vpV4l2Grabber Class Reference

#include <visp3/sensor/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 ()
VP_EXPLICIT	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 ()

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

Inherited functionalities from vpFramegrabber
unsigned int	getHeight () const
unsigned int	getWidth () const
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/vpConfig.h>
#include <visp3/core/vpImage.h>
#include <visp3/gui/vpDisplayOpenCV.h>
#include <visp3/gui/vpDisplayX.h>
#include <visp3/io/vpImageStorageWorker.h>
#include <visp3/sensor/vpV4l2Grabber.h>
 
#define USE_COLOR // Comment to acquire gray level images
 
void usage(const char *argv[], int error)
{
  std::cout << "SYNOPSIS" << std::endl
    << "  " << argv[0] << " [--device <index>]"
    << " [--scale <subsampling factor>]"
    << " [--seqname <sequence name>]"
    << " [--record <mode>]"
    << " [--no-display]"
    << " [--help] [-h]" << std::endl
    << std::endl;
  std::cout << "DESCRIPTION" << std::endl
    << "  --device <index> " << std::endl
    << "    Camera device index. Set 0 to dial with the first camera," << std::endl
    << "    and 1 to dial with the second camera attached to the computer." << std::endl
    << "    Default: 0 to consider /dev/video0 device." << std::endl
    << std::endl
    << "  --scale <subsampling factor>" << std::endl
    << "    Subsampling factor applied to the images captured by the device." << std::endl
    << "    Default: 1" << std::endl
    << std::endl
    << "  --seqname <sequence name>" << std::endl
    << "    Name of the sequence of image to create (ie: /tmp/image%04d.jpg)." << std::endl
    << "    Default: empty." << std::endl
    << std::endl
    << "  --record <mode>" << std::endl
    << "    Allowed values for mode are:" << std::endl
    << "      0: record all the captures images (continuous mode)," << std::endl
    << "      1: record only images selected by a user click (single shot mode)." << std::endl
    << "    Default mode: 0" << std::endl
    << std::endl
    << "  --no-display" << std::endl
    << "    Disable displaying captured images." << std::endl
    << "    When used and sequence name specified, record mode is internally set to 1 (continuous mode)."
    << std::endl
    << std::endl
    << "  --help, -h" << std::endl
    << "    Print this helper message." << std::endl
    << std::endl;
  std::cout << "USAGE" << std::endl
    << "  Example to visualize images:" << std::endl
    << "    " << argv[0] << std::endl
    << std::endl
    << "  Example to visualize images from a second camera:" << std::endl
    << "    " << argv[0] << " --device 1" << std::endl
    << std::endl
    << "  Examples to record a sequence:" << std::endl
    << "    " << argv[0] << " --seqname I%04d.png" << std::endl
    << "    " << argv[0] << " --seqname folder/I%04d.png --record 0" << std::endl
    << std::endl
    << "  Examples to record single shot images:\n"
    << "    " << argv[0] << " --seqname I%04d.png --record 1\n"
    << "    " << argv[0] << " --seqname folder/I%04d.png --record 1" << std::endl
    << std::endl;
 
  if (error) {
    std::cout << "Error" << std::endl
      << "  "
      << "Unsupported parameter " << argv[error] << std::endl;
  }
}
 
int main(int argc, const char *argv[])
{
#if defined(VISP_HAVE_V4L2) && defined(VISP_HAVE_THREADS)
#ifdef ENABLE_VISP_NAMESPACE
  using namespace VISP_NAMESPACE_NAME;
#endif
  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;
    bool opt_display = true;
 
    for (int i = 1; i < argc; i++) {
      if (std::string(argv[i]) == "--device") {
        opt_device = std::atoi(argv[i + 1]);
        i++;
      }
      else if (std::string(argv[i]) == "--scale") {
        opt_scale = (unsigned int)atoi(argv[i + 1]);
        i++;
      }
      else if (std::string(argv[i]) == "--seqname") {
        opt_seqname = std::string(argv[i + 1]);
        i++;
      }
      else if (std::string(argv[i]) == "--record") {
        opt_record_mode = std::atoi(argv[i + 1]);
        i++;
      }
      else if (std::string(argv[i]) == "--no-display") {
        opt_display = false;
      }
      else if (std::string(argv[i]) == "--help" || std::string(argv[i]) == "-h") {
        usage(argv, 0);
        return EXIT_SUCCESS;
      }
      else {
        usage(argv, i);
        return EXIT_FAILURE;
      }
    }
 
