[opendtv] Re: Popular screen aspect ratios

  • From: Craig Birkmaier <craig@xxxxxxxxx>
  • To: opendtv@xxxxxxxxxxxxx
  • Date: Mon, 17 Jan 2011 08:39:17 -0500

At 7:35 PM -0600 1/16/11, Manfredi, Albert E wrote:

 > Regardless of the restrictions placed on incoming MPEG-2 streams,

 the output side of STBs had to be restricted to some sensible set of
 display options like .



 As I have always thought, you continue to focus on only half the problem.
And oh by the way, if I'm not mistaken, in the early to mid 1990s, when ATSC was attempting to standardize display aspect rartios, virtually ALL computer displays were 4:3. All except perhaps the specialized machines. So if anything, the fact that DTV allowed for 4:3 or 16:9 display shapes was an improvement over what computers were doing, and caused certain computer companies to bitch loudly.
The different resolution settings available in computers of those days were (as far as I ever encountered) all for square pixel, 4:3 displays, and the resolution only used to determine how much text could be fit in the screen.
And now, the computer industry found it to their advantage to comply as well. Smart move!
Circumstantial evidence. By the way, the computer industry DID NOT complain about moving to a wider aspect ratio; they supported Hollywood in asking for 2:1 rather than 16:9.
In the late '80s and early '90s the computer industry, like the TV industry, had to deal with a major technical challenge: 

The DIPLAY.
The only viable display technology available in the era you are describing was the CRT. And CRTs are NOT a good technology for wide screens because of the issues of maintaining linearity near the horizontal edges of the screen, not to mention that large 16:9 CRTs weight a ton.
The breakthrough came a bit later with what I used to call "lithographed" displays. These are displays where the pixels are physically aligned with the screen such as Plasma, LCD, DLP and some of the newer technologies like OLED.
The computer industry had already standardized on square pixels for many reasons and strongly suggested that broadcasters do the same to support the convergence we are finally seeing today. But the broadcasters did not care about square pixels and wanted to maintain an archaic form of compression designed for CRTs called iNtErLaCe.
The computer industry pioneered the used of LCD displays, first in notebook computers. As the technology matured the industry DID move to wider display formats such as the 1.6:1 display on this laptop. My first laptop had a B&W 4:3 display; I bought it in 1992, in part to work on with ACATS to develop the U.S. DTV standard.
And the computer industry was way ahead of the TV industry in completing the migration from CRTs to lithographed displays. My first DTV was an analog projection unit with a 4:3 screen that I purchased in 1997. I chose 4:3 because almost all of the TV content at that time was 4:3, yet the set could deliver 16:9 at full screen width; it just made sense at the time. 

Regards
Craig


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