MV Bitmap Overlay DirectShow Filter

The MontiVision Bitmap Overlay filter overlays an image onto the output video stream. Either a colour for the transparent background is specified, a constant alpha value for the whole image is used or both modes are active simultaneous. If a background colour is specified, every pixel with this colour is set as transparent. If a constant alpha value is used, the output video is calculated as follows: Output = Input * Alpha + Overlay * (255-Alpha). The overlaid image can be repositioned and resized.

The filter uses the FreeImage library to load the images. Some of the supported types are: BMP, GIF, JPG, PNG, TIF, ....

 

File: bitmapoverlay.ax
CLSID: CLSID_MVBitmapOverlay

 

Interface

IMVBitmapOverlay

IMVBitmapOverlay2

IMVHistogram

IMVHistogram2

IMVHistogram3

IMVFilterData

IMVAbout

IMVFilterInfo

 

Supported COM Events

The filter supports following events through the IMVFilterEvents interface. Look at the filter events page for more information.

Event

Value

Description
MV_ALGORITHM_START_EVENT

0

 A filter starts processing a video frame or sample.
MV_ALGORITHM_END_EVENT

1

 A filter finishes processing a video frame or sample.

 

MV Bitmap Overlay Property Page

Uses the IMVBitmapOverlay configuration interface.

Montivision Bitmap Overlay DirectShow Filter Property Page

 

Enable Enables or disables the bitmap overlay.
Transparent background A transparent background is used. Every pixel with a specified colour is set as transparent.
Constant image alpha A constant alpha value is used for every pixel of the image.
Both modes a transparent background an a constant alpha value are used at the same time.
Background colour The currently selected background colour.
Video alpha value

Output pixel value = Input pixel value     *          Alpha + 
                               Overlay pixel value * (255-Alpha)
Relative Position Places the image within the selected corner.
Absolute Position Places the image exactly at the defined position relative to the upper left corner of the video stream.
Current bitmap Used to specify the overlay image and show the current filepath.
Enable resize Enables or disables the other resize controls. The original size of the overlay image will be restored, if it's unchecked.
Maintain aspect ratio If this box is checked, the aspect ratio of the overlay image will be kept.
Width Changes the width of the overlay image.
Height Changes the height of the overlay image.