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MCI_SIGNAL command

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The MCI_SIGNAL command sets a specified position in the workspace. Digital-video devices recognize this command. MCIAVI supports only one active signal at a time.

To send this command, call the mciSendCommand function with the following parameters.

MCIERROR mciSendCommand(
  MCIDEVICEID wDeviceID, 
  MCI_SIGNAL, 
  DWORD dwFlags, 
  (DWORD) (LPMCI_DGV_SIGNAL_PARMS) lpSignal
);

Parameters

wDeviceID

Device identifier of the MCI device that is to receive the command message.

dwFlags

MCI_NOTIFY, MCI_WAIT, or MCI_TEST. For information about these flags, see The Wait, Notify, and Test Flags.

lpSignal

Pointer to an MCI_DGV_SIGNAL_PARMS structure.

Return Value

Returns zero if successful or an error otherwise.

Remarks

The window whose handle you specify in the dwCallback member of the MCI_DGV_SIGNAL_PARMS structure receives the MM_MCISIGNAL message.

The following flags apply to digital-video devices:

MCI_DGV_SIGNAL_AT

A signal position is included in the dwPosition member of the structure identified by lpSignal.

MCI_DGV_SIGNAL_CANCEL

Removes the signal position specified by the value associated with MCI_DGV_SIGNAL_USERVAL.

MCI_DGV_SIGNAL_EVERY

A signal-period value is included in the dwPeriod member of the structure identified by lpSignal.

MCI_DGV_SIGNAL_POSITION

The device will send the position value with the Windows message instead of the user-specified value.

MCI_DGV_SIGNAL_USERVAL

A data value is included in the dwUserParm member of the structure identified by lpSignal. The data value associated with this request is reported back with the Windows message.

Requirements

Requirement Value
Minimum supported client
 Windows 2000 Professional [desktop apps only]
Minimum supported server
 Windows 2000 Server [desktop apps only]
Header
Mmsystem.h (include Windows.h)

See also

MCI

MCI Commands