Extremely Slow MIDI response

Questions & Suggestions
1

Hi folks,

I'm actually testing TouchOSC with Keyboard Maestro, which open quite some great perspectives.
However, I'm a bit surprised by how the thing is slow.
You'll find attached a screenshot of my basic test: setting the system volume based on the value sent by TouchOSC (simple slider from 0 to 100)
When I move the TouchOSC slider, values are instantly sent, but the system struggle to handle them. The system volume slider hangs, beach ball and so on.
I'm running a boosted Mac Pro early 2008 which doesn't show any significant performance issues (and should specially not for this kind of things).

Any idea? Thanks in advance.
41

2

Setting the system volume is done with AppleScript. So it is a relatively slow process. Even on my relatively fast Mac it takes about 0.2 seconds.

However a MIDI change can happen hundreds of times a second (probably more - and then Keyboard Maestro will have no chance of keeping up with it).

You will be able to improve your results a lot by ensuring that only one of these macros happens at a time using the Semaphore Lock action, something like this:

  • Set Variable Latest to %TriggerValue[3]%
  • Semaphore Lock "My MIDI Lock" with timeout 0.01 seconds, no failure notification
  • Until
    • Set Variable LocalValue to %Variable% Latest%
    • Use Variable LocalValue to set the system volume
  • Until variable LocalValue is %Variable% Latest%

It's not completely perfect, it is possible the final value set will not always be the final MIDI value sent for a number of race condition reasons, but generally it should work a lot better than your current macro.

1 Like
3

This have been a big help!
Thank you @peternlewis!