MIDI clock to AU unit

pianosnake

Hello dear loopy fans, not sure if this is a bug, or if I'm not understanding the capabilities of Loopy Pro. I am using StreamByter to count clock ticks and trigger other samples based on when the measure starts. But I can only do that with it as an external app.

When I open Loopy Pro and StreamByter as separate apps, I can add Streambyter as a MIDI device in the LoopyPro mixer (black and white logo), and I see the clock ticks in the StreamByter monitor. Here's the image of both apps side by side on my iPad:

But if I setup Loopy Pro with StreamByter as Audio Unit Input (color logo) then I do not see the clock ticks in the StreamByter monitor. Only thing I see is two Systex messages. I tired enabling Ableton Link, and setting "Virtual MIDI Out" as the MIDI Clock destination, and then "Virtual MIDI In" as the source for StreamByter, but no success either.

Why the difference? How can I get clock ticks in the second setup?

uncledave

Hi. StreamByter is not an "instrument"; it produces no audio output. I believe you want to load it as a MIDI device. You can route its output to whatever you want.

By the way, the Virtual MIDI Out and Virtual MIDI Out ports of Loopy Pro are visible to other external apps. They are not connected to each other.

Edit: Sorry. I overlooked that your "working" setup was running StreamByter stand-alone. You've already gotten good answers for the problem.

wim

AudioUnit plugins aren't designed to be driven by midi clock. They're designed to be synced by the host through a tighter timing integration. Probably Loopy simply isn't passing midi clock to plugins - by design.

Sending to Virtual MIDI Out won't be reflected back into Virtual MIDI In. There's nothing to handle the routing. But Streambyter Standalone can serve as something to bounce off of.

If you want clock available to plugins (few will make use of it), send it out to standalone Streambyter, then back in from Streambyter.

• Start up Streambyter in standalone.
• Set midi clock out to it.
• Add the Streambyter standalone port as a midi input.
• Now add your Streambyter AU and route the input from the standalone port to it.

espiegel123

@pianosnake : fwiw, Mozaic would be a better fit for this use-case as it directly supports host sync and tracks the transport state and tracks host beats and measures.

@wim’s suggestion of bouncing of the standalone StreamByter app works.

There is also a self-contained solution with Streambyter that doesn’t require SB as a standalone. Add Loopy Pro as a midi AU. Turn on host synch in it. Set Loopy Pro as a midi destination. In the Loopy host, add Virtual
midi In and Streambyter AU. Make streambyter a destination of the virtual midi in port.

espiegel123

This illustrates loopy loaded as a midi AU in loopy. The loopy AU sends clock to the Loopy Pro port. The Virtual Midi In port (that is where midi directed to loopy pro goes) passes the midi clock to streambyter au.

wim

Thanks @espiegel123. I was too lazy to post screenshots.

pianosnake

You're amazing @espiegel123, your self-contained solution works! I would have never thought of that!

wim

I couldn't say for sure without testing, but the self-contained solution is likely higher overhead than just bouncing off of standalone Streambyter. A full featured plugin vs. a very lightweight separate app.

Tidier though, I suppose.

espiegel123

@wim said:
I couldn't say for sure without testing, but the self-contained solution is likely higher overhead than just bouncing off of standalone Streambyter. A full featured plugin vs. a very lightweight separate app.

On my iPhone X and a buffer of 64, the CPU indicator is at 4% with this setup and 2% without the Loopy AU. So, it probably does use more resources, but in many use-cases the difference may be inconsequential.

wim

@espiegel123 said:
... but in many use-cases the difference may be inconsequential.

Yes, I should have added that.

wim

On the other hand, there is also memory consumption to consider.

espiegel123

@pianosnake : see this script from @uncledave that generates clock ticks itself:

https://audeonic.boards.net/thread/913/streambyter-script-newbie-lots-help?page=4#post-5396

pianosnake

Thanks @espiegel123 and @uncledave for your script which I shortened it a bit for my purpose. Putting it out here in case anybody else finds it useful. Starting with the sysex message for clock start from LoopyPro host, I can send clock ticks from StreamByter as AU. I'm sending out a drum note on each beat (I know F8 is supposed to go out 24 times per quarter note, but in this case once per quarter note is enough). I turned on the metronome in LoopyPro to make sure they're staying in sync.

IF LOAD
  ALIAS J0 ticking
  ALIAS J1 drift
  ALIAS J2 drift_accum #accumulation of drift
  ALIAS P0 delay #use large integer from P array
  ALIAS P1 adjusted_delay
  ASS J0 = 0 0 0
  ASS P0 = 0 0
END

SUB issue_tick
  # Accumulate the drift. If it's bigger than BPM make it equal to how much over BPM it is, and add a millisecond to the delay. Kinda like adding a "leap" millisecond that we lose when we send rounded down delays, which is done because the delay (P0) has to be an integer.

  MAT drift_accum = drift + drift_accum
  ASS adjusted_delay = delay
  IF drift_accum >= BPM
    MAT drift_accum = drift_accum % BPM
    MAT adjusted_delay = delay + 1
  END

  SND F8 +I +DP1 #+I so it gets sent to SB and this function gets triggered again and +D which is the adjusted delay
END

IF M0 == F0 7D 01 7A #sysex when starting host clock
  ASS ticking = 1
  # 60,000 ms in a bpm, multiply by 100 because built-in SB BPM variable is reported *100
  MAT delay = $6000000 / BPM
  MAT drift = $6000000 % BPM
  SND F8 +I
END

IF M0 == F0 7D 01 7C #sysex when stopping host clock
  ASS ticking = 0
  ASS J0 = 0 0 0
  ASS P0 = 0 0
END

IF M0 == F8
  IF ticking == 1
    SND 99 3C 40 #send out a drum note
    issue_tick
  END
END

wim

If you're curious about an approach using Mozaic, MIDI Clock Tool and Midi Clock Toolbox might be of interest.

pianosnake

@wim wow! I looked at Mozaic, and the same thing can be written in 3 lines:

@OnNewBeat
  SendMIDIOut 0xF8
@End

Mind blown, thank you!!!

wim

Yeh, a lot of StreamByter scripts are simpler and more compact than Mozaic, but as you've shown, some things are easier in Mozaic.