#include <vpVideoReader.h>

Inheritance diagram for vpVideoReader:

Public Member Functions
	vpVideoReader ()

	~vpVideoReader ()

void	acquire (vpImage< vpRGBa > &I)

void	acquire (vpImage< unsigned char > &I)

void	close ()

bool	end ()

bool	getFrame (vpImage< vpRGBa > &I, long frame)

bool	getFrame (vpImage< unsigned char > &I, long frame)

double	getFramerate () const

long	getFrameIndex () const

long	getLastFrameIndex () const

void	open (vpImage< vpRGBa > &I)

void	open (vpImage< unsigned char > &I)

void	resetFrameCounter ()

void	setFileName (const char *filename)

void	setFileName (const std::string &filename)

void	setFirstFrameIndex (const long first_frame)

void	setLastFrameIndex (const long last_frame)

unsigned int	getHeight () const

unsigned int	getWidth () const

Public Attributes
bool	init

Protected Attributes
unsigned int	height

unsigned int	width

Detailed Description

Class that enables to manipulate easily a video file or a sequence of images. As it inherits from the vpFrameGrabber Class, it can be used like an other frame grabber class.

The following example available in tutorial-grabber-video.cpp shows how this class is really easy to use. It enables to read a video file named video.mpeg.

#include <visp/vpDisplayX.h>
#include <visp/vpVideoReader.h>
int main()
{
#ifdef VISP_HAVE_FFMPEG
  try {
    vpImage<unsigned char> I;
    vpVideoReader g;
    g.setFileName("./video.mpg");
    g.open(I);
    std::cout << "video framerate: " << g.getFramerate() << "Hz" << std::endl;
    std::cout << "video dimension: " << I.getWidth() << " " << I.getHeight() << std::endl;
#ifdef VISP_HAVE_X11
    vpDisplayX d(I);
#else
    std::cout << "No image viewer is available..." << std::endl;
#endif
    vpDisplay::setTitle(I, "Video grabber");
    while (! g.end() ) {
      double t = vpTime::measureTimeMs();
      g.acquire(I);
      vpDisplay::display(I);
      vpDisplay::flush(I);
      if (vpDisplay::getClick(I, false)) break;
      vpTime::wait(t, 1000. / g.getFramerate());
    }
  }
  catch(vpException e) {
    std::cout << "Catch an exception: " << e << std::endl;
  }
#endif
}

As shown in the next example, this class allows also to access to a specific frame. But be careful, for video files, the getFrame() method is not precise and returns the nearest intra key frame from the expected frame. You can use the getFrame() method to position the reader in the video and then use the acquire() method to get the following frames one by one.

#include <visp/vpImage.h>
#include <visp/vpRGBa.h>
#include <visp/vpVideoReader.h>
int main()
{
#ifdef VISP_HAVE_FFMPEG
  vpImage<vpRGBa> I;
  vpVideoReader reader;
  // Initialize the reader.
  reader.setFileName("video.mpeg");
  reader.open(I);
  // Read the nearest key frame from the 3th frame
  reader.getFrame(I,2);
  // After positionning the video reader use acquire to read the video frame by frame
  reader.acquire(I);
  return 0;
#endif
}

The other following example explains how to use the class to read a sequence of images. The images are stored in the folder "./image" and are named "image0000.jpeg", "image0001.jpeg", "image0002.jpeg", ... As explained in setFirstFrameIndex() and setLastFrameIndex() it is also possible to set the first and last image numbers to read a portion of the sequence. If these two functions are not used, first and last image numbers are set automatically to match the first and image images of the sequence.

#include <visp/vpImage.h>
#include <visp/vpRGBa.h>
#include <visp/vpVideoReader.h>
int main()
{
  vpImage<vpRGBa> I;
  vpVideoReader reader;
  // Initialize the reader.
  reader.setFileName("./image/image%04d.jpeg");
  reader.setFirstFrameIndex(10);
  reader.setLastFrameIndex(20);
  reader.open(I);
  while (! reader.end() )
    reader.acquire(I);
  return 0;
}

Note that it is also possible to access to a specific frame using getFrame().

#include <visp/vpImage.h>
#include <visp/vpRGBa.h>
#include <visp/vpVideoReader.h>
int main()
{
  vpImage<vpRGBa> I;
  vpVideoReader reader;
  // Initialize the reader.
  reader.setFileName("./image/image%04d.jpeg");
  reader.open(I);
  // Read the 3th frame
  reader.getFrame(I,2);
  return 0;
}

Examples:: AROgre.cpp, AROgreBasic.cpp, imageSequenceReader.cpp, mbtEdgeKltTracking.cpp, mbtEdgeTracking.cpp, mbtKltTracking.cpp, templateTracker.cpp, trackMeNurbs.cpp, tutorial-grabber-video.cpp, tutorial-klt-tracker.cpp, tutorial-matching-surf-homography.cpp, tutorial-matching-surf.cpp, and videoReader.cpp.

