homebrew video mixer?

[housepig]

okay, another question for the technically inclined among us..

for a project that I'm going to have to do live - no computer - I want to mix multiple video feeds, super ghetto style - quality is not the aim, chaos is preferable.

what I would like is a 3-4 input, 1 output black box, with a simple rotary control for each input, so that if I turned each input down to 1/3 max, all three video streams would be battling it out for the output.

bonus would be if I could filter colors from the signal, so that only red passes on feed 1, only green on feed 2, etc.

I know I could do this for audio with about $10 in parts and an hour with a soldering iron - is it possible for video, or is it a pipe dream?

any links / info / derisive laughter* appreciated

( * derisive laughter must be accompanied by some technical info to be appreciated)

[Anonymous65]

Unfortunately, you cannot add video signals together like you can do audio. The video signals that are to be mixed need to be synched to each other (gen locked), meaning the vertical, horizontal and color subcarrier needs to be phase locked together. If not, you would not be able to fade between the video signals. You can do switches, but there will be a glicth when switching between two unlocked signals. The TV will all of a sudden need lock up to the vertical, horizontal and color carrier when you switch to another video source. No easy and cheap way of doing this...

[johns0]

Its much easier to buy a video mixer than to build one out of spare parts,here`s one mixer you can take a look at.
http://www.edirol.com/products/info/v4.html

[housepig]

The video signals that are to be mixed need to be synched to each other (gen locked), meaning the vertical, horizontal and color subcarrier needs to be phase locked together. If not, you would not be able to fade between the video signals. .

what would happen if they weren't genlocked? believe me, for what I am planning to do, I will accept a completely screwed-up image - as long as a) it's not a black screen, and b) there is some vestige of the original sources present (ie I don't want just a rolling non-signal horizontal bar).

so what would a multi-input-signal, non-genlocked output look like?

[Anonymous65]

If you mix two unlocked video signals the images will be rolling sideways and also up/down with respect to each other, and with color that is "spinning" out of control. Nice effect, but useless to watch!

[housepig]

Nice effect, but useless to watch!

not necessarily... this could be good.... thanks for the info!