I'm using OS X 10.10 and my iTunes (version 12.1.2.x) keeps opening. the only behavior pattern I could observe seemed really bizarre – It would open when I would click in my Firefox window. I retested many times, but I couldn't reproduce this after I removed my headphones.
I checked for anything suspicious in /private/var/log/system.log. I didn't see any odd interactions between Spotify and iTunes (i.e. an event in one that led to an immediate event in the other when looking at timestamps). The only thing sort of suspicious were these logs (there were many of these entries) from iTunes when I wasn't using it at all:
/private/var/log/system.log:Apr 24 11:12:06 ITADMINs-MacBook-Pro-4.local iTunes[8626]: ### PlayQueue::StartPlayingNextInternal: played off the end of the queue
/private/var/log/system.log:Apr 24 11:18:37 ITADMINs-MacBook-Pro-4.local iTunes[8680]: ### PlayQueue::StartPlayingNextInternal: played off the end of the queue
What could be happening?
Best Answer
WOW I finally figured this out.
Tampering with the audio jack will cause this to happen. I have headphones with the play/pause/skip control button, so the issue might not show up with standard headphones. If I tap (or double tap) the headphones where it is connected to the jack, the effect is the same as if I clicked the remote button that was designed to control playback.
What's happening is my movement is jarring the headphones and even a very slight tug will open iTunes and start playing music. Very frustrating when I'm using my headset for a phone call!