Listing video input device information

Sample code

The previous video capture device listing sample listed FriendlyName information only. When multiple device with the same FriendlyName is connected to the PC, more infomation must be retrieved to specify a video device. This page shows you how to retrieve all available information using IPropertyBag. For example, if the first video device found is a DV camera, this sample will show a MessageBox with the following message.

FriendlyName : Microsoft DV Camera and VCR
Description  : AVC Compliant DV Device
DevicePath   : \\?\avc#aaa&xx-dv111&camcoder&dv#123456#{abcd-1111-aaa-ccc}\global

The following is the sample code.

#include <stdio.h>

#include <dshow.h>

int
main()
{
 ICreateDevEnum *pCreateDevEnum = NULL;
 IEnumMoniker *pEnumMoniker = NULL;
 IMoniker *pMoniker = NULL;
 ULONG nFetched = 0;

 // Initialize COM
 CoInitialize(NULL);

 // Create CreateDevEnum to list device
 CoCreateInstance(CLSID_SystemDeviceEnum, NULL, CLSCTX_INPROC_SERVER, 
   IID_ICreateDevEnum, (PVOID *)&pCreateDevEnum);
    
 // Create EnumMoniker to list VideoInputDevice 
 pCreateDevEnum->CreateClassEnumerator(CLSID_VideoInputDeviceCategory,
   &pEnumMoniker, 0);
 if (pEnumMoniker == NULL) {
   // this will be shown if there is no capture device
   printf("no device\n");
   return 0;
 }

 // reset EnumMoniker
 pEnumMoniker->Reset();

 // get each Moniker
 while (pEnumMoniker->Next(1, &pMoniker, &nFetched) == S_OK) {
   IPropertyBag *pPropertyBag;
   TCHAR devname[256];
   TCHAR description[256];
   TCHAR devpath[256];

   // bind to IPropertyBag
   pMoniker->BindToStorage(0, 0, IID_IPropertyBag,
     (void **)&pPropertyBag);

   VARIANT var;


   // get FriendlyName
   // FrienlyName : The name of the device
   var.vt = VT_BSTR;

   pPropertyBag->Read(L"FriendlyName", &var, 0);

   WideCharToMultiByte(CP_ACP, 0,
     var.bstrVal, -1, devname, sizeof(devname), 0, 0);

   VariantClear(&var);


   // get Description
   // Description : A description of the device
   var.vt = VT_BSTR;

   pPropertyBag->Read(L"Description", &var, 0);

   WideCharToMultiByte(CP_ACP, 0,
     var.bstrVal, -1, description, sizeof(description), 0, 0);

   VariantClear(&var);


   // get DevicePath
   // DevicePath : A unique string
   var.vt = VT_BSTR;

   pPropertyBag->Read(L"DevicePath", &var, 0);

   WideCharToMultiByte(CP_ACP, 0,
     var.bstrVal, -1, devpath, sizeof(devpath), 0, 0);

   VariantClear(&var);


   // display result
   TCHAR result[1024];

   memset(result, 0, sizeof(result));
   sprintf(result,
	   "FriendlyName : %s\r\n"
	   "Description  : %s\r\n"
	   "DevicePath   : %s\r\n",
	   devname, description, devpath);

   MessageBox(NULL, result, "RESULT", MB_OK);


   // release
   pMoniker->Release();
   pPropertyBag->Release();
 }

 // release
 pEnumMoniker->Release();
 pCreateDevEnum->Release();

 // finalize COM
 CoUninitialize();

 return 0;
}