[opendtv] Re: Popular screen aspect ratios

  • From: Craig Birkmaier <craig@xxxxxxxxx>
  • To: opendtv@xxxxxxxxxxxxx
  • Date: Sat, 1 Jan 2011 10:46:19 -0500

At 5:52 PM -0500 12/31/10, Albert Manfredi wrote:
The STB has the MPEG decoder, not the display. So the STB has to know how to fill in that display shape. Since the STB is upstream of the display, without the two-way interface, YOU have to tell the STB, Craig. It's so simple.
I already addressed this. The location of the decoder "may" be in a STB, or it "may" be integrated in the TV. And in the case of using an antenna for off air AND a MVPD service, both decoders will typically be used.
But the choice of outputs from an external box is just as I described: if the box is connected to a legacy 4:3 display you set it to 4:3. If the box is connected to a digital TV you set it to 16:9. IN the first case aspect ratio accommodation is the responsibility of the external box. In the second case it is the responsibility of the display processor.
Obviously you will ALWAYS need to tell the ox what to do when connecting to a legacy analog display. For Digital TVs it will depend on the connections you choose. Only HDMI has the ability to negotiate with the external box. 




 And once again, the only decision for an MVPD STB is whether you are
 connecting to a legacy 4:3 display, which will rely on the STB to
 handle aspect ration accommodation, or a Digital TV, in which case
 the STB is set for 16:9


So, now you assume that a "digital" TV is 16:9? Interesting.
Not necessarily. I am assuming that the external box is going to output a widescreen signal; AND I am assuming that the display will deal with aspect ratio accommodation. I have had both 4:3 and 16:9 Digital TVs; for both the cable box setting is the same; dittos for the DVD player. The accommodation takes place in the display processor of the TV.
The ATSC did want the FCC to establish 16:9 as the "digital TV" display shape. But the FCC didn't grasp that without such a standard, displays makers could design oddities like 16:10 displays, or 1.25:1 displays, or any other weirdness, and that STBs would therefore have to incorporate all those options too. Or, obviously, mandate a two-way display interface, as we have already talked about, that didn't exist.
Rubbish. The underlying MPEG-2 standard has everything necessary to deal with automated aspect ratio accommodation for ANY format. A display manufacturer could easily have used this data to build products with ANY screen aspect ratio, which would deal properly with different formats.
This is not rocket science; we explained this to the FCC and they understood, which is why they agreed to pull Table 3 from the standard. It is the CE manufacturers who wanted to lock everything up because they did not understand how to build software based products that are compliant with multiple flexible standards. THEY WERE TRYING TO REPLACE A LEGACY PRODUCT THAT WAS CRIPPLED JUST LIKE THE LEGACY PRODUCT. 




 Why were you using the VGA interface?
It's obvious why. The TV has one, along with stereo audio mini-phone plug, the PC's video card that is incorporated in the motherboard has one, also with a mini-phone plug stereo audio, so I can use VGA without having to buy anything extra. I could have opted for the HDMI card, which is extra. Almost did, but then I realized it wasn't necessary. 

No DVI?

Too bad.
Which Dell model did you buy? I just looked up the Insperion 580 and it says it comes with HDMI.
And I always wondered how you continued to miss the obvious issues, Craig. I also wondered why you thought the "computer industry" was doing this any differently. I also wondered why the FCC couldn't get it. Just because a company might have developed a proprietary solution is not an excuse for misunderstanding the problem.
Neither the ATSC nor the FCC understood the problem. They were both trying to create an incremental update to the traditional broadcast TV model. We spent years trying to educate both about the real potential for moving to Digital TV. The net result was that we identified all of the potential barriers to interoperability, and the broadcasters and CE companies decided to build walls rather than embrace the real potential of the digital revolution.
Here we are nearly two decades later and EVERYTHING we explained and predicted has come to pass. The content oligopoly is quite happy about their ability to slow down the "digital transition" and interoperability with PCs. Now they are focused on controlling the Internet so that they can keep control of their little empire. 

Some things never change.
The simple truth is, Craig, that BOTH the TV industry AND the computer have ALWAYS had the same problem, when using analog interfaces at least. BOTH required the user to tell the MPEG decoder what the display looked like. BOTH created image distortion when the MPEG decoder wasn't set right.
Aside from the fact that what you wrote in this paragraph is technically wrong, the computer industry began to move away from analog display interfaces in the '90s.
You still do not understand the role that the decoder plays in all of this, or the inherent flexibility in the specifications for digital entropy encoders like MPEG-2 and h.264.
Formats are for the most part irrelevant; they are the product of legacy thinking. 

Regards
Craig


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