Good morning David,
you make this thread very interesting now.
Please tell me the name of the IC. Maybe I can find a datasheet at
Googel for it. Or do you have a link?
You wrote:
Top of the to-do list is completing the stereo mixer for sound, and a 3.5MHz notch filter on the vision side to prevent buzz on sound.
Look how I solved it. To make stereo to mono you need two 4K7 Ohms
resistors.
Kind regards
Darius