Re: At&T video

Don Johnson (johnson@magicnet.net)
Wed, 28 Jun 1995 11:41:10 -0400


>While Vistium and Picasso require some heavy duty hardware the video
>phone only requires compatible phones at both ends of the call. The
>phone transmits a 15 fps colour picture along with regular telephone
>voice. The phone was not an initial hot item - people complained
>about the slow picture updating, but it sure puts CU-SeeMe to shame.
>I hadn't thought to compare it to this software, but the comparison is
>quite logical. While not being an expert on either system I would
>imagine the faster (and colour) picture is due, in part, to hardware
>based compression.
>
>C. Duncan Hudson
>Information Management Member
>AT&T CCS, CIO/CTO

You're not going to get 15 FPS with any system over standard phone lines or
over standard modem connections. It just aint going to happen. You need the
wider bandwidth of ISDN. I don't think a 56k line will do it. CUSM is a
software based system designed to work over what is essentially a poor
medium technically but an excellent medium to reach the masses in an
inexpensive way. My guess is that given an ISDN connection at both ends and
at least a 100Mhz CPU, CUSM would compete well against any of the commercial
hardware based (and software if there are any) programs as far as speed
goes. They serve a completely different purpose. I don't know of any system
using hardware based or software based compression that reports much better
than 15 FPS using 128kbps ISDN. For purposes of discussion, it is
interesting but it's rather like comparing apples and oranges since there
are so many variables between the different systems. For instance, the
PictureTel PCS-100 desktop, hardware based compression, system has a
speaker phone which is very high quality. That feature isn't even brought up
in discussions of whose got the fastest and cheapest! It might be better to
consider whose got the best at the best price for a particular purpose.

Don Johnson
johnson@magicnet.net