IEnumDMO::Next method (mediaobj.h)

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4/26/2023

[The feature associated with this page, DirectShow, is a legacy feature. It has been superseded by MediaPlayer, IMFMediaEngine, and Audio/Video Capture in Media Foundation. Those features have been optimized for Windows 10 and Windows 11. Microsoft strongly recommends that new code use MediaPlayer, IMFMediaEngine and Audio/Video Capture in Media Foundation instead of DirectShow, when possible. Microsoft suggests that existing code that uses the legacy APIs be rewritten to use the new APIs if possible.]

The Next method retrieves a specified number of items in the enumeration sequence.

Syntax

HRESULT Next(
        DWORD  cItemsToFetch,
  [out] CLSID  *pCLSID,
  [out] LPWSTR *Names,
  [out] DWORD  *pcItemsFetched
);

Parameters

cItemsToFetch

Number of items to retrieve.

[out] pCLSID

Array of size cItemsToFetch that is filled with the CLSIDs of the enumerated DMOs.

[out] Names

Array of size cItemsToFetch that is filled with the friendly names of the enumerated DMOs.

[out] pcItemsFetched

Pointer to a variable that receives the actual number of items retrieved. Can be NULL if cItemsToFetch equals 1.

Return value

Returns an HRESULT value. Possible values include those in the following table.

Return code	Description
E_INVALIDARG	Invalid argument.
E_OUTOFMEMORY	Insufficient memory.
E_POINTER	NULL pointer argument.
S_FALSE	Retrieved fewer items than requested.
S_OK	Retrieved the requested number of items.

Remarks

If the method succeeds, the arrays given by the pCLSID and Names parameters are filled with CLSIDs and wide-character strings. The value of *pcItemsFetched specifies the number of items returned in these arrays.

The method returns S_OK if it retrieves the requested number of items (in other words, if *pcItemsFetched equals cItemsToFetch). Otherwise, it returns S_FALSE or an error code.

The caller must free the memory allocated for each string returned in the Names parameter, using the CoTaskMemFree function.

Requirements

Requirement	Value
Target Platform	Windows
Header	mediaobj.h (include Dmo.h)
Library	Dmoguids.lib

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