[mythtv-users] TV Picture and DVD playback quality

[David Watkins]

On 30/08/06, Lars Ove Claesson <lars at datek.no> wrote:
> Hi, all.
>
> This is kind of a noob-question, but I have searched kind of a lot and
> cannot find anything that might give me clues, so I'm asking here in
> stead.
>
> I have just set up an installation of MythTV on FC5, with a box
> containing
>
> Asus GeForce 7600GS 256MB DDRII Silent
> Intel Core Duo T2300 1.66GHz PC667
> Asus N4L-VM DH Motherboard
> Pioneer ND-3550 DVD-RW
> Hauppauge! WinTV-PVR-500MCE
>
> ...basically.
>
> My question is regarding the expected quality of DVD playback and TV
> from a HTPC-box like this. I realize that I have not fine-tuned or
> tweaked any parameters yet, but the image quality I get is actually very
> poor.
>
> I use a digital set-top, and when connecting a SCART directly to my TV
> the image is excellent. This box also provides me with RF-signal to use
> with my Hauppage, so the signal is good (as verified when connecting RF
> directly to my TV). But the image produced by the Hauppage is terrible.
> It does not fill the entire TV-screen, and the image is noisy with
> blurred edges (yes, I've set PAL). Is this just a matter of fine-tuning
> the frequency? Can I at all expect to reach the image quality produced
> by the SCART-cable connected directly to my TV from the digital box?

Probably not, because of the extra modulation/demodulation on the
signal.  Much better to feed the SCART(composite or S-Video?) input
into your capture card directly.

Edges will likely look ragged unless you set your video card up with
overscan. The nvidia-settings programme does this for the nvidia
driver.

> Second, regarding the DVD playback, how to explain this... the movie
> "freezes" for one second, then use the next second to run through those
> two seconds in fast forward, then freezes again... over and over. Also,
> the image fills the width of the screen, but only about 50% of the
> height is used (centered vertically). Could this be just a matter of
> tweaking mplayer? The sound seems continuous, though.

check that the nvidia driver is specified in /etc/X11/xorg.conf
(rather than the nv driver) and tinker with the video driver options
in mplayer.  Your CPU has plenty of horsepower.

Your best bet regarding picture size is to choose a sensible
resolution (800x600 or 720x576 would both be reasonable for standard
definition PAL) and a displaysize that matches the aspect ratio of
your screen and gives a dot-per-inch of about 100 (I'm assuming your
TV is a CRT).  Change the settings in /etc/X11/xorg.conf and see what
your actually getting in /var/log/Xorg.0.conf (on my Fedora system at
least).  You'll still have problems because some DVDs are at 1.85:1
and broadcast material can be at several different aspect ratios so
you'll sometimes have to zoom in or put up with black bars.

>
> Would appreciate some guidelines on how to proceed. And what I might
> expect from a correctly tweaked system.



You should expect playback quality noticeably better than that of a
VHS video recorder.


>
> Regards,
> Lars
>
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