Re: Looping with sequencers..

[buzzard@world.std.com (Sean T Barrett)]

>There are enough big differences between "sequencer looping" and "delay
>looping" to make them significantly different.
>Audially, the decay of past generations is
>somewhat more interesting with the later, although this is a purely
>subjective judgement.

Well... that depends _what_ you thing "decay of past generations"
should be.

Most audio loopists advocate "the old sound gets quieter and the
new sound gets mixed in".  Some "hardcore _tape_ loopists" demand
the sound of tape with that lowpass filter per loop evolution as
"the sound of decay" that they want.  Of course, by putting the
loop feedback outside of the looper, you can put any effects you
want in the loop, although probably at the cost of having to limit
the maximum feedback significantly.  (But, I don't know anyone
who actually does this on a regular basis.)

On the other hand, what can MIDI loops do?  As you say, "fading"
the velocity over time isn't really the same as fading the volume
over time.  Of course, you can program your synthesizer to do whatever
you want in response to the velocity, e.g. only fade volume, close
a filter, etc.

What you give up is the expressiveness of having the velocity
of the original note & the volume decreasing.

And that's it, right?  That's all you can do for decaying
a MIDI loop?

Well... how about:

- decay by shortening the durations each iteration
- "decay" by making the note sound less and less often each
  iteration (e.g. 4 seconds, then 8, then 16, then 32; or
  perhaps the fibonacci sequence when you want something
  more weird--or the prime numbers when you want something
  unpredictable)
- make each "iteration" transmit on its own MIDI channel;
  then you give each channel its own program, with a volume
  ramp across all the channels (giving you independent fade
  and key velocity).  Heck, while you're at it, you can make
  each channel use a different patch/sound/sample and get
  "echoes" that change instruments.  Or maybe use a single
  sound, but have the volume ramp _up_ instead of down, a
  sort of "reverse echo".

Wow!  It seems like there's a lot more possibilities
with MIDI looping than at first glance.

The big problems that I see:
>Also, most MIDI synthesizers can only play so many sustained notes
>at the same time; with a digital delay there is no such limitation.

I think it's safe to say ALL synthesizers have this problem.

This "problem" is of course exactly the thing you don't take
advantage if you "MIDI loop naively".  The delay doesn't need
to "resynthesize" the notes, but the MIDI looper does--so maybe
take advantage of that resynthesis.

I was thinking about just getting 1 or 2 64-voice MIDI synthesizers
to address this problem; that's a lot of money, unfortunately
(the Alesis NanoSynth and siblings aren't multi-timbral, and
I think they're limited in programming).

The other big problem turns out to be MIDI (boy, ZIPI would be
much better for this), since you're limited to 16 distinct
"channel configurations" (i.e. settings of channel volume,
channel pitch bend, etc) which limits how much interesting
echo effects you can do without relying on altering the
key velocity.

With an 8 second loop, 16 tracks of echo will disappear
in just over two minutes, though, which isn't _that_ bad.

I'm thinking of something like "do cool stuff for 15 echoes
and then just key velocity fade out the notes on the 16th
track".

Unfortunately, doing all of this gives up putting multi-timbral
input _into_ the MIDI looper, since each input channel would
need its own bank of output channels.

>In sum; you can't easily sound like a Frippertroid
>with just MIDI sequencer looping.

Not with any available software.
I'm working[1] on it though.

Sean Barrett
currently only in the design stages unfortunately