Amiga Genlock

[amiga-penn-wchester]

typically a genlock just takes amiga RGB and superimposes a composite input signal over it and you are getting color composite blend out the other end.

models like the GVP G-lock will give a SVHS out which should be better than composite, but you're still losing the RGB purity/independence when doing so

to add to the confusion, some C=108x monitors + internal genlocks will show crisp RGB over the genlocked signal in a certain mode because it can pass the composite signal thru the RGB port of the amiga, leaving then an extra genlocked output  on the genlock card itself for another recording device or monitor (composite).

but in general unless you're using the genlocking features of like a video toaster or something, the output quality is nearly always less than that of the RGB signal.

[amiga-penn-wchester]

a genlock overlays amiga gfx over NTSC or PAL color composite video.  Although the amiga's design lends itself to this type of thing, it's not available out of the box, you need to have a circuit that can reconcile horizontal and vertical timing and add the signals together.  We all spent hundreds on genlocks back in the day, and if they were available directly on the computer, it would have been nirvana.

please see

http://www.textfiles.com/computers/genlock.txt

which was apparently written by a Commodore engineer or tech support person.  You can see from this text that there are a lot of manipulations that need to happen for the overlay to occur.  

genlocks in and of themselves don't always guarantee quality composite video; they were used for vertical scroll titling and captioning.  It highly depends on the make of the genlock.  GVP GLock and Video toaster are the best of the bunch, I'm sure people can name others...