[mythtv-users] mpeg2 playback quality captured with PVR-150

Chandi Bernier Chandi.Bernier at Usherbrooke.ca
Sat Oct 6 23:22:29 UTC 2007

Oh guys, I'm ready to take time to tweak that great system !
(Only if I know people have succeeded getting a good quality from a PVR150)

Is there a way to lower the signal from my cable?? I guess using a second
splitter would do it but I'm afraid to introduce more noise in the loop. 
A resistance between the splitter and the PVR ? That would also put too much
noise in the link.

It seems to me that what I'm seeing is not mpeg2 artifacts but it's the
mpeg2 response to noise in the NTSC stream. 

I used to have digital cable at home (mpeg2) and it's image quality was way
higher than mine. I guess the encode from a (almost) noise-free source. 

I have to find a way to understand the problems in my signal. Is it too weak
or too strong? I know my 2-way splitter works fine since the output of
regular TV is perfect. The tuner in the PVR150 seems to be picky... Even
without a splitter it is barely watchable.

V4l2-ctl --all says my card gets 99% signal quality. 

Well..I try a few things and try to bring back some answers here. In the
meantime if somebody finds something, just let me know :)



-----Message d'origine-----
De : John Drescher [mailto:drescherjm at gmail.com] 
Envoyé : 5 octobre 2007 20:59
À : Chandi Bernier
Cc : Discussion about mythtv
Objet : Re: [mythtv-users] mpeg2 playback quality captured with PVR-150

> Is there a signal booster in the PVR-150? The signal level is perfect in
> TV which only is a splitter away from the PVR. But it only does the bars
> 2 channels out of 25.
No. The PVR 500 is the only one I know with a amp.

> What scares me the most is the pixelisation and other artifacts.
> You were right. I've got some messages in the dmesg.
> >ivtv0: All encoder MPEG stream buffers are full. Dropping data.
> >ivtv0: Cause: the application is not reading fast enough.
> Could that be the cause?
This will cause blocky off color artifacts.


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