MMProgRef - VSD Commands

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Multimedia Programming Reference

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The vendor-specific driver (VSD) interface is a generic device-driver like interface that effectively decomposes the high-level media control interface functions into more fundamental operations. The VSD layer resides in Ring 3 and provides a low-level function set that can keep pace with demanding data control and transport requirements. A Ring 3 stream handler can use the VSD_DDCMD command (described in this section) for data transportation. For this Ring 3 DLL interface, all pointers are 0:32 linear.

Note: Refer to the MMPM/2 Device Driver Reference for a complete description of the VSD interface definitions.

The interface to the VSD is a specific entry point-VSDEntry. First, issue DosLoadModule for the VSD's DLL. The DosLoadModule function returns a handle for the VSD. Next, using the VSD handle, call DosQueryProcAddr to receive the VSD entry point address. This must be done prior to issuing any VSD commands. Once the entry point address is received, calls to the VSD can be made with VSDEntry.

• VSDEntry
• [[VSD_DDCMD]