[mythtv-users] quality question.. ways to make it better?

[Steve Dobson]

Craig / Garry

On Wed, May 19, 2004 at 04:53:13PM -0700, Garry wrote:
> Craig Tinson wrote:
> >my current setup is a Athlon 1800XP / 120Gb / 512Mb / AverTV Studio 
> >for the backend
> >
> >an Athlon 1.4Ghz / 120gb / 512Mb / Radeon 9200 SE for the front end.. 
> >the composite out goes through to a composite-scart converter which is 
> >plugged into the TV.
> >
> >I'm in the UK and have NTL Cable.. so I have a coax arial cable from 
> >the output of the cable box running to the arial cable on the TV card 
> >in the backend..
> >
> >I've set the recording profile for LiveTV to mpeg4 and set it to 
> >pretty much maximum quality.. but its still quite "bitty" (not a lot.. 
> >but you can see it).. and the colors just seem really dull.. it seems 
> >to lose the vibrant quality from the original..
> >
> >Is there anything fundamentally wrong with this setup? is there 
> >anything I can do to make it better without shedding out tons of cash?
> >
> >I've tried pressing "G" and adjusting color/hue/brightness etc.. but 
> >that doesn't seem to do very much..
> >
> >Setup was from Jarods guide and am up to date I think with everything 
> >else.. (apt-get dist-upgrade says I am anyways)
> 
> Glad it't not just me. I too live in the uk, and use an RF feed from the 
> back of a Sky Digital box, via the arial socket on my PVR-250. TV out is 
> via the Pundits' onboard SiS/
> 
> Weird thing is... watching recordings is fine, not far off  watching 
> normal TV. And, burning to DVD results in a picture that looks as good 
> as normal TV (audio goes out of sync, but that's another thread :-) 
> )But, watching liveTV via myth is well, slightly less than perfect. You 
> can tell it's not 'real' tv. The motion seems to stutter. Maybe stutter 
> is too strong a word.. it just doesn't seem to flow properly. And the 
> colours are a bit washed out too.
> 
> I have the liveTV profile set with the bitrates up to the max, with a 
> low resolution.. (300 x 500 ish- can't remember the exact numbers)

I use a PVR-350 - so encoding and decoding are both MPEG-2 and handled
by the same hardware.  But I did some bench marks to find out how much
CPU was being used.

A simple raw copy (dd if=/dev/video0 of=/dev/video16 bs=64k) loaded my
VIA 586 533MHz CPU to 3%!!! (from about 2% when not doing the dd).

When "dd"ing via disk
    dd if=/dev/video0 of=/tmp/test.mpg bs=64k
    dd if=/tmp/test.mpg of=/dev/video16 bs=64k
The loading when up to 6%

When running MythTV the loading was higher, around 30% IIRC, so I think
it is your setup that is a problem here.

Try running top(1) to see what your CPU loading is.  The PVR-2550 (&-350)
is a MPEG-2 card not MPEG-4 - so I would guess that the CPU is overloaded.

Steve