Visual Servoing Platform  version 3.3.0
vpVideoWriter Class Reference

#include <vpVideoWriter.h>

Public Member Functions

 vpVideoWriter ()
 
virtual ~vpVideoWriter ()
 
void close ()
 
unsigned int getCurrentFrameIndex () const
 
void open (vpImage< vpRGBa > &I)
 
void open (vpImage< unsigned char > &I)
 
void resetFrameCounter ()
 
void saveFrame (vpImage< vpRGBa > &I)
 
void saveFrame (vpImage< unsigned char > &I)
 
void setCodec (const int fourcc_codec)
 
void setFileName (const char *filename)
 
void setFileName (const std::string &filename)
 
void setFirstFrameIndex (unsigned int first_frame)
 
void setFramerate (const double frame_rate)
 

Detailed Description

Class that enables to write easily a video file or a sequence of images.

This class has its own implementation to write a sequence of PGM and PPM images.

This class may benefit from optional 3rd parties:

  • libpng: If installed this optional 3rd party is used to write a sequence of PNG images. Installation instructions are provided here https://visp.inria.fr/3rd_png.
  • libjpeg: If installed this optional 3rd party is used to write a sequence of JPEG images. Installation instructions are provided here https://visp.inria.fr/3rd_jpeg.
  • OpenCV: If installed this optional 3rd party is used to write a sequence of images where images could be in TIFF, BMP, DIB, PBM, RASTER, JPEG2000 format. If libpng or libjpeg is not installed, OpenCV is also used to consider these image formats. OpenCV allows also to consider AVI, MPEG, MPEG4, MOV, OGV, WMV, FLV, MKV video formats. Installation instructions are provided here https://visp.inria.fr/3rd_opencv.

The following example available in tutorial-video-recorder.cpp shows how this class can be used to record a video from a camera by default in an mpeg file.

#include <visp3/core/vpTime.h>
#include <visp3/gui/vpDisplayGDI.h>
#include <visp3/gui/vpDisplayGTK.h>
#include <visp3/gui/vpDisplayOpenCV.h>
#include <visp3/gui/vpDisplayX.h>
#include <visp3/io/vpVideoWriter.h>
#include <visp3/sensor/vpV4l2Grabber.h>
int main(int argc, const char *argv[])
{
#if ((defined(VISP_HAVE_V4L2) || (VISP_HAVE_OPENCV_VERSION >= 0x020100)) && \
(defined(VISP_HAVE_X11) || defined(VISP_HAVE_GDI) || defined(VISP_HAVE_OPENCV) || defined(VISP_HAVE_GTK)))
std::string opt_videoname = "video-recorded.mpg";
int opt_device = 0;
for (int i = 0; i < argc; i++) {
if (std::string(argv[i]) == "--device")
opt_device = atoi(argv[i + 1]);
else if (std::string(argv[i]) == "--name")
opt_videoname = std::string(argv[i + 1]);
else if (std::string(argv[i]) == "--help") {
std::cout << "\nUsage: " << argv[0] << " [--device <device number>] [--name <video name>] [--help]\n"
<< std::endl;
return 0;
}
}
std::cout << "Use device: " << opt_device << std::endl;
std::cout << "Record video in: " << opt_videoname << std::endl;
try {
// vpImage<vpRGBa> I; // for color images
vpImage<unsigned char> I; // for gray images
#if defined(VISP_HAVE_V4L2)
std::ostringstream device;
device << "/dev/video" << opt_device;
g.setDevice(device.str());
g.setScale(1); // Acquire full resolution images
g.open(I);
g.acquire(I);
#elif defined(VISP_HAVE_OPENCV)
cv::VideoCapture g(opt_device);
if (!g.isOpened()) { // check if we succeeded
std::cout << "Failed to open the camera" << std::endl;
return -1;
}
cv::Mat frame;
g >> frame; // get a new frame from camera
#endif
std::cout << "Image size: " << I.getWidth() << " " << I.getHeight() << std::endl;
#if defined(VISP_HAVE_X11)
#elif defined(VISP_HAVE_GDI)
#elif defined(VISP_HAVE_OPENCV)
#elif defined(VISP_HAVE_GTK)
#endif
d.init(I, 0, 0, "Camera view");
vpVideoWriter writer;
#if VISP_HAVE_OPENCV_VERSION >= 0x030000
writer.setCodec(cv::VideoWriter::fourcc('P', 'I', 'M', '1')); // MPEG-1 codec
#elif VISP_HAVE_OPENCV_VERSION >= 0x020100
writer.setCodec(CV_FOURCC('P', 'I', 'M', '1'));
#endif
writer.setFileName(opt_videoname);
writer.open(I);
bool recording = false;
for (;;) {
#if defined(VISP_HAVE_V4L2)
g.acquire(I);
#elif defined(VISP_HAVE_OPENCV)
g >> frame;
#endif
if (recording == false) {
vpDisplay::displayText(I, 10, 10, "A click to start recording", vpColor::green);
if (vpDisplay::getClick(I, false))
recording = true;
} else {
writer.saveFrame(I);
vpDisplay::displayText(I, 10, 10, "Recording: A click to stop and exit", vpColor::red);
if (vpDisplay::getClick(I, false))
break;
}
}
std::cout << "The video was recorded in \"" << opt_videoname << "\"" << std::endl;
} catch (const vpException &e) {
std::cout << "Catch an exception: " << e << std::endl;
}
#else
(void)argc;
(void)argv;
std::cout << "Install OpenCV and rebuild ViSP to use this example." << std::endl;
#endif
}

