Cory Papenfuss wrote:
That's odd. From the chipset specs, the 150/500 has a more
advanced comb filter than the 250/350.... something about 4-line
adaptive vs. 3-line static or something IIRC. Have you (or anyone
else for that matter) played with enabling the additional features?
That's exactly why I got a 150; I was under the impression that the
comb filter would be better and I'd get better quality. I have not found
that to be the case though. The filters are enabled by default and I've
spent a ton of time trying to tweak them to get the picture better. I
usually use the composite input and a DVD source to rule out tuner
problems. You can try playing with them yourself, the relevant
registers are:
COMB_NOTCH_MODE=0-3
LCOMB_2LN_EN=0/1
LCOMB_3LN_EN=0/1
CCOMB_2LN_EN=0/1
LCOMB_3LN_EN=0/1
LCOMB_ERR_LIMIT=0-255
CCOMB_ERR_LIMIT=0-255
COMB_PHASE_LIMIT=0-255
I also like the results of enabling the sharpness enhancer (which is on
on 250/350s)
PEAK_EN=0/1
PEAK_SEL=0-2
I have *never* been very satisfied with the resolution out of
either of my 250's. One is a -15, the other is a -16 chip.
Basically, watching on the regular CRT SDTV always seems much crisper
than the 250 at *any* capture resolution. ... and yes, I'm *positive*
it's not the tvout from the computer. Homebrew hardware straight out
of the VGA port at SDTV frequencies. DVD's and test patterns played
from the mythbox look stellar (or as stellar as SDTV can look).
Anything over about 480x480 is unnoticable/immeasurable improvement.
I encourage you to play with the comb filters and see if you can
improve the picture quality. I've spent hours on it already and haven't
really come up with much. Here's my baseline:
http://capnbry.net/~bmayland/fi/pvr150/pvr150-250.jpg
I'm pretty sure the fuzzyness in the 150's shot is because the
CCOMB_ERR_LIMIT was exceeded and it had dropped back to notch. The
notch filter blurs things badly (try setting the err limit to 0 to
see). There's also a ton of errors in the vertical lines on the sci-fi
logo which look horrible even in motion.
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