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

Ray Olszewski ray at comarre.com
Mon Jul 7 10:02:34 EDT 2003


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.

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.

Finally, what is the CPU load  (as reported by "top") during capture, 
during playback, and during watching "live" TV? You probably mentioned your 
other hardware in earlier messages, but I do not recall what they said, and 
it is always possible that you are hitting CPU limits.





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