I need a way to capture images from a webcam and store them in memory. I'm experimenting with object tracking. (Wanting to write my self, I don't want a library for tracking.)
I don't want to save to a .bmp and then reload into memory.
I want something fast as I'll need to take images from the camera several times a second.
I don't really want to use something like OpenCV as it's likely too slow for my useage and has many features I don't really need. (Though if I'm wrong about it being slow, I may try it.)
Thanks in advance.
That should help you get images from the webcam. After you get the webcam image, you can do whatever with it. Save it to file or keep the buffer. Up to you.
You can also try DirectShow or VLC.
EDIT: since the website link has now changed
Microsoft Documentation of Capturing a Video and Audio: https://learn.microsoft.com/en-us/windows/win32/multimedia/using-video-capture
https://github.com/MicrosoftDocs/win32/blob/docs/desktop-src/Multimedia/using-video-capture.md
The code from the original website is:
// WM_CAP_SET_SCALE is set to true to enable the webcam picture to be resized to the dimensions of our camera window.
// WM_CAP_SET_PREVIEWRATE is set to 66 frames per second.
// To provide a reasonable moving picture without too much demand on resources.
// WM_CAP_SET_PREVIEW is set to true so a picture will be drawn on the camera window camhwnd.
// Calls WM_CAP_DRIVER_DISCONNECT to disconnect the webcam.
// WM_CAP_GRAB_FRAME to capture the Camera frame.
// WM_CAP_EDIT_COPY copies the grabbed frame to the clipboard. Then we copy the clipboard image data to a HBITMAP object called "hbm".
// WM_DESTROY
// Its important we disconnect the webcam if the user closes the window.
// Setup some defines you need to connect to a webcam
// You can put these in a header
// If you are using Microsoft Visual Studio you wont need them as they
// Are included in Microsoft's version of vfw.h
#define WM_CAP_START 0x0400
#define WM_CAP_DRIVER_CONNECT (WM_CAP_START + 10)
#define WM_CAP_DRIVER_DISCONNECT (WM_CAP_START + 11)
#define WM_CAP_EDIT_COPY (WM_CAP_START + 30)
#define WM_CAP_GRAB_FRAME (WM_CAP_START + 60)
#define WM_CAP_SET_SCALE (WM_CAP_START + 53)
#define WM_CAP_SET_PREVIEWRATE (WM_CAP_START + 52)
#define WM_CAP_SET_PREVIEW (WM_CAP_START + 50)
#define WM_CAP_DLG_VIDEOSOURCE (WM_CAP_START + 42)
#define WM_CAP_STOP (WM_CAP_START+ 68)
// End of defines
#include <windows.h>
#include <vfw.h>
// Remember to Link to vfw32 Library, gdi32 Library
LRESULT CALLBACK WindowProc (HWND, UINT, WPARAM, LPARAM);
PBITMAPINFO CreateBitmapInfoStruct(HWND hwnd, HBITMAP hBmp);
void CreateBMPFile(HWND hwnd, LPTSTR pszFile, PBITMAPINFO pbi, HBITMAP hBMP, HDC hDC);
char szAppName [] = TEXT("WebCam");
HWND camhwnd;
HDC hdc ;
HDC hdcMem;
PAINTSTRUCT ps;
HBITMAP hbm;
RECT rc;
//WinMain -- Main Window
int WINAPI WinMain ( HINSTANCE hInstance, HINSTANCE hPrevInstance,
LPSTR lpCmdLine, int nCmdShow )
{
HWND hwnd;
MSG msg;
WNDCLASS wc;
wc.style = CS_HREDRAW|CS_VREDRAW;
wc.lpfnWndProc = WindowProc;
wc.cbClsExtra = 0;
wc.cbWndExtra = 0;
wc.hInstance = hInstance;
wc.hIcon = LoadIcon(GetModuleHandle(NULL), IDI_APPLICATION);
wc.hCursor = LoadCursor (NULL, IDC_ARROW);
wc.hbrBackground = (HBRUSH) (COLOR_WINDOW+1);
wc.lpszMenuName = NULL;
wc.lpszClassName = szAppName;
RegisterClass (&wc);
// Create the window
hwnd = CreateWindow (szAppName,szAppName,WS_OVERLAPPED|WS_CAPTION|WS_SYSMENU|WS_MINIMIZEBOX,CW_USEDEFAULT,CW_USEDEFAULT,300,600,0,0,hInstance,0);
