set the right permissions by "sudo chmod a+rw /dev/video*".

If the grabbing fails when the camera is attached to a bttv PCI card, it means potentially that you have not configured the linux bttv kernel module according to your board.

For that, depending on your linux distribution check the card id in

• /usr/share/doc/kernel-doc-2.4.20/video4linux/bttv/CARDLIST
• or /usr/share/doc/kernel-doc-2.6.20/Documentation/video4linux/CARDLIST.bttv

For example, the card id of a Pinnacle PCTV Studio/Rave board is 39. Once this id is determined, you have to set the bttv driver with, by adding

  options bttv card=39

in one of theses files :

• /etc/modules.conf
• or /etc/modprobe.conf

This first example available in tutorial-grabber-v4l2.cpp shows how to grab and display images from an usb camera.

#include <visp3/core/vpImage.h>
#include <visp3/gui/vpDisplayX.h>
#include <visp3/gui/vpDisplayOpenCV.h>
#include <visp3/sensor/vpV4l2Grabber.h>
#include <visp3/io/vpImageStorageWorker.h>

//#define USE_COLOR // Comment to acquire gray level images

int main(int argc, const char *argv[])
{
#if defined(VISP_HAVE_V4L2) && (VISP_CXX_STANDARD >= VISP_CXX_STANDARD_11)
  try {
    int opt_device = 0;
    unsigned int opt_scale = 1; // Default value is 2 in the constructor. Turn
                                // it to 1 to avoid subsampling
    std::string opt_seqname;
    int opt_record_mode = 0;

    for (int i = 0; i < argc; i++) {
      if (std::string(argv[i]) == "--camera_device")
        opt_device = std::atoi(argv[i + 1]);
      else if (std::string(argv[i]) == "--scale")
        opt_scale = (unsigned int)atoi(argv[i + 1]);
      else if (std::string(argv[i]) == "--seqname")
        opt_seqname = std::string(argv[i + 1]);
      else if (std::string(argv[i]) == "--record")
        opt_record_mode = std::atoi(argv[i + 1]);
      else if (std::string(argv[i]) == "--help" || std::string(argv[i]) == "-h") {
        std::cout << "\nUsage: " << argv[0]
                  << " [--camera_device <camera device (default: 0)>] [--scale <subsampling factor (default: 1)>]"
                     " [--seqname <sequence name (default: empty>] [--record <0: continuous | 1: single shot (default: 0)>]"
                     " [--help] [-h]\n"
                  << "\nExample to visualize images:\n"
                  << "  " << argv[0] << "\n"
                  << "\nExample to visualize images from a second camera:\n"
                  << "  " << argv[0] << " --camera_device 1\n"
                  << "\nExamples to record a sequence:\n"
                  << "  " << argv[0] << " --seqname I%04d.png \n"
                  << "  " << argv[0] << " --seqname folder/I%04d.png --record 0\n"
                  << "\nExamples to record single shot images:\n"
                  << "  " << argv[0] << " --seqname I%04d.png --record 1\n"
                  << "  " << argv[0] << " --seqname folder/I%04d.png --record 1\n"
                  << std::endl;
        return 0;
      }
    }

    std::cout << "Use device : " << opt_device << std::endl;
    std::cout << "Recording  : " << (opt_seqname.empty() ? "disabled" : "enabled") << std::endl;

    std::string text_record_mode = std::string("Record mode: ") + (opt_record_mode ? std::string("single") : std::string("continuous"));

    if (! opt_seqname.empty()) {
      std::cout << text_record_mode << std::endl;
      std::cout << "Record name: " << opt_seqname << std::endl;
    }

#ifdef USE_COLOR
    vpImage<vpRGBa> I;        // To acquire color images
#else
    vpImage<unsigned char> I; // To acquire gray images
#endif

    vpV4l2Grabber g;
    std::ostringstream device;
    device << "/dev/video" << opt_device;
    g.setDevice(device.str());
    g.setScale(opt_scale);
    g.open(I);

    std::cout << "Image size : " << I.getWidth() << " " << I.getHeight() << std::endl;

#ifdef VISP_HAVE_X11
    vpDisplayX d(I);
#elif defined(VISP_HAVE_OPENCV)
    vpDisplayOpenCV d(I);
#else
    std::cout << "No image viewer is available..." << std::endl;
#endif

