Use ltmmCapture to Perform a Capture and Save It as a WMV File

  1. Create an instance of the ltmmCapture class. This is accomplished using the Win32 CoCreateInstance function,  as follows:

C Source

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

C++ Source

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

  1. Define the notification window, which receives the capture status notifications:

C Source

HWND hwndNotify; 
#define WM_CAPTURENOTIFY (WM_USER + 1000) 
IltmmCapture_SetNotifyWindow(pCapture, (long) hwndNotify, WM_CAPTURENOTIFY); 

C++ Source

HWND hwndNotify; 
#define WM_CAPTURENOTIFY (WM_USER + 1000) 
pCapture->SetNotifyWindow((long) hwndNotify, WM_CAPTURENOTIFY); 

The above code instructs the capture object to send WM_CAPTURENOTIFY messages to the window procedure of hwndNotify. The wParam parameter of the window message will contain the notification code.

Note: A capture can be accomplished without using a notification window, but the user would be required to poll the objects state to determine when the capture has finished.

3.Define a frame window for the video preview:

C Source

HWND  hwndFrame; 
IltmmCapture_put_VideoWindowFrame(pCapture, (long) hwndFrame); 

C++ Source

HWND hwndFrame; 
pCapture->put_VideoWindowFrame((long) hwndFrame); 

The user is required to create the window that serves as the video frame. ltmmCapture will subclass this window, so there is no need to forward any messages to the ltmmCapture object. By default, ltmmCapture will automatically maximize the video within the frame window. The video will automatically resize when the frame window size changes.

Note: The notification window and the video frame window can be the same.

  1. Set the Target file:

C Source

BSTR bstr; 
bstr = SysAllocString(L"c:\\captured.asf"); 
IltmmCapture_put_TargetFile(pCapture, bstr); 
SysFreeString(bstr); 

C++ Source

BSTR bstr; 
::SysAllocString(L"c:\\captured.asf"); 
pCapture->put_TargetFile(bstr); 
::SysFreeString(bstr); 

  1. Set the video device:

C Source

IltmmDevices* devices; 
IltmmCapture_get_VideoDevices(pCapture, &devices); 
IltmmDevices_put_Selection(devices, 0); 
IltmmDevices_Release(devices); 

C++ Source

IltmmDevices* devices; 
pCapture->get_VideoDevices(&devices); 
devices->put_Selection(0); 
devices->Release(); 

  1. Set the audio device:

C Source

HIltmmDevices* devices; 
IltmmCapture_get_AudioDevices(pCapture, &devices); 
IltmmDevices_put_Selection(devices, 0); 
IltmmDevices_Release(devices); 

C++ Source

IltmmDevices* devices; 
pCapture->get_AudioDevices(&devices); 
devices->put_Selection(0); 
devices->Release(); 

  1. Set the target format :

C Source

IltmmCapture_put_TargetFormat(pCapture, ltmmCapture_TargetFormat_Asf); 

C++ Source

pCapture->put_TargetFormat(ltmmCapture_TargetFormat_Asf); 

  1. When you want to start capturing, call the StartCapture function as follows:

C Source

IltmmCapture_StartCapture(pCapture, ltmmCapture_Mode_VideoAndAudio) 

C++ Source

pCapture->StartCapture(ltmmCapture_Mode_VideoAndAudio); 

  1. When you want to stop capturing, call the StopCapture function as follows:

C Source

IltmmCapture_StopCapture(pCapture); 

C++ Source

pCapture->StopCapture(); 

10.Release the capture object (and all active objects) when you are done.

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