[opendtv] Re: Popular screen aspect ratios

  • From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
  • To: "opendtv@xxxxxxxxxxxxx" <opendtv@xxxxxxxxxxxxx>
  • Date: Mon, 10 Jan 2011 15:57:08 -0600

Craig Birkmaier wrote:

> It is true that the cropping and any pan and scan would be done by the
> decoder. This is as the MPEG-2 standard intends, and is totally
> consistent with what I have been saying about what decoders must do
> for legacy 4:3 outputs.

Two different scenarios: (1) the "dumb as possible" display is dedicated to 
provide the output of a processor (TV STB or PC CPU), and (2) the integrated 
receiver and display designed to operate in a one way, one-to-many broadcast 
environment.
 
The reason the decoder in the STB or CPU does the heavy lifting in case 1 is 
simple, Craig. It's because you want to make the displays as cheap as possible. 
You don't want to have to send all the information to the display, and then let 
the display parse everything. In  the computer example, you don't want to send 
a huge amount of display information to low resolution displays that can't 
possibly handle it. This is the *opposite* case from the broadcast TV standard, 
where the broadcast nature of OTA TV does make it desirable to let the receiver 
parse through common data streams, and each receiver send to its display only 
what it can use.

> As for 16:9 displays, just hook up the analog component or HDMI input
> to the TV and let the display do any accommodation that the viewer
> desires. For example, in the .ts file that Ron sent, it appears that
> the actual movie clip is wider than 16:9, so it is stuffed into the
> 16:9 container in letterbox.

> Once again, this is totally consistent with what I have written
> previously.

You are once again, now, presuming the 16:9 standard that you previously 
claimed we didn't need. After-the-fact image accommodation assumes the 
distortion problem has been addressed already. That's what the 16:9, or 
possibly a couple more *standard* options, come in.

I do sympathize, though, if you are arguing that a TV receiver/display 
integrated box to be connected to an STB, given that the TV must already 
incorporate an ATSC receiver, would best use the ATSC standard signal, and let 
the receiver do more of the heavy lifting.

But that's NOT what is being discussed here. We are talking about the baseband 
display interfaces. We are talking about boxes that were and are designed to 
assume no ATSC or other significant smarts in the display.

> In addition to video signal, the VGA connector has some monitor
> identification pins (pins 11, 12 and 15) that allow PC video cards
> to determine what type of monitor is connected to the graphics card.

Ah, excellent. Thanks. I suspected as much, but was not finding the information 
online in a brief search.

Bert
 
 
----------------------------------------------------------------------
You can UNSUBSCRIBE from the OpenDTV list in two ways:

- Using the UNSUBSCRIBE command in your user configuration settings at 
FreeLists.org 

- By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word 
unsubscribe in the subject line.

Other related posts:

  1. Home
  2. opendtv
  3. Archive
  4. 01-2011