[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

RE: NAB Demonstrations



-----Original Message-----
From: bob at bluescreen.com [ mailto:bob at bluescreen.com
<mailto:bob at bluescreen.com> ]
Sent: Wednesday, April 08, 1998 4:52 PM
Subject: Re: NAB Demonstrations

On Tue, 31 Mar 1998 04:23:21 -0800, you wrote:
>Two things at NAB which may be of interest to this group:
>1) The Gang of Four will make an appearance in the Microsoft booth>
This was an interesting demo, although in typical NAB fashion not
completely what it seemed.  The graphics surrounding the monitors clearly
stated that each of the four screens contained footage shot in native
format, but the person doing the demo (I believe it was the same Mr McMahon
who posted the original message) admitted that the footage I was seeing was
shot single source and converted to all the other formats.  Hardly the same
thing.

My original Email was correct - the planned demo (which we ran in DC the
week before for The House, Senate, FCC and DoD) had been shot with native
format cameras with identical content.  That demo was cancelled in the wee
hours of the morning just before NAB show time.  There was no time to have
the signage corrected.  Microsoft personnel were very up front in explaining
that most of the demos we ran for the rest of the week were derived from a
new Panasonic 720P camera as the source.  (Format converted to 480P/I and
1080I.) 
 
Occasionally we also ran native 480P, 720P and 1035/30I footage of various
types, including the newest ABC 720P tape which was beautiful.   But those
demos we dropped late Monday in favor of trying to show the same exact
content side by side.  (All derived from the 720/60P source and converted
using Astro Design and/or Panasonic format converters.)
 
480P derived from 720P is very reasonable.  There can be no interlace
artifacts.  It results in a greater depth of modulation (MTF) than would
have been obtained with many of the first generation 480P cameras, therefore
representing what the new 480P is actually going to look like.  (Great.) 
This may very well happen in the real world, especially when you consider
that many HDTV sets will run with a 480P native CRT display, cable boxes
with a 480P output, and distribution systems possibly downconverting on the
way to the consumer.
 
1080I derived from 720P has no interlace artifacts in the acquisition
process but it results in somewhat lower spatial resolution than that which
would have been acquired from a native 1080 camera (especially for the
static scenes.)  It actually looks better for high temporal rates than
native 1080I.  Nevertheless, this is an interesting comparison as it may
very well happen in the network -> affiliate -> consumer food chain.  It
will be quite common for ABC or Fox 720P feeds to end up being displayed on
an HDTV set which runs its direct-view CRT at 1080I.
 



Also, the Microsoft demo (like almost all of them) ignored the practical
aspects of the comparison: on a 20-27 inch monitor viewed at 10-12 feet
with ordinary picture content, there isn't a real discernible difference
between 480/60P, 720/60P and 1080/30I.  If you stick your face into the
monitor you can clearly see differences, but people don't watch TV that
way.

Given the limited space in any practical booth there are limitations to what
you can do.   Except for those people coming through with a pre-existing
chip on their shoulders (about 1 in 20), most people thought this was an
interesting test.  It provoked further discussion and thought.  That, if
nothing else, was the intent.
 


Where the differences start to really show up is when picture size gets to
be on a bigger screen like the 45-60 inch boxes many people are expected to
buy when the DTV thing gets up to speed.  At 60 inches, and about 15 feet
away, on a bright, sharp display, the 720p and 1080i formats clearly pull
away from 480p. It is still difficult to tell the difference between 720p
and 1080i at that point, which I guess is one of the things the computer
jockeys pushing 720p have been saying.  

Absolutely agreed.
 
--- Tom McMahon, Microsoft Corporation

 


---
Thanks to Preferred Video Products for supporting the TIG in 1998..
No product marketing allowed on the main TIG.  Contact rob at alegria.com
944 subscribers in 36 countries on Fri Apr 10 15:19:26 PDT 1998 
complete information on the TIG website http://www.alegria.com/tig3/