#ifdef USE_COLOR
    vpImageQueue<vpRGBa> image_queue(opt_seqname, opt_record_mode);
    vpImageStorageWorker<vpRGBa> image_storage_worker(std::ref(image_queue));
    std::thread image_storage_thread(&vpImageStorageWorker<vpRGBa>::run, &image_storage_worker);
#else
    vpImageQueue<unsigned char> image_queue(opt_seqname, opt_record_mode);
    vpImageStorageWorker<unsigned char> image_storage_worker(std::ref(image_queue));
    std::thread image_storage_thread(&vpImageStorageWorker<unsigned char>::run, &image_storage_worker);
#endif

    bool quit = false;
    while (! quit) {
      double t = vpTime::measureTimeMs();
      g.acquire(I);

      vpDisplay::display(I);

      quit = image_queue.record(I);

      std::stringstream ss;
      ss << "Acquisition time: " << std::setprecision(3) << vpTime::measureTimeMs() - t << " ms";
      vpDisplay::displayText(I, I.getHeight() - 20, 10, ss.str(), vpColor::red);
      vpDisplay::flush(I);
    }
    image_queue.cancel();
    image_storage_thread.join();
  } catch (const vpException &e) {
    std::cout << "Catch an exception: " << e << std::endl;
  }
#else
  (void) argc;
  (void) argv;
#ifndef VISP_HAVE_V4L2
  std::cout << "Install Video 4 Linux 2 (v4l2), configure and build ViSP again to use this example" << std::endl;
#endif
#if (VISP_CXX_STANDARD < VISP_CXX_STANDARD_11)
  std::cout << "This turorial should be built with c++11 support" << std::endl;
#endif
#endif
}

This other example shows how to use this grabber with an analogic camera attached to a bttv PCI card.

#include <visp3/io/vpImageIo.h>
#include <visp3/sensor/vpV4l2Grabber.h>

int main()
{
#if defined(VISP_HAVE_V4L2)
  vpImage<unsigned char> I;
  vpV4l2Grabber g;
  g.setInput(2);    // Input 2 on the board
  g.setFramerate(vpV4l2Grabber::framerate_25fps); //  25 fps
  g.setWidth(768);  // Acquired images are 768 width
  g.setHeight(576); // Acquired images are 576 height
  g.setNBuffers(3); // 3 ring buffers to ensure real-time acquisition
  g.open(I);        // Open the grabber

  g.acquire(I);     // Acquire a 768x576 grey image
  vpImageIo::write(I, "image.pgm"); // Save the image on the disk
#endif
}

Author

Fabien Spindler (Fabie.nosp@m.n.Sp.nosp@m.indle.nosp@m.r@ir.nosp@m.isa.f.nosp@m.r), Irisa / Inria Rennes

See also

vpFrameGrabber

Examples:

grabV4l2.cpp, grabV4l2MultiCpp11Thread.cpp, HelloWorldOgre.cpp, HelloWorldOgreAdvanced.cpp, manGrabV4l2.cpp, mbot-apriltag-2D-half-vs.cpp, mbot-apriltag-ibvs.cpp, mbot-apriltag-pbvs.cpp, servoPioneerPanSegment3D.cpp, servoPioneerPoint2DDepth.cpp, servoPioneerPoint2DDepthWithoutVpServo.cpp, tutorial-apriltag-detector-live.cpp, tutorial-barcode-detector-live.cpp, tutorial-blob-tracker-live-v4l2.cpp, tutorial-face-detector-live-threaded.cpp, tutorial-face-detector-live.cpp, tutorial-grabber-v4l2-threaded.cpp, tutorial-grabber-v4l2.cpp, tutorial-klt-tracker-live-v4l2.cpp, tutorial-mb-generic-tracker-apriltag-webcam.cpp, tutorial-mb-generic-tracker-live.cpp, tutorial-me-ellipse-tracker.cpp, tutorial-me-line-tracker.cpp, tutorial-pose-from-points-live.cpp, and tutorial-video-recorder.cpp.

Definition at line 134 of file vpV4l2Grabber.h.

Member Enumeration Documentation

enum vpV4l2Grabber::vpV4l2FrameFormatType

Frame format type for capture.

Enumerator
V4L2_FRAME_FORMAT	a field only
V4L2_IMAGE_FORMAT	an interlaced image

Definition at line 157 of file vpV4l2Grabber.h.

enum vpV4l2Grabber::vpV4l2FramerateType

Frame rate type for capture.

Enumerator
framerate_50fps	50 frames per second
framerate_25fps	25 frames per second

Definition at line 149 of file vpV4l2Grabber.h.

enum vpV4l2Grabber::vpV4l2PixelFormatType

Pixel format type for capture.

Enumerator
V4L2_GREY_FORMAT	8 Greyscale
V4L2_RGB24_FORMAT	24 RGB-8-8-8
V4L2_RGB32_FORMAT	32 RGB-8-8-8-8
V4L2_BGR24_FORMAT	24 BGR-8-8-8
V4L2_YUYV_FORMAT	16 YUYV 4:2:2
V4L2_MAX_FORMAT

Examples:

grabV4l2.cpp.

Definition at line 165 of file vpV4l2Grabber.h.

Constructor & Destructor Documentation

vpV4l2Grabber::vpV4l2Grabber

(

)

Default constructor.

Setup the Video For Linux Two (V4L2) driver in streaming mode.

