[mythtv-users] Nvidia DPI 1080x540

[George Mari]

Chris Ribe wrote:
> On 10/28/07, George Mari <george_mythusers at mari1938.org> wrote:
>> Chris Ribe wrote:
>>> On 10/28/07, Chris Ribe <chrisribe at gmail.com> wrote:
>>>> Hello all,
>>>>       I am struggling to get my frontend to play video correctly on my
>> new
>>>> TV.   It is a 1080i RPTV that I have working with a custom 1080x540
>>>> modeline.   When I playback recording or watch live TV, I get
>> horizontally
>>>> squished video, as if myth believes there are square pixels.
>>>>
>>>> I am running last weeks SVN, the most recent Nvidia drivers with a
>> 7200GS
>>>> graphics card, and I have followed the instructions in several howtos
>> on the
>>>> wiki, which have lead me to this xorg.conf  (edited to remove
>> irrelevant
>>>> information):
>>>>
>>>>
>>>> Section "Device"
>>>>         Identifier      "7200GS"
>>>>         Driver          "nvidia"
>>>>         BusID           "PCI:2:0:0"
>>>>         Option  "NoBandWidthTest"       "true"
>>>>        Option  "UseEdidDpi"    "false"
>>>>        Option  "UseEDID"       "false"
>>>>        Option  "UseEdidFreqs"  "false"
>>>> Option  "ModeValidation"        "DFP-0: NoEdidModes,NoMaxPClkCheck,
>>>> NoVesaModes,
>>>>  AllowInterlacedModes,NoDFPNativeResolutionCheck, NoHorizSyncCheck,
>>>> NoVertRefres
>>>> hCheck"
>>>>         Option   "ExactModeTimingsDVI"   "true"
>>>>         Option          "UseFBDev"              "false"
>>>> EndSection
>>>>
>>>>
>>>> Section "Monitor"
>>>>         Identifier      "51S500"
>>>>         Option          "DPMS"
>>>>         DisplaySize     243.84 137.16
>>>>         HorizSync 15-46
>>>>         VertRefresh 59-61
>>>>        Modeline "720hitachi" 79.5 1920 2088 2142 2412 540 572 576 592
>>>> -hsync -vs
>>>> ync
>>>> EndSection
>>>>
>>>>
>>>> From my understanding, the combination of the "UseEdidDpi"  "false"
>> tag,
>>>> the DisplaySize tag, and the resolution should lead the drive to
>> compute a
>>>> non-square DPI and video should display correctly.   Unfortunately,
>> this
>>>> isn't happening.
>>>>
>>>> Any suggestions would be greatly appreciated.
>>>
>>> So, I was just googling things like "xorg" "DPI"  and "non square
>> pixels,"
>>> and one search returned my original message from the archives as it's
>> 2nd
>>> result.  That was disheartening.
>>>
>>> Anyhow,  it caused me to reread my own message and discover that I said
>>> 1080x540 when I meant 1920x540.
>>>
>>> So, 1920x540 is the resolution I'm working at, 100,50 is the DPI I'm
>> looking
>>> for.
>>>
>> I'm not an expert on non square pixels, but when you say the video is
>> horizontally squished, does the image not extend all the way to the left
>> and right edges of your display?
>>
>> Are your recordings in 4:3 aspect or 16:9?
> 
> 
> 
> 4:3 recordings are displayed at a 2:3 aspect ratio.  It is a 16:9 display
> that myth is treating like a 32:9 display because the resolution is set to
> 1920x540.
> 
> 

I hope I'm not leading you down a blind alley, but this sounds an awful 
lot like what Jarod Wilson describes on his How-To:

http://wilsonet.com/mythtv/mythhd.php

He describes setting up a 540p modeline for his first HDTV, and he has 
some info on why 540p and 1080i are electriconically equivalent, etc.

He also seems to use a value of 960 - half of 1920 - throughout his 
Xorg.conf and modeline.  Maybe this is causing your squished image?

Then again, maybe that was one of the how-tos you mentioned that you had 
read.  Hopefully someone else with a little more knowledge on X and 
modelines, etc., can respond.