Definition at line 157 of file vpVideoReader.h.

Constructor & Destructor Documentation

vpVideoReader::vpVideoReader ( )

Basic constructor.

Definition at line 57 of file vpVideoReader.cpp.

vpVideoReader::~vpVideoReader ( )

Basic destructor.

Definition at line 70 of file vpVideoReader.cpp.

Member Function Documentation

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

virtual

Grabs the current (k) image in the stack of frames and increments the frame counter in order to grab the next image (k+1) during the next use of the method. If open() was not called priviously, this method opens the video reader.

This method enables to use the class as frame grabber.

Parameters

I	: The image where the frame is stored.

Implements vpFrameGrabber.

Examples:: AROgre.cpp, AROgreBasic.cpp, mbtEdgeKltTracking.cpp, mbtEdgeTracking.cpp, mbtKltTracking.cpp, templateTracker.cpp, tutorial-grabber-video.cpp, tutorial-klt-tracker.cpp, tutorial-matching-surf-homography.cpp, tutorial-matching-surf.cpp, and videoReader.cpp.

Definition at line 286 of file vpVideoReader.cpp.

References vpDiskGrabber::acquire(), vpFFMPEG::acquire(), and open().

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

virtual

Grabs the kth image in the stack of frames and increments the frame counter in order to grab the next image (k+1) during the next use of the method.

This method enables to use the class as frame grabber.

Parameters

I	: The image where the frame is stored.

Implements vpFrameGrabber.

Definition at line 311 of file vpVideoReader.cpp.

References vpDiskGrabber::acquire(), vpFFMPEG::acquire(), and open().

void vpVideoReader::close ( )

inlinevirtual

This virtual function is used to de-allocate the memory used by a specific frame grabber

Implements vpFrameGrabber.

Examples:: AROgre.cpp, AROgreBasic.cpp, mbtEdgeKltTracking.cpp, mbtEdgeTracking.cpp, mbtKltTracking.cpp, and templateTracker.cpp.

Definition at line 212 of file vpVideoReader.h.

bool vpVideoReader::end ( void )

inline

Returns: true if the end of the sequence is reached.

Examples:: AROgre.cpp, AROgreBasic.cpp, mbtEdgeKltTracking.cpp, mbtEdgeTracking.cpp, mbtKltTracking.cpp, templateTracker.cpp, tutorial-grabber-video.cpp, tutorial-klt-tracker.cpp, tutorial-matching-surf-homography.cpp, and tutorial-matching-surf.cpp.

Definition at line 217 of file vpVideoReader.h.

bool vpVideoReader::getFrame	(	vpImage< vpRGBa > &	I,
		long	frame
	)

Gets the $ frame $ th frame and stores it in the image $ I $ .

Warning: For the video files this method is not precise, and returns the nearest key frame from the expected frame. But this method enables to position the reader where you want. Then, use the acquire method to grab the following images one after one.

Parameters

I	: The vpImage used to stored the frame.
frame	: The index of the frame which has to be read.

Returns: It returns true if the frame could be read. Else it returns false.

Examples:: imageSequenceReader.cpp, trackMeNurbs.cpp, and videoReader.cpp.

Definition at line 340 of file vpVideoReader.cpp.

References vpDiskGrabber::acquire(), vpFFMPEG::getFrame(), and vpERROR_TRACE.

Referenced by open().

bool vpVideoReader::getFrame	(	vpImage< unsigned char > &	I,
		long	frame
	)

Gets the $ frame $ th frame and stores it in the image $ I $ .

Warning: For the video files this method is not precise, and returns the nearest key frame from the expected frame. But this method enables to position the reader where you want. Then, use the acquire method to grab the following images one after one.

Parameters

I	: The vpImage used to stored the frame.
frame	: The index of the frame which has to be read.

Returns: It returns true if the frame could be read. Else it returns false.

Definition at line 381 of file vpVideoReader.cpp.

References vpDiskGrabber::acquire(), vpFFMPEG::getFrame(), and vpERROR_TRACE.

long vpVideoReader::getFrameIndex ( ) const

inline

Get the current frame index. This index is updated at each call of the acquire method. It can be used to detect the end of a file (comparison with getLastFrameIndex()).

Returns: Returns the current frame index.

Examples:: templateTracker.cpp.

Definition at line 233 of file vpVideoReader.h.

double vpVideoReader::getFramerate ( ) const

Return the framerate in Hz used to encode the video stream.

If the video is a sequence of images, return -1.

Examples:: tutorial-grabber-video.cpp.

Definition at line 555 of file vpVideoReader.cpp.

References vpFFMPEG::getFramerate().

unsigned int vpFrameGrabber::getHeight ( ) const

inlineinherited

Return the number of rows in the image.

