IMDSPObject2::ReadOnClearChannel

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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