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Posted by Joshua Zyber on 12/06/06 23:38
"Jukka Aho" <jukka.aho@iki.fi> wrote in message
news:4Qzdh.954$kD4.560@reader1.news.saunalahti.fi...
> The aspect ratio switching works on a computer screen because the
> (software-based implementation of a) DVD player on a computer can
> directly read the aspect ratio flags off the original MPEG-2 stream.
> The situation is different when you're watching DVDs using a set-top
> DVD player and a regular tv set. The tv set does not have any direct
> access to the original MPEG-2 stream, much less to the aspect ratio
> flags within that stream. Only the DVD player has access to that
> information.
>
> It is possible to relay the aspect information from a set-top DVD
> player to the tv set - and that is indeed what is being done in 625/50
> countries. For that to work, however, you need an aspect ratio
> signaling specification: some sort of standard that is universally
> agreed upon among DVD player manufacturers and tv manufacturers.
>
> Two such widescreen signaling standards have been devised for the
> 625/50 system. Both are widely used in the PAL countries. But neither
> of these methods is directly applicable to the 525/60 ("NTSC")
> signals.
>
> What I'm interested in, and what my original question was about, is
> whether there are similar (widely-used and widely-supported)
> widescreen signaling standards for the 525/60 world - and if so, how
> do they work, and where are they specified.
Yes, this does exist for NTSC content, but the aspect ratio flag is only
transmittable over an HDMI connection. There are a number of televisions
and external video processors that can read the aspect ratio flag and
automatically switch to the correct screen mode.
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