IMFAttributes::GetBlob method (mfobjects.h)

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
);

Parameters

[in] guidKey

GUID that identifies which value to retrieve. The attribute type must be MF_ATTRIBUTE_BLOB.

[out] pBuf

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.

[in] cbBufSize

The size of the pBuf buffer, in bytes.

[out] pcbBlobSize

Receives the size of the byte array. This parameter can be NULL.

Return value

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

Remarks

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 with Service Pack 2 (SP2) and later.
• Windows XP Media Center Edition 2005 with KB900325 (Windows XP Media Center Edition 2005) and KB925766 (October 2006 Update Rollup for Windows XP Media Center Edition) installed.

Examples

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;
}

Requirements

See also

Attributes and Properties

IMFAttributes

MF_ATTRIBUTE_TYPE