[mythtv-users] Vizio LCD native resolution problem over DVI->HDMI [SOLVED]

Andrew Berry andrewberry at sentex.net
Fri May 16 18:59:18 UTC 2008

On 16-May-08, at 2:10 PM, Richard Shaw wrote:

> I now have it working over VGA at 1366x768 with no overscan which I
> guess I'll live with. I may sell my DVI->HDMI cable to buy a nicer VGA
> cable than the one I'm using.

I just went through this process on my machine. I was using the same  
video card, but am currently using an AT 9800 pro with the  radeon  
driver and won't be able to switch back to the Nvidia card for a few  
days - so hopefully this still works with the other card!

Essentially, the problem was that my TV (Sharp Aquos) was reporting a  
physical size of 0x0mm for 1360x768 over HDMI, but the proper size  
over VGA. By default, xorg will interpret this as an invalid modeline,  
and ignore it. Manually extracting the modelines from the Xorg logs  
and turning off EDID didn't help. But, the full resolution was still  
detected by xrandr! So:

$ xrandr -s 1360x768

would work, after logging in. Since I'm using Mythbuntu, I just set  
the screen resolution applet for the user to change the resolution on  
login. So GDM runs at 1280x720, but only until you log in.

And even stranger, xrandr shows a physical size, but it calculates to  
a 37" screen, not my 32". Even though this TV actually runs an  
embedded linux kernel (w00t!), yet again programmers were lazy and  
copied the software from a different model.

mythtv at uberphoenix:~$ xrandr
Screen 0: minimum 320 x 200, current 1360 x 768, maximum 1360 x 1200
VGA-0 disconnected (normal left inverted right x axis y axis)
DVI-0 connected 1360x768+0+0 (normal left inverted right x axis y  
axis) 820mm x 461mm
    1280x720       60.0 +
    1360x768       60.0*
    1024x768       75.1     70.1     60.0
    800x600        72.2     75.0     60.3     56.2
    640x480        75.0     72.8     60.0
    720x400        70.1
S-video disconnected (normal left inverted right x axis y axis)

Anyways, it seems really strange that xrandr is getting different info  
than the X server, but perhaps there's an option somewhere to say "I  
know this EDID seems wrong but use it anyways".

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