I'm sitting here with my processing book cracked open and have been scanning the forums for a few hours trying to sort this out.  Ive taken the "recordlinein" minim example and have began hacking it up to suit my needs.  Essentially what I would like to do is assign a color range to the lines that are drawn as a result of the audio input so that, for example, when there is little noise activity, lines are within the blue-green range, and when there is a lot of activity they are red, orange, etc.  I'm pretty new to processing so any insight is greatly appreciated.  Code is below.  

Thanks,

Evan 

Columbia GSAPP

2. 
   
3.  * This sketch demonstrates how to an <code>AudioRecorder</code> 
4.  * to record audio to disk. To use this sketch you need to have 
5.  * something plugged into the line-in on your computer. Press 'r' 
6.  * to toggle recording on and off and the press 's' to save to disk. 
7.  * The recorded file will be placed in the sketch folder of 
8.  * the sketch.
9.  */
10. 
    
11. import ddf.minim.*;
12. 
    
13. Minim minim;
14. AudioInput in;
15. AudioRecorder recorder;
16. 
    
17. void setup()
18. {
19.   size(1000, 800, P2D);
20.   textMode(SCREEN); 
21.   
22.   minim = new Minim(this);
23.   minim.debugOn();
24. 
    
25.   // get a stereo line-in: sample buffer length of 2048
26.   // default sample rate is 44100, default bit depth is 16
27.   in = minim.getLineIn(Minim.STEREO, 1000);
28.   // create a recorder that  will record from the input to the filename specified, using buffered recording
29.   // buffered recording means that all captured audio will be written into a sample buffer
30.   // then when save() is called, the contents of the buffer will actually be written to a file
31.   // the file will be located in the sketch's root folder.
32.   recorder = minim.createRecorder(in, "01.wav", true);
33.   
34.   textFont(createFont("SanSerif", 12));
35. }
36. 
    
37. void draw()
38. {
39.   background(0); 
40.   stroke(255,0,0);
41.   // draw the waveforms
42.   // the values returned by left.get() and right.get() will be between -1 and 1,
43.   // so we need to scale them up to see the waveform
44.   for(int i = 0; i < in.bufferSize() - 1; i++)
45.   {
46.     line(i, 50  + in.left.get(i)*50, i+1, 50 +  in.left.get(i+1)*200);
47.     line(i, 150 + in.right.get(i)*50, i+1, 150 + in.left.get(i+1)*200);
48.     line(i, 250 + in.right.get(i)*50, i+1, 250 + in.left.get(i+1)*200);
49.     line(i, 350 + in.right.get(i)*50, i+1, 350 + in.left.get(i+1)*200);
50.     line(i, 450 + in.right.get(i)*50, i+1, 450 + in.left.get(i+1)*200);
51.     line(i, 550 + in.right.get(i)*50, i+1, 550 + in.left.get(i+1)*200);
52.     line(i, 650 + in.right.get(i)*50, i+1, 650 + in.left.get(i+1)*200);
53.     line(i, 750 + in.right.get(i)*50, i+1, 750 + in.left.get(i+1)*200);
54.   }
55.   
56.   if ( recorder.isRecording() )
57.   {
58.     text("Currently recording...", 5, 15);
59.   }
60.   else
61.   {
62.     text("Not recording.", 5, 15);
63.   }
64. }
65. 
    
66. void keyReleased()
67. {
68.   if ( key == 'r' ) 
69.   {
70.     // to indicate that you want to start or stop capturing audio data, you must call
71.     // beginRecord() and endRecord() on the AudioRecorder object. You can start and stop
72.     // as many times as you like, the audio data will be appended to the end of the buffer 
73.     // (in the case of buffered recording) or to the end of the file (in the case of streamed recording). 
74.     if ( recorder.isRecording() ) 
75.     {
76.       recorder.endRecord();
77.     }
78.     else 
79.     {
80.       recorder.beginRecord();
81.     }
82.   }
83.   if ( key == 's' )
84.   {
85.     // we've filled the file out buffer, 
86.     // now write it to the file we specified in createRecorder
87.     // in the case of buffered recording, if the buffer is large, 
88.     // this will appear to freeze the sketch for sometime
89.     // in the case of streamed recording, 
90.     // it will not freeze as the data is already in the file and all that is being done
91.     // is closing the file.
92.     // the method returns the recorded audio as an AudioRecording, 
93.     // see the example  AudioRecorder >> RecordAndPlayback for more about that
94.     recorder.save();
95.     println("Done saving.");
96.   }
97. }
98. 
    
99. void stop()
100. {
101.   // always close Minim audio classes when you are done with them
102.   in.close();
103.   minim.stop();
104.   
105.   super.stop();
106. }