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;    
}