MFTEnum function (mfapi.h)

Enumerates Media Foundation transforms (MFTs) in the registry.

Starting in Windows 7, applications should use the MFTEnumEx function instead.

Syntax

HRESULT MFTEnum(
  [in]  GUID                   guidCategory,
  [in]  UINT32                 Flags,
  [in]  MFT_REGISTER_TYPE_INFO *pInputType,
  [in]  MFT_REGISTER_TYPE_INFO *pOutputType,
  [in]  IMFAttributes          *pAttributes,
  [out] CLSID                  **ppclsidMFT,
  [out] UINT32                 *pcMFTs
);

Parameters

[in] guidCategory

GUID that specifies the category of MFTs to enumerate. For a list of MFT categories, see MFT_CATEGORY.

[in] Flags

Reserved. Must be zero.

[in] pInputType

Pointer to an MFT_REGISTER_TYPE_INFO structure that specifies an input media type to match.

This parameter can be NULL. If NULL, all input types are matched.

[in] pOutputType

Pointer to an MFT_REGISTER_TYPE_INFO structure that specifies an output media type to match.

This parameter can be NULL. If NULL, all output types are matched.

[in] pAttributes

Reserved. Set to NULL.

[out] ppclsidMFT

Receives a pointer to an array of CLSIDs. To create an MFT from this list, call CoCreateInstance with one of the CLSIDs. To get information about a particular MFT from its CLSID, call MFTGetInfo. The caller must free the memory for the array by calling CoTaskMemFree.

[out] pcMFTs

Receives the number of elements in the ppclsidMFT array. The value can be zero.

Return value

If this function succeeds, it returns S_OK. Otherwise, it returns an HRESULT error code.

Remarks

This function returns a list of all the MFTs in the specified category that match the search criteria given by the pInputType, pOutputType, and pAttributes parameters. Any of those parameters can be NULL.

If no MFTs match the criteria, the method succeeds but returns the value zero in pcMFTs.

Examples

To find a decoder, set guidCategory to MFT_CATEGORY_AUDIO_DECODER or MFT_CATEGORY_VIDEO_DECODER and specify the encoding format in pInputType. You would typically set pOutputType to NULL in this case.

HRESULT FindDecoder(
    const GUID& subtype,        // Subtype
    BOOL bAudio,                // TRUE for audio, FALSE for video
    IMFTransform **ppDecoder    // Receives a pointer to the decoder.
    )
{
    HRESULT hr = S_OK;
    UINT32 count = 0;

    CLSID *ppCLSIDs = NULL;

    MFT_REGISTER_TYPE_INFO info = { 0 };

    info.guidMajorType = bAudio ? MFMediaType_Audio : MFMediaType_Video;
    info.guidSubtype = subtype;

    hr = MFTEnum(   
        bAudio ? MFT_CATEGORY_AUDIO_DECODER : MFT_CATEGORY_VIDEO_DECODER,
        0,      // Reserved
        &info,  // Input type
        NULL,   // Output type
        NULL,   // Reserved
        &ppCLSIDs,
        &count
        );

    if (SUCCEEDED(hr) && count == 0)
    {
        hr = MF_E_TOPO_CODEC_NOT_FOUND;
    }

    // Create the first decoder in the list.

    if (SUCCEEDED(hr))
    {
        hr = CoCreateInstance(ppCLSIDs[0], NULL,
            CLSCTX_INPROC_SERVER, IID_PPV_ARGS(ppDecoder));
    }

    CoTaskMemFree(ppCLSIDs);
    return hr;
}

To find an encoder, set guidCategory to MFT_CATEGORY_AUDIO_ENCODER or MFT_CATEGORY_VIDEO_ENCODER and specify the encoding format in pOutputType. You would typically set pInputType to NULL in this case.

HRESULT FindEncoder(
    const GUID& subtype, 
    BOOL bAudio, 
    IMFTransform **ppEncoder
    )
{
    HRESULT hr = S_OK;
    UINT32 count = 0;

    CLSID *ppCLSIDs = NULL;

    MFT_REGISTER_TYPE_INFO info = { 0 };

    info.guidMajorType = bAudio ? MFMediaType_Audio : MFMediaType_Video;
    info.guidSubtype = subtype;

    hr = MFTEnum(   
        bAudio ? MFT_CATEGORY_AUDIO_ENCODER : MFT_CATEGORY_VIDEO_ENCODER,
        0,          // Reserved
        NULL,       // Input type
        &info,      // Output type
        NULL,       // Reserved
        &ppCLSIDs,
        &count
        );

    if (SUCCEEDED(hr) && count == 0)
    {
        hr = MF_E_TOPO_CODEC_NOT_FOUND;
    }

    // Create the first encoder in the list.

    if (SUCCEEDED(hr))
    {
        hr = CoCreateInstance(ppCLSIDs[0], NULL,
            CLSCTX_INPROC_SERVER, IID_PPV_ARGS(ppEncoder));
    }

    CoTaskMemFree(ppCLSIDs);
    return hr;
}

Requirements

See also

Adding a Decoder to a Topology

MFTEnumEx

MFTRegister

Media Foundation Functions

Media Foundation Transforms

Registering and Enumerating MFTs