Re: XServer and TV

[Andrew C Aitchison]

On Thu, 22 Apr 2004, Henry Berg =?iso-8859-1?q? wrote:

 (I posted this first to XFree86 list, but I got no answer. I think
 this is the right forum.) 
   
 I have made a little gadget to get the right sync from VGA to SCART in
 my TV.

 I like to try this modeline:  
 13382000   640  656  712  848   480  480  483  526   Concatenate  
   
 Concatenate (concatenate 2 fields to get a frame):
 Concatenate is a flag, which does not exist in XServer and is only
 here for explanation. 

 Is it possible to configure XServer to concatenate fields?

XFree86 has a feature very like concatenate, but called Interlace.

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Re: XServer and TV

[Henry Berg =?iso-8859-1?q?]

Hi,   
  
Interlace:
First field contains 1,3,5,7,9525 scanlines in the frame. Second   
field contains 2,4,6,8,10524 scanlines in the frame.   
  
Concatenate:  
First field contains 1,2,3,4,5 263 scanlines in the frame. Second  
field contains 264,265,266,267,268526 scanlines in the frame. First
field will contain the top half of the screen and the second field
will contain the bottom half of the screen.   
  
I like to use the TV for Internet browsing with Konqueror.
The TV with Interlace flickers too much on horizontal lines.  
The TV has good picture (no flickers) with non-interlace 262  
scanlines, but it has too few scanlines (too much vertical scrolling  
on Internet browsing).
  
I hope I could get rid of the horizontal color line flickering with   
Concatenating. My thought is that only scanline 263 and 264 in  
the frame can flicker if the scanlines are of different color with
Concatenating method.   
  
Best Regards, 
Evald 
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Re: XServer and TV

[Andrew C Aitchison]

(Mail direct to you bounced. My copy of your original mail
has invalid characters in the local part of your address).

On Thu, 22 Apr 2004, Henry Berg =?iso-8859-1?q? wrote:

 Interlace:
 First field contains 1,3,5,7,9525 scanlines in the frame. Second   
 field contains 2,4,6,8,10524 scanlines in the frame.   
   
 Concatenate:  
 First field contains 1,2,3,4,5 263 scanlines in the frame. Second  
 field contains 264,265,266,267,268526 scanlines in the frame. First
 field will contain the top half of the screen and the second field
 will contain the bottom half of the screen.   

That would give you a bigger problem than flicker: the top and
bottom half of the screen will alternately fill the whole screen,
at 50 or 60 Hz.

 With this Modeline the picture is Ok and no flicker, but it has too   
 few scanlines.
 13331000   640  656  712  848   240  240  241  262

This has no flicker becuase each line appears in both fields.

You would be able to approach the effect of having more resolution
without the flicker by averaging pairs of framebuffer rows into one
displayed row - sort of the the reverse of DoubleScan, or antialiasing 
rows together.

With a fixed frequency monitor (your TV) the only way I can see to
do this would be if you can have your X framebuffer in offscreen memory,
which blitted and *down*scaled this to appear on the screen.
You might be able to do this blit with the texture unit or the
video unit of your graphics chip (although on many chips the video unit 
used by the XVideo extension only does *up*scaling).

This would give you more lines, but the detail would be lost (that is 
the price of losing the flicker).
It is also possible that the blits would tear with the interlacing,
causing flicker when the image changed.

-- 
Andrew C. Aitchison Cambridge
[EMAIL PROTECTED]


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