The following example shows also how this class can be used to write an image sequence. The images are stored in the folder "./image" and are named "image0000.jpeg", "image0001.jpeg", "image0002.jpeg", ...

#include <visp3/core/vpConfig.h>
#include <visp3/io/vpVideoWriter.h>
int main()
{
//Initialize the writer.
writer.setFileName("./image/image%04d.jpeg");
writer.open(I);
for ( ; ; )
{
//Here the code to capture or create an image and stores it in I.
//Save the image
writer.saveFrame(I);
}
writer.close();
return 0;
}

The other following example explains how to use the class to write directly an mpeg file.

#include <visp3/io/vpVideoWriter.h>
int main()
{
vpVideoWriter writer;
// Set up the framerate to 30Hz. Default is 25Hz.
writer.setFramerate(30);
#if VISP_HAVE_OPENCV_VERSION >= 0x030000
writer.setCodec( cv::VideoWriter::fourcc('P','I','M','1') );
#elif VISP_HAVE_OPENCV_VERSION >= 0x020100
writer.setCodec( CV_FOURCC('P','I','M','1') );
#endif
writer.setFileName("./test.mpeg");
writer.open(I);
for ( ; ; )
{
// Here the code to capture or create an image and store it in I.
// Save the image
writer.saveFrame(I);
}
writer.close();
return 0;
}
Examples
grabV4l2MultiCpp11Thread.cpp, tutorial-grabber-1394-writer.cpp, and tutorial-video-recorder.cpp.

Definition at line 158 of file vpVideoWriter.h.

Constructor & Destructor Documentation

◆ vpVideoWriter()

vpVideoWriter::vpVideoWriter ( )

Basic constructor.

Definition at line 54 of file vpVideoWriter.cpp.

◆ ~vpVideoWriter()

vpVideoWriter::~vpVideoWriter ( )
virtual

Basic destructor.

Definition at line 78 of file vpVideoWriter.cpp.

Member Function Documentation

◆ close()

void vpVideoWriter::close ( )

Deallocates parameters use to write the video or the image sequence.

Examples
tutorial-grabber-1394-writer.cpp.

Definition at line 271 of file vpVideoWriter.cpp.

◆ getCurrentFrameIndex()

unsigned int vpVideoWriter::getCurrentFrameIndex ( ) const
inline

Gets the current frame index.

Returns
Returns the current frame index.

Definition at line 212 of file vpVideoWriter.h.

◆ open() [1/2]

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

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

Parameters
I: One image with the right dimensions.

Definition at line 166 of file vpVideoWriter.cpp.

◆ open() [2/2]

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

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

Parameters
I: One image with the right dimensions.
Examples
grabV4l2MultiCpp11Thread.cpp, tutorial-grabber-1394-writer.cpp, and tutorial-video-recorder.cpp.

Definition at line 131 of file vpVideoWriter.cpp.

◆ resetFrameCounter()

void vpVideoWriter::resetFrameCounter ( )
inline

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

By default the first frame index is set to 0.

Definition at line 221 of file vpVideoWriter.h.

◆ saveFrame() [1/2]

void vpVideoWriter::saveFrame ( vpImage< unsigned char > &  I)

Saves the image as a frame of the video or as an image belonging to the image sequence.

Each time this method is used, the frame counter is incremented and thus the file name change for the case of an image sequence.

Parameters
I: The image which has to be saved

Definition at line 238 of file vpVideoWriter.cpp.

◆ saveFrame() [2/2]

void vpVideoWriter::saveFrame ( vpImage< vpRGBa > &  I)

Saves the image as a frame of the video or as an image belonging to the image sequence.

Each time this method is used, the frame counter is incremented and thus the file name change for the case of an image sequence.

Parameters
I: The image which has to be saved
Examples
grabV4l2MultiCpp11Thread.cpp, tutorial-grabber-1394-writer.cpp, and tutorial-video-recorder.cpp.

Definition at line 205 of file vpVideoWriter.cpp.

◆ setCodec()

void vpVideoWriter::setCodec ( const int  fourcc_codec)
inline
Examples
tutorial-video-recorder.cpp.

