Amiga Genlock

[lassie]

Hi what is a amiga genlock? i have found out so far, it is something to do with picture, does it give amiga better picture quality?

[TCMSLP]

A genlock allows Amiga video output to be mixed with another video source.  Typical examples would be text or titles added to music videos.

[lassie]

A genlock allows Amiga video output to be mixed with another video source.  Typical examples would be text or titles added to music videos.

okay so it has nothing to do with better picture quality when connected to a monitor/television?

[TCMSLP]

No, nothing to do with video quality.

[jj]

If I may "muddy" the waters here.  I believe some people have, or at least suggested, using some models of genlock to output RGB or Svideo from the amiga and hence improving the picture quality over teh composite or RF out.
 
Am i talking bollocks here ?

[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.

[danbeaver]

On some poor monitors/TV's you may see a difference in the composite output, but the answer is an RBG / VGA monitor; use the former for C64's and the like and the latter on Amiga's and such.

[psxphill]

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.

What everyone refers to as a genlock is actually a video mixer.
 
The Amiga chipset can synchronise it's output to an external video source, so the genlock is actually internal.

[danbeaver]

I'm not sure this thread is oriented to the 7.14MHz CPU clock speed of the 68000 or why it was chosen.

[JimS]

I'm not sure this thread is oriented to the 7.14MHz CPU clock speed of the 68000 or why it was chosen.

That clock speed is exactly twice the color clock of a composite color video signal. A genlock also derives that clock from the external video that you're trying to super over. The video and amiga need to use the same clock otherwise the overlaid video will shift colors with respect to the amiga... or vice versa. The genlock also derives the horizontal and vertical sync pulses from the external video so the pictures don't roll with respect to each other.

[danbeaver]

Yep, this thread has gone definately off topic (as to a genlock improving the video signal)

[psxphill]

I'm not sure this thread is oriented to the 7.14MHz CPU clock speed of the 68000 or why it was chosen.

I don't see anyone mentioning that before you, the original question was "What is an Amiga genlock?". And the answer is, it's a video mixer.

[danbeaver]

 This refers to the CPU being clocked so as to coordinate the video output for mixing, plus other uses.  Or did you not know that is why the CPU runs at an "odd" speed?

[psxphill]

This refers to the CPU being clocked so as to coordinate the video output for mixing, plus other uses. Or did you not know that is why the CPU runs at an "odd" speed?

The CPU clock speed isn't related to mixing. It's to make it easier/cheaper to share the chip ram between the 68000 and agnus.

[danbeaver]

Uh, we'll that's a point, but the video timing was set around the clock speed (well vise-versa) and that is why the guys at Newtek chose the Amiga as the Toaster platform. I personally thought you knew that, but I'm sorry to imply otherwise. Let's drop the discussion as it does not relate to the thread. If you like, just start a new thread about the Amiga's development and engineering choices.