Default settings are:

• Device name: /dev/video0: To change it use setDevice()
• Number of ring buffers: 3. To change this value use setNBuffers(). For non real-time applications the number of buffers should be set to 1. For real-time applications to reach 25 fps or 50 fps a good compromise is to set the number of buffers to 3.
• Framerate acquisition: 25 fps. Use setFramerate() to set 25 fps or 50 fps. These framerates are reachable only if enought buffers are set.
• Input board: vpV4l2Grabber::DEFAULT_INPUT. Video input port. Use setInput() to change it.
• Image size acquisition: vpV4l2Grabber::DEFAULT_SCALE. Use either setScale() or setWidth() and setHeight() to change it.

vpImage<unsigned char> I; // Grey level image

vpV4l2Grabber g;
g.setInput(2);    // Input 2 on the board
g.setWidth(768);  // Acquired images are 768 width
g.setHeight(576); // Acquired images are 576 height
g.setNBuffers(3); // 3 ring buffers to ensure real-time acquisition
g.open(I);        // Open the grabber

g.acquire(I);     // Acquire a 768x576 grey image

The grabber allows also to grab a portion of an image using a region of interest. The following example shows how to grab a 320x240 region located on the top/left corner of the image that has a higher resolution (ie 640x480).

#include <visp3/gui/vpDisplayX.h>
#include <visp3/io/vpImageIo.h>
#include <visp3/sensor/vpV4l2Grabber.h>

int main()
{
#if defined(VISP_HAVE_V4L2) && defined(VISP_HAVE_X11)
  vpDisplayX *d;
  vpImage<vpRGBa> I;
  vpRect roi(0, 0, 320, 240); // specify the region to crop

  vpV4l2Grabber g;

  bool first = true;
  while (1) {
    g.acquire(I, roi);
    if(first) {
      d = new vpDisplayX(I);
      first = false;
    }
    vpDisplay::display(I);
    vpDisplay::flush(I);
    if (vpDisplay::getClick(I, false))
      break;
  }
  vpImageIo::write(I, "image.pgm"); // Save the last image
  delete d;
#endif

Definition at line 149 of file vpV4l2Grabber.cpp.

References DEFAULT_INPUT, DEFAULT_SCALE, framerate_25fps, vpFrameGrabber::init, setDevice(), setFramerate(), setInput(), setNBuffers(), setPixelFormat(), setScale(), and V4L2_YUYV_FORMAT.

vpV4l2Grabber::vpV4l2Grabber ( bool  verbose )

explicit

Default constructor.

Setup the Video For Linux Two (V4L2) driver in streaming mode.

Parameters

verbose

: If true activates the verbose mode.

Default settings are:

• Device name: /dev/video0: To change it use setDevice()
• Number of ring buffers: 3. To change this value use setNBuffers(). For non real-time applications the number of buffers should be set to 1. For real-time applications to reach 25 fps or 50 fps a good compromise is to set the number of buffers to 3.
• Framerate acquisition: 25 fps. Use setFramerate() to set 25 fps or 50 fps. These framerates are reachable only if enought buffers are set.
• Input board: vpV4l2Grabber::DEFAULT_INPUT. Video input port. Use setInput() to change it.
• Image size acquisition: vpV4l2Grabber::DEFAULT_SCALE. Use either setScale() or setWidth() and setHeight to change it.

vpImage<unsigned char> I; // Grey level image

vpV4l2Grabber g(true); // Activates the verbose mode
g.setInput(2);    // Input 2 on the board
g.setWidth(768);  // Acquired images are 768 width
g.setHeight(576); // Acquired images are 576 height
g.setNBuffers(3); // 3 ring buffers to ensure real-time acquisition
g.open(I);        // Open the grabber

g.acquire(I);     // Acquire a 768x576 grey image

Definition at line 205 of file vpV4l2Grabber.cpp.

References DEFAULT_INPUT, DEFAULT_SCALE, framerate_25fps, vpFrameGrabber::init, setDevice(), setFramerate(), setInput(), setNBuffers(), setPixelFormat(), setScale(), and V4L2_YUYV_FORMAT.

vpV4l2Grabber::vpV4l2Grabber	(	unsigned	input,
		unsigned	scale = vpV4l2Grabber::DEFAULT_SCALE
	)

Constructor.

Setup the Video For Linux Two (V4L2) driver in streaming mode.

Parameters

input	: Video input port.
scale	: Decimation factor.

Default settings are:

• Device name: /dev/video0: To change it use setDevice()
• Number of ring buffers: 3. To change this value use setNBuffers(). For non real-time applications the number of buffers should be set to 1. For real-time applications to reach 25 fps or 50 fps a good compromise is to set the number of buffers to 3.
• Framerate acquisition: 25 fps. Use setFramerate() to set 25 fps or 50 fps. These framerates are reachable only if enought buffers are set.

vpImage<unsigned char> I; // Grey level image

vpV4l2Grabber g(1, 2); // Select input 1, and half full size resolution images.
g.open(I);             // Open the grabber

g.acquire(I);          // Acquire a 384x288 grey image

Definition at line 251 of file vpV4l2Grabber.cpp.

