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 Posted by moviePig on 12/05/06 22:14 
Jukka Aho wrote: 
> Howard Brazee wrote: 
> 
> >>>>> Okay, I'm shopping right now for HD tvs.  I take it your set 
> >>>>> somehow senses the DVD anamorphic signal? 
> 
> >>>>> If everything is configured correctly (no guarantee of 
> >>>>> that, of course), that's pretty standard. 
> 
> >>>> How is that done in NTSC/ATSC land? You don't have SCART 
> >>>> connectors, so you can't use SCART pin 8 widescreen 
> >>>> signaling. You also can't use PALplus style line 23 WSS 
> >>>> signaling - at least not on line 23. So how does the set 
> >>>> know whether it is receiving full-screen 16:9 (16F16) or 
> >>>> full-screen 4:3 (12F12) signal from a DVD player? 
> 
> >>> I get OTA digital HD to my Sharp Aquos, I don't want to pay for 
> >>> cable or sat. Shows that are widescreen come in widescreen, those 
> >>> that come in 4:3, come in regular. The tv changes everything on 
> >>> its own, as broadcasted. 
> 
> >> That's understandable for OTA HDTV broadcasts. If the set has a 
> >> built-in ATSC (HDTV) tuner/decoder it can read the aspect ratio 
> >> flags straight off the digital stream. 
> >> 
> >> But what about playing back DVDs (which is what the original question 
> >> was about)? How does the DVD player tell the tv set "this signal is 
> >> full-screen 16:9" or "this signal is full-screen 4:3"? 
> 
> > It wouldn't take much programming for a decoder to determine the 
> > aspect ratio. 
> 
> DVD players and their MPEG-2 decoders can read the aspect ratio flags 
> straight off the MPEG stream on the disc. That was not the question. The 
> question was, as you can see from the above, how this information is 
> relayed to the tv set so that aspect ratio switching works 
> automatically. (Note: we're talking about full-frame 4:3 and full-frame 
> 16:9 signals here. There are no black bars in the incoming signal that 
> the tv set could detect.) 
 
Doesn't the player send a digital stream of "square" pixels to the 
(digital) tv?  If so, it'd seem the aspect ratio's gotta be in there 
somewhere, either explicitly or implicitly. 
 
-- 
 
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