IWMDRMTranscryptor::Read method (wmsdkidl.h)

Artikel
4/26/2023

[The feature associated with this page, Windows Media Format 11 SDK, is a legacy feature. It has been superseded by Source Reader and Sink Writer. Source Reader and Sink Writer have been optimized for Windows 10 and Windows 11. Microsoft strongly recommends that new code use Source Reader and Sink Writer instead of Windows Media Format 11 SDK, when possible. Microsoft suggests that existing code that uses the legacy APIs be rewritten to use the new APIs if possible.]

[Read is available for use in the operating systems specified in the Requirements section. It may be altered or unavailable in subsequent versions. Instead, use Microsoft PlayReady. ]

The Read method reads data from the file loaded in the transcryptor and encrypts it for streaming to devices that support Windows Media DRM 10 for Network Devices.

Syntax

HRESULT Read(
  [in]      BYTE  *pbData,
  [in, out] DWORD *pcbData
);

Parameters

[in] pbData

Address of a buffer that receives the data.

[in, out] pcbData

Address of a variable containing the size of the data buffer pointed to by pbData. On input, set to the size of the buffer.On output, the value is changed to the number of bytes actually read.

Return value

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

Return code	Description
S_OK	The method succeeded.
NS_E_INVALID_REQUEST	The transcryptor is not ready for reading. OR Another read is in progress.

Return code

Description

S_OK

The method succeeded.

NS_E_INVALID_REQUEST

The transcryptor is not ready for reading.

Another read is in progress.

Remarks

This method is asynchronous. It returns immediately, but processing is not complete until a WMT_TRANSCRYPTOR_READ message is sent to the IWMStatusCallback::OnStatus callback method. Neither the buffer referenced by pbData nor the buffer length referenced by pcbData are updated until the WMT_TRANSCRYPTOR_READ message is sent.

The HRESULT sent with the WMT_TRANSCRYPTOR_READ message contains the return value for the read operation. A special success code, NS_S_TRANSCRYPTOR_EOF, is sent to indicate that the data from this read operation includes the end of the file.

Requirements

Requirement	Value
Minimum supported client	Windows XP [desktop apps only],Windows Media Format 9.5 SDK
Minimum supported server	Windows Server 2003 [desktop apps only]
Target Platform	Windows
Header	wmsdkidl.h (include Wmsdk.h)
Library	WMStubDRM.lib

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