[mythtv-users] Bitrate/quality on PVR-150

Scott Traurig straurig at comcast.net
Wed Aug 13 10:36:58 UTC 2008

> Date: Tue, 12 Aug 2008 19:14:46 -0700
> From: Brad DerManouelian <myth at dermanouelian.com>
> On Aug 12, 2008, at 6:23 PM, Scott Traurig wrote:
>>> Date: Tue, 12 Aug 2008 09:32:35 -0500
>>> From: jedi <jedi at mishnet.org>
>>> ...place the blame where it really belongs: with your cable
>>> operator. 
>> Not at all! The thread has taken some interesting twists and turns
>> during
>> the day, but getting back to comparing apples to apples...
>> If I use my Pioneer DVR to record off the same composite output of
>> my STB
>> that is the input to my Myth box the resulting quality is
>> substantially
>> better on the Pioneer. I have a dual tuner setup with a 150 and a
>> 250. They 
>> both look equally bad compared to the Pioneer. Things are even
>> further apart
>> when comparing the Pioneer tuner performance to the PVR-x50 tuner
>> performance. So cable performance is the same constant in both
>> equations.
>> I would guess that the real problem on the PVR-x50 series products
>> is the
>> poor performance of the tuner and analog sections, not poor
>> performance of
>> the ADCs or encoder hardware (or cable signal).
> If you want to compare apples to apples, you would need to play back
> what is captured from the PVR-150 (with the highest quality settings)
> through the same converters as your pioneer DVR. Blame could just as
> easily be placed on the video card you chose to put in your myth box
> or the settings you are using on either your PVR-150 or your video
> card or maybe the video card driver itself.

Perhaps you weren't following the entire thread, Brad. I had already written
that decoder and video card performance is not an issue as DVDs played with
my Myth setup look fantastic, actually better than the Pioneer. So no
problem there.

> Again, my PVR-150 looks much better than the Tivo I used to use and is
> just about as good as going directly into my TV (after I bumped up the
> bitrate/size settings to 720x480 and I think my bitrate is around
> 8000). My money is on some setting you are using that makes it look
> bad. If you post a sample of it maybe someone who knows more about
> video compression could see what's happening.

My bitrate is 6 AVG/8 PK but in my extensive efforts to make the PVR-x50
look good I've had it as high as 9 with no joy. I have always run 720x480.
There is no mistake being made. I've adjusted other settings, too, using
v4l2 with no improvement. I did some extensive work with the Nvidia settings
tool to get things color corrected and properly scaled, as well.
> Oh.. I just re-read and see that you are using composite video. Do you
> mean composite through RF? You could be getting interference from the
> other components in your machine (like your power supply). Try it with
> s-video.

Been there, done that, no improvement. Besides, if there were interference
problems would they not also affect the Pioneer which was stacked up with
the same equipment?

And before someone says "Maybe your card is broken" consider that I've got
one -150 and on -250 and they both look equally poor.

With all the comments on how PVR-x50's look better than Tivo I'm sure glad I
didn't get a Tivo!

Scott (PVR-x50 anti-apologist!)
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