Latency and Blokas pisound HAT

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@kniknoo Please read the MIDI in section in the built-in tutorial (11.1) - particularly the section on removing latency:

Removing Latency

Before we can remove the pause, we need to know why it’s there. In order to keep all the synths and FX well-timed across a variety of differently capable CPUs, Sonic Pi schedules the audio in advance by 0.5s by default. (Note that this added latency can be configured via the fns set_sched_ahead_time! and use_sched_ahead_time). This 0.5s latency is being added to our :piano synth triggers as it is added to all synths triggered by Sonic Pi. Typically we really want this added latency as it means all synths will be well timed. However, this only makes sense for synths triggered by code using play and sleep. In this case, we’re actually triggering the :piano synth with our external MIDI device and therefore don’t want Sonic Pi to control the timing for us. We can turn off this latency with the command use_real_time which disables the latency for the current thread. This means you can use real time mode for live loops that have their timing controlled by syncing with external devices, and keep the default latency for all other live loops. Let’s see:

live_loop :midi_piano do
  use_real_time
  note, velocity = sync "/midi/nanokey2_keyboard/0/1/note_on"
  synth :piano, note: note, amp: velocity / 127.0
end

Update your code to match the code above and hit Run again. Now we have a low latency piano with variable velocity coded in just 5 lines. Wasn’t that easy!

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