Capturing Video on windows using C++

Vikas Patial — Sun, 13 Jun 2010 05:05:42 +0000

Using Webcam on windows should be easy, that is what i thought when i started out and wasted three days trying to get thing to work reliably. Most people used Video for Windows (VFW) in tutorials , but i found it very unreliable and crashing often, also when debugging it threw wired errors. Then I made up my mind to use the DirectX based DirectShow methods, Its needs DirectX SDK to build it and on downloading it and finally looking for the files i found that functionality have been moved to platform SDK. Anyhow i was not downloading another 4.5 GB of SDK to test if it worked. So after some Googling i found about the VideoInput library (uses DirectShow methods) which people sometimes use for OpenCV. I wished i had found it earlier , here is a small tutorial on hot to get started using it , since the original files which came with it did not work for me.There are a whole host of features supported so you can explore the documentation for more .

VideoInput Library homepage

How to use webcam/tv tuner/capture cards in VC++ to capture video and take pictures –

1. Create simple Dialog based MFC project.

2. In the dialog make a Picture control and a Button , Picture control will Display the Video stream and the button will be used to capture a snapshot.Change Picture control to type Bitmap and attach a CStatic variable to it.

3. Now we will use a simple timer ( WM_TIMER ) to update the image being captured there are better way but this should do for a tutorial. In OnInitDialog() set the timer to refresh at say 10 times a second,

SetTimer(NULL,100,NULL)

4. Include the video videoInput.h header file. Also add the videoinput.lib in the linker input and for ignore library atlthunk.lib ( if it causes errors ).

5. Initialize the device using VideoInput API .

// in header int device,width,height,size; videoInput VI; unsigned char * captureBuffer;


	// in InitDoalog

	device = 0; // first webcam

	VI.setupDevice(device,320,240); // 320 x 240 resolution 
	width  = VI.getWidth(device);

	height = VI.getHeight(device);

	size   = VI.getSize(device); // size to initialize buffer

captureBuffer = new unsigned char[size]; // our capturebuffer

6. Now lets capture video and display frame in the OnTimer

if(VI.isFrameNew(device)) { VI.getPixels(device,captureBuffer, false, true); DisplayImage(&m_webcam,height,width,captureBuffer); }

7. There is also example of how to capture image using libjpeg, please download the source and check it out.

Note: There is a file embedded within this post, please visit this post to download the file.

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Capturing Video on windows using C++