re-transmit the same captured video stream with a different audio

[issax]

hey there,

i have a very strange idea of capturing a stream video, and i need to recorded it, embed an audio recording over it, then re-transmit the same captured video stream with a different audio...
what i'm looking for is the device, or the software that can handle the video recording and save it to a certain buffer, record the voice then retransmit the buffered video with the new audio.
you help is need, it's a challenging problem, any ideas from your side would be helpful...

cheers,

issax