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The ReadOnClearChannel method reads data from the object at the current position without using secure authenticated channels. This is still secure for use with DRM-protected content. This operation is valid only if the storage object represents a file. If IMDSPObject2 is supported, this method must be implemented. Windows Media Device Manager does not fall back to IMDSPObject::Read if this method fails.
Syntax
HRESULT ReadOnClearChannel(BYTE*pData,DWORD*pdwSize);
Parameters
pData
[out] Pointer to a buffer to receive the data read from the object.
pdwSize
[in, out] Pointer to a DWORD specifying the number of bytes of data to read. Upon return, this parameter contains the actual amount of data read*.*
Return Values
The method returns an HRESULT. All the interface methods in Windows Media Device Manager 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 an extenstive 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. |
| WMDM_E_BUSY | The media device is busy. |
| WMDM_E_INTERFACEDEAD | The file or folder was previously deleted. |
| WMDM_E_CALL_OUT_OF_SEQUENCE | Open was not called before calling Read. |
| E_INVALIDARG | A parameter is an invalid or NULL pointer. |
Remarks
This method can be used for DRM-protected content. This method is more efficient than IMDSPObject::Read because this method does not involve encrypting and decrypting parameters.
Requirements
Header: Defined in mswmdm.h.
Library: mssachlp.lib
See Also