HOWTO insert video keying on the fly in streaming videos

[pofpof98]

Hi
I would to insert (on the fly) viewer information inside the streaming video as video keying.
At this time the only way to have this feature is to duplicate the video source for all the subscribed viewers before it is delivered which can cause heavy server activity and big disk space.
I am looking for a streaming server solution that could do the job on the fly by simply mixing the original video source with the viewer profile as video keying (like "This video is dedicated to M.Smith")
Can anyone help ?
regs
pofpof