Examples:: AROgre.cpp, AROgreBasic.cpp, HelloWorldOgre.cpp, and HelloWorldOgreAdvanced.cpp.

Definition at line 119 of file vpFrameGrabber.h.

long vpVideoReader::getLastFrameIndex ( ) const

inline

Gets the last frame index.

Returns: Returns the last frame index.

Examples:: imageSequenceReader.cpp, and videoReader.cpp.

Definition at line 240 of file vpVideoReader.h.

unsigned int vpFrameGrabber::getWidth ( ) const

inlineinherited

Return the number of columns in the image.

Examples:: AROgre.cpp, AROgreBasic.cpp, HelloWorldOgre.cpp, and HelloWorldOgreAdvanced.cpp.

Definition at line 121 of file vpFrameGrabber.h.

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

virtual

Sets all the parameters needed to read the video or the image sequence.

Grab the first frame and stores it in the image $ I $ .

Parameters

I	: The image where the frame is stored.

Implements vpFrameGrabber.

Examples:: AROgre.cpp, AROgreBasic.cpp, imageSequenceReader.cpp, mbtEdgeKltTracking.cpp, mbtEdgeTracking.cpp, mbtKltTracking.cpp, templateTracker.cpp, trackMeNurbs.cpp, tutorial-grabber-video.cpp, and videoReader.cpp.

Definition at line 135 of file vpVideoReader.cpp.

References vpFFMPEG::COLORED, vpException::fatalError, getFrame(), vpImage< Type >::getHeight(), vpImage< Type >::getWidth(), vpFrameGrabber::height, vpFFMPEG::initStream(), vpException::ioError, vpImageException::noFileNameError, vpFFMPEG::openStream(), vpDiskGrabber::setGenericName(), vpDiskGrabber::setImageNumber(), vpERROR_TRACE, and vpFrameGrabber::width.

Referenced by acquire().

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

virtual

Sets all the parameters needed to read the video or the image sequence.

Grab the first frame and stores it in the image $ I $ .

Parameters

I	: The image where the frame is stored.

Implements vpFrameGrabber.

Definition at line 210 of file vpVideoReader.cpp.

References vpException::fatalError, getFrame(), vpImage< Type >::getHeight(), vpImage< Type >::getWidth(), vpFFMPEG::GRAY_SCALED, vpFrameGrabber::height, vpFFMPEG::initStream(), vpException::ioError, vpImageException::noFileNameError, vpFFMPEG::openStream(), vpDiskGrabber::setGenericName(), vpDiskGrabber::setImageNumber(), vpERROR_TRACE, and vpFrameGrabber::width.

void vpVideoReader::resetFrameCounter ( )

inline

Reset the frame counter and sets it to the first image index.

By default the first frame index is set to 0.

This method is useful if you use the class like a frame grabber (ie with theacquire method).

Definition at line 251 of file vpVideoReader.h.

void vpVideoReader::setFileName ( const char * filename )

It enables to set the path and the name of the file(s) which as/have to be read.

If you want to read a video file, $ filename $ corresponds to the path to the file (example : /local/video.mpeg).

If you want to read a sequence of images, $ filename $ corresponds to the path followed by the image name template. For exemple, if you want to read different images named image0001.jpeg, image0002.jpg, ... and located in the folder /local/image, will be "/local/image/image%04d.jpg".

Parameters

filename : Path to a video file or file name template of a image sequence.

Examples:: AROgre.cpp, AROgreBasic.cpp, imageSequenceReader.cpp, mbtEdgeKltTracking.cpp, mbtEdgeTracking.cpp, mbtKltTracking.cpp, templateTracker.cpp, trackMeNurbs.cpp, tutorial-grabber-video.cpp, tutorial-klt-tracker.cpp, tutorial-matching-surf-homography.cpp, tutorial-matching-surf.cpp, and videoReader.cpp.

Definition at line 94 of file vpVideoReader.cpp.

References vpException::memoryAllocationError, vpImageException::noFileNameError, and vpERROR_TRACE.

Referenced by setFileName().

void vpVideoReader::setFileName ( const std::string & filename )

It enables to set the path and the name of the file(s) which as/have to be read.

If you want to read a video file, $ filename $ corresponds to the path to the file (example : /local/video.mpeg).

If you want to read a sequence of images, $ filename $ corresponds to the path followed by the image name template. For exemple, if you want to read different images named image0001.jpeg, image0002.jpg, ... and located in the folder /local/image, will be "/local/image/image%04d.jpg".

Parameters

filename : Path to a video file or file name template of a image sequence.

Definition at line 123 of file vpVideoReader.cpp.

References setFileName().

void vpVideoReader::setFirstFrameIndex ( const long first_frame )

inline

Enables to set the first frame index if you want to use the class like a grabber (ie with the acquire method).

Parameters

first_frame : The first frame index.