[mythtv-users] Re: Custom Modeline

[Jarod Wilson]

On Thursday 15 July 2004 13:37, Chris Vargas wrote:
> --- Cory wrote:
> > You need to be careful on that. I'm assuming you're
> > trying to drive an HDTV with the VGA directly
> > (through an A960 YPbPr transcoder or something)?
> > If so, then the 1080i *is* the spec, and will not
> > like having more or less actual scanlines. You can
> > adjust the *visible* lines (e.g. 1920x980i) but the
> > number of total scanlines is limited by the spec.
>
> Cory: your initial reply to John caught my eye,
> because I'm in John's same boat. At first I thought
> I'd be able to correct it given your great explanation
> of modelines, but now I'm not so sure.

Cory is THE MAN when it comes to modelines... :-)

> I have a 9A60 transcoder (thanks yet again, Jarod!),

:-)

> and am trying to adjust the vertical dimension as
> well. My 480p modeline plays back anamorphic DVDs
> correctly, but my 540p and 1080i modelines (derived
> via Powerstrip) are all stretched too far vertically,
> so that an anamorphic test pattern displays circles as
> ovals.

I haven't really even had time to play with 1080i modes, but I did spend some 
time a while back further tweaking my 540p mode, because I had a bit too much 
vertical. I started with this 960x540p mode:

# My 960x540p mode
Mode "960x540p"
        DotClock 37.26
        HTimings 960 976 1008 1104
        VTimings 540 542 548 563
        Flags "+HSync" "+VSync"
EndMode

Then went to this mode, which eliminated all horizontal overscan, but left a 
tad bit of vertical overscan:

# My 888x508in540p mode
Mode "in540p"
        DotClock 37.26
        HTimings 888 944 1048 1104
        VTimings 508 534 548 563
        Flags "+HSync" "+VSync"
EndMode

Then to this, which is an absolutely perfect fit:

# My 880x480in540p mode
Mode "in540p"
        DotClock 37.26
        HTimings 880 944 1048 1104
        VTimings 480 506 520 563
        Flags "+HSync" "+VSync"
EndMode

The big problem I had with the second one was that while I could initially 
reduce the resolution a bit vertically, I couldn't get the picture to slide 
down, until dropping WAY down in resolution and using a much lower number for 
the first one after the vertical resolution (I don't know these things quite 
like Cory does ;-).

Also, xvidtune was great for experimenting with. Just knock your res down a 
little, but within a mode you know works, then use xvidtune to slide it 
around the screen. Or something like that. One of these days, I'll finish 
getting the 6106 drivers installed and configured on my HDTV-connected system 
and play w/1080i...


-- 
Jarod C. Wilson, RHCE
jcw at wilsonet.com

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