[opendtv] Re: Popular screen aspect ratios

  • From: Albert Manfredi <bert22306@xxxxxxxxxxx>
  • To: <opendtv@xxxxxxxxxxxxx>
  • Date: Wed, 29 Dec 2010 21:56:52 -0500

Craig Birkmaier wrote:
 
> But there is nothing to say that all sources must be optimized for 4:3
> or 16:9. It is quite easy to optimize source for any display resolution
> and aspect ratio. This happens all the time via the Internet,
 
No, you continue to miss the point.
 
How do you set up your PC display, Craig?
 
Answer: you choose from a discrete set of options supported by your grahics 
card. Just as you do with the STB to a TV set, but the options are (a) more 
numerous than just two, and (b) labeled as square pixel combinations, rather 
than aspect ratio per se. You can determine the aspect ratio with simple 
division.
 
What if you have an oddball display that doesn't show up in the graphics card 
options?
 
Answer: PC displays come with their own setup CD. The CD has to be used to 
enter the correct display aspect ratio and resolution choice into the graphics 
card. THEN you are given the opportunity to select a choice that won't distort. 
If you choose wrong, you WILL see image distortion. Same as you do with the STB 
setup. Try it if you don't believe me.
 
Here is the way I'll bet you a truckload of cash the Philips 21:9 display works.
 
The source STB or DVD player must be set to 16:9. The source frame arriving 
into the Philips display is always assumed to be a 16:9 image, and by default, 
the Philips adds two black pillars, to make the frame fit centered in its 21:9 
frame.
 
Obviously, that incoming 16:9 image may already have its own black bars, e.g. 
if it's in fact a 4:3 image, or if it's in fact a 21:9 image. But those 
incoming black bars are just assumed to be incoming image content by the 
Philips display. So, it may have to add its own two pillars to already existing 
pillars, for example. That's how 4:3 images end up with enormous pillars at the 
two sides.
 
Let's say you are watching a 21:9 movie. The image arrives at the Philips 
display as a 16:9 letterboxed image. Then the Philips adds two black bars left 
and right, same as always, creating an image that's both letterboxed and 
pillarboxed. I'll bet you dollars to doughnuts that this is how you initially 
see the 2.35:1 movie. THEN the user can zoom in, eliminating the black bars, or 
use whatever other options, after the fact.
 
So, there is no major difference in how this stuff is done on TVs and PCs, 
Craig. Except that the ATSC did not expect that STBs would provide for setup CD 
inputs, to accommodate any and all oddball display shapes, so they instead 
wanted to create a pre-selected set of options only.
 
For some odd reason, the FCC didn't get this.
 
I will agree that in a parallel universe, all displays might be required to 
have a standardized two-way interface with any STB, so that the STB can 
automatically accommodate any shape imaginable of display, and render the image 
correctly.
 
Bert
                                           
 
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