[mythtv-users] TV-Out with Matrox Marvel G400-TV

Joseph A. Caputo jcaputo1 at comcast.net
Mon Jul 7 13:27:17 EDT 2003


> -----Original Message-----
> From: mythtv-users-bounces at snowman.net
> [mailto:mythtv-users-bounces at snowman.net]On Behalf Of Ray Olszewski
> Sent: Monday, July 07, 2003 12:03 PM
> To: Discussion about mythtv
> Subject: Re: [mythtv-users] TV-Out with Matrox Marvel G400-TV
>
>
> At 11:16 AM 7/7/2003 -0400, Wayne Veilleux wrote:
> [...]
> >The only problem now is the really poor resolution when watch or
> >recording TV. I had a Hauppauge WinTV before and it was using CPU
> >but the quality of the resolution was much better. Is there
> anything I can
> >do to have much better resolution ? I went to the
> Configuration->TV Options
> >->Recording and put the resolution to 720x480 for "Default" and
> "Live TV" and
> >it does not seems to change anything.
> >
> >Does anyone have a clue ?
>
> First, can you describe "really poor resolution" in more detail? Is the
> image blurry? Pixillated? Fuzzy around the edges of moving figures?
> Something else?
>
> Second, have you ruled out problems with the input source? Does the image
> look good if you connect a TV to the EXACT same feed without changing
> *anything* else in the house? Or if you run xawtv to watch live TV at the
> seme screen size you use with Myth?
>
> Third, what screen resolution are you using in X? This thought is not
> certain, but I believe I've seen resolution problems caused by
> imperfections in the ability of XVideo drivers to rescale to
> fullscreen. In
> general, I've found that setting X resolution to 640x480 looks better for
> full-motion video with any card/display combo I've actually tested than
> using (say) 1024x768, or the 800x600 that is (or used to be)
> Myth's default
> setting.


My understanding was that this same setup was being used before with a WinTV
card & produced (in his opinion) better captures.


> Fourth, what capture bitrate are you using? Two parts to this. One, what
> settings are you using in Myth? Two, what are some actual, observed rates
> (MB/hr) from captures? If you have this set too low, increasing the
> resolution will not improve capture quality (or not very much,
> anyway). Oh,
> and do mention which encoder choice you are using, since it
> affects bitrate.

I don't think 'bitrate' is applicable with Hardware MJPEG captures.  The
relevant settings are 'quantization' or something like that, and I seem to
recall (long ago) some posts to the effect that nobody had been able to do
better than (2,2) for the quantization setting.  Don't recall what that
corresponds to...

-JAC



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