References framerate_25fps, vpFrameGrabber::init, setDevice(), setFramerate(), setInput(), setNBuffers(), and setScale().

vpV4l2Grabber::vpV4l2Grabber	(	vpImage< unsigned char > &	I,
		unsigned	input,
		unsigned	scale = vpV4l2Grabber::DEFAULT_SCALE
	)

Constructor.

Setup the Video For Linux Two (V4L2) driver in streaming mode.

Parameters

I	: Image data structure (grey 8 bits image)
input	: Video input port.
scale	: Decimation factor.

Default settings are:

• Device name: /dev/video0: To change it use setDevice()
• Number of ring buffers: 3. To change this value use setNBuffers(). For non real-time applications the number of buffers should be set to 1. For real-time applications to reach 25 fps or 50 fps a good compromise is to set the number of buffers to 3.
• Framerate acquisition: 25 fps. Use setFramerate() to set 25 fps or 50 fps. These framerates are reachable only if enought buffers are set.

vpImage<unsigned char> I; // Grey level image

vpV4l2Grabber g(I, 1, 2); // Select input 1, and half full size resolution
                          // images and open the grabber

g.acquire(I);             // Acquire a 384x288 grey image

Definition at line 297 of file vpV4l2Grabber.cpp.

References framerate_25fps, vpFrameGrabber::init, open(), setDevice(), setFramerate(), setInput(), setNBuffers(), and setScale().

vpV4l2Grabber::vpV4l2Grabber	(	vpImage< vpRGBa > &	I,
		unsigned	input,
		unsigned	scale = vpV4l2Grabber::DEFAULT_SCALE
	)

Constructor.

Setup the Video For Linux Two (V4L2) driver in streaming mode.

Parameters

I	: Image data structure (Color RGB32 bits image)
input	: Video input port.
scale	: Decimation factor.

Default settings are:

• Device name: /dev/video0: To change it use setDevice()
• Number of ring buffers: 3. To change this value use setNBuffers(). For non real-time applications the number of buffers should be set to 1. For real-time applications to reach 25 fps or 50 fps a good compromise is to set the number of buffers to 3.
• Framerate acquisition: 25 fps. Use setFramerate() to set 25 fps or 50 fps. These framerates are reachable only if enought buffers are set.

vpImage<vpRGBa> I;        // Color image

vpV4l2Grabber g(I, 1, 2); // Select input 1, and half full size resolution
                          // images and open the grabber

g.acquire(I);             // Acquire a 384x288 color image

Definition at line 346 of file vpV4l2Grabber.cpp.

References framerate_25fps, vpFrameGrabber::init, open(), setDevice(), setFramerate(), setInput(), setNBuffers(), and setScale().

vpV4l2Grabber::~vpV4l2Grabber ( )

virtual

Destructor.

See also

close()

Definition at line 368 of file vpV4l2Grabber.cpp.

References close().

Member Function Documentation

void vpV4l2Grabber::acquire ( vpImage< unsigned char > &  I )

virtual

Acquire a grey level image.

Parameters

I	: Image data structure (8 bits image)

Exceptions

vpFrameGrabberException::initializationError

: Frame grabber not initialized.

See also

getField()

Implements vpFrameGrabber.

Examples:

grabV4l2.cpp, grabV4l2MultiCpp11Thread.cpp, HelloWorldOgre.cpp, HelloWorldOgreAdvanced.cpp, manGrabV4l2.cpp, mbot-apriltag-2D-half-vs.cpp, mbot-apriltag-ibvs.cpp, mbot-apriltag-pbvs.cpp, tutorial-barcode-detector-live.cpp, tutorial-face-detector-live.cpp, tutorial-grabber-v4l2-threaded.cpp, tutorial-grabber-v4l2.cpp, tutorial-klt-tracker-live-v4l2.cpp, tutorial-mb-generic-tracker-apriltag-webcam.cpp, and tutorial-video-recorder.cpp.

Definition at line 526 of file vpV4l2Grabber.cpp.

Referenced by acquire(), and operator>>().

void vpV4l2Grabber::acquire	(	vpImage< unsigned char > &	I,
		const vpRect &	roi
	)

Acquire a grey level image.

Parameters

I	: Image data structure (8 bits image)
roi	: Region of interest to grab from the full resolution image.

Exceptions

vpFrameGrabberException::initializationError

: Frame grabber not initialized.

See also

getField()

Definition at line 545 of file vpV4l2Grabber.cpp.

References acquire().

void vpV4l2Grabber::acquire	(	vpImage< unsigned char > &	I,
		struct timeval &	timestamp,
		const vpRect &	roi = vpRect()
	)

Acquire a grey level image.

Parameters

I	: Image data structure (8 bits image).
timestamp	: Timeval data structure providing the unix time at which the frame was captured in the ringbuffer. Warning: some v4l2 drivers do not return the time since 1970 (the one returned by gettimeofday() or vpTime) but rather a time that counts from the boot time (i.e. uptime).
roi	: Region of interest to grab from the full resolution image. By default acquire the whole image.