ShowWindow (hwnd,SW_SHOW);
UpdateWindow (hwnd);
while (GetMessage(&msg,0,0,0))
{
if (!IsDialogMessage(hwnd, &msg))
{
TranslateMessage (&msg);
DispatchMessage (&msg);
}
}
return msg.wParam;
}
//Main Window Procedure WindowProc
LRESULT CALLBACK WindowProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
HINSTANCE hInstance = GetModuleHandle(NULL);
//some buttons
HWND hButtStartCam;
HWND hButtStopCam;
HWND hButtGrabFrame;
switch (message) /* handle the messages */
{
case WM_CTLCOLORSTATIC:
SetBkMode(hdc,TRANSPARENT);
return (LRESULT)CreateSolidBrush(0xFFFFFF);
case WM_CREATE:
{
hButtStartCam = CreateWindowEx(0,"BUTTON","Start Camera",WS_CHILD | WS_VISIBLE,
0,0,100,20,hwnd,(HMENU)1,hInstance, 0);
hButtStopCam = CreateWindowEx(0,"BUTTON","Stop Camera",WS_CHILD | WS_VISIBLE,
0,25,100,20,hwnd,(HMENU)2,hInstance, 0);
hButtGrabFrame = CreateWindowEx(0,"BUTTON","Grab Frame",WS_CHILD | WS_VISIBLE,
0,50,100,20,hwnd,(HMENU)3,hInstance, 0);
camhwnd = capCreateCaptureWindow ("camera window", WS_CHILD , 0, 100, 300, 300, hwnd, 0);
SendMessage(camhwnd,WM_CAP_DRIVER_CONNECT,0,0);
SendMessage(camhwnd,WM_CAP_DLG_VIDEOSOURCE,0,0);
break;
}
case WM_COMMAND:
{
switch (LOWORD(wParam))
{
case 1:
{
ShowWindow(camhwnd,SW_SHOW);
SendMessage(camhwnd,WM_CAP_DRIVER_CONNECT,0,0);
SendMessage(camhwnd, WM_CAP_SET_SCALE, true , 0);
SendMessage(camhwnd, WM_CAP_SET_PREVIEWRATE, 66, 0);
SendMessage(camhwnd, WM_CAP_SET_PREVIEW, true , 0);
break;
}
case 2:
{
ShowWindow(camhwnd,SW_HIDE);
SendMessage(camhwnd, WM_CAP_DRIVER_DISCONNECT, 0, 0);
break;
}
case 3:
{
//Grab a Frame
SendMessage(camhwnd, WM_CAP_GRAB_FRAME, 0, 0);
//Copy the frame we have just grabbed to the clipboard
SendMessage(camhwnd, WM_CAP_EDIT_COPY,0,0);
//Copy the clipboard image data to a HBITMAP object called hbm
hdc = BeginPaint(camhwnd, &ps);
hdcMem = CreateCompatibleDC(hdc);
if (hdcMem != NULL)
{
if (OpenClipboard(camhwnd))
{
hbm = (HBITMAP) GetClipboardData(CF_BITMAP);
SelectObject(hdcMem, hbm);
GetClientRect(camhwnd, &rc);
CloseClipboard();
}
}
//Save hbm to a .bmp file called Frame.bmp
PBITMAPINFO pbi = CreateBitmapInfoStruct(hwnd, hbm);
CreateBMPFile(hwnd, "Frame.bmp", pbi, hbm, hdcMem);
SendMessage(camhwnd,WM_CAP_DRIVER_CONNECT,0,0);
SendMessage(camhwnd, WM_CAP_SET_SCALE, true , 0);
SendMessage(camhwnd, WM_CAP_SET_PREVIEWRATE, 66, 0);
SendMessage(camhwnd, WM_CAP_SET_PREVIEW, true , 0);
break;
}
}
break;
}
case WM_DESTROY:
{
SendMessage(camhwnd, WM_CAP_DRIVER_DISCONNECT, 0, 0);
PostQuitMessage(0); /* send a WM_QUIT to the message queue */
break;
}
default: /* for messages that we don't deal with */
return DefWindowProc(hwnd, message, wParam, lParam);
}
return 0;
}
void CreateBMPFile(HWND hwnd, LPTSTR pszFile, PBITMAPINFO pbi, HBITMAP hBMP, HDC hDC)
{
HANDLE hf; // file handle
BITMAPFILEHEADER hdr; // bitmap file-header
PBITMAPINFOHEADER pbih; // bitmap info-header
LPBYTE lpBits; // memory pointer
DWORD dwTotal; // total count of bytes
DWORD cb; // incremental count of bytes
BYTE *hp; // byte pointer
DWORD dwTmp;
pbih = (PBITMAPINFOHEADER) pbi;
lpBits = (LPBYTE) GlobalAlloc(GMEM_FIXED, pbih->biSizeImage);
if (!lpBits)
{
MessageBox(hwnd,"GlobalAlloc","Error", MB_OK );
}
// Retrieve the color table (RGBQUAD array) and the bits
// (array of palette indices) from the DIB.
if (!GetDIBits(hDC, hBMP, 0, (WORD) pbih->biHeight, lpBits, pbi,DIB_RGB_COLORS))
{
MessageBox(hwnd,"GetDIBits","Error",MB_OK );
}
// Create the .BMP file.
