[mythtv-users] DVI to Sony HS420 series HDTV

[Paul Miller]

I did quite a bit of messing around with the television and video card 
yesterday.  I believe that all HD sources must be in 16:9 format, 
regardless of what they are outputting to.  So, I think you are 
partially right with (c), but the television automatically adds the 
black bars on the top and bottom of the screen.  It must be capable 
of doing 1440 lines (though actually only displaying on 1080) for 
widescreen videos.  For letterbox videos, the user needs to press 
zoom to view it in fullscreen, otherwise there'll be black bars on 
all sides.

I also tried using the AIW HDTV output cable (YPrPb) that came with my 
card.  In Windows, I can output 720p and 1080i on this cable.  It 
looks very sharp.  Unfortunately, when I play DVDs, the television 
blanks out after the FBI warning, even if the window is not 
maximized.  I suspect that the driver or hardware does this blanking 
whenever a copyrighted signal is being displayed.  On the regular 
component or S-video outputs, no such blanking occurs.  I wonder if 
the DVI-to-HDTV adaptor would do the same.

http://shop.ati.com/product.asp?sku=2538004 (AIW HDTV cable)
http://shop.ati.com/product.asp?sku=2537967 (DVI-to-HDTV adaptor)

In Linux, it's a disaster.  With the AIW HDTV output cable plugged in, 
the video card thinks the HDTV is now the primary display device.  My 
CRT monitor remains in powersave mode until I bring up X.  After X is 
launched, the HDTV is scrambled and nearly solid fluorescent pink.

-Paul

On Saturday 22 January 2005 10:06 pm, Brad Templeton wrote:
> 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.