The unfreeze command reenables video acquisition to the frame buffer after it has been disabled by the freeze command. Digital-video, VCR, and video-overlay devices recognize this command.

To send this command, call the mciSendString function with the lpszCommand parameter set as follows.

  TEXT("unfreeze %s %s %s"), 



Identifier of an MCI device. This identifier or alias is assigned when the device is opened.


Flag for reenabling video acquisition to the frame buffer. The following table lists device types that recognize the unfreeze command and the flags used by each type.

Value Meaning
digitalvideo at rectangle
overlay at rectangle
vcr input output

The following table lists the flags that can be specified in the lpszUnfreeze parameter and their meanings.

Value Meaning
at rectangle Specifies the region that will have video acquisition reenabled. The rectangle is relative to the video buffer origin and is specified as X1 Y1 X2 Y2. The coordinates X1 Y1 specify the upper left corner of the rectangle, and the coordinates X2 Y2 specify the width and height.
input Unfreeze the input image.
output Unfreeze the output image. If neither "input" nor "output" is given, "output" is assumed.


Can be "wait", "notify", or both. For digital-video and VCR devices, "test" can also be specified. For more information about these flags, see The Wait, Notify, and Test Flags.

Return Values

Returns zero if successful or an error otherwise.


The following command unfreezes a region of the video buffer:

unfreeze vboard at 10 20 90 165


  Windows NT/2000/XP: Included in Windows NT 3.1 and later.
  Windows 95/98/Me: Included in Windows 95 and later.

See Also

MCI, MCI Command Strings, freeze