[opendtv] Re: Learning From the Veterans - local news in HD

  • From: Craig Birkmaier <craig@xxxxxxxxx>
  • To: opendtv@xxxxxxxxxxxxx
  • Date: Wed, 28 Apr 2010 07:54:51 -0400

At 2:36 PM -0500 4/27/10, Manfredi, Albert E wrote:

 > Honestly, I think that if broadcasters would start going to wide

 screen anamorphic exclusively, that would get us just about the
 same effect as AFD. Certainly on 16:9 displays, which as you
 point out, are taking over. STBs used on 4:3 sets could give the
 user a choice of letterboxing or cropping.
To clarify here, use wide screen anamorphic even when transmitting 4:3 content.
The result is, on wide screen monitors, you get a properly pillarboxed 4:3 image always, you get a full screen display when content is 16:9, and you get letterboxed display when content is wider than 16:9. Never any distortion.
This would have been a step backwards. The new sets have sufficient smarts to accommodate all formats and with the header and descriptor data could automatically provide the best accommodation of SD content. This approach would have further reduced the resolution available to new 16:9 sets when a broadcaster was delivering legacy 4:3 content, which STILL is most of the time.
On 4:3 sets, via the STB, you normally see full screen for 4:3 or 16:9 content (which is cropped). And you get letterboxing for content that's wider than 16:9.
This is less than optimal, as you still need to protect the 4:3 safe area for 4:3 sets, thus making it necessary to fill the 16:9 frame with throw away information. 



Don't know how AFD can make the situation much better.
AFD was not and still is not the best answer, although it is part of the solution - to be completely correct, the proper identification of the format in the headers and descriptors is the solution, which is what AFD is all about.
The best answer is to send ANY content in any resolution and any aspect ratio following one simple rule. Encode the content using orthogonal samples (square pixels) and report the raster size and aspect ratio in the headers. Make every set accommodate the content the best way possible for the local display. The ONLY limitation here is the performance profiles that are used for encoding - i.e. the level and profile used for the particular video compression codec. And this only sets an upper limit on samples per second, not the formats that can be supported at that sample rate.
Ironically, this is what has happened with Internet video because the target displays are EXPECTED to have the intelligence to accommodate ANY source properly and the folks encoding the content are using the compression technology as it was designed and intended to be used. 

Regards
Craig


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