Exceptions

vpFrameGrabberException::initializationError

: Frame grabber not initialized.

See also

getField()

Definition at line 571 of file vpV4l2Grabber.cpp.

References vpImageConvert::BGRToGrey(), vpImage< Type >::bitmap, close(), vpImageTools::crop(), vpRect::getHeight(), vpRect::getWidth(), vpFrameGrabber::height, vpFrameGrabber::init, vpFrameGrabberException::initializationError, open(), vpImage< Type >::resize(), vpImageConvert::RGBaToGrey(), vpImageConvert::RGBToGrey(), V4L2_BGR24_FORMAT, V4L2_GREY_FORMAT, V4L2_RGB24_FORMAT, V4L2_RGB32_FORMAT, V4L2_YUYV_FORMAT, vpFrameGrabber::width, and vpImageConvert::YUYVToGrey().

void vpV4l2Grabber::acquire ( vpImage< vpRGBa > &  I )

virtual

Acquire a color image.

Parameters

I	: Image data structure (32 bits image)

Exceptions

vpFrameGrabberException::initializationError

: Frame grabber not initialized.

See also

getField()

Implements vpFrameGrabber.

Definition at line 652 of file vpV4l2Grabber.cpp.

References acquire().

void vpV4l2Grabber::acquire	(	vpImage< vpRGBa > &	I,
		const vpRect &	roi
	)

Acquire a color image.

Parameters

I	: Image data structure (32 bits image)
roi	: Region of interest to grab from the full resolution image.

Exceptions

vpFrameGrabberException::initializationError

: Frame grabber not initialized.

See also

getField()

Definition at line 671 of file vpV4l2Grabber.cpp.

References acquire().

void vpV4l2Grabber::acquire	(	vpImage< vpRGBa > &	I,
		struct timeval &	timestamp,
		const vpRect &	roi = vpRect()
	)

Acquire a color image.

Parameters

I	: Image data structure (32 bits image).
timestamp	: Timeval data structure providing the unix time at which the frame was captured in the ringbuffer. Warning: some v4l2 drivers do not return the time since 1970 (the one returned by gettimeofday() or vpTime) but rather a time that counts from the boot time (i.e. uptime).
roi	: Region of interest to grab from the full resolution image. By default acquire the whole image.

Exceptions

vpFrameGrabberException::initializationError

: Frame grabber not initialized.

See also

getField()

Definition at line 697 of file vpV4l2Grabber.cpp.

References vpImageConvert::BGRToRGBa(), vpImage< Type >::bitmap, close(), vpImageTools::crop(), vpRect::getHeight(), vpImage< Type >::getHeight(), vpRect::getLeft(), vpRect::getTop(), vpRect::getWidth(), vpImage< Type >::getWidth(), vpImageConvert::GreyToRGBa(), vpFrameGrabber::height, vpFrameGrabber::init, vpFrameGrabberException::initializationError, open(), vpImage< Type >::resize(), vpImageConvert::RGBToRGBa(), V4L2_BGR24_FORMAT, V4L2_GREY_FORMAT, V4L2_RGB24_FORMAT, V4L2_RGB32_FORMAT, V4L2_YUYV_FORMAT, vpFrameGrabber::width, and vpImageConvert::YUYVToRGBa().

void vpV4l2Grabber::close ( )

virtual

Close the video device.

Implements vpFrameGrabber.

Examples:

grabV4l2.cpp.

Definition at line 842 of file vpV4l2Grabber.cpp.

References FRAME_SIZE, vpFrameGrabber::height, vpFrameGrabberException::initializationError, MAX_BUFFERS, MAX_CTRL, MAX_FORMAT, MAX_INPUTS, MAX_NORM, open(), vpFrameGrabberException::otherError, vpFrameGrabberException::settingError, V4L2_BGR24_FORMAT, V4L2_FRAME_FORMAT, V4L2_GREY_FORMAT, V4L2_IMAGE_FORMAT, V4L2_RGB24_FORMAT, V4L2_RGB32_FORMAT, V4L2_YUYV_FORMAT, vpERROR_TRACE, and vpFrameGrabber::width.

Referenced by acquire(), getField(), open(), setScale(), and ~vpV4l2Grabber().

bool vpV4l2Grabber::getField

(

)

Return the field (odd or even) corresponding to the last acquired frame.

This method is to call after acquire() and has only a mean if the acquisition framerate is set to 50 fps.

Returns

Field of the acquired frame (0 if odd field, 1 if even field).

Exceptions

vpFrameGrabberException::otherError

: Video device returns a bad frame field.

See also

acquire(), setFramerate()

Definition at line 791 of file vpV4l2Grabber.cpp.

References close(), and vpFrameGrabberException::otherError.

vpV4l2Grabber::vpV4l2FramerateType vpV4l2Grabber::getFramerate

(

)

Return the framerate of the acquisition.

