[mythtv-users] PVR-500 picture quality

Jerome Yuzyk jerome at supernet.ab.ca
Mon Feb 1 06:51:48 UTC 2010

On Sunday 31 January 2010, Joey Morris <rjmorris at nc.rr.com> wrote:
> I'm new to MythTV, and I've installed a PVR-500 to capture standard
> def programming from my cable company. The picture quality of the
> captured streams appears to be slightly lower than what I see when I
> connect the cable directly to my standard def TV. This is true for the
> card's coax connection (connecting directly from the wall) and for its
> composite and S-Video connections (connecting from the cable box).
> I've made sure the recording resolution is 720x480, I've increased the
> bitrates to 7000/8000, I'm using a G210 card with VDPAU enabled, and
> I've tried using a signal amplifier. I think I may be maxing out my
> PVR-500's performance.
> The quality is certainly tolerable. Although I notice the difference
> when comparing them side-by-side, I'm not sure I would if I viewed the
> card's output in isolation. Is the slight drop in picture quality just
> the nature of analog capture? Those of you using the PVR-500s, do you
> just live with it so you can enjoy the numerous benefits of MythTV? Or
> are there other things I can try to make the picture quality match
> what I see when I connect the cable box directly to the TV? If I
> eventually move to HD, can I expect a similarly slight quality drop
> when using the component output to an HD-PVR?
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It's the PVR-500. There is a certain loss of sharpness relative to a 
standard TV. It can vary with channel, even with day. Some channels show 
distinct herringbone, some seem to be quantized funny. I RMAed my first 
one because I thought it was bad. I had the cable company in to check all 
my connections. MythTV 0.22 made things better, especially the 
deinterlacer - picking the right profile made a noticeable difference. I 
have an old NVidia onboard that can't do VDPAU.

I've come to live with it - I judge it to be 80% as crisp as TV, but 
totally worth it for the MythTV experience. Going to HD means going to 
digital and that's just not worth the effort. I just watched a MythBusters 
that was shot in HD but letterboxed to SD and it was as good as it gets. 

One thing that will help encourage people to HD is the differences in 
handling of the HD material shown on SD channels. Discovery letterboxes, 
whereas PBS clips. The nice e-mail I got from PBS claims nothing can be 
done about it - so it might be a capability issue or simply laziness.

A signal amplifier may make the problem worse since overdriving the 
later-model tuners makes the LNAs (Low Noise Amplifiers) noisier. There is 
some fiddling you could try with IVTV.

If your picture wuality is only "slightly lower" then you're doing pretty 

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