ICreateDevEnum::CreateClassEnumerator method (strmif.h)

The CreateClassEnumerator method creates an enumerator for a specified device category.


HRESULT CreateClassEnumerator(
  [in]  REFCLSID     clsidDeviceClass,
  [out] IEnumMoniker **ppEnumMoniker,
  [in]  DWORD        dwFlags


[in] clsidDeviceClass

Specifies the class identifier (CLSID) of the device category. See Filter Categories.

[out] ppEnumMoniker

Receives a pointer to the IEnumMoniker interface. The caller must release the interface.

[in] dwFlags

Bitwise combination of zero or more flags. If zero, the method enumerates every filter in the category. If any flags are set, the enumeration includes only filters that match the specified flags. The following flags are defined:

Flag Description
CDEF_DEVMON_CMGR_DEVICE Enumerate audio or video codecs, using the audio compression manager (ACM) or video compression manager (VCM).
CDEF_DEVMON_DMO Enumerate DirectX Media Objects (DMOs).
CDEF_DEVMON_FILTER Enumerate native DirectShow filters.
CDEF_DEVMON_PNP_DEVICE Enumerate Plug and Play hardware devices.

Return value

Returns one of the following HRESULT values.

Return code Description
Out of memory.
The category specified by clsidDeviceClass does not exist or is empty.
NULL pointer argument.


If the category does not exist or is empty, the return value is S_FALSE, and the ppEnumMoniker parameter receives the value NULL. Therefore, test for the return value S_OK instead of using the SUCCEEDED macro:

IEnumMoniker *pEnum = NULL;
hr = pSysDevEnum->CreateClassEnumerator(
    CLSID_VideoCompressorCategory, &pEnum, 0);
if (hr == S_OK) 
    // Safe to dereference pEnum.
Use the IEnumMoniker interface to enumerate monikers that represent the filters in the device category. Monikers support the IMoniker interface. The monikers created by CreateClassEnumerator also support the IGetCapabilitiesKey interface.


Minimum supported client Windows 2000 Professional [desktop apps only]
Minimum supported server Windows 2000 Server [desktop apps only]
Target Platform Windows
Header strmif.h (include Dshow.h)
Library Strmiids.lib

See also

Error and Success Codes

ICreateDevEnum Interface