Returns

The actual framerate of the framegrabber.

See also

setFramerate()

Definition at line 837 of file vpV4l2Grabber.cpp.

unsigned int vpFrameGrabber::getHeight ( ) const

inlineinherited

Return the number of rows in the image.

Examples:

AROgre.cpp, AROgreBasic.cpp, and testPylonGrabber.cpp.

Definition at line 114 of file vpFrameGrabber.h.

vpV4l2PixelFormatType vpV4l2Grabber::getPixelFormat ( )

inline

Get the pixel format used for capture.

Returns

Camera pixel format coding.

Definition at line 239 of file vpV4l2Grabber.h.

Referenced by open().

unsigned int vpFrameGrabber::getWidth ( ) const

inlineinherited

Return the number of columns in the image.

Examples:

AROgre.cpp, AROgreBasic.cpp, and testPylonGrabber.cpp.

Definition at line 116 of file vpFrameGrabber.h.

void vpV4l2Grabber::open ( vpImage< unsigned char > &  I )

virtual

Initialize image acquisition in grey format. Set the pixel format acquisition to vpV4l2Grabber::V4L2_GREY_FORMAT.

Parameters

I	: Image data structure (8 bits image). Once the device is open, the image is resized to the current acquisition size.

Exceptions

vpFrameGrabberException::settingError

: Wrong input channel.

Implements vpFrameGrabber.

Examples:

grabV4l2.cpp, grabV4l2MultiCpp11Thread.cpp, HelloWorldOgre.cpp, HelloWorldOgreAdvanced.cpp, manGrabV4l2.cpp, servoPioneerPanSegment3D.cpp, servoPioneerPoint2DDepth.cpp, servoPioneerPoint2DDepthWithoutVpServo.cpp, tutorial-apriltag-detector-live.cpp, tutorial-blob-tracker-live-v4l2.cpp, tutorial-face-detector-live-threaded.cpp, tutorial-grabber-v4l2-threaded.cpp, tutorial-grabber-v4l2.cpp, tutorial-klt-tracker-live-v4l2.cpp, tutorial-mb-generic-tracker-live.cpp, tutorial-pose-from-points-live.cpp, and tutorial-video-recorder.cpp.

Definition at line 410 of file vpV4l2Grabber.cpp.

References close(), getPixelFormat(), vpFrameGrabber::height, vpFrameGrabber::init, open(), vpImage< Type >::resize(), setPixelFormat(), vpFrameGrabberException::settingError, V4L2_MAX_FORMAT, and vpFrameGrabber::width.

Referenced by acquire(), close(), open(), and vpV4l2Grabber().

void vpV4l2Grabber::open ( vpImage< vpRGBa > &  I )

virtual

Initialize image acquisition in color RGB32 format. Set the pixel format acquisition to vpV4l2Grabber::V4L2_RGB32_FORMAT.

Parameters

I	: Image data structure (RGB32 bits image). Once the device is open, the image is resized to the current acquisition size.

Implements vpFrameGrabber.

Definition at line 471 of file vpV4l2Grabber.cpp.

References getPixelFormat(), vpFrameGrabber::height, vpFrameGrabber::init, open(), vpImage< Type >::resize(), setPixelFormat(), V4L2_MAX_FORMAT, and vpFrameGrabber::width.

vpV4l2Grabber & vpV4l2Grabber::operator>>

(

vpImage< unsigned char > &

I

)

Operator that allows to capture a grey level image.

Parameters

I	: The captured image.

#include <visp3/sensor/vpV4l2Grabber.h>

int main()
{
  vpImage<unsigned char> I;
  vpV4l2Grabber g;
  g >> I;
}

Definition at line 1455 of file vpV4l2Grabber.cpp.

References acquire().

vpV4l2Grabber & vpV4l2Grabber::operator>>

(

vpImage< vpRGBa > &

I

)

Operator that allows to capture a grey level image.

Parameters

I	: The captured image.

#include <visp3/sensor/vpV4l2Grabber.h>

int main()
{
  vpImage<vpRGBa> I;
  vpV4l2Grabber g;
  g >> I;
}

Definition at line 1477 of file vpV4l2Grabber.cpp.

References acquire().

void vpV4l2Grabber::setDevice ( const std::string &  devname )

inline

Set the device name.

Parameters

devname

: Device name (like /dev/video0).

Examples:

grabV4l2.cpp, grabV4l2MultiCpp11Thread.cpp, mbot-apriltag-2D-half-vs.cpp, mbot-apriltag-ibvs.cpp, mbot-apriltag-pbvs.cpp, servoPioneerPanSegment3D.cpp, servoPioneerPoint2DDepth.cpp, servoPioneerPoint2DDepthWithoutVpServo.cpp, tutorial-apriltag-detector-live.cpp, tutorial-barcode-detector-live.cpp, tutorial-blob-tracker-live-v4l2.cpp, tutorial-face-detector-live-threaded.cpp, tutorial-face-detector-live.cpp, tutorial-grabber-v4l2-threaded.cpp, tutorial-grabber-v4l2.cpp, tutorial-klt-tracker-live-v4l2.cpp, tutorial-mb-generic-tracker-apriltag-webcam.cpp, tutorial-mb-generic-tracker-live.cpp, tutorial-pose-from-points-live.cpp, and tutorial-video-recorder.cpp.

