[opendtv] Re: (No Date: Tue, 28 Sep 2004 10:30:37 -0400

  • From: "John Willkie" <johnwillkie@xxxxxxxxxx>
  • To: <opendtv@xxxxxxxxxxxxx>
  • Date: Thu, 21 Oct 2004 10:14:23 -0700

mismatched aspect ratios is a "digital legacy" problem, cured by proper use
of the MPEG-2 active format descriptor (AFD).

The FCC's mandatory dynamic PSIP decision references the use of the MPEG-2
active format descriptor in PSIP, and hints that if stations do not use it
properly, it's use will be mandated.

AFD describes the letterbox "bar" and active picture areas, so that
receivers will know how to deal with pictures that have another aspect ratio
from the screen.

John Willkie

-----Original Message-----
From: opendtv-bounce@xxxxxxxxxxxxx
[mailto:opendtv-bounce@xxxxxxxxxxxxx]On Behalf Of Craig Birkmaier
Sent: Thursday, October 21, 2004 7:41 AM
To: opendtv@xxxxxxxxxxxxx
Subject: [opendtv] Re: (No Date: Tue, 28 Sep 2004 10:30:37 -0400


At 12:04 PM -0400 10/20/04, Manfredi, Albert E wrote:
>I'm baffled why you think it's "more clever" to
>design a DTV system that will perpetuate image
>distortions for all time.

Huh.
The DTV system is not perpetuating distortions; it is simply
delivering you a programs that may not match the aspect ratio of your
screen. What i detailed is simply ONE of several modes that can be
used to accommodate the content to a wider screen. Another option is
to view the 4:3 program with pillar boxes, WITHOUT distortion.

Sorry Bert, but the world is not going to migrate to a single TV
aspect ratio...again.

>
>Of course, *anyone* who has ever used a wide screen
>TV knows all too well about distorted images. The
>only way to rationalize having to put up with that
>is the knowledge that soon, the 16:9 ratio will be
>the norm rather than the exception. And that is
>what the TV show producers have done, whether or
>not the FCC buckled under back in the mid 1990s.
>DTT transmissions, be they SD or HD, are now 16:9.

Your missing it again Bert. 16:9 is simply an option, it is not the
norm. The majority of DVD movies are NOT presented in 16:9 - they are
presented in their original aspect ratio.

>
>>  We are never going back to only one aspect
>>  ratio.
>
>Wanna bet?

Sure. But there is no way you can win this bet in our lifetimes since
therre are massive archive in place at MANY aspect ratios.

>Naturally, just like always, a TV transmission
>does not need to fill ther entire screen in
>*principle*. That goes without saying, and has been
>true for as long as I've watched TV. But if you
>want to avoid distortions *and* if producers want
>to avoid having viewers crop their carefully
>crafted frames at will to fill their odd-sized
>screens, the simple answer is to use a standard
>display aspect ratio.

The principle you are basing your point on is ludicrous. Yes, you
could send an NTSC raster with images in a "window." But EVERYTHING
had to fit in the same containe up to the limits of that container.
In a digital world the content and the transmission system are
decoupled. The tranmission system knows only one thing...packet data.


The rest was redundant and thus deleted.

Regards
Craig

 
 
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