Headset Blocker
If you own a Nexus One, you may be familiar with this scenario: you load up your N1 with some rocking tunes. You plug in your headphones and go out exercising with it. Suddenly, the tunes start skipping. Why?
The problem is that the headset jack is interpreting what you are doing as a control signal. The exact cause hasn't been shown to me yet; there are a number of theories from a lack of software noise filtering to the difference between TRS and TRRS connectors. Regardless, it's a serious issue - some people can't even listen to music in their cars with the N1 because it skips so much.
Luckily, in the last few days I was shown an answer. The control commands from headsets are actually sent out as a chain broadcast, MEDIA_BUTTON. As with any chain broadcast, your receiver can abort the broadcast. So the simple solution is to make a BroadcastReceiver with an ultra-high priority that intercepts and aborts the MEDIA_BUTTON broadcast.
To that end, I've put a small app on the Market, Headset Blocker. It's a small, free widget that allows you to enable/disable blocking of the MEDIA_BUTTON broadcast. You can get it here:
One interesting choice I had to make when writing this app was how to toggle the blocking. I had one of two options:
1. Use SharedPreferences to track when blocking is enabled. Capture all MEDIA_BUTTON broadcasts, but only abort when the preference is enabled.
2. Enable/disable my app's BroadcastReceiver. It will always abort when enabled, but is only enabled via the widget.
I went with the latter option, as I felt that would save just a little bit more battery when disabled (as the BroadcastReceiver itself would be disabled).