Use ltmmCapture to Perform Simple Still Image Capture

  1. To begin simple still image capturing, create an instance of the ltmmCapture class. This is accomplished using the Win32 CoCreateInstance function as follows:

    C API
    IltmmCapture* pCapture;   
    CoCreateInstance(&CLSID_ltmmCapture, NULL, CLSCTX_INPROC_SERVER, &IID_IltmmCapture, (void**) &pCapture); 
    C++
    IltmmCapture* pCapture;    
    CoCreateInstance(CLSID_ltmmCapture, NULL, CLSCTX_INPROC_SERVER, IID_IltmmCapture, (void**) &pCapture); 

  2. Define the video devices to be used as the capture source. The ltmmCapture object contains video device collection objects. The first video device can be selected for capture by calling the device collection's put_Selection function:

    C API
    IltmmDevices* pDevices;   
    // get an interface into video devices collection   
    IltmmCapture_get_VideoDevices(pCapture, &pDevices);    
    // select the first video device   
    IltmmDevices_put_Selection (pDevices, 0);   
    // release collection   
    IUnknown_Release(pDevices); 
    C++
    IltmmDevices* pDevices;    
    // get an interface into video devices collection   
    pCapture->get_VideoDevices(&pDevices);   
    // select device   
    pDevices->put_Selection(0);   
    // release collection   
    pDevices->Release(); 

  3. Define the target or output file, as demonstrated with the following code:

    C API
    BSTR bstr;    
    // create a string containing the target file path   
    bstr = SysAllocString(L"c:\\target.mpg");    
    // assign the target file path to the capture object   
    IltmmCapture_put_TargetFile (pCapture, bstr);    
    // free the string   
    SysFreeString(bstr); 
    C++
    BSTR bstr;    
    // create a string containing the target file path   
    bstr = SysAllocString(L"c:\\target.mpg");    
    // assign the target file path to the capture object   
    pCapture->put_TargetFile (bstr);    
    // free the string   
    SysFreeString(bstr); 

  4. Start capturing still image data. This is accomplished with the following code:

    C API
    IltmmCapture_StartCapture (pCapture, ltmmCapture_Mode_Still); 
    C++
    pCapture->StartCapture (ltmmCapture_Mode_Still); 

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LEADTOOLS Multimedia C API Help

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© 1991-2023 LEAD Technologies, Inc. All Rights Reserved.