Capture to Play Object Interfacing for C++

The following code demonstrates grabbing samples from the capture object and feeding them to the play object. It is intended to demonstrate the basic function set that would be required to remote the playback of media samples.

#include "stdafx.h"



// include the LEAD Multimedia TOOLKIT header

#include "ltmm.h"



#include "resource.h"

#include <tchar.h>

#include <stdio.h>

#include <math.h>

#include <assert.h>



#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

      g_pPlay->put_VideoWindowFrame((long) hwnd); 



      // assign the media source

      g_pPlay->put_SourceObject(g_pSource); 

#ifdef _DEBUG

   {

      IUnknown* punk; 

      g_pPlay->get_SourceObject(&punk); 

      assert(punk != NULL); 

      if(punk) 

         punk->Release();

   }

#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; 



   g_hInstance = hInstance; 



   // initialize 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; 



   // no preview

   g_pCapture->put_Preview(VARIANT_FALSE); 



   // select the first video device

   g_pCapture->get_VideoDevices(&pDevices); 

   pDevices->put_Selection(0); 

   pDevices->Release();



   // select the LEAD video compressor

   g_pCapture->get_VideoCompressors(&pCompressors); 

   bstr = SysAllocString(L"@device:sw:{33D9A760-90C8-11D0-BD43-00A0C911CE86}\\LEAD 
 MCMP/MJPEG Codec (2.0)");

   pCompressors->Find(bstr, &index); 

   SysFreeString(bstr); 

   pCompressors->put_Selection(index); 

   pCompressors->Release();



   // set the capture output object

   g_pCapture->put_TargetObject(g_pTarget); 

#ifdef _DEBUG

   {

      IUnknown* punk; 

      g_pCapture->get_TargetObject(&punk); 

      assert(punk != NULL); 

      if(punk) 

         punk->Release();

   }

#endif

   // start running

   hr = g_pCapture->StartCapture(ltmmCapture_Mode_Video); 

   if(FAILED(hr)) 

      goto error; 

      

   // retirve the video media type



   g_pTarget->GetConnectedMediaType(&pMediaType); 

   

   // could just assign the media type to the source object, 

   // but let's get the portable type instead

   pMediaType->GetPortableType(&var);   

   

   // have the portable type, don't need this anymore

   pMediaType->Release();



   // create a new media type

   CoCreateInstance(CLSID_ltmmMediaType, NULL, CLSCTX_INPROC_SERVER, IID_IltmmMediaTypeDisp, (void**) &pMediaType); 



   // initialize it with the portable type

   pMediaType->SetPortableType(var); 



   // assign it to the source object

   g_pSource->SetMediaType(pMediaType); 



#ifdef _DEBUG

   {

      IltmmMediaTypeDisp* punk;

      g_pSource->GetMediaType( &punk);

      assert(punk != NULL);

      if(punk)

         punk->Release();

   }

#endif



   // release the media type

   pMediaType->Release();



   // 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 = g_pTarget->GetSample(1000, &pSample); 

         if(FAILED(hr)) 

            break; 

         // deliver it

         hr = g_pSource->DeliverSample(1000, pSample); 

         pSample->Release();

         if(FAILED(hr)) 

            goto error; 

      }

   }

   g_pCapture->StopCapture();

   g_pSource->DeliverEndOfStream(1000); 

   g_pPlay->Stop();

error: 

   if(g_pSource) 

      g_pSource->Release();

   if(g_pTarget) 

      g_pTarget->Release();

   if(g_pCapture) 

      g_pCapture->Release();

   if(g_pPlay) 

      g_pPlay->Release();



   CoUninitialize();



   return 0;   

}