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MTP_COMMAND_DATA_OUT (deprecated)

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This is preliminary documentation and subject to change.

This topic documents a feature of the Windows Media Device Manager SDK. We recommend that you migrate your application to use the Windows Portable Devices API. For more information, see the Windows Portable Devices SDK.

The MTP_COMMAND_DATA_OUT structure contains Media Transport Protocol (MTP) responses that are filled by the device driver on exiting a call to IWMDMDevice3::DeviceIoControl.

Syntax

typedef struct _MTP_COMMAND_DATA_OUT{
  WORD  ResponseCode;
  DWORD  NumParams;
  DWORD  Params[MTP_RESPONSE_MAX_PARAMS];
  DWORD  CommandReadDataSize;
  BYTE   CommandReadData[1];
} MTP_COMMAND_DATA_OUT, *PMTP_COMMAND_DATA_OUT;

Members

ResponseCode

Response code.

NumParams

Number of parameters for this response.

Params

Parameters of the response. MTP_RESPONSE_MAX_PARAMS is a defined constant with a value of 5.

CommandReadDataSize

Data size of CommandReadData[1], in bytes.

CommandReadData[1]

Optional, first byte of data to read from the device if MTP_COMMAND_DATA_IN.NextPhase is MTP_NEXTPHASE_READ_DATA.

Remarks

The input buffer is expected to contain an appropriately filled out MTP_COMMAND_DATA_IN structure. On exit, the device driver will fill out the MTP_COMMAND_DATA_OUT structure and save it to the output buffer. Therefore, any request must have an input buffer of at least SIZEOF_REQUIRED_COMMAND_DATA_IN bytes, which is defined as the following:

#define SIZEOF_REQUIRED_COMMAND_DATA_IN (sizeof(MTP_COMMAND_DATA_IN)-1)

Any request must also have an output buffer of at least SIZEOF_REQUIRED_COMMAND_DATA_OUT bytes, which is defined as the following:

#define SIZEOF_REQUIRED_COMMAND_DATA_OUT (sizeof(MTP_COMMAND_DATA_OUT)-1)

It is assumed that all commands are self-contained, that is, they can be processed completely in one call. This has implications on lengthy data transfers, because chunking in the traditional sense is not supported. (For example, to issue a read for 3megabytes, the caller would have to ensure that it allocates an output buffer of 3 MB plus SIZEOF_REQUIRED_COMMAND_DATA_OUT bytes.) Lengthy data transfers should not be done with this method, but rather through normal data transfer APIs.

Requirements

Header: Defined in MtpExt.h.

Library: mssachlp.lib

See Also