[mythtv-users] 720x480 interlaced modeline for nvidia/svideo

[Louie Ilievski]

On Tuesday 07 March 2006 21:08, Nick Bartos wrote:
> I am trying to get an interlace modeline for my nvidia svideo output,
> basically trying to get it so that I don't need to use deinterlacing.
>
> Anyway I can't seem to get one to work.  One way or another X won't use
> the modes I am trying.  I can get one 720x480 mode to work that was
> created by gtf, but it doesn't have the "interlace" keyword in it so I
> didn't think that was what I wanted (still need to deinterlace, otherwise
> I get a lot of motion jitter).
>
> Does anyone have one of these, or point me in a direction to a modeline
> generator that will do this.  I have tried gtf and videogen.  Also I have
> tried several that I copied from web pages but none worked.  Also I see I
> can use HD480i instead of NTSC-M in the xorg.conf, but I haven't been able
> to get it to work at all.

I hope this isn't too discouraging, but I would suggest you not bother trying.  
I have spent an unbelievable amount of hours trying to do exactly the same 
thing as you.  I have never been successful.  After a while I would see 
something that gives me hope and then spend hours again tinkering with 
settings but just end up failing again.

Just a week or two ago I slapped together another Myth box from parts I had, 
including a PVR-350 I hadn't used in a while.  I was extremely pleased when I 
noticed that it produced a perfect interlaced output to the TV - and this is 
NOT when using the decoder.  I am only using Xv and the framebuffer.  This 
gave me hope of getting my Nvidia 5200 card to do the same thing with the 
right settings.  Hours later, I finally gave up once again.

I've scoured the web for this stuff, but nobody has a success story for what 
you and I want.  I've only seen people say that it really isn't possible to 
do with these cards, and I have pretty much accepted this now.

If you set your overscan to the max setting (250 using the 6629 driver), and 
pause the video, it LOOKS like there is no scaling going on and that the 
interlaced lines are being displayed properly...but, of course, when you play 
the video, it just isn't so smooth and there is horrible jitter and stuff.  
I've played with every setting I can think of, with/without OpenGL Vsync, 
etc.  I was even about to try to find the datasheet for the tv encoder on the 
card and see if I could possibly generate a perfect modeline that would give 
me what I want, but I've basically just burned myself out too much on 
tinkering with it to go much further.

As far as your problems with the modelines you HAVE tried, you can get those 
to work by specifying a range for the horizontal and vertical refresh rates 
in your xorg.conf.  In my case, I just put a huge range so it would accept it 
(although this is totally wrong)..  I did something like 10-100.  It accepted 
most modelines at that point, but still, the results were the same.

Also, for 720x480 modelines, I have never been able to get recordings to 
actually fill the screen without using the Fill aspect override option.  It 
would be square, with black on the left and right sides.  This shouldn't be 
necessary, as the PVR-350 output is full screen with aspect override Off 
(once again, NOT using the decoder, but just Xv).

Anyway, if you or anyone else finds out the secret (if there is one), PLEASE 
let me know.  I will supply many, many brews for this  :-)

For now, it's Bob for me.  Good thing I am going to be looking into a new HD 
tv in the relatively new future.  Maybe I can get what I want then, using DVI 
or whatnot.

Good luck,

~Lou

P.S.  CNN's ticker is a great test to see if it's truly working as it should 
be  :-)