Visual Servoing Platform  version 3.5.1 under development (2022-07-01)
vpVideoWriter Class Reference

#include <visp3/io/vpVideoWriter.h>

Public Member Functions

 vpVideoWriter ()
 
virtual ~vpVideoWriter ()
 
void close ()
 
unsigned int getCurrentFrameIndex () const
 
std::string getFrameName () 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 std::string &filename)
 
void setFirstFrameIndex (int first_frame)
 
void setFramerate (const double framerate)
 
void setFrameStep (const int frame_step)
 

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::string(argv[i]) == "-h") {
std::cout << "\nUsage: " << argv[0] << " [--device <device number>] [--name <video name>] [--help][-h]\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
}
static const vpColor red
Definition: vpColor.h:217
static const vpColor green
Definition: vpColor.h:220
Display for windows using GDI (available on any windows 32 platform).
Definition: vpDisplayGDI.h:129
The vpDisplayGTK allows to display image using the GTK 3rd party library. Thus to enable this class G...
Definition: vpDisplayGTK.h:135
The vpDisplayOpenCV allows to display image using the OpenCV library. Thus to enable this class OpenC...
Use the X11 console to display images on unix-like OS. Thus to enable this class X11 should be instal...
Definition: vpDisplayX.h:135
void init(vpImage< unsigned char > &I, int win_x=-1, int win_y=-1, const std::string &win_title="")
static bool getClick(const vpImage< unsigned char > &I, bool blocking=true)
static void display(const vpImage< unsigned char > &I)
static void flush(const vpImage< unsigned char > &I)
static void displayText(const vpImage< unsigned char > &I, const vpImagePoint &ip, const std::string &s, const vpColor &color)
error that can be emited by ViSP classes.
Definition: vpException.h:72
static void convert(const vpImage< unsigned char > &src, vpImage< vpRGBa > &dest)
unsigned int getWidth() const
Definition: vpImage.h:246
unsigned int getHeight() const
Definition: vpImage.h:188
Class that is a wrapper over the Video4Linux2 (V4L2) driver.
void open(vpImage< unsigned char > &I)
void setScale(unsigned scale=vpV4l2Grabber::DEFAULT_SCALE)
void setDevice(const std::string &devname)
void acquire(vpImage< unsigned char > &I)
Class that enables to write easily a video file or a sequence of images.
void saveFrame(vpImage< vpRGBa > &I)
void setFileName(const std::string &filename)
void open(vpImage< vpRGBa > &I)
void setCodec(const int fourcc_codec)

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()
{
vpVideoWriter writer;
//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;
}
void setFramerate(const double framerate)
Examples
grabV4l2MultiCpp11Thread.cpp, tutorial-grabber-1394-writer.cpp, tutorial-video-manipulation.cpp, and tutorial-video-recorder.cpp.

Definition at line 159 of file vpVideoWriter.h.

Constructor & Destructor Documentation

◆ vpVideoWriter()

vpVideoWriter::vpVideoWriter ( )

Basic constructor.

Definition at line 56 of file vpVideoWriter.cpp.

◆ ~vpVideoWriter()

vpVideoWriter::~vpVideoWriter ( )
virtual

Basic destructor.

Definition at line 74 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 259 of file vpVideoWriter.cpp.

References vpException::notInitialized.

◆ getCurrentFrameIndex()

unsigned int vpVideoWriter::getCurrentFrameIndex ( ) const
inline

Gets the current frame index.

Returns
Returns the current frame index.

Definition at line 216 of file vpVideoWriter.h.

◆ getFrameName()

std::string vpVideoWriter::getFrameName ( ) const
inline

Return the name of the file in which the last frame was saved.

Examples
tutorial-video-manipulation.cpp.

Definition at line 220 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.

This function will also create recursively the folders to host the video or the sequence of images.

Parameters
I: One image with the right dimensions.

Definition at line 155 of file vpVideoWriter.cpp.

References vpException::fatalError, vpImage< Type >::getHeight(), vpIoTools::getParent(), vpImage< Type >::getWidth(), vpIoTools::makeDirectory(), and vpImageException::noFileNameError.

◆ open() [2/2]

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

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

This function will also create recursively the folders to host the video or the sequence of images.

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

Definition at line 116 of file vpVideoWriter.cpp.

References vpException::fatalError, vpImage< Type >::getHeight(), vpIoTools::getParent(), vpImage< Type >::getWidth(), vpIoTools::makeDirectory(), and vpImageException::noFileNameError.

◆ 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 229 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 227 of file vpVideoWriter.cpp.

References vpImageConvert::convert(), vpException::notInitialized, and vpImageIo::write().

◆ 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, tutorial-video-manipulation.cpp, and tutorial-video-recorder.cpp.

Definition at line 195 of file vpVideoWriter.cpp.

References vpImageConvert::convert(), vpException::notInitialized, and vpImageIo::write().

◆ setCodec()

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

Definition at line 235 of file vpVideoWriter.h.

◆ setFileName()

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

It enables to set the path and the name of the video or sequence of images 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.

Note
The function open() will create recursively the folders to host the video or the sequence of images.
Parameters
filename: filename template of an image sequence.
Examples
grabV4l2MultiCpp11Thread.cpp, tutorial-grabber-1394-writer.cpp, tutorial-video-manipulation.cpp, and tutorial-video-recorder.cpp.

Definition at line 90 of file vpVideoWriter.cpp.

References vpException::badValue, and vpImageException::noFileNameError.

◆ setFirstFrameIndex()

void vpVideoWriter::setFirstFrameIndex ( int  first_frame)

Enables to set the first frame index.

Parameters
first_frame: The first frame index. Value should be positive.
Examples
tutorial-video-manipulation.cpp.

Definition at line 337 of file vpVideoWriter.cpp.

References vpException::fatalError.

◆ setFramerate()

void vpVideoWriter::setFramerate ( const double  framerate)
inline

Sets the framerate in Hz of the video when encoding.

Parameters
framerate: The expected framerate.

By default the framerate is set to 25Hz.

Note
Framerate can only be set when OpenCV > 2.1.0.

Definition at line 251 of file vpVideoWriter.h.

◆ setFrameStep()

void vpVideoWriter::setFrameStep ( const int  frame_step)
inline

Set frame step between 2 successive images when a sequence of images is considered.

Parameters
frame_step: Step between 2 successive images. The default value is 1.

Definition at line 259 of file vpVideoWriter.h.