[opendtv] Re: Popular screen aspect ratios

  • From: Craig Birkmaier <craig@xxxxxxxxx>
  • To: opendtv@xxxxxxxxxxxxx
  • Date: Thu, 30 Dec 2010 09:29:04 -0500

At 9:56 PM -0500 12/29/10, Albert Manfredi wrote:

No, you continue to miss the point.

How do you set up your PC display, Craig?

I don't. When I plug in a display it is automatically recognized and the display is set up to its native resolution. THe only things I may adjust are the position of one screen to another when using multiple screens, and whether or not to mirror the second display.

You are correct that there are many other graphic card modes that can be used, but it is very rare that I run a display at anything other than its native resolution.

BUT NONE OF THIS HAS ANYTHING TO DO WITH HOW VARIOUS SOURCES ARE PRESENTED ON THE ATTACHED DISLAYS.

Sources open in a window that is the correct aspect ratio, typically with a 1:1 relationship between source samples and display samples. If I choose to expand the source to full screen, the player, typically QuickTime, automatically scales the source to fill one axis of the screen with black bars on the other axis. SIMPLE.

What if you have an oddball display that doesn't show up in the graphics card options?

You may need a driver for the display. The graphics card simply needs to know what it is going to output. IT can deal with anything up to its design limits.


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.

Dumb PCs.

Mac negotiates with the display and sets the graphic card up correctly. I always wondered why every device I buy that works with a PC comes with those discs I never use...

Regards
Craig



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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