Sonic-pi: octaver swallows notes, strange behavior

[benmaier]

I encountered a strange problem with the effect :octaver. I play two notes relatively close after another (16th note separation). Sometimes the second note gets swallowed, sometimes it doesn't. Since I'm new to Sonic Pi, I'm sorry if I'm doing something obviously wrong.

Here's a minimal example:

use_bpm 128

live_loop :octv do
  use_synth :beep
  with_fx :octaver do

    16.times do
      sleep 1/2.0
      play :Fs3, amp: 0.5, attack: 0, release: 1
      sleep 1/4.0
      play :Fs3, amp: 0.2, attack: 0, release: 1
      sleep 1/4.0
    end
  end
end

Here's a short sound file of what this sounds like on my machine: https://github.com/benmaier/IWasntLying/blob/master/weird_octaver_behavior.mp3

There's nothing special written in the logs.

I'm using Sonic Pi v2.11.1 on a MacBook Pro (Retina, 13-inch, Mid 2014), OSX 10.10.5 .

[ethancrawford]

It seems that it's not directly related to the FX, as the same thing happens when that is commented out.
From a few short tests I did, it seems to happen when one or both of the calls to play has a release that is greater than the sleeps in between them - ie if either has a release greater than 0.25, the 'cancelling out' occurs. More often/more noticeably if both are over 0.25, less if only one is (or maybe I was imagining it in this case? was hard to tell...), and not at all if both release values are 0.25 or less. Perhaps there's a simple explanation for this, (reminds me of destructive sound interference where a sound wave and its inverted copy cancel each other out) but I'm not totally sure if it's exactly that sort of problem...

[benmaier]

hm, may be, however it's strange that it only happens seemingly randomly.