Definition at line 227 of file vpVideoWriter.h.

◆ setFileName() [1/2]

void vpVideoWriter::setFileName ( const char *  filename)

It enables to set the path and the name of the files which will be saved.

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

Parameters
filename: filename template of an image sequence.
Examples
grabV4l2MultiCpp11Thread.cpp, tutorial-grabber-1394-writer.cpp, and tutorial-video-recorder.cpp.

Definition at line 91 of file vpVideoWriter.cpp.

◆ setFileName() [2/2]

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

It enables to set the path and the name of the files which will be saved.

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

Parameters
filename: filename template of an image sequence.

Definition at line 124 of file vpVideoWriter.cpp.

◆ setFirstFrameIndex()

void vpVideoWriter::setFirstFrameIndex ( unsigned int  first_frame)
inline

Enables to set the first frame index.

Parameters
first_frame: The first frame index.

Definition at line 237 of file vpVideoWriter.h.

◆ setFramerate()

void vpVideoWriter::setFramerate ( const double  frame_rate)
inline

Sets the framerate in Hz of the video when encoding.

Parameters
frame_rate: the expected framerate.

By default the framerate is set to 25Hz.

Definition at line 246 of file vpVideoWriter.h.

vpDisplayX
Use the X11 console to display images on unix-like OS. Thus to enable this class X11 should be instal...
Definition: vpDisplayX.h:149
vpV4l2Grabber::open
void open(vpImage< unsigned char > &I)
Definition: vpV4l2Grabber.cpp:409
vpVideoWriter::saveFrame
void saveFrame(vpImage< vpRGBa > &I)
Definition: vpVideoWriter.cpp:205
vpV4l2Grabber::setDevice
void setDevice(const std::string &devname)
Definition: vpV4l2Grabber.h:284
vpImageConvert::convert
static void convert(const vpImage< unsigned char > &src, vpImage< vpRGBa > &dest)
Definition: vpImageConvert.cpp:78
vpVideoWriter::setFramerate
void setFramerate(const double frame_rate)
Definition: vpVideoWriter.h:246
vpDisplayGDI
Display for windows using GDI (available on any windows 32 platform).
Definition: vpDisplayGDI.h:127
vpVideoWriter::open
void open(vpImage< vpRGBa > &I)
Definition: vpVideoWriter.cpp:131
vpV4l2Grabber::acquire
void acquire(vpImage< unsigned char > &I)
Definition: vpV4l2Grabber.cpp:525
vpDisplayOpenCV
The vpDisplayOpenCV allows to display image using the OpenCV library. Thus to enable this class OpenC...
Definition: vpDisplayOpenCV.h:140
vpColor::green
static const vpColor green
Definition: vpColor.h:181
vpDisplay::display
static void display(const vpImage< unsigned char > &I)
Definition: vpDisplay_uchar.cpp:739
vpDisplayGTK
The vpDisplayGTK allows to display image using the GTK 3rd party library. Thus to enable this class G...
Definition: vpDisplayGTK.h:136
vpDisplay::displayText
static void displayText(const vpImage< unsigned char > &I, const vpImagePoint &ip, const std::string &s, const vpColor &color)
Definition: vpDisplay_uchar.cpp:663
vpImage::getHeight
unsigned int getHeight() const
Definition: vpImage.h:221
vpVideoWriter::setFileName
void setFileName(const char *filename)
Definition: vpVideoWriter.cpp:91
vpDisplayX::init
void init(vpImage< unsigned char > &I, int winx=-1, int winy=-1, const std::string &title="")
Definition: vpDisplayX.cpp:251
vpV4l2Grabber
Class that is a wrapper over the Video4Linux2 (V4L2) driver.
Definition: vpV4l2Grabber.h:133
vpDisplay::flush
static void flush(const vpImage< unsigned char > &I)
Definition: vpDisplay_uchar.cpp:715
vpImage< unsigned char >
vpVideoWriter::close
void close()
Definition: vpVideoWriter.cpp:271
vpDisplay::getClick
static bool getClick(const vpImage< unsigned char > &I, bool blocking=true)
Definition: vpDisplay_uchar.cpp:764
vpV4l2Grabber::setScale
void setScale(unsigned scale=vpV4l2Grabber::DEFAULT_SCALE)
Definition: vpV4l2Grabber.cpp:386
vpVideoWriter
Class that enables to write easily a video file or a sequence of images.
Definition: vpVideoWriter.h:158
vpVideoWriter::setCodec
void setCodec(const int fourcc_codec)
Definition: vpVideoWriter.h:227
vpException
error that can be emited by ViSP classes.
Definition: vpException.h:70
vpColor::red
static const vpColor red
Definition: vpColor.h:178
vpImage::getWidth
unsigned int getWidth() const
Definition: vpImage.h:279