Adjusting
Speed, Volume, and Zoom
The speed,
volume, and zoom macros provide the functionality of the View, Volume,
and Speed commands on the MCIWnd menu. The macros described in this section
are generally used with video and other devices that display images during
playback.
Some devices
support multiple playback speed changes. You can set the playback speed for
these devices by using the MCIWndSetSpeed macro. This macro defines the playback speed as
1000. Higher values indicate faster speeds. Lower values indicate slower
speeds.
You can
retrieve the current playback speed by using the MCIWndGetSpeed macro. This macro uses the
same values and range as those used by MCIWndSetSpeed.
Some devices
support volume changes. You can adjust or set the volume by using the MCIWndSetVolume macro. This macro defines
the normal volume level as 1000. Higher values indicate louder volumes. Lower
values indicate quieter volumes.
You can
retrieve the current volume level by using the MCIWndGetVolume macro. This macro uses the
same numerical values and range as those used by MCIWndSetVolume.
For devices
that use a playback window, MCIWnd supports a zoom feature that sets the size
of the playback image. You can set the playback image size by using the MCIWndSetZoom macro. The macro redefines
the playback image size while maintaining a constant aspect ratio for the
image. The zoom value is defined as a percentage of the original image size.
Thus, 100 represents the original image size, 50 indicates the image shown is
half its original size, and 200 indicates that the image shown is twice its
original size.
You can
retrieve the current zoom value by using the MCIWndGetZoom macro. This macro uses the
same values and range as those used by MCIWndSetZoom.
Note The standard
MCI CD audio and waveform-audio drivers do not support volume or speed changes.