[mythtv-users] Capture card with best tuner - BT8x8, SA713x or PVR-250?

[Joe Votour]

An update on the continuing saga...

I decided to try to figure out whether it was the
backend or the frontend causing the problems, so I did
a recording only at 352x480.  The playback of the
resulting video was jerky in both MythTV and mplayer
(with the nuv patch installed) in the same places. 
Thus, I'm concluding that mythbackend is the culprit.

I then installed MythTV 0.11 on my Pentium 4, 2.4GHz,
512MB RAM, using the same capture card (Pinnacle
PCTV), and still had the same problems with
rebuffering messages an dropped frames.

At that point, I decided to splurge and get a PVR-250
card, just to see how it helps things (I put it in the
Athlon XP+ 2400 system I'm using for MythTV).  I can't
capture at 720x480 or 544x480 (still getting
stuttering/pausing, but very rarely) not even 480x480
works (though this might be the "ghosting" issue that
is known about).  Maybe 480x480 isn't a correct
resolution for the PVR-250?

I'm guessing that the "rebuffering" message comes up
only during software enoding (from a bt8x8 card, for
instance), since when I got the pausing with the
PVR-250, there was nothing on the console where
mythbackend was running.

So, given this, I can only consider that it's one of
four things:
1. Red Hat 9 is broken, even with a kernel upgrade to
2.4.22.
2. MythTV is somehow broken.
3. DMA is broken with Western Digital hard drives (and
the kernel and hdparm lie about it).  All of the hard
drives I'm using are WD's (I used a 60GB model, a
100GB model and a 120GB model, all 7200RPM, 2MB
buffer).  Unfortunately, the only hard drives I have
kicking around here are WD.
4. The signal from my cable provider really is to
blame.  Unfortunately, this may not be fixable (need
to talk to the landlord to see if they've looked into
it).

I will say that the picture from the PVR-250 is
clearer than that which I got from my Pinnacle card,
but for $150, I want more than a pretty picture - I
want a pretty picture that doesn't skip.

I guess we'll see what happens while I watch Live TV
tonight.

-- Joe

--- Richard Lee-Morlang <rick at webtownis.bc.ca> wrote:
> On Sat, 2003-08-23 at 11:42, Joe V wrote:
> 
> 
> > It's possible that the OS is doing something else,
> I
> > suppose, but I boot into run-level 3 and start
> MythTV
> > from there (using a .xinitrc).  I've removed as
> many
> > of the services as I could using ntsysv (Red Hat
> 9).
> 
> 
> Essentially the same thing I did, though I ended up
> booting into
> runlevel 5 and using gdm's autologin and so on from
> there. Still, if
> it's a system that's basically dedicated to myth,
> you shouldn't be
> running into that sort of trouble with your
> hardware.
> 
> 
> > The pictures that I took, those were of the TV. 
> It
> > was like that before I even started building the
> > MythTV box.
> 
> 
> Then it sounds like your best course of action would
> be to try to
> eliminate as much signal noise as possible in
> whatever ways you can.
> (Building management, cable company, etc..) 
> 
> 
> > As for the capture card, I've used two different
> ones
> > - a LeadTek Winfast 2000 XP Deluxe (which seemed
> to be
> > pretty bad), as well as a Pinnacle PCTV Rave,
> which
> > seems to be a bit better.  That's why I was asking
> > what kinds of cards/tuners people are using.
> 
> 
> Can't offer much help here, since the card I use
> seems to work great,
> and I haven't had any need to try any others.
> (Though I've got a PVR-250
> on my shopping list. ;-) 
> 
> I can say that I was really disappointed with the
> SAAxxxx TV-encoding
> chipset though. Don't have the exact chipset handy,
> but I could look it
> up if anyone wanted to know.
> 
> 
> > One thing that could be a cause of the problem is
> that
> > on both the Leadtek and the Pinnacle cards the
> coax
> > barrel connector isn't part of the tuner itself,
> it
> > connects to the tuner (it's a slide-on connector,
> > looks like a composite connector).  I'm thinking
> that
> > this might have something to do with it, but I
> don't
> > know how many cards actually are like this.
> 
> 
> My WinTV has the whole tuner unit, including the
> connectors, as part of
> a shielded housing built onto the card. Though I can
> see the setup you
> have possibly adding some more noise, if your
> picture isn't
> significantly noisier since you added your myth
> setup, I doubt you'd
> solve your frameloss problems with a different
> connector housing design
> or a different hookup configuration. :-(
> 
> 
> > Now then, one final question for you...  If you
> look
> > at the console, do you see any "rebuffering (X,Y)"
> > messages (where X and Y are numbers)?  Depending
> on
> > the channel I'm watching, I see these messages
> > anywhere from every 10 seconds to every 10 minutes
> > (sometimes I get a few of them every 10 seconds
> and
> > then they go away for 5-10 minutes).  In order to
> keep
> > track of the times, I modified the RingBuffer.cpp
> file
> > to print out the date/time.
> 
> 
> Yes, I've seen them, though by the looks of the
> recent console output on
> my two frontends, it only happens when I go into
> cutlist edit mode. It
> might be happening on my remote frontend during
> regular playback too,
> I'm not sure. I'll keep my eye on it.
> 
> Rick
> > _______________________________________________
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> mythtv-users at mythtv.org
>
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> 


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