hf = CreateFile(pszFile,GENERIC_READ | GENERIC_WRITE,(DWORD) 0,NULL,CREATE_ALWAYS,FILE_ATTRIBUTE_NORMAL,(HANDLE) NULL);
if (hf == INVALID_HANDLE_VALUE)
{
MessageBox( hwnd,"CreateFile","Error", MB_OK);
}
hdr.bfType = 0x4d42; // File type designator "BM" 0x42 = "B" 0x4d = "M"
// Compute the size of the entire file.
hdr.bfSize = (DWORD) (sizeof(BITMAPFILEHEADER) + pbih->biSize + pbih->biClrUsed * sizeof(RGBQUAD) + pbih->biSizeImage);
hdr.bfReserved1 = 0;
hdr.bfReserved2 = 0;
// Compute the offset to the array of color indices.
hdr.bfOffBits = (DWORD) sizeof(BITMAPFILEHEADER) + pbih->biSize + pbih->biClrUsed * sizeof (RGBQUAD);
// Copy the BITMAPFILEHEADER into the .BMP file.
if (!WriteFile(hf, (LPVOID) &hdr, sizeof(BITMAPFILEHEADER), (LPDWORD) &dwTmp, NULL) )
{
MessageBox(hwnd,"WriteFileHeader","Error",MB_OK );
}
// Copy the BITMAPINFOHEADER and RGBQUAD array into the file.
if (!WriteFile(hf, (LPVOID) pbih, sizeof(BITMAPINFOHEADER) + pbih->biClrUsed * sizeof (RGBQUAD), (LPDWORD) &dwTmp, NULL))
{
MessageBox(hwnd,"WriteInfoHeader","Error",MB_OK );
}
// Copy the array of color indices into the .BMP file.
dwTotal = cb = pbih->biSizeImage;
hp = lpBits;
if (!WriteFile(hf, (LPSTR) hp, (int) cb, (LPDWORD) &dwTmp,NULL))
{
MessageBox(hwnd,"WriteFile","Error",MB_OK );
}
// Close the .BMP file.
if (!CloseHandle(hf))
{
MessageBox(hwnd,"CloseHandle","Error",MB_OK );
}
// Free memory.
GlobalFree((HGLOBAL)lpBits);
}
PBITMAPINFO CreateBitmapInfoStruct(HWND hwnd, HBITMAP hBmp)
{
BITMAP bmp;
PBITMAPINFO pbmi;
WORD cClrBits;
// Retrieve the bitmap color format, width, and height.
if (!GetObject(hBmp, sizeof(BITMAP), (LPSTR)&bmp))
{
MessageBox(hwnd,"GetObject","Error",MB_OK );
}
// Convert the color format to a count of bits.
cClrBits = (WORD)(bmp.bmPlanes * bmp.bmBitsPixel);
if (cClrBits == 1)
cClrBits = 1;
else if (cClrBits <= 4)
cClrBits = 4;
else if (cClrBits <= 8)
cClrBits = 8;
else if (cClrBits <= 16)
cClrBits = 16;
else if (cClrBits <= 24)
cClrBits = 24;
else cClrBits = 32;
// Allocate memory for the BITMAPINFO structure. (This structure
// contains a BITMAPINFOHEADER structure and an array of RGBQUAD
// data structures.)
if (cClrBits != 24)
{
pbmi = (PBITMAPINFO) LocalAlloc(LPTR,sizeof(BITMAPINFOHEADER) + sizeof(RGBQUAD) * (1<< cClrBits));
}
// There is no RGBQUAD array for the 24-bit-per-pixel format.
else
pbmi = (PBITMAPINFO) LocalAlloc(LPTR, sizeof(BITMAPINFOHEADER));
// Initialize the fields in the BITMAPINFO structure.
pbmi->bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
pbmi->bmiHeader.biWidth = bmp.bmWidth;
pbmi->bmiHeader.biHeight = bmp.bmHeight;
pbmi->bmiHeader.biPlanes = bmp.bmPlanes;
pbmi->bmiHeader.biBitCount = bmp.bmBitsPixel;
if (cClrBits < 24)
{
pbmi->bmiHeader.biClrUsed = (1<<cClrBits);
}
// If the bitmap is not compressed, set the BI_RGB flag.
pbmi->bmiHeader.biCompression = BI_RGB;
// Compute the number of bytes in the array of color
// indices and store the result in biSizeImage.
// For Windows NT, the width must be DWORD aligned unless
// the bitmap is RLE compressed. This example shows this.
// For Windows 95/98/Me, the width must be WORD aligned unless the
// bitmap is RLE compressed.
pbmi->bmiHeader.biSizeImage = ((pbmi->bmiHeader.biWidth * cClrBits +31) & ~31) /8 * pbmi->bmiHeader.biHeight;
// Set biClrImportant to 0, indicating that all of the
// device colors are important.
pbmi->bmiHeader.biClrImportant = 0;
return pbmi; //return BITMAPINFO
}