[mythtv-users] Video Out Quality Hauppauge PVR-350 vs Geforce 4 MX

Boyd II, Willy wboyd at fulbright.com
Wed Nov 19 10:21:56 EST 2003


>-----Original Message-----
>From: Taylor Jacob [mailto:rtjacob at earthlink.net] 
>Sent: Tuesday, November 18, 2003 10:20 PM
>To: mythtv-users at mythtv.org
>Subject: [mythtv-users] Video Out Quality Hauppauge PVR-350 vs 
>Geforce4 MX
>
>
>I recently setup MythTV on a box using a GeforceMX AGP video 
>card and got it hooked up to my TV.  One of the first things 
>that I noticed was the black bars around the video in X.  I 
>added the OverScanLines setting to my XFree86Config file, and 
>got the black bars reduced considerably, yet there is still a 
>small area that is noticable at the Maximum setting of 1.0.
>
>My main problem is that I have noticed that horizontal 
>movement seems to be jerky even with de-interlacing turned on. 
> It is not that noticable when you are watching the news or a 
>sitcom, but I attempted to watch a hockey game and very 
>quickly had to stop watching because it became too irritating 
>with all the jerking.

I get the same thing.  Usually it's not *too* irritating though.  It's
because the Nvidia cards (ours anyway?) don't support interlaced modes.

>
>I looked at all of the supported video modes on the geforce 
>card in my XFree86 log file, and I noticed there was no 
>resolution that would be for NTSC (or PAL for that matter) at 
>all.  (720x480 or something slighly higher to deal with 
>vertical blanking like 720x525).  I tried a few different 
>settings and all seemed to yield the same results.
>
>Is it correct to assume that this problem lies in the fact 
>that the Geforce card simply scales video output from 640x480 
>(or whatevr resolution you are running your X Session as) down 
>to something that will fit on a tv plus a bit of black to make 
>sure nothing is lost in the natural overscan of the TV?  
>Resulting in scanlines being misplaced and scaling not being 
>done on a 1:1 ratio which would make panning very noticable?  
>If this is the case, then I can't see these cards as being a 
>real good solution for MythTV (At least in my opinion).

I don't think it's so much the scaling, as it is the interlacing.  Without
a true interlaced mode, and with a simple deinterlacing filter in Myth,
you'll see
that blockiness on fast moving scenes.  I guess finding a video card with tv
out
and supporting an interlaced mode suitable for tv out would be nice, but the
gf4mx 
cards seem really popular, so maybe such an animal doesn't exist?

>
>I was looking at the Hauppauge PVR 350 card since it has a TV 
>out. I noticed somewhere on the list that it had been 
>mentioned that it keeps interlacing intact.  Does it do this 
>by running at a resolution that is native to Televion output 
>and therefore requires no scaling?

Yes, and yes it will keep interlacing intact.  I've read that the pvr350
is a great improvement, for mpeg2 output (the mythTV functions).  For other
video, like divx, quicktime, or the mythmusic visualizations, it may take a
while
for the driver to improve before those can be displayed adequately.

>
>I guess to sum things up after my quite longwinded post will 
>the output from a Hauppuage PVR 350 solve my complaints, and 
>also how does the Hauppauge deal with the overscan area?  Does 
>it "box" everything like my Geforce4 MX card is doing, or 
>should I expect video that is the same quality as from my tivo.

>From what I hear you should expect video on par with the tivo.

- Willy

>
>Taylor
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