[mythtv-users] pvr150 encoding quality (motion artifacts)

Nick Bartos spam1001 at 2thebatcave.com
Wed Feb 22 05:38:48 UTC 2006


My myth setup is almost functioning perfect, but there is one problem that
I am still trying to resolve.

I get some "stuttering" sometimes when there is motion.  It is fairly
subtle, but it is annoying for me.  I would assume that some people
probably wouldn't even notice it.  I have concluded that it is related to
the pvr150 encoding, since anything created with the pvr150 exhibits the
problem (even when played on another machine, and using different
players), while I am able to play other content not created with the
pvr150 without incident.  Also if I play cable directly to the tv (without
myth), then there is no problem either.

I have played around with all the settings available in the recording
profiles (trying very high bitrates, changing from mpeg-ps to ts to dvd,
etc...) but nothing helps.

A bit about my setup:

2 comcast motorola hd receivers, using s-video output to s-video input on
2 pvr150's.  I use firewire to change the channels only.  I would love to
just use firewire for everything, but unfortunately not all the channels I
get can be received on firewire (at least not unencrypted).

video card is nvidia 6600
pentium D 3.2GHz
4GB RAM
intel d955 motherboard
300GB seagate 7200 rpm sata hard drive
via firewire card (there is one on board too.  I have 1 cable box plugged
into the onboard 1394, and the other one plugged into the 1394 card so
that 6200ch can always change the channel on the right box, since
sometimes nodes switch but the ports are always the same).

2.6.15.4 kernel
ivtv 0.4.3
lirc 0.8.0
pvr firmware from pvr150_20_35_23348.zip
7676 nvidia driver
myth 0.19


I have done a fair amount of playing with the playback
(xvmc/opengl/drivers/etc), but I'm fairly certain that it's the fault of
the pvr150 because of the above noted testing.

I tried myth a couple of years ago using the pvr250s and was unsatisfied
with the quality.  Seems like the pvr150s are decently better (from what I
remember, but then again it has been a couple of years).

Any ideas?  I thought maybe there might be some tweaking that could be
done to the 150.  Or possibly there is a higher quality card than the 150,
although I would prefer not to spend any more money at this point if
possible.


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