🚀 go-pugleaf

Last week I posted several questions about recording video from the  
NeXTDimension, and mentioned that my early attempts had been less than  
fully successful.

Thanks to all who responded via email, and in comp.graphics.* and  
rec.video.production.  

I was most impressed that I received a telephone call from NeXT in  
response to my posting.  Their project leader for the ND board called to  
offer helpful suggestions and comments about the use of the product. 

Thanks to all you helpful folks, I find that recording short animated  
sequences from the ND to videotape is very easy and produces results that  
are just fine for scientific presentations, though well short of  
"broadcast" quality.

Here is a summary of the information I received:

1) All US video (NTSC standard) is 30 frames per second, interlaced.  This  
means odd-numbered and even-numbered scanlines (vertical resolution is in  
scanlines) are displayed alternately.  Therefore the presence of any  
horizontal lines that are 1 pixel tall in the animation will cause  
annoying flicker at 30 cycles per second. Avoiding such lines in my  
animation produced *much* better results.

2) S-VHS and Hi-8 formats are *much* better than VHS in terms of color and  
clarity.  3/4 inch tape is better still. It's no problem at all to make a  
stright VHS copy of the animation off of a higher quality deck when you're  
finished.  All you need is coax cable.  The nicer high-quality machines  
also offer far superior editing features, although they are pricey  
($1-3K).

3) The only way to record long animations (more frames than will fit in  
RAM) is to do it a frame at a time.  This requires a specialized recording  
setup which basically rewinds the tape a bit, then rolls forward far  
enough to record a single frame (1/30 second) for every frame.  This beats  
the motors to death quickly, so these machines cost thousands of dollars.   
You also might/might not need a controller so the computer can tell the  
recorder it's ready to do the next frame.  This unit also costs thousands  
of $.   A really good setup for long, high-quality animations would cost  
upwards of $25K. Too expensive for me.  I'll just do shorter animations.

4) Don't hold your breath for real-time video compression in hardware on  
any NeXT platform.


--
A. Scott Denning    (303)491-8346
<scott@abyss.atmos.colostate.edu>
Dept. of Atmospheric Science
Colorado State University
Fort Collins, CO 80523