nf-mfidl-mftranscodegetaudiooutputavailabletypes.md

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NF:mfidl.MFTranscodeGetAudioOutputAvailableTypes	MFTranscodeGetAudioOutputAvailableTypes function (mfidl.h)	Gets a list of output formats from an audio encoder.	MFT_FIELDOFUSE_UNLOCK_Attribute MFTranscodeGetAudioOutputAvailableTypes MFTranscodeGetAudioOutputAvailableTypes function [Media Foundation] MF_TRANSCODE_ENCODINGPROFILE MF_TRANSCODE_QUALITYVSSPEED mf.mftranscodegetaudiooutputavailabletypes mfidl/MFTranscodeGetAudioOutputAvailableTypes	mf\mftranscodegetaudiooutputavailabletypes.htm	mf	8750eacb-7e6f-4c17-987b-f4baa4eea847	12/05/2018	MFT_FIELDOFUSE_UNLOCK_Attribute, MFTranscodeGetAudioOutputAvailableTypes, MFTranscodeGetAudioOutputAvailableTypes function [Media Foundation], MF_TRANSCODE_ENCODINGPROFILE, MF_TRANSCODE_QUALITYVSSPEED, mf.mftranscodegetaudiooutputavailabletypes, mfidl/MFTranscodeGetAudioOutputAvailableTypes	mfidl.h		Windows	Windows 7 [desktop apps only]	Windows Server 2008 R2 [desktop apps only]										Mf.lib	Mf.dll		Windows			19H1	MFTranscodeGetAudioOutputAvailableTypes mfidl/MFTranscodeGetAudioOutputAvailableTypes	c++	APIRef kbSyntax	DllExport	mf.dll	MFTranscodeGetAudioOutputAvailableTypes

MFTranscodeGetAudioOutputAvailableTypes function

-description

Gets a list of output formats from an audio encoder.

-parameters

-param guidSubType [in]

Specifies the subtype of the output media. The encoder uses this value as a filter when it is enumerating the available output types. For information about the audio subtypes, see Audio Subtype GUIDs.

-param dwMFTFlags [in]

Bitwise OR of zero or more flags from the _MFT_ENUM_FLAG enumeration.

-param pCodecConfig [in]

A pointer to the IMFAttributes interface of an attribute store. The attribute store specifies the encoder configuration settings. This parameter can be NULL. The attribute store can hold any of the following attributes.

Value	Meaning
MFT_FIELDOFUSE_UNLOCK_Attribute	Set this attribute to unlock an encoder that has field-of-use descriptions.
MF_TRANSCODE_ENCODINGPROFILE	Specifies a device conformance profile for a Windows Media encoder.
MF_TRANSCODE_QUALITYVSSPEED	Sets the tradeoff between encoding quality and encoding speed.

-param ppAvailableTypes [out]

Receives a pointer to the IMFCollection interface of a collection object that contains a list of preferred audio media types. The collection contains IMFMediaType pointers. The caller must release the interface pointer.

-returns

The function returns an HRESULT. Possible values include, but are not limited to, those in the following table.

Return code	Description
S_OK	The function call succeeded.
MF_E_TRANSCODE_NO_MATCHING_ENCODER	Failed to find an encoder that matches the specified configuration settings.

-remarks

This function assumes the encoder will be used in its default encoding mode, which is typically constant bit-rate (CBR) encoding. Therefore, the types returned by the function might not work with other modes, such as variable bit-rate (VBR) encoding.

Internally, this function works by calling MFTEnumEx to find a matching encoder, and then calling IMFTransform::GetOutputAvailableType to get the encoder's output types.

Examples

The following example creates a transcode profile for Windows Media Audio (WMA).

template <class Q>
HRESULT GetCollectionObject(IMFCollection *pCollection, DWORD index, Q **ppObj)
{
    IUnknown *pUnk;
    HRESULT hr = pCollection->GetElement(index, &pUnk);
    if (SUCCEEDED(hr))
    {
        hr = pUnk->QueryInterface(IID_PPV_ARGS(ppObj));
        pUnk->Release();
    }
    return hr;
}

HRESULT CreateTranscodeProfile(IMFTranscodeProfile **ppProfile)
{
    IMFTranscodeProfile *pProfile = NULL;     // Transcode profile.
    IMFCollection   *pAvailableTypes = NULL;  // List of audio media types.
    IMFMediaType    *pAudioType = NULL;       // Audio media type.
    IMFAttributes   *pAudioAttrs = NULL;      // Copy of the audio media type.
    IMFAttributes   *pContainer = NULL;       // Container attributes.

    DWORD dwMTCount = 0;
    
    // Create an empty transcode profile.
    HRESULT hr = MFCreateTranscodeProfile(&pProfile);
    if (FAILED(hr))
    {
        goto done;
    }

    // Get output media types for the Windows Media audio encoder.

    // Enumerate all codecs except for codecs with field-of-use restrictions.
    // Sort the results.

    DWORD dwFlags = 
        (MFT_ENUM_FLAG_ALL & (~MFT_ENUM_FLAG_FIELDOFUSE)) | 
        MFT_ENUM_FLAG_SORTANDFILTER;

    hr = MFTranscodeGetAudioOutputAvailableTypes(MFAudioFormat_WMAudioV9, 
        dwFlags, NULL, &pAvailableTypes);
    if (FAILED(hr))
    {
        goto done;
    }

    hr = pAvailableTypes->GetElementCount(&dwMTCount);
    if (FAILED(hr))
    {
        goto done;
    }
    if (dwMTCount == 0)
    {
        hr = E_FAIL;
        goto done;
    }

    // Get the first audio type in the collection and make a copy.
    hr = GetCollectionObject(pAvailableTypes, 0, &pAudioType);
    if (FAILED(hr))
    {
        goto done;
    }

    hr = MFCreateAttributes(&pAudioAttrs, 0);       
    if (FAILED(hr))
    {
        goto done;
    }

    hr = pAudioType->CopyAllItems(pAudioAttrs);
    if (FAILED(hr))
    {
        goto done;
    }

    // Set the audio attributes on the profile.
    hr = pProfile->SetAudioAttributes(pAudioAttrs);
    if (FAILED(hr))
    {
        goto done;
    }

    // Set the container attributes.
    hr = MFCreateAttributes(&pContainer, 1);
    if (FAILED(hr))
    {
        goto done;
    }

    hr = pContainer->SetGUID(MF_TRANSCODE_CONTAINERTYPE, MFTranscodeContainerType_ASF);
    if (FAILED(hr))
    {
        goto done;
    }

    hr = pProfile->SetContainerAttributes(pContainer);
    if (FAILED(hr))
    {
        goto done;
    }

    *ppProfile = pProfile;
    (*ppProfile)->AddRef();

done:
    SafeRelease(&pProfile);
    SafeRelease(&pAvailableTypes);
    SafeRelease(&pAudioType);
    SafeRelease(&pAudioAttrs);
    SafeRelease(&pContainer);
    return hr;
}

-see-also

IMFCollection::GetElement

MFCreateTranscodeProfile

Media Foundation Functions

Tutorial: Encoding a WMA File