Capture to Play Object Interfacing for C

// define helper macros for using the interfaces under C 
#ifndef COBJMACROS 
#define COBJMACROS 
#endif 
// include the LEAD Multimedia TOOLKIT header 
#include "ltmm.h" 
#include <tchar.h> 
#include <stdio.h> 
#include <math.h> 
#include <assert.h> 
#define UNUSED_PARAMETER(x) (void) (x) 
#define SZ_WNDCLASS_PLAY _T("PLAY WNDCLASS") 
#define WM_PLAYNOTIFY (WM_USER + 1000) 
HINSTANCE g_hInstance;    // application instance handle 
HWND g_hwndPlay;      // video frame window 
IltmmPlay* g_pPlay;      // play object interface pointer 
IltmmCapture* g_pCapture;   // capture object interface pointer 
IltmmSampleTarget* g_pTarget;   // target object, used with capture 
IltmmSampleSource* g_pSource;   // source object, used with play 
// 
// PlayWndProc 
// video frame window procedure 
// 
LRESULT CALLBACK PlayWndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam) 
{ 
   switch (message) 
   { 
   case WM_CREATE: 
      g_hwndPlay = hwnd; 
      // window is the video window frame 
      IltmmPlay_put_VideoWindowFrame(g_pPlay, (long) hwnd); 
      // assign the media source 
      IltmmPlay_put_SourceObject(g_pPlay, (IUnknown*) g_pSource); 
#ifdef _DEBUG 
      { 
         IUnknown* punk; 
         IltmmPlay_get_SourceObject(g_pPlay, &punk); 
         assert(punk != NULL); 
         if(punk) 
            IUnknown_Release(punk); 
      } 
#endif 
      return 0; 
      break; 
   case WM_DESTROY: 
      PostQuitMessage(0); 
      break; 
   } 
   return DefWindowProc(hwnd, message, wParam, lParam); 
} 
int APIENTRY WinMain(HINSTANCE hInstance, 
HINSTANCE hPrevInstance, 
LPSTR     lpCmdLine, 
int       nCmdShow) 
{ 
   MSG msg; 
   HRESULT hr; 
   WNDCLASSEX wcex; 
   IltmmDevices* pDevices; 
   VARIANT var; 
   IltmmMediaTypeDisp* pMediaType; 
   BSTR bstr; 
   long index; 
   IltmmCompressors* pCompressors; 
   UNUSED_PARAMETER(lpCmdLine); 
   UNUSED_PARAMETER(hPrevInstance); 
   g_hInstance = hInstance; 
   // initialize the COM library 
   hr = CoInitialize(NULL); 
   if(FAILED(hr)) 
      goto error; 
   // register the video frame window class 
   wcex.cbSize = sizeof(WNDCLASSEX); 
   wcex.style         = CS_HREDRAW | CS_VREDRAW; 
   wcex.lpfnWndProc   = PlayWndProc; 
   wcex.cbClsExtra    = 0; 
   wcex.cbWndExtra    = 0; 
   wcex.hInstance      = g_hInstance; 
   wcex.hIcon         = NULL; 
   wcex.hCursor      = LoadCursor(NULL, IDC_ARROW); 
   wcex.hbrBackground   = (HBRUSH) (COLOR_APPWORKSPACE + 1); 
   wcex.lpszMenuName   = NULL; 
   wcex.lpszClassName   = SZ_WNDCLASS_PLAY; 
   wcex.hIconSm      = NULL; 
   if(!RegisterClassEx(&wcex)) 
      goto error; 
   // create the play object 
   hr = CoCreateInstance(&CLSID_ltmmPlay, NULL, CLSCTX_INPROC_SERVER, &IID_IltmmPlay, (void**) &g_pPlay); 
   if(FAILED(hr)) 
      goto error; 
   // create the capture object 
   hr = CoCreateInstance(&CLSID_ltmmCapture, NULL, CLSCTX_INPROC_SERVER, &IID_IltmmCapture, (void**) &g_pCapture); 
   if(FAILED(hr)) 
      goto error; 
   // create the target object 
   hr = CoCreateInstance(&CLSID_ltmmSampleTarget, NULL, CLSCTX_INPROC_SERVER, &IID_IltmmSampleTarget, (void**) &g_pTarget); 
   if(FAILED(hr)) 
      goto error; 
   // create the source object 
   hr = CoCreateInstance(&CLSID_ltmmSampleSource, NULL, CLSCTX_INPROC_SERVER, &IID_IltmmSampleSource, (void**) &g_pSource); 
   if(FAILED(hr)) 
      goto error; 
   // do not use preview 
