[mythtv-users] DVI to Sony HS420 series HDTV

[Brad Templeton]

On Sat, Jan 22, 2005 at 08:18:44PM -0600, Paul Miller wrote:
> 
> I read somewhere that all HD sources use a 16:9 aspect ratio.  My 
> television is 4:3.  Should the DVI signal still be 16:9?

DVI contains no information on aspect ratio, as far as I know, it's
a digital version of component video.

I have not played with 4:3 HDTVs.  They are rarer (though they actually
make sense in the transition period when most of your content is still
4:3.   During this mixed period you are going to "waste" screen real
estate one way or another by watching stuff of a different aspect
ratio on your tube.  If you think it will mostly be 4:3 you watch your
choice makes sense, though it will make less sense in a few years.)

I can imagine a few ways this might work

a) The TV pretends to be a 16:9 TV when it sees a signal with 720 or
1080 lines.   Unfortunately it can't tell with 480 lines what you are
sending.   Well with DVI it could count pixels, but I have not heard
of that, since the TVs also have component and mostly use it.

b) The TV has a mode on it you put in to tell it when to pretend to be
a 16:9 TV.   In the pretending mode, it only displays into a 16:9 box
with letterbox bars done by the TV.

c) The TV is a 4:3 TV.  Your transmitting box is expected to know this.
Thus you would feed it 1280 x 960, not 1280x720, and 1920 x 1440, not
1920 x 1080.   Your box would be putting in the letterbox bars.  This is
what myth and xvideo will do, it's what you get if you run Myth on
your computer monitor.

Now C seems most likely.  All HDTV STBs have a menu setting asking if
the TV is widescreen or 4:3 in them.   Myth doesn't have one per se,
you have to put fields into xorg.conf and edit the command lines myth
uses to call mplayer to make it work on a 16:9 TV -- which you don't have,
so you're golden!

What I don't know is if the HTDV STBs know as much about 4:3 based
HDTVs.  I presume they do since they are rarer but not unknown.

A proper 4:3 HDTV has to have more than 1080 lines of course, it needs
1440 to do the full res.  Which I believe the fancy Sony does.