A dual loop machine

[Mark Hamburg <mhamburg@Adobe.COM>]

The discussion a while ago regarding undo on the EDP got me thinking in
general about snapshoting as a mechanism for undo in a looper. Basically,
the idea is that you want to be able to take your current loop at any given
time and make a snapshot of it. If you later make changes that you don't
like, you can go back to the snapshot. (Or Photoshop-style, you can bounce
back and forth between various snapshots.)

This, however, got me thinking about what would happen if you had a looper
capable of moving pointers through two loops simultaneously. Let's assume
we have an A loop and a B loop. Let's also assume that all recording
happens in loop A and is subject to the usual EDP operations (multiply,
overdub, etc.). A loop consists of a bunch of recorded information and a
pointer cycling through it. Here is a list of some possibly interesting
operations:

1. Swap A & B. (Since I only allowed for recording in one of them.)

2. Copy loop A to loop B. (i.e., save my loop)

3. Copy B to A. (i.e., restore my loop -- not essentially given swapping
but probably useful)

4. Crossfade between A and B.

5. Fade the loop volumes independently.

5. Overdub from B onto A. If the loops are of the same length, this is just
a gradual replacement. If they are of different lengths, then this is a way
to build up a complex wash.

This obviously extends to having more than two loops but the user interface
would get more complicated.

Would it be possible to support something like this on the EDP? Mapping the
options to the available user interface controls might take a bit of work,
but I think it's probably doable. (Could we use the feedback input as a
general A/B mix control instead?) The big question is whether the EDP has
enough processing power to run and mix two simultaneous loops.

Mark