[mythtv-users] Seeking Advice

[Tim Phipps]

On Wednesday 25 July 2007 8:27 pm, Michael T. Dean wrote:
> On 07/25/2007 02:58 PM, Tim Phipps wrote:
> > On Wednesday 25 July 2007 6:10 pm, Michael T. Dean wrote:
> >> IMHO, you
> >> can get a much better result using a video card running at 800x600 or
> >> 1024x768 with the TV-out chip sampling from that picture.  (And, BTW,
> >> regardless of what people may tell you, there's no equivalent of 1:1
> >> pixel mapping for SDTV using a TV out.)
> >
> > True, but only because pixels don't exist for SDTV with a TV out. Lines
> > do exist and they are important. Using a TV-out chip to sample is going
> > to involve scaling and deinterlacing, both of which will degrade your
> > picture.
>
> So you agree that you get a better result using 800x600 (for GUI)?  The
> point is that 800x600 isn't possible using a PVR-350's TV out.
>
Only for the GUI, which gets about 1% of my eyeball time on the frontend. I 
wouldn't let the quality of the GUI override the quality of TV playback when 
choosing hardware. What I was objecting to was your use of the fact that 
TV-out doesn't have pixels to justify the statement that scaling down will 
give you a better picture. There is hardware that can eliminate scaling and 
my experience of this is that it gives very good results. The Unichrome chips 
can do this and I think Nvidia can too. If you have a progressive scan TV you 
may never know what interlaced programmes look like on interlaced displays 
since there will always be a de-interlacer in there somewhere.

For film material it makes no difference since it's shot at 24fps and has lots 
of motion blur for the cinema, TV progrmmmes are interlaced though and even 
worse (better) are CGI cartoons that have no motion blur at all. Try a Noddy 
DVD (I don't know if NTSC Noddy's are available). Watching one of these 
through a scaler you can see the ghost image quite clearly.

Cheers,
Tim.