[mythtv-users] ivtv capture is good, but mythtv hoses it

[Aaron Nauman]

On 6/17/07, Brian Wood <beww at beww.org> wrote:
>
> Aaron Nauman wrote:
> >> > > I am running ivtv 0.10.3 on PVR 350 and PVR 150 on fc6 2.6.20.  If
> > I run a
> >> > > capture test with cat
> >> > >
> >> > > cat /dev/video1 > test.mpg
> >> > >
> >> > > The capture looks great.  If I start mythtv and watch live tv, I
> > get jitter.
> >> > >  Every couple of seconds the video pauses for a second of so.
> >> >
> >> >  In MythTV, what resolution/bitrate do you have set for your LiveTV
> >> >  profile for MPEG2 Hardware Encoders? If you change the resolution
> for
> >> >  LiveTV to 720x480 do things improve?
> >>
> >> Thanks for the reply Nick.
> >>
> >> I am running with the default settings: 480 x 480 with 368K bitrate.
> > I tried 720 x 480 and get no improvement.
> >>
> >> I have tested my hard drive and it is getting good throughput.  Any
> > other ideas?
> >>
> >> Thanks,
> >> Aaron
> >
> > I have tried changing the resolution and bitrate settings around, with
> > no improvement.
> > I am getting some "NVP: prebuffering pause" messages.
> > I tried output through PVR-350, but still have the jitter, so I am
> > pretty sure it is on capture.
> >
> > I have read through the troubleshooting sections on ivtv and mythtv and
> > everything else I can find with google and haven't found anything that
> > makes a difference.  And that includes rebuilding the machine from
> > scratch.  I am really worried that I am going to have an expensive
> > doorstop on my hands, unless someone can help get me on the right track.
>
> >
> > Any thoughts anyone?
>
> What sort of system? Myth puts a significant load on system resources,
> if you have an underpowered CPU it might work fine running a cat command
> but fall on its knees running Myth.


What CPU and what load running Myth? Are you running X and all graphical
> stuff when you run your cat command? Is your RAM limited, ie" are you
> swapping when running Myth but not when running the cat?
>
>
I don't think it is a performance issue.  I have had myth running on this
machine with no jitter problems with ubuntu.  I was having stability and
lirc problems with Ubuntu and Jarod's howto is so nice, that I switched to
Fedora.

The machine has
Sempron 3400+ (2 GHz)
2 GB RAM

There is basically nothing running on the machine other than KDE that is
resource intensive.  No swapping happening while watching live TV, but
jitter is there.

What I find confusing is that capture with cat jitters after exiting myth. I
seems that this would point to the problem.  I just don't know enough about
this stuff to figure it out.

Thanks,
Aaron
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