roundtable: RE: $witched digital?

roundtable: RE: $witched digital?

RE: $witched digital?

Gene Harlow (harlow_g@WIZARD.COLORADO.EDU)
Fri, 4 Mar 1994 20:24:39 -0700 

Date: Fri, 4 Mar 1994 20:24:39 -0700
From: harlow_g@WIZARD.COLORADO.EDU (Gene Harlow)
Subject: RE: $witched digital?
To: roundtable@cni.org
Message-Id: <01H9KFVGO5FK8WW6OO@WIZARD.COLORADO.EDU>

I don't know what the resistance is to 384K and 56K since it may not be 
the "best" quality, it certainly meets the needs of video conference, 
minimal on-line video for business information transfer and can be 
transported ubiquitously on internet and other installed technologies.  
I believe we are discussing technology ahead of the present envelope but 
you have to crawl before you can walk.

The question is " If we want full motion video at commercial quality, 
who can afford it and where will the bandwidth for the quality come from?"  
In a recent recommendation in Colorado, the minimum bandwidth to the home 
is rationally set for 1.5M but the facilities are not available for 
universal service.  This then calls for alternatives that are workable 
and narrowing the bandwidth seems the solution even though some store 
and forward will be required.

Has anyone determined what the average consumer would want to use the 
video linkages for except to wastch movies?  What would be needed for 
someone to use the video channel for the total communications and 
entertainment options?  I think consumers want something that is usable 
at reasonable cost to meet basic needs at first.  Over time, exotic uses 
of video would evolve and then greater bandwidth would be essential.

I didn't state that a 2000:1 compression for video on 56K is the plan, 
I stated that there are 384K and 56K implementations that are being
established that will meet limited needs at the present.  Maybe these
approaches are economically feasible while everyone argues for greater
bandwidth and commercial quality video to the home.  The possibility of
1.5M for voice and video may be an acceptable benchmark in the near future
as a flat rate price.  This is about what combined voice and video costs
the consumer now and may be a realistic flat rate if the volume is there.

THX, Gene Harlow
<harlow_g@wizard.colorado.edu>

>James Love <love@essential.org> writes:
>>How much bandwidith is needed for switched video into the home, 
>>and what are the costs of provding that bandwidith, given current 
>>technology?
>
>     An analog cable channel requires 6 MHz.  However, as the MIT Media 
>Lab folks are fond of telling us, the bandwidth required to send video 
>information (at a given picture quality) is also dependent on how smart 
>the devices send and receiving the signal are.  For example, if you have 
>incredible amounts of memory, and you're willing to wait a *long* time, 
>you could send an entire movie through a 1200 bps modem, store it on your 
>gobs of disk, and play it back when it all arrives.  (This would be the 
>equivalent of filling a supertanker through a straw, however. :-)
>
>     Assuming that you are asking about real-time video (i.e. not 
>store-and-play), the MPEG-1 digital video compression format is optimized 
>to provide video (352 x 240 pixels at 30 frames/second) at a data rate of 
>1.5 Mbits/s.  This is approximately equivalent to a T1 line, which costs 
>around $200-$300/month around here.  Hardware implementations of MPEG are 
>becoming more common, so an MPEG card for one's microcomputer could soon 
>cost in the hundreds of dollars.
>
>     Preliminary work on MPEG-4 (MPEG-2 is optimized for 3-10 Mbits/s,
>MPEG-3 is for HDTV), which is designed for low bitrate applications
>(up to 64 Kbps, 176 x 144 at 10 frames/s) has begun.  *Notice that these
>are bitrates which are achievable over standard POTS or ISDN lines.*
>It can be done - AT&T sells a video phone which runs over normal
>phone lines, albeit with extremely poor picture quality.  It's fairly
>safe to assume that it will be at least a couple of years before MPEG-4
>hardware implementations are widely available.
>
>     From a policy perspective, I think it's important that we start
>to tariff flate-rate digital local loop access.  Bitrates will increase
>with improving technology, and compression standards will evolve, but
>it's important to encourage content providers to develop applications
>by providing a conduit for these services in the local loop, even if
>they are constrained by low picture quality, or store-and-play
>applications.
>
>Michael Chui
>mchui@cs.indiana.edu

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