[opendtv] Re: Some results - 1080p @ 60 is Next?

  • From: Craig Birkmaier <craig@xxxxxxxxx>
  • To: opendtv@xxxxxxxxxxxxx
  • Date: Tue, 15 May 2007 12:45:03 -0400

At 11:15 AM -0400 5/15/07, Manfredi, Albert E wrote:

Besides which, with the prices of 1080p displays falling rapidly,
there's no reason at all to get stuck on 720p for archiving or
acquisition. What's the point?

There is nothing wrong with oversampling displays. However, the added expense is only justified for screen sizes that need the extra resolution to prevent the the perception of the raster and raster related artifacts.

I know of no one who has suggested that 720P should be used as an archival format (except for live programming that was originated in the 720P format.

There are MANY reasons to use 720P for acquisition, especially for programming with high motion content.

First, 720P is more than adequate for programming that will be delivered as SD, ED and lower quality for hand helds and mobile applications.

Second, for high action, 720@60P is superior to higher resolution formats due to the improved encoding for emission. This DOES NOT mean that the acquisition system should be limited to 1280 x 720 - it means that it is beneficial to oversample in the camera to produce the highest quality 720P possible to feed to the emission encoder.



 Bottom line, let's stop this endless pursuit of ever higher
 numbers, and focus on ever higher delivered image quality.

The numbers are not ever higher. They are the upper bound of HDTV.
That's where everything will converge, simply because that's how HDTV
was standardized.

The upper bound of HDTV as standardized for emission has a reference clock of 74.25 MHz - this is used for both 720@60P and 1080@30i. SMPTE 274M also includes the 148.5 MHz clock for the 1080@60p formats. These format may have a place for acquisition and archiving, however, to deliver them with adequate quality we will need significantly more bandwidth than is available in any DTV emission standard - it won't even fit on HD-DVD or Blue-Ray.

I am amazed that so many people think we need to move to 1080@60P, just because a handful of cameras now exist to acquire it.

ONE MORE TIME: with Digital TV, acquisition/production, emission, and display are decoupled.

We expect the display system to deal with anything you can throw at it (although the ATSC restricted the possible formats). Soon we will expect our TVs to display anything that we can access, from OTA DTV, Cable, DBS, IPTV, packaged media AND Internet downloads. A video on YouTube may be just as important (to a viewer) as a prime time show from the media conglomerates.

And speaking of convergence Bert...

Would you care to guess at a date when Standard Definition TV will cease to exist?

Just because we created a DTV system capable of delivering HDTV, this DOES NOT mean that everything will converge on HDTV. It's just an application.

I am writing a feature story on Mobile TV for Broadcast Engineering bert...

Would you care to guess when we will deliver AT LEAST 720P to every portable/mobile device and telephone handset?


But while we're at it, a good test would be to compare, on a new 1080p
display that can sync up to 1080 at 24p, a 1080 at 24p transmission of
material acquired at 1080 at 24p against a 720 at 24p transmission of
material acquired at 720 at 24p. Since these are already both standard
formats for acquisition and for transmission, that should be a doable
do. Oversampling might be a good thing, but increasing the bandwidth of
the entire chain is even better.

This is a useful comparison.

How are we going to increase the bandwidth of the entire chain Bert?

It is easy to see how we can keep improving the acquisition and display components of the DTV system. We may even develop new distribution formats that can deliver higher quality than the DTV formats.

But to increase the bandwidth of the emission system we will need to change the emission standards. Would you like to move to 8MHz channels? Or perhaps we can develop new modulation systems that can carry more bits - whoops, I forgot your constant reminders that we are already approaching the theoretical limits for channel coding.

You are missing a very important, and equally obvious issue here Bert.

Our DTV standard was designed to deliver TV to the masses, NOT to videophiles. One can make a very strong argument that we do not even need HDTV to deliver high quality images to the AVERAGE sized consumer display.

It is absurd to be talking about raising the upper limits on HDTV at this time - let's figure out how to use what we've got without the constant appearance of compression artifacts.



With that info in hand, one should be able to see whether it makes sense
to pursue 1080 at 60p transmission.

With the info at hand it is obvious that we DO NOT need to pursue 1080@60P as an emission standard.

Regards
Craig


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