So I am writing a voice activated recording program, and one of the things I would like it to do is plot the current and past volume level on a JPanel.
Write now I am simply reading one byte from the audio buffer, converting it to an int, taking its absolute value, and more or less directly plotting the value on a JPanel. Things more or less work, but I get the feeling that my method is not very orthodox.
So my question basically boils down to the following:
how is audio data typically interpreted when used to represent the current volume level?
Here are some bits of code:
In the following code the byte read from the microphone input is converted to an int, and sent to the JPanel osc, for drawing.
int bufferSize = (int)format.getSampleRate() * format.getFrameSize();
byte buffer[] = new byte[bufferSize];
...
while (running) {
int count =
line.read(buffer, 0, buffer.length);
if (count > 0) {
osc.addLevel(Math.abs((int)buffer[0]));
out.write(buffer, 0, count);
}The following is the actual JPanel code used to plot the int.
public void addLevel(int i)
{
columns.add(i);
draw();
}
public void draw()
{
g = getGraphics();
int bottom = getHeight();
g.setColor(Color.black);
g.fillRect(0,0,getWidth(),bottom);
g.setColor(Color.green);
//int mult = bottom/128;
int edge = getWidth()-1;
for(int c = columns.size()-1; c>-1; c--)
{
g.drawRect(--edge,bottom-columns.get(c),1,columns.get(c));
System.out.println(edge+" "+bottom+" 1 "+columns.get(c));
}
}The previous code results in this:
[IMG]http://i12.photobucket.com/albums/a202/kimbokasteniv/panle.png[/IMG]
And the actual audio format:
float sampleRate = 8000;
int sampleSizeInBits = 8;
int channels = 1;
boolean signed = true;
boolean bigEndian = true;So how should this be done? Should I read more bytes? Should I take an average of several bytes? Or is using plain byte information for the volume level foolish altogether?
