[mythtv-users] PVR-500 picture quality

Brian Wood beww at beww.org
Mon Feb 1 02:36:20 UTC 2010

On Sunday 31 January 2010 05:16:50 pm Joey Morris 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?

I see a very slight degradation as well, though others claim they do not see 
it. I'm probably more critical than most viewers, having worked in the "biz" 
for many years.

The PVRs use a consumer grade encoder, which I would expect to behave this 
way, the degradation is not enough to bother me, considering the source is 
analog CATV, which is not all that great to start with.

There are many parameters you can tweak on the encoders, but even if 
performing at the optimum, I would expect a slight degradation from the PVR 

As for the HD-PVR, even at the max bitrate I can see some artifacts, but it is 
certainly good enough, especially for the price.

A really high quality "Broadcast" encoder, say from from Rhode and Schwartz or 
Tandberg, would cost MUCH more, an order of magnitude or two at least, so I am 
very happy with my HD-PVR. Lucent makes some slightly less expensive units, 
but they still cost on the order of a new car, and it's unlikely you are 
getting signals of that quality into your home in any case.

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