[mythtv-users] What don't I get here? (Interlaced playback...)
ryan.goat at gmail.com
Fri Jun 15 12:18:38 UTC 2007
The nvidia S-video out does send an interlaced signal. Just not the correct
interlaced signal. For a TV signal (PAL or NTSC) the two fields that make
up one frame are from two slightly different points in time. But for a
computer monitor signal an interlaced signal is made from one frame (one
point in time) and then split into two fields. The nvidia card is incapable
of correctly displaying the interlacing correctly.
If you really want a good S-video output get a hauppauge pvr-350. It has a
hardware mpeg decoder that preserves the correct interlacing signal. Though
setting up the pvr-350's X drivers can be a pain. I used a pvr-350 until I
upgraded to HDTV (connecting with DVI is very easy now). For me the nvidia
s-video output was simply unacceptable.
On 6/15/07, Steve Smith <st3v3.sm1th at gmail.com> wrote:
> Thanks everybody for the answers... as a quicky I'll give bob a go, then
> I'll build the RGB cable it seems the only way to get the picture I really
> want (given my lowly P3).
> (Pity I wanted to be able to use a composite vid/s-video input to the
> telly as the RGB is hogged by the cable box itself and needs to be manually
> switched over. Got to keep the WAF up ;-)!!!!).
> On 14/06/07, Mark Kendall <mark.kendall at gmail.com> wrote:
> > On 6/14/07, Steve Smith <st3v3.sm1th at gmail.com> wrote:
> > > So am I correct in my analysis? Is the mythfrontend actually playing
> > 25 full
> > > frames a second or 50 fields a second?
> > The pedantic answer is that it's actually doing both, but I don't
> > think that's really your issue :)
> > Your number one problem is s-video. It's been a long time since I used
> > it in anger but I never had a good quality picture using s-video
> > input. The main problem (I think) is that the nvidia drivers do a
> > certain (large) amount of scaling and I'm not even sure that the final
> > output is properly interlaced.
> > > How can I get the "correct" output of 50 fields a second where
> > potentially
> > > the two fields in each frame can contain movement?
> > > Would using a CRT output (RGB to SCART) instead of S-VIDEO help? (in
> > this
> > > respect not just overall quality)
> > If you've only got a scart input (ie no dvi etc), an RGB to SCART
> > converter is definitely the way to go. You'll notice an immediate
> > improvement in picture quality if you get it working correctly (I've
> > been playing with scart input to my lcd and crt tv's today). I'd
> > probably go as far as to say that it's the best picture quality you'll
> > get for standard definition PAL - i.e. if you can get it working
> > well, it will match the quality from stb's, dvd players etc.
> > >i.e. is the NVidia TV-Out doing something
> > > to the timing...e.g. insisting on using 60hz without telling me thus
> > > throwing out the timings, or maybe even forcibly de-interlacing the
> > picture?
> > Probably the latter...
> > regards
> > Mark
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