[mythtv-users] native resolution vs 1080i for HDTV and SD on 1280x768 lcd?

Steve Adeff adeffs at gmail.com
Thu Nov 17 11:02:23 EST 2005

On Thursday 10 November 2005 15:19, mrwester wrote:
> Hi-
> I'm contemplating adding a HDTV tuner and have a few quick questions, but
> 1st, some brief background. Current myth setup is FC4 and 18.1 on AMD 2900,
> 512mb ram, 500gb of hard disks, 1xPVR-350, 1xPVR-500, chaintech fx5200,
> Olevia 30" LCD TV that has DVI, VGA, S-video in as well as HDTV ready
> (1080i, 720p, 480i) component inputs YPbPr and YCbCr. DVI out at HDTV are
> not an option. Native resolution of the panel is 1280x768. I'm currently
> running the tv-out of the PVR-350 for my myth needs and am very happy with
> it. Because I don't archive many shows and have plenty of spare drive space
> I capture at 720x480 resolution at the default or higher bitrate. Picture
> quality is comprable to cable straight into the tuner of the TV.
> I know that the pvr-350 won't work for HDTV, so I've begun tinkering with
> the Nvidia card. I can run the FX5200 at native resolution 1280x768 for the
> LCD via DVI and mythtv itself, the menus, etc.. look fantastic-much sharper
> than the PVR-350. Playback of recordings or live tv from the PVRs is a
> different story. No matter what deinterlace I try within mythtv, the CNN
> ticker stutters every few seconds and is blocky and it just doesn't quite
> compare up to the PVR-350's TV-out. Probably watchable overall, but not
> perfect and difficult to tolerate when I've got the PVR-350 in the box.
> I've tried running the tv-out of the fx5200, using flicker filter (nvidia
> hardware de-interlace?) and the overall quality is still even worse. I'm
> running the latest 7676 drivers without XvMC. I'm not 100% sure why the DVI
> stutters on the 5200 FE/BE as I can play to a remote Pundit-R frontend
> using it's ATI based vga out to a lcd monitor without any stuttering of CNN
> but that's a whole other story/question...
> If I do add a HDTV tuner (planning to use OTA or QAM, not cable tv provided
> external box) to the setup, I'll need to use the FX5200. I've searched and
> googled for a few days now and perhaps since my questions are so basic,
> I've not found the answers. My questions are- Should I output via DVI at
> native resolution? 

Yes, always when possible. ie. my HDTV converts everything to 1080i but I 
can't find a DVI 1080i modeline that will work with my geforce so I'm forced 
to output at 720p, I might eventually get a newer geforce with an HDTV output 
chip and use that, I'll prbly end up buying a new TV before that happens 

> Or should I get an external transcoder box to process 
> the DVI or VGA out to component 1080i or 720p and let the tv scale to
> 1280x768? What about one of the Nvidia 6200 or 6600 cards that have the
> HDTV component outputs? 

see above. They work well if needed. Quieter aftermarket gpu fans can be 
purchased as well if it bothers you that much.

> they have a fan (a minus), but since these cards 
> are now cheaper than a transcoder box may make more sense if the component
> outputs work in Linux. And finally, when you have a SD/HDTV myth setup, do
> you watch your SD content over the 1080i connection and let the video card
> scale?

From what I can tell theres no way to have Myth output vary depending on the 
source resolution. If it did/does, and your HDTV supports 480p native (ie 
doesn't scale it to another resolution) then it would be best to output SD at 
480p and HD at its native HD resolution.


> or would it be best to use 720p and use deinterlacing in mythtv? (I 
> will only be getting a few HD channels, most of my viewing is still SD) Or
> is there another completely differnt way to do this and I've just missed
> it? Thanks,
> Mike

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