    if ((!opt_display) && (!opt_seqname.empty())) {
      opt_record_mode = 0;
    }
    std::cout << "Use device : " << opt_device << std::endl;
    std::cout << "Recording  : " << (opt_seqname.empty() ? "disabled" : "enabled") << std::endl;
    std::cout << "Display    : " << (opt_display ? "enabled" : "disabled") << 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;
 
    vpDisplay *d = nullptr;
    if (opt_display) {
#if !(defined(VISP_HAVE_X11) || defined(VISP_HAVE_OPENCV))
      std::cout << "No image viewer is available..." << std::endl;
      opt_display = false;
#endif
    }
    if (opt_display) {
#ifdef VISP_HAVE_X11
      d = new vpDisplayX(I);
#elif defined(HAVE_OPENCV_HIGHGUI)
      d = new vpDisplayOpenCV(I);
#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();
 
    if (d) {
      delete d;
    }
  }
  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 tutorial 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>
 
#ifdef ENABLE_VISP_NAMESPACE
using namespace VISP_NAMESPACE_NAME;
#endif
 
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
}

See also

vpFrameGrabber

Examples

HelloWorldOgre.cpp, HelloWorldOgreAdvanced.cpp, grabV4l2.cpp, grabV4l2MultiCpp11Thread.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 131 of file vpV4l2Grabber.h.

Member Enumeration Documentation

vpV4l2FrameFormatType

enum vpV4l2Grabber::vpV4l2FrameFormatType

Frame format type for capture.

Enumerator
V4L2_FRAME_FORMAT	a field only
V4L2_IMAGE_FORMAT	an interlaced image

Definition at line 155 of file vpV4l2Grabber.h.

vpV4l2FramerateType

enum vpV4l2Grabber::vpV4l2FramerateType

Frame rate type for capture.

Enumerator
framerate_50fps	50 frames per second
framerate_25fps	25 frames per second

Definition at line 146 of file vpV4l2Grabber.h.

vpV4l2PixelFormatType

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 164 of file vpV4l2Grabber.h.

Constructor & Destructor Documentation

vpV4l2Grabber() [1/5]

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>
 
#ifdef ENABLE_VISP_NAMESPACE
using namespace VISP_NAMESPACE_NAME;
#endif
 
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 148 of file vpV4l2Grabber.cpp.

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

vpV4l2Grabber() [2/5]

vpV4l2Grabber::vpV4l2Grabber

(

bool

verbose

)

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 203 of file vpV4l2Grabber.cpp.

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

vpV4l2Grabber() [3/5]

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 248 of file vpV4l2Grabber.cpp.

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

vpV4l2Grabber() [4/5]

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 enough 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 294 of file vpV4l2Grabber.cpp.

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

vpV4l2Grabber() [5/5]

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 341 of file vpV4l2Grabber.cpp.

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

~vpV4l2Grabber()

vpV4l2Grabber::~vpV4l2Grabber ( )

virtual

Destructor.

See also

close()

Definition at line 363 of file vpV4l2Grabber.cpp.

References close().

Member Function Documentation

acquire() [1/6]

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

HelloWorldOgre.cpp, HelloWorldOgreAdvanced.cpp, grabV4l2.cpp, grabV4l2MultiCpp11Thread.cpp, manGrabV4l2.cpp, mbot-apriltag-2D-half-vs.cpp, mbot-apriltag-ibvs.cpp, mbot-apriltag-pbvs.cpp, servoPioneerPanSegment3D.cpp, tutorial-apriltag-detector-live.cpp, tutorial-barcode-detector-live.cpp, tutorial-blob-tracker-live-v4l2.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 525 of file vpV4l2Grabber.cpp.

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

acquire() [2/6]

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 544 of file vpV4l2Grabber.cpp.

References acquire().

acquire() [3/6]

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 570 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().

acquire() [4/6]

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 651 of file vpV4l2Grabber.cpp.

References acquire().

acquire() [5/6]

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 670 of file vpV4l2Grabber.cpp.

