Logo Filter for VirtualDub
(Version 1.3)

[Place this text file in the VirtualDub plugins directory to make
it available via the Help button on the filter configuration dialog
box. The computer must have a program called Notepad available in
its search path.]

This filter provides the ability to overlay a logo contained in a bitmap
file. The position of the bitmap may be specified. Selectable alpha
blending allows variable merging with the video, and a transparent
color may be selected to obtain a free-floating effect. Animated logos
can be created by defining a series of bitmaps. Filter preview is supported.

This filter is ideal for unobtrusively placing a logo on the video as is
done on many cable TV channels.

Two test bitmaps and an animated bitmap sequence are provided in the zip file.

How to Make a Static Logo
------------------------------

Create a 24-bit-depth windows bitmap file with the desired size and with
a transparent color zone if desired. The transparency color may be arbitrarily
selected and then configured in the filter configuration.

In the filter configuration dialog box, enter the input file. If the specified bitmap file
cannot be found, or if it is not a bitmap file, or if it is of the wrong depth,
the output frame will be all black. Set the desired X and Y coordinates, the starting
frame and the duration (in frames). Set the desired alpha blend and transparent color.

How to Make an Animated Logo
------------------------------------

To make an animated logo, create a series of bitmap files named name0000.bmp,
name0001.bmp, name0002.bmp, etc. (you can replace "name" with desired text).
Specify the first one as the input file and check the 'Animation sequence' checkbox.
Set the duration to be the number of frames to display each bitmap file before moving
to the next one. Set the loop count to the number of repetitions desired for the sequence.
Set the other parameters as described for static logos.

Note that stepping forward and rewinding will operate correctly, but stepping backward
is currently not supported.

A sample sequence is provided that produces a spinning earth. To run it, set the duration
to 1, loops to 0, and enable a transparent color of 0/0/0.

Detailed Option Descriptions
--------------------------------

The following options are provided:

Input file: 
Specifies the full pathname of the bitmap file to be used.

Animation sequence: Check this to enable an animated sequence.

X: This option determines the X offset of the start of the bitmap on the video.

Y: This option determines the Y offset of the start of the bitmap on the video.

Starting frame: The frame number on which to begin displaying the logo.

Duration: For a static bitmap, the number of frames for which to display the logo.
For animated bitmaps, the number of frames to display each bitmap before moving to
the next bitmap. To display a bitmap for the whole clip length, select 0.

Loops: For static logos, this has no effect. For animated logos, the number of repetitions
of the bitmap sequence. To loop forever, select 0.

Alpha: This option determines the blending of the bitmap with the video.
For full bitmap and no video, use the value 255. As this value is reduced toward 0,
more and more of the video is blended in. An alpha of about 100-128 gives a
nice unobtrusive overlay.

Fade: 
These options allow for the logo to be faded in and/or out. 

For fade-in, the starting frame number of the fade is determined by the logo starting frame. 
The length of the fade is determined by the In Len value. 

For fade-out, the ending frame number of the fade is determined by the Out End value.

The length of the fade is determined by the Out Len value. 
If fade-in and fade-out overlap, fade-out overrides. 
Even if the logo is otherwise enabled such that it would appear beyond the end of a fade-out 
if the fade-out were not there, the logo will be suppressed after the fade-out. 
Finally, if you put silly values in the fade boxes, you will get what you deserve.

Enable transparent color: 
Check this if you have made a transparent color zone in your bitmap. 
Then select the transparent color in the Red, Green, and Blue edit boxes. 
Full video shows in the transparent areas. The tolerance box allows you to specify a 'sloppiness' factor fo the match to the transparent color. 
As long as the difference between each color channel and the corresponding specified transparent color is not greater than the specified tolerance, 
then the color will be considered to be transparent. 
For example, if the tolerance is 10 and the specified transparent color is
37:45:10, then a color 39:44:5 will be considered transparent, while a color 39:56:11
will not be transparent (because one color channel's difference exceeds tolerance).

For additional information, version updates, and other filters, please
go to the following web site:

Filters for VirtualDub
http://www.geocities.com/Colosseum/Pressbox/8699/index.html

Donald Graft
December 28, 2000
(C) Copyright 2000, All Rights Reserved