Stream handlers can communicate with their attached devices using the VSD_DDCMD calls. The DDCMD interface is the primary method of moving data to and from devices in OS/2 multimedia.
This command is sent using VSDEntry as follows:
VSDEntry(hvsd, ulFunc, ulFlags, pRequest)
hvsd (HVSD)
ulFunc (ULONG)
ulFlags (ULONG)
DDCMD_CONTROL
pRequest is a pointer to DDCMDREADWRITE structure.
pRequest is a pointer to DDCMDREADWRITE structure.
pRequest (PVOID)
rc (ULONG)