Not all devices support distorting the source rectangle image to fit the display rectangle. The MCI_GETDEVCAPS message (MCI_DGV_GETDEVCAPS_CAN_DISTORT) can be used to determine whether the device supports distorting.

If either the width or the height of the rectangle specified with MCI_DGV_PUT_DESTINATION and MCI_DGV_RECORD is not a multiple of eight, then that value is rounded to the nearest multiple of eight. If the device cannot distort and the rectangle specified with MCI_DGV_PUT_SOURCE and MCI_DGV_RECORD is not an integral multiple of the rectangle specified with MCI_DGV_PUT_DESTINATION and MCI_DGV_RECORD, the source and destination rectangles are adjusted to find the nearest values that will make the source be an integral multiple of the destination and the destination be a multiple of eight.

When the device is monitoring while recording or monitoring while cued for input, the video seen in the monitor window will be the content in the record source rectangle set with MCI_DGV_PUT_SOURCE and MCI_DGV_RECORD. When the device is monitoring while not recording or cued for input, the video seen in the monitor window will be the maximum source (full video extent of the capture card reported by MCI_DGV_STATUS_X_EXTENT and MCI_DGV_STATUS_Y_EXTENT), and an animated, dashed-line rectangle will be drawn on the monitor window to indicate the relative position of the record source rectangle.

If both window move and size flags are specified, then all four window coordinates must be provided.

An application-supplied alternate video window will not be affected by the window move or size flags.