Re: best config

Brian Godette (bgodette@idcomm.com)
Thu, 17 Jul 1997 17:17:12 -0600


At 12:36 AM 7/18/97 +0200, you wrote:
>Brian Godette wrote:
>>
>> At 11:16 PM 7/17/97 +0200, you wrote:
>> You forgot to mention that was for White Pine 3.0, if you were to use WP
>> 2.1.* or Cornell's version a 486-100 with 16 meg of ram and a 1 meg video
>> card would be just fine. :)
>I disagree: Especially for video conferencing, with all the frames on
>the screen, a 1024x768 display is really the minimum, with 65K colors.

And on a modem? You're only going to get one or two windows clearly.
Another amazing dirty little secrete about CU is those higher xmit rates
really don't buy you much. I've been on refs that allow receive rates of
500Kbps using the T1 here with less than 2% loss, and those 60 and 80Kbps
vids look *NO* different from a 15Kbps vid except the frame rate is now 1-2
instead of 0-1 fps for a moving person, big woopty-do. What the higher send
rates do get you however is clear audio, *IF*, and only if, the other end
is able to receive at a higher rate than you're attempting to send. BTW
Delta-Mod 16 takes up exactly 27Kbps of bandwidth to send streaming audio,
this is what it stabilizes at and both the Cornell and WP client and my ref
code agree on this number, Digitalk 8.5 takes up 12Kbps (roughly). Sorta
explains why audio never really worked over modems on a ref with more than
about three people, the OC packets alone would take up enough bandwidth to
make audio impractical. If you want clear reliable audio, use some other
net-phone product like FreeTel.

>For 1200x1024 (64K colors), You need a 4 M graphics card, or for a
>1600x1200 (64K colors), you need a 8 M grapics card.
>
>Note that You need a 17" monitor for 1024x768, and 20" or 21" for

Don't tell that to my old (about 7 years) Seiko CM-1440 (14"), does
1024x768x16bit all day long, and is perfectly viewable. Mind you the
machine I normaly use at home has a 17", but it's definately not a
*requirement*, just nice for those people who like to sit about 5 feet away
from the monitor and still read 8 point fonts.

>1200x1000 and bigger. And the graphics card must be able to drive
>this screen with at least 70 hz on the highest resolution and color
>depth !!!

For 1024x768 @ 32/64k colors all you need is a 2MB video card, 1MB will get
you 256 colors which is all you need for B&W which is all the cornell
version will do. This is of course ignoring the fact that is damned hard to
find a new video card with less than 2MB on it nowadays.

>
>And to drive such a vast graphics memory (video phones allow moving
>*local* video !), You need a fast new graphics card and a fast CPU, too.

Hardly, 160x120x24bit (16mil colors) @ 15FPS is 864Kbytes/sec, which is
only 64Kbyte/sec faster than your standard ISA bus. Also consider than any
decent capture card usually provides YUV9 or YUV12 or a 15bit capture mode,
all of which are 50% or less traffic, the issue of bus speed becomes rather
irrelevent. This of course also ignores the fact that with any current
video phone product out there you're never going to be sending 15FPS, and
also ignores VESA-Local-bus video cards and capture boards. Now I will
grant that the color codecs in WP's product do need some CPU horsepower
behind them for *compression*, however the decrompession task is very
lightweight, even so I was able to get and junky old 486-66 (16mb of ram,
'95) to send color video using CU-Doodle at roughly 6fps using SFM and 3fps
using MJPEG, looped back in a self-reflect conference over the LAN at home.
Now consider that CU-Doodle itself is fairly processor intenstive compared
to a real capture board...