[opendtv] Optimizing the system

  • From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
  • To: "OpenDTV (E-mail)" <opendtv@xxxxxxxxxxxxx>
  • Date: Thu, 16 Dec 2004 15:15:35 -0500

Craig Birkmaier wrote:

> > For example, if a given movie will fit in an HD-DVD
> > either as 720 at 24p or as 1080 at 24p, why bother
> > with 720 at 24p? The DVD will cost no less if you
> > load it with 720p.
> 1. It is likely that 720P will deliver higher quality
> samples at the available bit rate;

This is a valid comment *only* if the channel bit rate
or available storage capacity are inadequate for 1080.
Of course. I agree that the constraining channel width
or storage capacity are the primary concern here.

When Tom Barry proposed use of a higher compression
encoding algorithm, such as H.264, it was
specifically to ensure that the bit rate or storage
capacity would be adequate for 1080. If it fits,
use it.

It's your next two points that continue to be non

> 2. More than 90% of viewers will still be
> watching the SDTV down conversion;

Which is irrelevant by itself, even if true (which
it is not anymore). If the DVD plays in their
DVD players, or the signal fits in the 6 MHz TV
channel, no need to limit the quality of the signal.

> 3. Unless your display is larger than 100 inch
> diagonal you WILL NOT see any difference.

Which continues to be irrelevant to the problem
of optimization.

"Optimization" means maximizing (or minimizing)
an objective subject to a list of constraints.
Aside from your #1 point, the other two points
aim to reduce quality (i.e. the objective)
possibly below that allowed by the constraint set.
There's no valid excuse for this.

Since the highest quality of HD has been defined
to be 1080 lines, that is where HDTV will
migrate over time. The Europeans are exactly
correct to question any pre-conceived one size
fits all 720p notion, especially if they are
not constained to MPEG-2 for HD.

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