[opendtv] Re: Optimization

  • From: Craig Birkmaier <craig@xxxxxxxxx>
  • To: opendtv@xxxxxxxxxxxxx
  • Date: Fri, 17 Dec 2004 09:53:47 -0500

At 6:33 PM -0500 12/16/04, Manfredi, Albert E wrote:
>Craig Birkmaier wrote:
>>  But 480P is STILL plenty adequate for many applications,
>>  and more important, why not improve the quality of ALL
>>  TV, not just HDTV?
>Exactly, Craig. Which means, cram as much info in the
>channel or storage medium as capacity permits, subject
>to the constraint that the channel or storage medium
>is compatible with ALL TVs! This will improve the
>quality of all TVs, small ones AND big ones.

Compatibility is not a problem. Formats are just numbers. ANY DTV 
display must have the necessary scaling to deal with multiple 
formats. Once you byte that bullet you can support ALL formats up to 
the performance limit of the box.

What you are suggesting is that ALL boxes must be optimized for the 
highest level of performance.  This is unnecessary overkill.

There is no reason that every form of content must fill the pipe. The 
determination of delivered image quality should be made by the people 
producing the content, based on the needs of their application. Based 
on this premise, I would suggest that we have seen a decline in 
acceptable image quality during the first phase of the DTV 
transition. The vast majority of digital distribution systems are 
delivering something less than NTSC quality. The masses are paying 
for expanded choice over expanded quality...for now.

I see no indication that the masses are suddenly going to jump to the 
highest level of quality available - like everything else in the 
world of consumer electronics, the masses will migrate up the quality 
scale in small measured steps, as they can afford to do so.

>So, 480 at 24p is probably a good choice for a station
>wanting to multicast decent quality programs.

Why 24P? That is a producers decision, not the distributor. I am 
pleased that you at least raised the bar to 480P, as I have been 
suggesting. This is exactly what I meant by saying that we can 
improve the quality of ALL programming for the mass markets.

>But 480 at 24p is not a good choice for next gen movie
>DVD, as long these DVDs can hold an entire HD movie.
>What are you saving that space for? Another movie in
>the same disk? Does anyone care about that?

Agreed. I have no problem with 720P for HD-DVD.  it is the best choice.

But for channels that are bandwidth constrained, e.g. broadcast 
multiplexes, 480 or 576P may make more sense.

>Similarly, a station wanting to broadcast sports and
>attract a large audience of large screen fanatics will
>opt for true HDTV, like 720 at 60p or 1080i, for the
>duration of that game.

720P. In my book, 1080i is not HDTV. Likewise, any other interlaced 
format does not belong in DTV. Sadly, even in this country, most 
content is still being optimized for 480i.

>A station wanting to multicast one good quality sports
>program along with an HD program will have to use 480
>at 60p for the sports show, and may fit a 720 at 24p
>for the HD program. Or certainly they can multicast
>one 480 at 60p and one 480 at 24p stream.


Now that you have made this intuitive leap, I would suggest that the 
game still be shot in 720P, then downconverted to 480P for emission, 
if for no other reason than the fact that some distribution systems 
will havve the capacity to deliver the full HD resolution, while 
others may dchoose to optimize for multicasting. The good news with 
progressive formats is that it is easy to do this, and the quality of 
the resampled 480P program will be better than if shot using 480P.

>>  There are many applications for progressive video
>>  that is not HDTV.
>As long as you are *not* negotiating a unicast
>session over a relatively slow link, or otherwise
>limited in channel capacity, there's just no reason to
>limit the bitstream JUST BECAUSE you can do so.

One word: ECONOMICS.

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