IMFAttributes::GetBlob Method

Artikel
07/27/2011

Retrieves a byte array associated with a key. This method copies the array into a caller-allocated buffer.

Syntax

HRESULT GetBlob(
  [in]   REFGUID guidKey,
  [out]  UINT8 *pBuf,
  [in]   UINT32 cbBufSize,
  [out]  UINT32 *pcbBlobSize
);

Parameter

guidKey [in]
GUID that identifies which value to retrieve. The attribute type must be MF_ATTRIBUTE_BLOB.
pBuf [out]
Pointer to a buffer allocated by the caller. If the key is found and the value is a byte array, the method copies the array into this buffer. To find the required size of the buffer, call IMFAttributes::GetBlobSize.
cbBufSize [in]
The size of the pBuf buffer, in bytes.
pcbBlobSize [out]
Receives the size of the byte array. This parameter can be NULL.

Rückgabewert

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

Rückgabecode	Beschreibung
S_OK	The method succeeded.
E_NOT_SUFFICIENT_BUFFER	The buffer is not large enough to the array.
MF_E_ATTRIBUTENOTFOUND	The specified key was not found.
MF_E_INVALIDTYPE	The attribute value is not a byte array.

Hinweise

You can also use the IMFAttributes::GetAllocatedBlob method, which allocates the buffer to hold the byte array.

This interface is available on the following platforms if the Windows Media Format 11 SDK redistributable components are installed:

Windows XP mit Service Pack 2 (SP2) und höher.
Windows XP Media Center Edition 2005 with KB900325 (Windows XP Media Center Edition 2005) and KB925766 (Oktober 2006 Updaterollup für Windows XP Media Center Edition) installed.

Beispiele

The following code example shows how to get an attribute whose value is a byte array.

HRESULT AttributeGetBlob(IMFAttributes *pAttributes)
{
    HRESULT hr = S_OK;
    UINT32 cbBlob = 0;
    BYTE *pBlob = NULL;

    hr = pAttributes->GetBlobSize(MY_ATTRIBUTE, &cbBlob);
    
    if (SUCCEEDED(hr))
    {
        pBlob = new BYTE[cbBlob];
        if (pBlob == NULL)
        {
            hr = E_OUTOFMEMORY;
        }
    }

    if (SUCCEEDED(hr))
    {
        hr = pAttributes->GetBlob(MY_ATTRIBUTE, pBlob, cbBlob, &cbBlob);
    }

    if (pBlob)
    {
        delete [] pBlob;
    }
    return hr;
}

Anforderungen

Mindestens unterstützter Client	Windows Vista
Mindestens unterstützter Server	Windows Server 2008
Header	Mfobjects.h (include Mfidl.h)
Bibliothek	Mfuuid.lib

Siehe auch

IMFAttributes

MF_ATTRIBUTE_TYPE

Attributes and Properties

Freigeben über