MCI_CUE
The MCI_CUE
command cues a device so that playback or recording begins with minimum
delay.Digital-video, VCR, and waveform-audio devices recognize this command.
MCIERROR mciSendCommand(MCIDEVICEID wDeviceID,
MCI_CUE,
DWORD dwFlags, (DWORD)
(LPMCI_GENERIC_PARMS) lpCue);
Parameters
wDeviceID
Device
identifier of the MCI device that is to receive the command message.
dwFlags
MCI_NOTIFY,
MCI_WAIT, or, for digital-video and VCR devices, MCI_TEST. For information
about these flags, see The Wait, Notify, and Test Flags.
lpCue
Address of an
MCI_GENERIC_PARMS
structure. (Devices with extended command sets might replace this structure
with a device-specific structure.)
Return Values
Returns zero
if successful or an error otherwise.
Remarks
The following
additional flags are used with the digitalvideo device type:
MCI_DGV_CUE_INPUT
A
digital-video instance should prepare for recording. If the application has not
reserved disk space, the device reserves the disk space using its default
parameters. The application can omit this flag if the current presentation
source is already the external input. (This flag has no effect on selecting the
presentation source.)
MCI_DGV_CUE_NOSHOW
A digital-video
instance should prepare for playing the frame specified with the command
without displaying it. When this flag is specified, the display continues to
show the image in the frame buffer even though its corresponding frame is not
the current position. For example, if the frame buffer contains the image from
frame 7, the device continues to show frame 7 when this flag is used to cue the
device to any other position. A subsequent cue command without this flag and
without the MCI_TO flag displays the current frame.
MCI_DGV_CUE_OUTPUT
A
digital-video instance should prepare for playing. If the workspace is paused,
no positioning occurs. If the workspace is stopped, the position might change
to a previous key-frame image. The application can omit this flag if the
current presentation source is already the workspace.
MCI_TO
A workspace
position is included in the dwTo member of the structure identified by lpCue.
The units assigned to position values are specified using the
MCI_SET_TIME_FORMAT flag of the MCI_SET command. This is equivalent to seeking to a
position, except the device is paused after the command.
For digitalvideo
devices, the lpCue parameter points to an MCI_DGV_CUE_PARMS structure.
The following
additional flags are used with the vcr device type:
MCI_FROM
The dwFrom
member of the structure pointed to by lpCue contains the starting
location specified in the current time format.
MCI_TO
The dwTo member
of the structure pointed to by lpCue contains the ending (pausing)
location specified in the current time format.
MCI_VCR_CUE_INPUT
Prepare for
recording.
MCI_VCR_CUE_OUTPUT
Prepare for
playing. If neither MCI_VCR_CUE_INPUT nor MCI_VCR_CUE_OUTPUT is
specified, MCI_VCR_CUE_OUTPUT is assumed.
MCI_VCR_CUE_PREROLL
Cue the
device to the current position, or the dwFrom position, minus the
preroll duration. This will allow the device to prepare itself before entering
record or playback mode.
MCI_VCR_CUE_REVERSE
The direction
of the next play or record command is reverse.
When cueing
for playback by using the MCI_CUE command with the MCI_VCR_CUE_OUTPUT
flag, you can cancel MCI_CUE by issuing the MCI_PLAY command with MCI_FROM,
MCI_TO, or MCI_VCR_PLAY_REVERSE.
When cueing
for recording by using MCI_CUE with the MCI_VCR_CUE_INPUT flag, you can
cancel MCI_CUE by issuing the MCI_RECORD command with MCI_FROM,
MCI_TO, or MCI_VCR_RECORD_INITIALIZE.
For vcr
devices, the lpCue parameter points to an MCI_VCR_CUE_PARMS structure.
The following
additional flags are used with the waveaudio device type:
MCI_WAVE_INPUT
A
waveform-audio input device should be cued.
MCI_WAVE_OUTPUT
A
waveform-audio output device should be cued. This is the default flag if a flag
is not specified.
See Also