[mythtv-users] HDTV Modeline Help
Richard Shaw
rshaw2 at midsouth.rr.com
Mon Dec 12 21:43:02 EST 2005
It looks like you're right. I tried a 1080i modeline and it did work. I
would be happy with that but at 27" the text in Firefox was so I
couldn't read it. Right now I'm messing with 540p which I have working
but it doesn't look very good. It could be I'm trying to get it to work
in 4:3 ratio instead of 16:9. I don't really want to have it in
widescreen since it's not a widescreen television. I guess I shouldn't
complain too much, the picture is otherwise good and I only paid $450
for it.
Cory Papenfuss wrote:
> If you believe your EDID data, you cannot run 720p. Indeed, the
> fact that you forced it to 45kHz and it was "jumpy" is an indicator
> that it will not sync there. Look here (or lots of other places in
> the 'net I'm too lazy to look up right now):
> http://www.plasmatvbuyingguide.com/dtv-hdtv-comparison19.html
> The bottom chart shows
> 480i: 31.5kHz/60Hz
> 720p: 45.0kHz/60Hz
> 1080i: 33.75kHz/60Hz
>
>> I did a Xorg -probeonly and it did not find any compatible
>> resolutions over 848x480, however I was not supprised since I've read
>> that many do not have proper EDID info. It states that my hsync is
>> 30-35kHz and my vsync is 58-62Hz. Using modeline calculators it
>> appears that if I specify 960x720p that it is not possible to satisfy
>> both sync requirements. I tried bumping the max hsync up to 45 but
>> was greeted with a "jumpy" screen so it appears is that part may
>> correct.
>>
> Here's the modeline that I use. I believe it's pretty much
> frequency-spec compliant with the standard (or at least as close as
> can be made with NVidia's restrictions)
>
> ModeLine "1080i" 74.175824 1920 1960 2008 2200 1080 1084 1094 1125
> interlace -hsync -vsync
>
> That puts out 33.72kHz HSYNC and 29.970 VSYNC. It will be
> underwheliming to use as a desktop resolution because it will be huge
> and very flickery with the interlacing at 30Hz. It should work with
> the TV though.
>
> One of the reasons your modeline generate probably didn't work is
> because they rarely offer the "interlace" option. That effectively
> halves the horizontal scanrate required for a given resolution.
> 30-35kHz pretty much limits you to somewhere between 640x480-800x600
> in computer-ese resolutions. Not much more over EDTV.
>
> Cheers
> -Cory
>
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