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	Rex Ballard - Director of Electronic Distribution
	http://cnj.digex.net/~rballard


On Sat, 2 Nov 1996, Christopher Harper wrote:

> I have several dumb questions about streaming video.  If I use Avid or
> Lightworks to convert a one-minute piece of video, I can adjust the
> quality of the image to limit the amount of storage space necessary for
> that video.  The recording time is one minute per one minute from metal
> tape to finished digitizing.  Faster, if the source is digital.  Why is
> necessary to make streaming video at 8 frames per second rather than the
> normal 30 frames per second?  Is the software program on the Avid or
> Lightworks that much more sophisticated than what is available for Web
> production?  Or is it that the amount of bandwidth for 30 frames per
> second is huge versus eight frames per second?

640x480x30 = 9 Megabytes/second (76 mbits/second).  You still have to do
compression, dithering, and scaling, for each frame.  The poor little
pentium is working has hard as it can, so is the little S3 chip.
Actually, under MS-Windows, it's thrashing the cache to death, but we
don't want to go there do we?

>  If so, how much
> larger?   
At 8 frames/second, the bandwidth drops to 2.5 megabytes/second.  Much
more managable, and well within the capabilities of a disk drive with
write=back caching.  When the compression is complete, the bandwidth drops
to about 10kbytes/second, depending on action, background, and fractal
characteristics (repeating patterns).  Leaves on trees and martial arts
scenes are much more bulky.

> Respond privately unless there's an interest on the list to
> discuss streaming video.  Jeremyw, where are you when I need you?
> Cheers.
> 
> 
> ____________________________________________________________
> Christopher Harper           Associate Professor
> New York University        Department of Journalism
> 10 Washington Place	      New York, NY 10003
> 212-998-3846                     http://pages.nyu.edu/~harperc
> 
> "Even if you are on the right track, you'll get run over if you just sit
> there."
>   - Will Rogers
> +---------------------------------------------------------------------------+
> Posted to ONLINE-NEWS. Made possible by Nando.net - http://www.nando.net
> 


From rballard@cnj.digex.net Fri Nov  8 01:05:08 1996
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