Re: Modem Speed & Video Quality

Enigma (enigma@wolfenet.com)
Sat, 23 Dec 1995 11:34:44 -0800 (PST)


>Subject: Modem Speed
>Message-ID: <Chameleon.4.01.2.951216222529.soron@>
>
>Hello folks,
>A while ago I asked if upgrading my modem from 14.4 to 28.8 will improve
>video quality.

snip

>My question is:
>
>What good would a 28.8 modem do if the communication links allow only up to
>12kbs, at least in my case.

A number of things could be limiting the data rate to 12kbs... I typically
see "bursting" into the mid 20's with my 28.8 connection. It could be your
provider but is more likely the person/reflector on the other end and the
path between. A 28.8 modem DOES help! If the person sending has their
tranmit rate capped to 12kbs, that's all you're going to usually see
(sometimes it sneaks above somehow).

>>From reading many postings of the members, I get the impression that they
>are very happy with the video but have lots of problems with the audio.
>The video I am receiving now is a technological feat but I could hardly rate
>it as satisfactory. At best it is a series of stills that come one after the
>other and updating slowly. Perhaps others have better experience with the
>video. I would like people to post a reference to my observation. I might
>learn something.

You're correct, the "video" at best with dial-up modem connections, is often
a series of still frames but it's a lot better than a single still, isn't
it? I've seen sustained frame rates of 8fps or so with dial up if it's a
very fast connection (still 28.8 at both ends) and there's very little
motion in the picture (so there's little change from frame to frame). 8fps
isn't like going to the movies, but it's not bad. As is discussed in the
FAQs and elsewhere, it takes something like several HUNDRED kpbs to start to
approximate smooth live video. I've seen cuseeme running with a T1 (1.5
mbps connection) and it's much more impressive but the net is still often a
limiting factor to it being really smooth. Also, this amount of bandwidth,
if many were using it, would quickly bury portions of the net and render it
slow for everyone! Considering cuseeme is "free", it's really quite amazing
just as it is.

Mike