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IWMDMOperation3::TransferObjectDataOnClearChannel

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The TransferObjectDataOnClearChannel method transfers a clear, unencrypted block of data.

Syntax

HRESULT TransferObjectDataOnClearChannel(
  BYTE*  pData,
  DWORD*  pdwSize
);

Parameters

pData

[in, out]  Pointer to an unencrypted byte buffer.

pdwSize

[in, out]  Pointer to a DWORD containing the buffer size.

Return Values

The method returns an HRESULT. All the interface methods in Windows Media Device Manager and Service Provider can return any of the following classes of error codes:

  • Standard COM error codes
  • Windows error codes converted to HRESULT values
  • Windows Media Device Manager error codes

For a complete list of possible error codes, see Error Codes.

Possible values include, but are not limited to, those in the following table.

Return code Description
S_OK The method succeeded.
S_FALSE The data was transferred. There is no more data, and no more has been requested.
WMDM_E_USER_CANCELLED The application instructs Windows Media Device Manager to cancel the current operation without waiting for it to finish.

Remarks

Depending on the context, this application-supplied callback method can either receive data from Windows Media Device Manager or accept data from the application that is being supplied to Windows Media Device Manager.

When using the application-supplied IWMDMOperation base interface pointer, Windows Media Device Manager first does a QueryInterface for IWMDMOperation3. If IWMDMOperation3 is available, the assumption is that the TransferObjectDataOnClearChannel is implemented and data is transferred using this method. However if the QueryInterface for IWMDMOperation3 fails, Windows Media Device Manager falls back to using the base IWMDMOperation interface, calling the TransferObjectData method with encrypted data instead. Using the fallback IWMDMOperation::TransferObjectData results in the object data being encrypted and decrypted twice, whereas IWMDMOperation3::TransferObjectDataOnClearChannel is more efficient; performing encryption and decryption only once.

Requirements

Header: Defined in wmdm.idl.

Library: mssachlp.lib

See Also