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Re: MIDI sync with Time Signature Retention

At 12:50 AM -0400 9/17/10, Matt Walsh wrote:
>I'm somewhat new to audio looping. I have been doing a form of 
>looping by building up tracks with my Akai MPC60 and sampler. I am 
>thinking about syncing some audio loops into the mix, as it were.
>So I am thinking of getting a real-deal audio looper. It will need 
>to slave to to the Akai, and it will need to be a piece of hardware. 
>Thing is, it will not only need to slave tempo, but will need to 
>slave time signature as well. I'm not opposed to having to load a 
>patch that has this data in it, if need be. But it definitely needs 
>to respond to play/stop commands and stay in sync with the MPC.

You may be out of luck as far as hardware goes, since I believe that 
almost all hardware units respond to Midi Clock Sync and MMC (Midi 
Machine Control) commands.  IIRC, Time Signature is a rather esoteric 
specification buried in MTC (Midi Time Code), which there is little 
reason for audio loopers to implement.  (Even back when I did a lot 
of soundtrack and post-production work, we never bothered with that 
function.  In fact, I'd forgotten it existed until I just did a 

MTC is mainly useful when syncing to SMPTE.  In most setups, you'd 
want to be able to shuttle to different parts of a composition and 
have all the instruments immediately know which section of the score 
at which they should begin.  Since most loopers merely record an 
audio loop then replay it over and over (yes, I know I'm 
oversimplifying here guys) there's little advantage to MTC over Clock 
Sync + MMC, so most manufacturers don't bother with it.  In fact, I 
can't think of any hardware loopers at all that support it off the 
top of my head.

I'm curious, though, why this is a requirement?  Are you going to be 
recording a loop in realtime and then suddenly changing its time 
signature?  If so, then there are perhaps some other functions that 
might assist you with doing that rather than using the MTC spec.  For 
instance, changing 4/4 to 3/4 would be rather easy by simply 
truncating the loop.  4/4 to 7/4 would be a 2x multiply, then a quick 
truncate from 8 beats to 7.  Many other time signature changes are 
going to be very difficult with recorded audio data, however.  But, 
then again, merely changing the time signature via MTC spec isn't 
going to do any deep editing of the lines either.

If you can give us some idea why you need this over just standard 
Clock + MMC, maybe we can help with a more comprehensive answer.

FWIW, a few hardware loopers I know if that support Clock are the 
Looperlative, EDP, and Repeater.  Probably a couple more I'm 
forgetting too.

"beyond this window, night is shuddering and the earth grinds to a halt
    beyond this window, something unknown is watching you and me...."