[mythtv-users] Any hope for 1080i content at 1080i with nVidia?

[Seth Daniel]

On Thu, Aug 23, 2007 at 08:35:00PM -0400, Doug Larrick wrote:
> Seth Daniel wrote:
> > On Thu, Aug 23, 2007 at 07:56:12PM -0400, Doug Larrick wrote:
> >> Seth Daniel wrote:
> >>
> >>> I don't know if it's the TV, the driver, or just my incompetence, but I
> >>> cannot get 1920x540 (the 540pw mode described in the above link) to
> >>> work.  My custom 1080i mode is:
> >>>
> >>>   Mode "1080i"
> >>>     DotClock 74.25
> >>>     HTimings   1920 2008 2052 2200
> >>>     VTimings   1080 1084 1089 1124
> >>>     Flags      "Interlace" "+HSync" "+VSync"
> >>>   EndMode
> >>>
> >>> For the 540pw mode I changed it to:
> >>>
> >>>   Mode "540pw"
> >>>     DotClock   79.912
> >>>     HTimings   1920 2008 2052 2200
> >>>     VTimings   540   542  544  562
> >>>     Flags      "+HSync" "+VSync"
> >>>   EndMode
> >> If you have a working 1080i mode, you want the 540pw vertical timings to
> >> be *exactly* half of the corresponding numbers in the 1080i mode.
> >> Everything else should be identical.  You want the TV to think it's
> >> still receiving a 1080i mode.
> > 
> > They are exactly half.  Hmmm.  Except for 544...what's exactly half of
> > 1089?  Can you place fractional values in the vtimings section?
> 
> Yeah, sorry, read '562' as '652' and got carried away.
> 
> So your problem is likely to be the dot clock then.
> 79.921 MHz / 2200 dots is 36.3 kHz horizontal frequency, divided by 1124
> lines is 32.3 Hz vertical frequency.
> 74.25 MHz / 2200 dots is 33.75 kHz, / 562 is 60.05 Hz.
> 
> I think the former mode is too far from the ATSC standard for the set to
> sync.  In my experience the most important value is the horizontal
> frequency.

The former mode (1080i) actually works (kinda [1]).  It's the latter mode
(540pw) that I'm having issues with.  It sounds like your saying I need
to try signifcantly lower the dotclock?


[1] I get a 1080i picture that has alternating moments of perfection and
blurriness.  These moments are interleaved and come at around 10-13
second intervals.  To get any sort of 1080i picture I had to take the
EDID timings and double the vtimings to get it to work.  If I just use
the EDID directly I would get a 'virtual' 1920x1080 screen where I could
just view the top half (the first 540 lines) of the screen.  This
appears to be a driver issue.  It used to work with the 7xxx and 8xxx
driver (except that XV playback hard locked the system), but the 9xxx
(and beyond) driver broke it.

-- 
seth / @sethdaniel.org
Eat drink and be merry, for tomorrow they may make it illegal.