Add line-in audio support.
The idea here is to add a mode that takes USB soundcard line-in audio, does the FFT in realtime, and controls the lights based upon the audio coming in live. Changes that will need to be made include at least:
(1) Support for line-in audio (see http://www.raspberrypi.org/phpBB3/viewtopic.php?p=314087#p314087 for sample code doing just that)
(2) Possibly adding back in some sort of floating average / std.dev. calculation that takes the last 10 seconds of audio into account (or 30s?) ... as currently the code calculates the average / std.dev. of each channel after the initial playback using the entire song. This floating average may be useful anyhow for initial playback of songs.
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