[Openchrome-users] Troublshooting NoScale Problems on VT1622A

[Jake Thompson]

So good news.

I seem to have solved the playback issue with some help from some myth
users.  I had the recoding profile set to 4:3, changing it to 16:9 seems to
clear up any playback issue, then I just override the playback aspect ration
to 4:3 and it looks beutiful.  I have no idea why this works, but my test
has been watching baseball games, alot of motion and alot of color with the
crowd background, using this has a drastic improvement.

I have set my mode to 720x480Over for now, since this has no color
distortion and the flicker is not there, well let me clarify that, the
overall screen flicker is not there, but the thin white line test still
flickers but not as bad.  Since this is to be expected, I do not think there
is anything wrong.

When I used xrandr to force 720x480Noscale to 50hz, it made for a better
picture, but was well inside the outer boundries of the tv, so the picture
had wavy edges.

If anyone has anything they would like me to try out, let me know.

-Jake


On 5/10/06, Ivor Hewitt <ivor at ivor.org> wrote:
>
> On Wednesday 10 May 2006 04:44, Jake Thompson wrote:
> > So after alot of playing and tweaking, I am still having the "Green
> Fade"
> > issue with my VT1622A.
> >
> > Running the display in 720x480Noscale causes a green fade on the top of
> the
> > screen and alot of refresh flicker(enough to give me a headache).
> >
> > If I run in 720x480Over, these problems disappear, however due to the
> Over
> > scaling video playback is no longer smooth and looks bad.
> >
> Well according to the table, for NTSC 720x480Over is also an unscaled mode
> which should look the same as 720x480Noscale (it did for me). But it
> seemed
> the refresh rate isn't calculated quite right for it and it isn't quite,
> but
> I had no image quality problems.
>
> Can you confirm from your log that 720x480Noscale is definitely being used
> (and not 800x600).... and if so could you quantify "video playback is no
> longer smooth and looks bad"
>
> > Thin white lines and other white object you can notice a flicker, also
> it
> > seems to affect all the pixels across the screen, so you can see a
> > difference in the screen along the horizontal where the flickering is
> > taking place.
> >
> That's to be expected. Unless you're talking about something different.
> The
> unscaled modes are for displaying video playback. If you display computer
> generated images with thin straight lines you will get horrible flicker
> unless the application has been written with "TV knowledge"
>
> (hmm I think we need a wiki FAQ for TV modes)
>
> > The green fade takes about 15-25% of the top of the screen.
> >
> Yeah it's green. The ntsc noscale has incorrect timings.
>
> > What else can I do to help resolve this problem, I will try out anything
> > you think might help.
> >
> If 720x480Over works... wait for a bit.... if it doesn't I'll see about
> generating some ntsc tv modes manually with my generator for you to play
> with. At the moment I'm concentrating on getting nice working PAL modes
> (for
> obvious reasons).
>
> Many thanks,
>
> --
> Ivor Hewitt.
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