[opendtv] Re: Food for thought

  • From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
  • To: <opendtv@xxxxxxxxxxxxx>
  • Date: Thu, 15 Feb 2007 16:30:26 -0500

Mark Schubin wrote:

> In ATTC's testing, unfortunately, they found two models of DTT
> receivers that could not handle 720 x 480 imagery at certain
> frame rates (different rates for the two receivers). 720 is not
> only in Rec. 601, but it is also divisible by 16. Unfortunately,
> it's not in the infamous Table 3.

I'm not sure what the answer is, other than for the FCC or the ATSC to
take periodic surveys of receiver manufacturers to see what they
support. And then periodically revisit Table 3. At some point in time,
one might add 720 X 480 into Table 3, if all manufacturers in the past
15 or 20 years have tested to it.

A similar situation exists between STBs and monitors. The output of STBs
is not wide open. It's either composite (480i), S-video (480i),
component (at typically only 480p, 720p, and 1080i), and the digital DVI
or HDMI, at the 60 frames or fields/sec, or thereabouts. The monitor is
expected to take one of these options, at least, and display them
correctly in whatever native format the monitor uses.

Of course, the monitor manufacturers might prefer to add other options,
such as 50i and 50p, but STB manufacturers for the US market would
probably be wise to make certain basic options *always* available.

To me, these are related. Broadcasters would probably also be wise to
stick to a limited list of options. Of course, nothing precludes adding
black bars top and bottom or on the sides, if they want to indulge in
multiple aspect ratios, at some loss of resolution. That was true in
analog TV too.

Bert
 
 
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