How to capture camera's video in real time?

Question

I'm using Usb 3.0 Basler camera acA640-750uc to capture the video and here is the program to use 2 cameras and grab the frame:

the problem is when i runed this program my computer captured the video from 2 cameras but the video is slower than my actual movement about 2 sec.It means my video is slower than the real time and I want to capture the video in real time. How can I solve this problem?

I've tried to change the condition of for (size_t i = 0; i < cameras.GetSize(); ++i) from ++i to i++ , but it doesn't work.

#include <pylon/PylonIncludes.h>
#ifdef PYLON_WIN_BUILD
#include <pylon/PylonGUI.h>
#endif

// Namespace for using pylon objects.
using namespace Pylon;

// Namespace for using cout.
using namespace std;

// Number of images to be grabbed.
static const uint32_t c_countOfImagesToGrab = 1000;

// Limits the amount of cameras used for grabbing.
// It is important to manage the available bandwidth when grabbing with 
// multiple cameras.
// This applies, for instance, if two GigE cameras are connected to the 
// same network adapter via a switch.
// To manage the bandwidth, the GevSCPD interpacket delay parameter and 
// the GevSCFTD transmission delay
// parameter can be set for each GigE camera device.
// The "Controlling Packet Transmission Timing with the Interpacket and 
// Frame Transmission Delays on Basler GigE Vision Cameras"
// Application Notes (AW000649xx000)
// provide more information about this topic.
// The bandwidth used by a FireWire camera device can be limited by 
// adjusting the packet size.
static const size_t c_maxCamerasToUse = 2;

int main(int argc, char* argv[])
{
// The exit code of the sample application.
int exitCode = 0;

// Before using any pylon methods, the pylon runtime must be initialized. 
PylonInitialize();

try
{
// Get the transport layer factory.
CTlFactory& tlFactory = CTlFactory::GetInstance();

// Get all attached devices and exit application if no device is found.
DeviceInfoList_t devices;
if (tlFactory.EnumerateDevices(devices) == 0)
{
throw RUNTIME_EXCEPTION("No camera present.");
}

// Create an array of instant cameras for the found devices and avoid 
// exceeding a maximum number of devices.
CInstantCameraArray cameras(min(devices.size(), c_maxCamerasToUse));

// Create and attach all Pylon Devices.
for (size_t i = 0; i < cameras.GetSize(); ++i)
{
cameras[i].Attach(tlFactory.CreateDevice(devices[i]));

// Print the model name of the camera.
cout << "Using device " << cameras[i].GetDeviceInfo().GetModelName() << 
endl;
}

// Starts grabbing for all cameras starting with index 0. The grabbing
// is started for one camera after the other. That's why the images of 
// all
// cameras are not taken at the same time.
// However, a hardware trigger setup can be used to cause all cameras to 
// grab images synchronously.
// According to their default configuration, the cameras are
// set up for free-running continuous acquisition.
cameras.StartGrabbing();

// This smart pointer will receive the grab result data.
CGrabResultPtr ptrGrabResult;
// Grab c_countOfImagesToGrab from the cameras.
for (uint32_t i = 0; i < c_countOfImagesToGrab && cameras.IsGrabbing(); 
++i)
{
cameras.RetrieveResult(5000, ptrGrabResult, 
TimeoutHandling_ThrowException);

// When the cameras in the array are created the camera context value
// is set to the index of the camera in the array.
// The camera context is a user settable value.
// This value is attached to each grab result and can be used
// to determine the camera that produced the grab result.
intptr_t cameraContextValue = ptrGrabResult->GetCameraContext();

#ifdef PYLON_WIN_BUILD
// Show the image acquired by each camera in the window related to each 
// camera.

Pylon::DisplayImage(cameraContextValue, ptrGrabResult);
#endif

// Print the index and the model name of the camera.
cout << "Camera " << cameraContextValue << ": " << 
cameras[cameraContextValue].GetDeviceInfo().GetModelName() << endl;

// Now, the image data can be processed.
cout << "GrabSucceeded: " << ptrGrabResult->GrabSucceeded() << endl;
cout << "SizeX: " << ptrGrabResult->GetWidth() << endl;
cout << "SizeY: " << ptrGrabResult->GetHeight() << endl;
const uint8_t* pImageBuffer = (uint8_t*)ptrGrabResult->GetBuffer();
cout << "Gray value of first pixel: " << (uint32_t)pImageBuffer[0] << 
endl << 
endl;
}
}
catch (const GenericException& e)
{
// Error handling
cerr << "An exception occurred." << endl
<< e.GetDescription() << endl;
exitCode = 1;
}

// Comment the following two lines to disable waiting on exit.
cerr << endl << "Press Enter to exit." << endl;
while (cin.get() != '\n');
// Releases all pylon resources. 
PylonTerminate();

return exitCode;
}

Answer 1

I am not experienced in this field but changing ++i to i++ obviously does not solve your problem as they are equivalent in this for definition ( for (size_t i = 0; i < cameras.GetSize(); ++i) ).
I am not sure but accourding to comments in code you may need to configure cameras manually (cameras may configured differently):

// According to their ***default configuration***, the cameras are
// set up for free-running continuous acquisition.
cameras.StartGrabbing();

Also, please read these comments from the code carefully and see if you correctly configure your network and parameters. I suggest you try with one camera first:

// Limits the amount of cameras used for grabbing.
// It is important to manage the available bandwidth when grabbing with 
// multiple cameras.
// This applies, for instance, if two GigE cameras are connected to the 
// same network adapter via a switch.
// To manage the bandwidth, the GevSCPD interpacket delay parameter and 
// the GevSCFTD transmission delay
// parameter can be set for each GigE camera device.
// The "Controlling Packet Transmission Timing with the Interpacket and 
// Frame Transmission Delays on Basler GigE Vision Cameras"
// Application Notes (AW000649xx000)
// provide more information about this topic.
// The bandwidth used by a FireWire camera device can be limited by 
// adjusting the packet size.