[mythtv-users] How do I get decent quality SVideo output? (Using PVR-150 and Geforce4 MX)

Erik Pettersen pettersen at gmail.com
Mon Aug 22 23:40:57 UTC 2005


well granted it would be different, but you complained about what I
presume to be pixelation/blockiness type artifacts, which *could* be
your processor struggling to keep up with decoding or there could be
some horrible recording artifact from snowy analog cable.

I'm trying to eliminate possibilities to narrow down the issue.  Even
if you drag the file over to another more robust machine on your
network, and play it back on a PC monitor hopefully you can
tell/verify (less the interlacing) if it exhibits the same undesirable
features you're seeing on your TV via myth.

If you do that you'll know it's not the encoding/recording.

Next, (and here you'll have to forgive me lords of the myth as I know
precious little about how mythtv handles playback or how to tweak it)
I'd close down myth front end and fire up mplayer or xine or vlc on
the 1ghz box and try the different playback options to see if it
helps.

I'm not sure what to do after you've found a combination that works for you... 

I have a geforce4mx 420 in my test knoppmyth box (XP 1700) and was
playing around with playing back HD streams from the HD-3000 card
outside of mythtv.  Unfortunately I'm not sure what settings worked
best for me (although increasing buffers helped alot)... because it
was like -vo xv worked in one (mplayer?) and -vo xvmc worked in the
other (xine?) but not vice versa... I picked up a geforce fx5200 to
play with as it has more robust media accelleration than the geforce4,
and want to see how that goes =)  One OT question: with the 7174
nvidia drivers if you close out from X to terminal single user mode do
you get all black with green random ANSI looking blocks, or is that
just me?

Sorry for the slightly half baked advice, I think the basic approach
is right to narrow things down, but I start to lose it when you'd need
to be specific about how to adjust playback settings in mythtv/linux. 
In windows world, I'd just say "install the nvidia pure video decoder
trial" and see how that goes =P

e.
--
http://www.byopvr.com

On 8/22/05, David Peeters <dpeeters at gmail.com> wrote:
> It's a 1Ghz P3.
> 
> I really have no other way to play back the file unfortunately as I
> only have the single TV and the playback on a non-interlaced monitor
> would look different anyways.
> 
> When I use XvMC, the OSD goes black and white and flickers badly.
> Using XV picture controls only changes the contrast/hue... don't they?
> I'm not sure what you mean by overlay.
> 
> On 8/22/05, Erik Pettersen <pettersen at gmail.com> wrote:
> > What speed machine? Usually I suggest trying to play back a recorded
> > file in another player (or on another system) to verify that it's a
> > playback/decoding only issue.
> >
> > I'm not sure of the linux or mythtv terminology for this, but what's
> > your video renderer?
> >
> > i.e. overlay, vs xv/Xvmc ?
> >
> > *shrug* maybe that's a start?
> >
> > E.
> > --
> > http://www.byopvr.com
> >
> > On 8/21/05, David Peeters <dpeeters at gmail.com> wrote:
> > > I've been having alot of trouble getting decent picture quality output
> > > from my mythtv box to my TV.
> > >
> > > I'm using KnoppMyth.
> > >
> > > I have a PVR-150 non-mce, and Geforce 4MX 420
> > >
> > > I have the S-Video out of my Dish Network box connected to the S-Video
> > > in on my PVR-150.  Then an S-Video out from the Geforce goes to the
> > > TV. (the picture looks fine with going straight from the Dish Network
> > > box to the TV.  The picture looks fantastic when I play a DVD in my
> > > Mythtv box).
> > >
> > > I'm using IVTV version 0.3.7h, and NVidia driver version 7174.
> > >
> > > I'm using the XF86Config-4.nvidia-tvout.sample.
> > >
> > > I have all my capture and transcoding resolutions set to 720x480.
> > >
> > > Recording bitrate is set at 6600 with 8800 max
> > >
> > > I have the Bob de-interlacing set.
> > >
> > > The picture on the TV looks like i'm watching a overly compressed
> > > video on my computer.  there is blockiness and streaking.
> > >
> > > I've tried the denoise3d filter and the result was no better.
> > >
> > > are there settings that I should be using or different drivers that
> > > will improve my quality?
> > >
> > > I'll gladly provide any other required information.
> > >
> > > Thanks for any help!
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