I need a program/tool to do the following:

1. Whenever sound is detected on a particular audio input (call it 'A') or on a particular midi input (call it 'B') (either will work--i don't need both)

2. Start recording in different audio input (call it 'C') and and start also logging the midi input on B



The idea is that i'm often improvising at my digital piano working on compositions and on vocal music etc, and i like having an audio back log of all the ideas i was trying. I've had straight-sound activated recording tools running before, but then that captures a lot of useless noise i have to sift through (like me watching hte simpsons, talking on the phone, etc.)
So, if it only activates when it recieves input from the piano (via MIDI OR audio, it doesn't matter) then i'll have a nice log of only the relevant audio. Any good ideas on how to do this?