Definition at line 285 of file vpV4l2Grabber.h.

Referenced by vpV4l2Grabber().

void vpV4l2Grabber::setFramerate

(

vpV4l2Grabber::vpV4l2FramerateType

framerate

)

Set the frame format depending on the framerate acquisition.

Parameters

framerate

: The framerate for the acquisition. If vpV4l2Grabber::framerate_25fps use vpV4l2Grabber::V4L2_IMAGE_FORMAT, else if vpV4l2Grabber::framerate_50fps use vpV4l2Grabber::V4L2_FRAME_FORMAT.

Warning

If you want to acquire frames at 25 fps or 50 fps, you have to be aware of the number of buffers required for the streaming. A typical value could be 3 (see setNBuffers()).

See also

getFramerate(), setNBuffers()

Examples:

grabV4l2.cpp.

Definition at line 818 of file vpV4l2Grabber.cpp.

References framerate_25fps, V4L2_FRAME_FORMAT, and V4L2_IMAGE_FORMAT.

Referenced by vpV4l2Grabber().

void vpV4l2Grabber::setHeight ( unsigned  h )

inline

Set image height to acquire.

Examples:

manGrabV4l2.cpp.

Definition at line 262 of file vpV4l2Grabber.h.

References DEFAULT_SCALE.

Referenced by setScale().

void vpV4l2Grabber::setInput

(

unsigned

input = vpV4l2Grabber::DEFAULT_INPUT

)

Set the video input port on the board.

Examples:

grabV4l2.cpp, manGrabV4l2.cpp, servoPioneerPanSegment3D.cpp, servoPioneerPoint2DDepth.cpp, and servoPioneerPoint2DDepthWithoutVpServo.cpp.

Definition at line 373 of file vpV4l2Grabber.cpp.

Referenced by vpV4l2Grabber().

void vpV4l2Grabber::setNBuffers ( unsigned  nbuffers )

inline

Set the number of buffers required for streaming data.

For non real-time applications the number of buffers should be set to 1. For real-time applications to reach 25 fps or 50 fps a good compromise is to set the number of buffers to 3.

Parameters

nbuffers

: Number of ring buffers.

Examples:

manGrabV4l2.cpp.

Definition at line 277 of file vpV4l2Grabber.h.

Referenced by vpV4l2Grabber().

void vpV4l2Grabber::setPixelFormat ( vpV4l2PixelFormatType  pixelformat )

inline

Set the pixel format for capture.`If the specified pixel format is out of range, we set the V4L2_RGB24_FORMAT.

Parameters

pixelformat

: Camera pixel format coding.

Examples:

grabV4l2.cpp.

Definition at line 294 of file vpV4l2Grabber.h.

Referenced by open(), and vpV4l2Grabber().

void vpV4l2Grabber::setScale

(

unsigned

scale = vpV4l2Grabber::DEFAULT_SCALE

)

Set the decimation factor applied to full resolution images (768x576).

Exceptions

vpFrameGrabberException::settingError

: Wrong scale (should be between 1 and 16).

Parameters

scale

: Decimation factor. If scale is set to 2, 384x288 images will be acquired.

An other way to specify the image size is to use setWidth() and setHeight().

Examples:

grabV4l2.cpp, grabV4l2MultiCpp11Thread.cpp, mbot-apriltag-2D-half-vs.cpp, mbot-apriltag-ibvs.cpp, mbot-apriltag-pbvs.cpp, servoPioneerPanSegment3D.cpp, servoPioneerPoint2DDepth.cpp, servoPioneerPoint2DDepthWithoutVpServo.cpp, tutorial-apriltag-detector-live.cpp, tutorial-barcode-detector-live.cpp, tutorial-face-detector-live-threaded.cpp, tutorial-face-detector-live.cpp, tutorial-grabber-v4l2-threaded.cpp, tutorial-grabber-v4l2.cpp, tutorial-mb-generic-tracker-apriltag-webcam.cpp, tutorial-mb-generic-tracker-live.cpp, tutorial-pose-from-points-live.cpp, and tutorial-video-recorder.cpp.

Definition at line 387 of file vpV4l2Grabber.cpp.

References close(), setHeight(), vpFrameGrabberException::settingError, setWidth(), and vpERROR_TRACE.

Referenced by vpV4l2Grabber().

void vpV4l2Grabber::setVerboseMode ( bool  verbose )

inline

Activates the verbose mode to print additional information on stdout.

Parameters

verbose

: If true activates the verbose mode.

