When I run my AUv3 synth inside a host on an iPad under certain conditions I'm receiving repeated MIDI events. Still figuring out what the exact trigger is. Could be a CPU overload, not sure yet. Thought I'd ask here if anyone else has ideas as to what might be going on.
After inspecting the passed in variable AURenderEvent* realtimeEventListHead, it looks like it contains MIDI events that were already handled in previous callbacks. These MIDI events have timestamps that are older than the passed in AudioTimeStamp* timestamp. I sometimes receive the same events like 8 times in a row. i.e. in 8 render callbacks. And these events all have the same timestamp. So I'm not sure why I'm receiving them again. Could system be assuming they weren't handled and is sending them again?
I'm on iOS 15. (Not sure if this is happening on iOS 14 also. Don't have an iOS 14 device to test it on.) I reproduced this issue, both in AUM and GarageBand.