Zebra2, possible bug with MIDI + wave warp

[bmrzycki]

Urs,
I was experimenting with Wavetable morphing and discovered that fast midi modulations of the wave knob sometimes caused the OSC to enter an unstable state.

Here are the steps to reporoduce (Zebra 2.5.2 64-bit/Reaper 4.02 64-bit/Windows 7 SP1 64-bit).

1. Load a blank patch.
2. Load 00_TRI_Double tri to ... in contrary motion from Sendy's Zebroscillators presets. It happens on other patches, it's just very audible with this one.
3. Hold a fairly low note, say C3.
4. Move the Modwheel from max to min very quickly.

Sometimes it works perfectly. Other times it's almost as if Zebra misses some of the messages and picks one to stay at. The worst case is when Zebra gets in a state where the modulation continues external from the source. The wave will keep moving a bit as if you're moving the controller even when you're not.

I've made a 4MB LICEcap animated .gif video of the problem in action. I'm using ReaControlMIDI + Mouse to move the Modwheel from max to min quickly. The first few passes you'll see that when the mouse reaches 0 the wave is not completely at the end of the table, as if CC message values of 1,2,3 or somewhere in that range are where it stopped. The next state is the oscillating one. Finally I reset the state with a slow sweep of the modwheel slider.

I tried this also with CC Breath, same thing. It doesn't occur with internal sources such as envelopes or LFOs.

I got this to happen with ReaControlMIDI as well as external midi sources. I also verified with a midi logger that CC 1 value 0 is correctly being sent to Zebra.

Link to the video:
http://www.box.net/shared/2iyay75jh1ujb7yxu3gm

[Urs]

Hmmm... strange stuff, indeed. Will check it out!