🚀 go-pugleaf

petsalo@lut.fi (Jyrki Petsalo) wrote:
>   : On top of this, the would-be Line-Doubler would have to be able to intercept both the 
>   : even and odd scan lines, by predicting the change between frames for each field for 
>   : every frame, convert it to 30kHz, and redisplay both even and odd field scan lines as 
>   : a composite image.  The prediction part is what separates the Faroudja between lesser 
>   : line-doublers.
>
>Our upcoming DblScan 4000 handles NTSC and PAL modes great. In comes 15kHz, 
>out goes 30kHz. Even interlace looks great on any VGA monitor.
>
>What do you need to predict?  Can you make a scandoubler in any other way
>than blazing out the incoming signal at double speed, line by line,
>field by field? If you are making composites from fields, or buffering
>the fields together, you have a flicker fixer, which kills moving video
>converting it from 50/60 Hz to 25/30 Hz. Great for A3000 with no fast 
>native 30kHz modes, not good for much else.

It's been a while since I read the original description on how the line-doublers 
work.  I believe that the article stated that prediction was needed since the video 
stream was coming from a unit designed only for showing 1 field (half of a frame) 
every 60th of a second.  In order for the line doubler to work, it seemed to need 
both fields in the same amount of time.  Therefore, prediction was needed in order to 
correctly draw both fields.  I'm sure that it stated that when the second frame 
finally came in, a comparison took place, and the on-screen image was altered a bit 
to find a happy median between what was shown and what was sent.  I think there was a 
complaint about image fuzziness caused when what was predicted didn't exactly match 
what was intended to be sent.
>

>Line-quadrupler?  Don't you need 60kHz monitor/projector/whatever for
>that?

I have no idea how the line-quadrupler works, or with what kind of monitor/projector, 
I just saw the ad and the stratospheric price.    It would be hard to imagine a 60khz 
projector.  The data-grade 30khz projectors are rare enough.

D. G.