On Wed, 09 Feb 2005 13:09:08 +0000 
Neil Bird <[EMAIL PROTECTED]> wrote: 
 
. . . 
   On a side note (if anyone's still reading 
this :-) ):  anyone using an RGB->S-Video 
converter?  The one I've got *works*, but the 
output is pretty pants;  everything's *far* too 
bright/colourful, and fiddling with ivtv's 
settings can't really fix it again as too much 
info.'s been lost in the high brightness.  
Beginning to think I'll be better off  
using composite video ... 
 
--- end quote --- 
Neil, it sounds to me like a lack-of-termination 
problem. Does the converter have a switch to 
enable termination on the rgb signals -- a 
switch labeled "Hi-Z" or "Bridging" vs. "75 ohm" 
or "Term", perhaps? If so, the switch should be 
in the 75 ohm or term position.  Does it have 
two high-density 15-pin VGA connectors, an In 
and an Out? If so, it's probably designed to 
bridge (sample the video lines without loading 
them) -- the signal may look normal when you 
connect a monitor to the VGA Out connector. 
 
Explanation: video signals require transmission 
lines that are terminated in their 
characteristic impedance at both the driving and 
the receiving end to prevent the signal from 
reflecting off the impedance mismatch and 
creating echos or ghosts in the picture. A 
monitor has terminators in it. If your converter 
is in Bridging mode it does not have line 
terminating resistors connected. This causes the 
video signals to be too "hot" because the signal 
levels are too high, resulting in that 
too-bright, washed-out condition you describe.  
 
Hope this helps, 
Bob 
 

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