Examples:

grabV4l2.cpp.

Definition at line 248 of file vpV4l2Grabber.h.

References DEFAULT_INPUT.

void vpV4l2Grabber::setWidth ( unsigned  w )

inline

Set image width to acquire.

Examples:

manGrabV4l2.cpp.

Definition at line 257 of file vpV4l2Grabber.h.

Referenced by setScale().

Member Data Documentation

const unsigned int vpV4l2Grabber::DEFAULT_INPUT = 2

static

Definition at line 137 of file vpV4l2Grabber.h.

Referenced by setVerboseMode(), and vpV4l2Grabber().

const unsigned int vpV4l2Grabber::DEFAULT_SCALE = 2

static

Definition at line 138 of file vpV4l2Grabber.h.

Referenced by setHeight(), and vpV4l2Grabber().

const unsigned int vpV4l2Grabber::FRAME_SIZE = 288

static

Definition at line 144 of file vpV4l2Grabber.h.

Referenced by close().

unsigned int vpFrameGrabber::height

protectedinherited

Number of rows in the image.

Definition at line 107 of file vpFrameGrabber.h.

Referenced by vpPylonGrabberGigE::acquire(), vpPylonGrabberUsb::acquire(), vpDiskGrabber::acquire(), vpFlyCaptureGrabber::acquire(), acquire(), vp1394TwoGrabber::acquire(), close(), vp1394TwoGrabber::dequeue(), vpVideoReader::getFrame(), vp1394TwoGrabber::getHeight(), vpDiskGrabber::open(), open(), vp1394CMUGrabber::open(), vp1394CMUGrabber::selectCamera(), vpVideoReader::setFileName(), vp1394TwoGrabber::setFormat7ROI(), vp1394CMUGrabber::setVideoMode(), vp1394TwoGrabber::setVideoMode(), vp1394CMUGrabber::vp1394CMUGrabber(), and vp1394TwoGrabber::vp1394TwoGrabber().

bool vpFrameGrabber::init

inherited

Set to true if the frame grabber has been initialized.

Definition at line 104 of file vpFrameGrabber.h.

Referenced by acquire(), vp1394CMUGrabber::close(), vp1394TwoGrabber::close(), vpPylonGrabberGigE::connect(), vpPylonGrabberUsb::connect(), vpFlyCaptureGrabber::connect(), vpPylonGrabberUsb::disconnect(), vpPylonGrabberGigE::disconnect(), vpFlyCaptureGrabber::disconnect(), vpDiskGrabber::open(), open(), vp1394TwoGrabber::resetBus(), vp1394CMUGrabber::selectCamera(), vp1394TwoGrabber::setFormat7ROI(), vpPylonGrabberUsb::startCapture(), vpPylonGrabberGigE::startCapture(), vpFlyCaptureGrabber::startCapture(), vpPylonGrabberGigE::stopCapture(), vpPylonGrabberUsb::stopCapture(), vpFlyCaptureGrabber::stopCapture(), vp1394CMUGrabber::vp1394CMUGrabber(), vp1394TwoGrabber::vp1394TwoGrabber(), vpDiskGrabber::vpDiskGrabber(), and vpV4l2Grabber().

const unsigned int vpV4l2Grabber::MAX_BUFFERS = 32

static

Definition at line 143 of file vpV4l2Grabber.h.

Referenced by close().

const unsigned int vpV4l2Grabber::MAX_CTRL = 32

static

Definition at line 142 of file vpV4l2Grabber.h.

Referenced by close().

const __u32 vpV4l2Grabber::MAX_FORMAT = 32

static

Definition at line 141 of file vpV4l2Grabber.h.

Referenced by close().

const __u32 vpV4l2Grabber::MAX_INPUTS = 16

static

Definition at line 139 of file vpV4l2Grabber.h.

Referenced by close().

const __u32 vpV4l2Grabber::MAX_NORM = 16

static

Definition at line 140 of file vpV4l2Grabber.h.

Referenced by close().

unsigned int vpFrameGrabber::width

protectedinherited

Number of columns in the image.

Definition at line 108 of file vpFrameGrabber.h.

Referenced by vpPylonGrabberGigE::acquire(), vpPylonGrabberUsb::acquire(), vpDiskGrabber::acquire(), vpFlyCaptureGrabber::acquire(), acquire(), vp1394TwoGrabber::acquire(), close(), vp1394TwoGrabber::dequeue(), vpVideoReader::getFrame(), vp1394TwoGrabber::getWidth(), vpDiskGrabber::open(), open(), vp1394CMUGrabber::open(), vp1394CMUGrabber::selectCamera(), vpVideoReader::setFileName(), vp1394TwoGrabber::setFormat7ROI(), vp1394CMUGrabber::setVideoMode(), vp1394TwoGrabber::setVideoMode(), vp1394CMUGrabber::vp1394CMUGrabber(), and vp1394TwoGrabber::vp1394TwoGrabber().