[opendtv] Re: Definition of Anamorphic
- From: Tom Barry <trbarry@xxxxxxxxxxx>
- To: opendtv@xxxxxxxxxxxxx
- Date: Tue, 06 Oct 2009 17:26:52 -0400
Manfredi, Albert E wrote:
> ...
> Which begs the question, why couldn't the BD simply display the proper 1.37:1
> Academy Ratio, then? Given that it bothered to include the pillars as part of
> the data, why not make the pillars slightly less wide?
>
> But back to Dan's question. The first time I saw "anamorphic" used to
> describe *digital* content was when it was used to describe a wide-screen
> DVD. My interpretation was, resolution was not wasted by letterboxing the DVD
> content, to create the wide screen effect, but rather the entire DVD frame
> was used to paint the 16:9 aspect ratio. So there is the analogy with film
> anamorphic content.
>
> I believe that DVDs are encoded as 720 X 480, at least in Region 1. That
> translates to 1.5:1 aspect ratio. So no matter whether you're viewing a 4:3
> DVD or a 16:9 DVD, the encoding pixels are never square.
>
> And yet, no one has ever referred to a 4:3 "full frame" DVD as "anamorphic."
> So the term is not typically used in a square pixel sense.
>
> I conclude that "anamorphic," when applied to DVDs anyway, means "compressed
> horizontally with respect to the traditional 4:3 DVD frame, and requiring a
> corresponding horizontal stretching in playback."
>
> Bert
>
>
I think the definition of "anamorphic" meant the encoded ratio was
different than the intended display ratio. But the intended display
ratio of DVD's was always 720x480, after overscan. That was never
square pixels on the intended 4:3 monitor anyway but was the intended
"full screen". Square pixels were never very relevant for scanning
CRT's. It was only with discussions of PC video cards and frame buffers
that actual horizontal pixel counts became more important, along with
the interlace wars.
I think I remember an old AVS discussion where BD's were never going to
be anamorphic. And they would always have any needed black bars encoded
into them. But the players were supposed to have any needed zoom/crop
options to display correctly.
- Tom
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