Web cam image capture - c++

Question

I am trying to write an application to capture an image from a webcam. I have written a C++ console application and whilst I can get an image, I have difficulty setting the resolution, I want to get higher resolution images and would like to be able to get 4k from a logitech brio webcam for example.
On Windows 10 with a lower resolution usb camera I was able to get 1280x720. On Windows 11 with a 4k USB camera I am only getting 640x480
Here is my code:
#include "vfw.h"
#include <cstdio>
#include <cstdint>
#pragma comment(lib, "Vfw32.lib")
int main(int argc, char** argv)
{
char device_name[100];
char filename[100];
size_t sz = 0;
char* userpath = nullptr;
strcpy_s(device_name, "");
strcpy_s(filename, userpath);
strncat_s(filename, "\\Documents\\image.bmp", 20);
// create the preview window
HWND hCam = capCreateCaptureWindow (
"FMCamCapture",
WS_CHILD | WS_VISIBLE,
0, 0, 1024, 768,
::GetDesktopWindow(), 0);
CAPDRIVERCAPS CapDrvCaps;
capDriverGetCaps(hCam, &CapDrvCaps, sizeof(CAPDRIVERCAPS));
int driver_number = 0;
int n = 1;
//Driver argument
while (n < argc)
{
if (strcmp(argv[n], "/drivernum") == 0)
{
// Set device number to specified value
if (++n < argc) {
driver_number = atoi(argv[n]);
}
else printf("Error: invalid device number");
if (driver_number <= 0)
printf("Error: invalid device number");
}
if (strcmp(argv[n], "/showdrivers") == 0)
{
// Show the list of available drivers and pause and exit
TCHAR szDeviceName[80];
TCHAR szDeviceVersion[80];
for (int wIndex = 0; wIndex < 10; wIndex++)
{
if (capGetDriverDescription(
wIndex,
szDeviceName,
sizeof(szDeviceName),
szDeviceVersion,
sizeof(szDeviceVersion)
))
{
printf("\nEach Driver may represent a different camera. The default driver is 0. Set a differnt driver to change cameras.\nAvailable Drivers:\n\%i - %s\n", wIndex, szDeviceName);
// Append name to list of installed capture drivers
// and then let the user select a driver to use.
}
}
system("pause");
return 0;
}
n++;
}
fprintf(stderr, "Saved file location: %s\n", filename);
CAPTUREPARMS captureParms;
BITMAPINFO bMInfo;
// connect to the first Driver
// for other cameras try index
// 1, 2, in place of the 0 below
if(capDriverConnect(hCam, driver_number))
{
capGetVideoFormat(hCam, &bMInfo, sizeof(BITMAPINFO));
//printf("height %ld", bMInfo.bmiHeader.biHeight);
//printf("width %ld", bMInfo.bmiHeader.biWidth);
//printf("bisize %lu", bMInfo.bmiHeader.biSizeImage);
//printf("compression %lu", bMInfo.bmiHeader.biCompression);
bMInfo.bmiHeader.biWidth = 1280;
bMInfo.bmiHeader.biHeight = 720;
bMInfo.bmiHeader.biSizeImage = 0;
//bMInfo.bmiHeader.biSizeImage = (bMInfo.bmiHeader.biHeight) * (((bMInfo.bmiHeader.biWidth * 2) * bMInfo.bmiHeader.biBitCount + 31) / 32) * 4;
bMInfo.bmiHeader.biCompression = BI_RGB;
if (capSetVideoFormat(hCam, &bMInfo, sizeof(BITMAPINFO))) {
//printf("set res success setvidformat");
}
capFileSaveDIB(hCam, filename);
//printf("Saved!");
capDriverDisconnect(hCam);
}
else
{
printf("Check camera?");
}
DestroyWindow(hCam);
return 0;
}```