Registering Your Synthesizer

After your software synthesizer is created, it must be added to the system registry so that it is available to applications as a DirectMusic port that can be enumerated. When the installation program calls your DLL's DllRegisterServer COM function to tell the DLL to register itself as a COM object, the function can register the synthesizer as well. To do so, the function adds an entry to the list of available software synthesizers by creating a key in the following path:


Header file dmusicc.hdefines constant REGSTR_PATH_SOFTWARESYNTHS to represent this path.

The key is named with the class identifier of the synthesizer COM object. Within the key is a string field called "Description" with the name of the synthesizer.

The following example code shows a function, RegisterSynth, that can be called from DllRegisterServer to register the synthesizer:

  const char cszSynthRegRoot[] = REGSTR_PATH_SOFTWARESYNTHS "\\";
  const char cszDescriptionKey[] = "Description";
  const int CLSID_STRING_SIZE = 39;
  HRESULT CLSIDToStr(const CLSID &clsid, char *szStr, int cbStr);

  HRESULT RegisterSynth(REFGUID guid,
                        const char szDescription[])
      HKEY hk;
      char szRegKey[256];

      HRESULT hr = CLSIDToStr(guid, szCLSID, sizeof(szCLSID));
      if (!SUCCEEDED(hr))
          return hr;

      strcpy(szRegKey, cszSynthRegRoot);
      strcat(szRegKey, szCLSID);

      if (RegCreateKey(HKEY_LOCAL_MACHINE,
          return E_FAIL;

      hr = S_OK;
      if (RegSetValueEx(hk,
                        (const unsigned char *)szDescription,
                        strlen(szDescription) + 1))
          hr = E_FAIL;

      return hr;

CLSIDToStr is a locally defined function (not shown in the preceding code example) that converts a CLSID value to a character string. It is similar to the StringFromCLSID function that is described in the Microsoft Windows SDK documentation.