References acquire().

acquire() [6/6]

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 696 of file vpV4l2Grabber.cpp.

References vpImageConvert::BGRToRGBa(), vpImage< Type >::bitmap, close(), vpImageTools::crop(), vpImage< Type >::getHeight(), vpRect::getHeight(), vpRect::getLeft(), vpRect::getTop(), vpImage< Type >::getWidth(), vpRect::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().

close()

void vpV4l2Grabber::close ( )

virtual

Close the video device.

Implements vpFrameGrabber.

Examples

grabV4l2.cpp.

Definition at line 844 of file vpV4l2Grabber.cpp.

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

getField()

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 793 of file vpV4l2Grabber.cpp.

References close(), and vpFrameGrabberException::otherError.

getFramerate()

vpV4l2Grabber::vpV4l2FramerateType vpV4l2Grabber::getFramerate

(

)

Return the framerate of the acquisition.

Returns

The actual framerate of the framegrabber.

See also

setFramerate()

Definition at line 839 of file vpV4l2Grabber.cpp.

getHeight()

BEGIN_VISP_NAMESPACE unsigned int vpFrameGrabber::getHeight ( ) const

inherited

Return the number of rows in the image.

Examples

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

Definition at line 38 of file vpFrameGrabber.cpp.

References vpFrameGrabber::height.

getPixelFormat()

vpV4l2PixelFormatType vpV4l2Grabber::getPixelFormat ( )

inline

Get the pixel format used for capture.

Returns

Camera pixel format coding.

Definition at line 241 of file vpV4l2Grabber.h.

Referenced by open().

getWidth()

unsigned int vpFrameGrabber::getWidth ( ) const

inherited

Return the number of columns in the image.

Examples

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

Definition at line 43 of file vpFrameGrabber.cpp.

References vpFrameGrabber::width.

open() [1/2]

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

HelloWorldOgre.cpp, HelloWorldOgreAdvanced.cpp, grabV4l2.cpp, grabV4l2MultiCpp11Thread.cpp, manGrabV4l2.cpp, servoPioneerPanSegment3D.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 405 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(), open(), and vpV4l2Grabber().

open() [2/2]

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 468 of file vpV4l2Grabber.cpp.

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

operator>>() [1/2]

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>
 
#ifdef ENABLE_VISP_NAMESPACE
using namespace VISP_NAMESPACE_NAME;
#endif
 
int main()
{
  vpImage<unsigned char> I;
  vpV4l2Grabber g;
  g >> I;
}

Definition at line 1445 of file vpV4l2Grabber.cpp.

References acquire().

operator>>() [2/2]

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>
 
#ifdef ENABLE_VISP_NAMESPACE
using namespace VISP_NAMESPACE_NAME;
#endif
 
int main()
{
  vpImage<vpRGBa> I;
  vpV4l2Grabber g;
  g >> I;
}

Definition at line 1471 of file vpV4l2Grabber.cpp.

References acquire().

setDevice()

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, 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 287 of file vpV4l2Grabber.h.

Referenced by vpV4l2Grabber().

setFramerate()

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, and servoPioneerPanSegment3D.cpp.

Definition at line 820 of file vpV4l2Grabber.cpp.

References framerate_25fps, V4L2_FRAME_FORMAT, and V4L2_IMAGE_FORMAT.

Referenced by vpV4l2Grabber().

setHeight()

void vpV4l2Grabber::setHeight ( unsigned  h )

inline

Set image height to acquire.

Examples

manGrabV4l2.cpp.

Definition at line 264 of file vpV4l2Grabber.h.

Referenced by setScale().

setInput()

void vpV4l2Grabber::setInput

(

unsigned

input = vpV4l2Grabber::DEFAULT_INPUT

)

Set the video input port on the board.

Examples

grabV4l2.cpp, manGrabV4l2.cpp, and servoPioneerPanSegment3D.cpp.

Definition at line 368 of file vpV4l2Grabber.cpp.

Referenced by vpV4l2Grabber().

setNBuffers()

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 279 of file vpV4l2Grabber.h.

Referenced by vpV4l2Grabber().

setPixelFormat()

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 296 of file vpV4l2Grabber.h.

