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

  • From: Craig Birkmaier <craig@xxxxxxxxx>
  • To: opendtv@xxxxxxxxxxxxx
  • Date: Thu, 29 Apr 2010 07:30:17 -0400

At 2:57 PM -0500 4/28/10, Manfredi, Albert E wrote:
This is what I'm talking about. If the HDTV picture must be set up to use common sides with a 4:3 aspect ratio display, and if that content is also to be viewed intelligibily in analog CRTs (which is THE reason for supporting 4:3 TV anymore), then the content displayed in the horizontal dimension is not going to be any more than the content that can intelligibly be displayed on an old analog set. 

Yes the horizontal content is the same, but the resolution IS NOT.
An HD version is extracted from the original high resolution 4:3 source using tilt and scan techniques to extract the 16:9 HD version. This could be 1280 x 720 or 1920 x 1080 depending on the resolution of the original source. Then the entire 4:3 version is resampled for SD output. This would typically be 704 x 480 in ATSC/NTSC land. Thus there is true HD resolution in the 16:9 HD version and SD resolution in the 480 line versions (both digital and analog).
Ergo, the HD resolution has not been exploited properly. Similar to viewing 320 X 200 graphics on a VGA display. Even if the original capture was in UHDTV, makes no difference. At best, you see more of the facial hair.
Sorry, but you are incorrect. Common sides allows the PROPER creation of both HD and SD versions with new information entering both frames at the same time from the sides. The SD version actually shows more image content but at significantly lower resolution, and the extra information on the 4:3 display is now the "Throw Away" information, while ALL OF THE INFORMATION in the 16:9 frame is within the "safe area."
You need to think like a cinematographer or videographer. When working with multiple aspect ratios you need a common safe area which needs to include the information that everyone must see. Working with safe areas has always been a concern for TV because of the use of overscanning. Hollywood often shoots with a safe area that is well within the edges of the acquisition frame so that they can have some control over the portion of the image that is actually used in the movie. Thus in the theater, you may see only what is in the safe area, or a subset of the safe area (zoom in), or an area that is larger than the safe area (zoom out). The high resolution (over-sampling) of the film negative allows this flexibility when printing the release frames.
As sampling resolution increases in electronic acquisition (e.g. 4k x 2K) it becomes possible to use these same variable extraction techniques in post production. You still seem to be living in a world where video cameras samples at the same resolution as what will eventually be displayed, and what the cameraman sees is essentially what you see at home.
You need to think of acquisition as being decoupled from emission. Acquisition SHOULD employ oversampling in order to deliver the best possible emission quality at multiple levels of resolution and in multiple aspect ratios. 




 If broadcasters would have been serious about the HD transition they
 would have started shooting everything in 16:9 HD and letterboxed it
 into the legacy 4:3 display. This would have solved the common sides
 problem and acted as a continuous advertisement to the holdouts to
 upgrade to a 16:9 display, where the screen would be filled AND
 higher in resolution.
I agree totally with the concept, but not with who's at fault. It wasn't necessarily BROADCASTERS. In fact, our Fox affiliate used to transmit their prime time shows letterboxed, on their NTSC channel, until the network found out, or until they got too many complaints, and then it was back to so-called "full screen." In the Fox case at least, it was network policy, Craig. No letterboxing on analog sets. Not the broadcasters. 


Fox is a broadcaster.

Thank you for making my point!

Regards
Craig


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