   IltmmCapture_put_Preview(g_pCapture, VARIANT_FALSE); 
   // select the first video device 
   IltmmCapture_get_VideoDevices(g_pCapture, &pDevices); 
   IltmmDevices_put_Selection(pDevices, 0); 
   IUnknown_Release(pDevices); 
   // select the LEAD video compressor 
   IltmmCapture_get_VideoCompressors(g_pCapture, &pCompressors); 
   bstr = SysAllocString(L"@device:sw:{33D9A760-90C8-11D0-BD43-00A0C911CE86}\\LEAD MCMP/MJPEG Codec (2.0)"); 
   IltmmCompressors_Find(pCompressors, bstr, &index); 
   SysFreeString(bstr); 
   IltmmCompressors_put_Selection(pCompressors, index); 
   IUnknown_Release(pCompressors); 
   // set the capture output object 
   IltmmCapture_put_TargetObject(g_pCapture, (IUnknown*) g_pTarget); 
#ifdef _DEBUG 
   { 
      IUnknown* punk; 
      IltmmCapture_get_TargetObject(g_pCapture, &punk); 
      assert(punk != NULL); 
      if(punk) 
         IUnknown_Release(punk); 
   } 
#endif 
   // start running 
   hr = IltmmCapture_StartCapture(g_pCapture, ltmmCapture_Mode_Video); 
   if(FAILED(hr)) 
      goto error; 
   // retreive the video media type 
   IltmmSampleTarget_GetConnectedMediaType(g_pTarget, &pMediaType); 
   // could just assign the media type to the source object, 
   // but let us get the portable type instead 
   IltmmMediaTypeDisp_GetPortableType(pMediaType, &var); 
   // have the portable type, so do not need this anymore 
   IUnknown_Release(pMediaType); 
   // create a new media type 
   CoCreateInstance(&CLSID_ltmmMediaType, NULL, CLSCTX_INPROC_SERVER, &IID_IltmmMediaTypeDisp, (void**) &pMediaType); 
   // initialize it with the portable type 
   IltmmMediaTypeDisp_SetPortableType(pMediaType, var); 
   // assign it to the source object 
   IltmmSampleSource_SetMediaType(g_pSource, pMediaType); 
#ifdef _DEBUG 
   { 
      IltmmMediaTypeDisp* punk; 
      IltmmSampleSource_GetMediaType(g_pSource, &punk); 
      assert(punk != NULL); 
      if(punk) 
         IUnknown_Release(punk); 
   } 
#endif 
   // release the media type 
   IUnknown_Release(pMediaType); 
   // done with portable type 
   VariantClear(&var); 
   // create the video frame window 
   if(!CreateWindow(SZ_WNDCLASS_PLAY, _T("Play"), WS_OVERLAPPEDWINDOW | WS_CLIPCHILDREN, 
      CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, NULL, NULL, g_hInstance, NULL)) 
   goto error; 
   ShowWindow(g_hwndPlay, nCmdShow); 
   UpdateWindow(g_hwndPlay); 
   // process until done 
   for(;;) 
   { 
      if(PeekMessage(&msg, NULL, 0, 0, PM_NOREMOVE)) 
      { 
         if(!GetMessage(&msg, NULL, 0, 0)) 
            break; 
         TranslateMessage(&msg); 
         DispatchMessage(&msg); 
      } 
      else 
      { 
         IltmmMediaSampleDisp* pSample; 
         // fetch a sample 
         hr = IltmmSampleTarget_GetSample(g_pTarget, 1000, &pSample); 
         if(FAILED(hr)) 
            break; 
         // deliver it 
         hr = IltmmSampleSource_DeliverSample(g_pSource, 1000, pSample); 
         IUnknown_Release(pSample); 
         if(FAILED(hr)) 
            goto error; 
      } 
   } 
   IltmmCapture_StopCapture(g_pCapture); 
   IltmmSampleSource_DeliverEndOfStream(g_pSource, 1000); 
   IltmmPlay_Stop(g_pPlay); 
error: 
   if(g_pSource) 
      IUnknown_Release(g_pSource); 
   if(g_pTarget) 
      IUnknown_Release(g_pTarget); 
   if(g_pCapture) 
      IUnknown_Release(g_pCapture); 
   if(g_pPlay) 
      IUnknown_Release(g_pPlay); 
   CoUninitialize(); 
   return 0; 
}