Referenced by open(), and vpV4l2Grabber().

setScale()

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 382 of file vpV4l2Grabber.cpp.

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

Referenced by vpV4l2Grabber().

setVerboseMode()

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 250 of file vpV4l2Grabber.h.

setWidth()

void vpV4l2Grabber::setWidth ( unsigned  w )

inline

Set image width to acquire.

Examples

manGrabV4l2.cpp.

Definition at line 259 of file vpV4l2Grabber.h.

Referenced by setScale().

Member Data Documentation

DEFAULT_INPUT

BEGIN_VISP_NAMESPACE const unsigned int vpV4l2Grabber::DEFAULT_INPUT = 2

static

Definition at line 134 of file vpV4l2Grabber.h.

Referenced by vpV4l2Grabber().

DEFAULT_SCALE

const unsigned int vpV4l2Grabber::DEFAULT_SCALE = 2

static

Definition at line 135 of file vpV4l2Grabber.h.

Referenced by vpV4l2Grabber().

FRAME_SIZE

const unsigned int vpV4l2Grabber::FRAME_SIZE = 288

static

Definition at line 141 of file vpV4l2Grabber.h.

height

unsigned int vpFrameGrabber::height

protectedinherited

Number of rows in the image.

Definition at line 134 of file vpFrameGrabber.h.

Referenced by vpDiskGrabber::acquire(), vpPylonGrabberGigE::acquire(), vpPylonGrabberUsb::acquire(), vpFlyCaptureGrabber::acquire(), acquire(), vp1394TwoGrabber::acquire(), vp1394TwoGrabber::dequeue(), vpDirectShowGrabber::getFormat(), vpVideoReader::getFrame(), vpFrameGrabber::getHeight(), vp1394TwoGrabber::getHeight(), vpDiskGrabber::open(), vp1394CMUGrabber::open(), open(), vpDirectShowGrabber::setFormat(), vp1394TwoGrabber::setFormat7ROI(), vpDirectShowGrabber::setImageSize(), vp1394CMUGrabber::setVideoMode(), vp1394TwoGrabber::setVideoMode(), vp1394CMUGrabber::vp1394CMUGrabber(), and vp1394TwoGrabber::vp1394TwoGrabber().

init

bool vpFrameGrabber::init

inherited

Set to true if the frame grabber has been initialized.

Definition at line 102 of file vpFrameGrabber.h.

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

MAX_BUFFERS

const unsigned int vpV4l2Grabber::MAX_BUFFERS = 32

static

Definition at line 140 of file vpV4l2Grabber.h.

MAX_CTRL

const unsigned int vpV4l2Grabber::MAX_CTRL = 32

static

Definition at line 139 of file vpV4l2Grabber.h.

MAX_FORMAT

const __u32 vpV4l2Grabber::MAX_FORMAT = 32

static

Definition at line 138 of file vpV4l2Grabber.h.

MAX_INPUTS

const __u32 vpV4l2Grabber::MAX_INPUTS = 16

static

Definition at line 136 of file vpV4l2Grabber.h.

MAX_NORM

const __u32 vpV4l2Grabber::MAX_NORM = 16

static

Definition at line 137 of file vpV4l2Grabber.h.

width

unsigned int vpFrameGrabber::width

protectedinherited

Number of columns in the image.

Definition at line 135 of file vpFrameGrabber.h.

Referenced by vpDiskGrabber::acquire(), vpPylonGrabberGigE::acquire(), vpPylonGrabberUsb::acquire(), vpFlyCaptureGrabber::acquire(), acquire(), vp1394TwoGrabber::acquire(), vp1394TwoGrabber::dequeue(), vpDirectShowGrabber::getFormat(), vpVideoReader::getFrame(), vpFrameGrabber::getWidth(), vp1394TwoGrabber::getWidth(), vpDiskGrabber::open(), vp1394CMUGrabber::open(), open(), vpDirectShowGrabber::setFormat(), vp1394TwoGrabber::setFormat7ROI(), vpDirectShowGrabber::setImageSize(), vp1394CMUGrabber::setVideoMode(), vp1394TwoGrabber::setVideoMode(), vp1394CMUGrabber::vp1394CMUGrabber(), and vp1394TwoGrabber::vp1394TwoGrabber().