Events and MC Values
It is often useful to obtain values from an audio signal and use them in event-level processing. With standard MSP signals, you can use the snapshot~ object to get an instantaneous value from an audio signal at a regular interval.
In the case of multichannel signals, things are more complex: at each measurement, you would get a large number of values. Rather than create a list of arbitrary size, the mc.snapshot~ has an additional outlet that provides a voice number.
At each sampling interval, mc.snapshot~ outputs each of the values from each of the incoming samples, but outputs the voice number before the signal value. This combination of values can be used with a routing object (like mc.route) to send each value to a unique location.
Voice outputs from poly~ and mc.poly~
You can use the voice output, along with a routing object such as mc.route to use the event output to control other parts of your patch.