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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