Re: Printing the CU-SeeMe window

Robert Munafo (
Fri, 2 Dec 1994 16:25:06 -0500

You haven't specified enough about your hardware, but I'd be willing to
guess that you have an AV-equipped Power Mac and you're using the AV
video input as your video digitizing source.

When you use the Apple AV hardware to display video in a window, the
image that you see is not a single simple pixmap in video RAM.
Instead, what you're seeing are two pixmaps, each in its own partition of
VRAM, and the AV hardware fetches data from one bank or the other on the
fly when it needs it, on a pixel-by-pixel basis. This is what enables
you to have 16-bit color video in a window when your monitor is set to 2
colors ("black & white"). (This is all done with multiple buses and
multi-ported RAM, etc. The reason is so that the writes to VRAM by the
video digitizer board don't compete with writes from the processor when it
draws the windows)

When you do the screen dump, the Mac just dumps the pixmap containing the
menubar, desktop, and windows. The video window is filled with a solid
pattern (on mine it's always black or dark green).

The only workaround for this that I have seen is to run the CloseView
extension, turned on with magnification on or off (your choice). When you
run CloseView, the sequence grabber component (or maybe the vdig) knows
that it has to manually grab frames and write them into the window. Of
course this is being done in software so the frame rate goes down.

I think there is a general-purpose signaling mechanism going on here. I
don't know what it is, but I imagine the sequence grabber client
(that would be CU-SeeMe in this case) could use it if it wanted to. Since
it reduces the frame rate it would have to be some sort of
user-controlled option.

On Fri, 2 Dec 1994, Richard S Neale wrote:
> Subject: Printing the CU-SeeMe window
> I am trying to print/save the desktop image which contains a CU-SeeMe
> window. When it prints, the windows are missing. There are no options
> to print/save on the File menu for CU-SeeMe.
> This contains a great PR shot and MUST be cought. HOW??? HELP...before
> its lost.
> Platform: PPC running 7.5
> Rich

Robert P. Munafo