[opendtv] Re: Optimizing the system

  • From: Craig Birkmaier <craig@xxxxxxxxx>
  • To: opendtv@xxxxxxxxxxxxx
  • Date: Thu, 23 Dec 2004 09:11:28 -0500

At 4:12 PM -0500 12/22/04, Manfredi, Albert E wrote:
>So tell me this: what would you lose by storing everything
>as 1080 line in the HD-DVD, vs 720 line?

Quality, especially during peak bitrate demands that exceed the 
channel capacity.

The point I am trying to make is that there would be little if ANY 
perceived difference in quality on any set, and that for 99% of ALL 
sets, you would not be able to see the difference even if the 1080P 
encoding is "perfect." By encoding 720P at a high quality level you 
will make more consistent use of the available channel which will 
benefit EVERYONE.

>Would it cost more? No.

Actually yes, because it would require more attention during encoding 
to deal with the scenes that fall apart with 1080P.

>Would it be incompatible with some players? No.


>Would it mandate that users buy a more expensive display?
>No. It just means that some or even most won't be able
>to enjoy the full glory of the recorded material, but
>so what? This would still provide as good a picture as
>their sets will allow.

some. Those who can afford a 1080P display that is more than 100 inch 
in diagonal.

MOST (99%) will still see the full glory of the source because it 
will be of higher quality than their displays. And the difference 
seen by those in the "some" category will be negligible at best. They 
will see slightly more detail on less demanding scenes, and slightly 
more compression artifacts on the demanding scenes. Actually they may 
see significantly more compression artifacts anyway, simply by virtue 
of having a screen larger than 100" diagonal, which tends to make all 
compression artifacts more visible.

>Gee, it seems there's no point in compromising the
>software, then. And, of course, upconversion does not
>create information out of nothing. So the "economic"
>issue is just vapor.

Upconversion does not NEED to create information out of nothing. It 
is already there. Once again you are ignoring the FACT that MPEG-2 
removes resolution in order to achieve high levels of compression 
efficiency. During stressful scenes, the 720P encoding is likely to 
deliver HIGHER QUALITY samples than a 1080P encoding. I would MUCH 
prefer to watch an upconversion of high quality source than a 
compromised 1080P version that modulates in resolution and falls 
apart during stressful scenes.

>Which is why I have repeated every single time that this
>is subject to channel capacity *only*. Nothing else. (At
>least, nothing else after local stations have upgraded
>their own production facilities to HD, which they're sure
>to do in due course, just as their audio facilities have
>been upgraded to true hifi audio since the early 1970s.)

Many stations will NEVER upgrade to HD. They have NO reason to do so. 
Many stations have NEVER upgraded to local stereo audio production. 
And Hi-Fi. Obviously you have never worked at a TV station...

>You have absolutely no logical economic reason to
>restrict HD quality to less than 1080 lines. The only
>valid excuse is RF channel or storage device capacity, as
>I've said all along, which is considered on a case by
>case basis.

I certainly do. It is not needed for digital television distribution 
system which targets the mass market. It is UNNECESSARY overkill. 
1080P will find a home in THEATERS with BIG screens, not home 
theaters with TV screens.

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