[mythtv-users] PVR-500 picture quality

[Mw]

On 1/31/2010 8:36 PM, Brian Wood wrote:
> On Sunday 31 January 2010 05:16:50 pm Joey Morris wrote:
<snip>
>> 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.

I see a significant drop in quality with my 500. Specifically, diagonal 
banding from lower left to upper right. It may be related to the type B 
Philips tuners on it. The very early PVR-350 I was using was almost spot 
on. Hardly any artifacts at all.

> 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.

Noise in the source from the headend can greatly impact the quality of 
the PVRs. Typically, the analog SD from my Comcast feed is pretty noisy. 
The encoders on my 500 seem to be very sensitive to this noise and 
compression artifacts are obvious.

Every now and then, one of the HE techs isn't paying attention and the 
signal becomes really, really clear. Almost as clear as unscrambled 480i 
digital. The artifacts are hardly noticeable on these recordings  but 
the banding remains. Eventually, the technician will fiddle with the mux 
chain until the signal gets crappy again.

<snip>

> 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.

nCube/C-Cor and SeaChange ad insertion encoders are monsters. 4U rack 
units such as VELA and Minerva are a whole different animal than the 
consumer offerings. Like Brian said, used gear is generally $20K or more.

--
mw