android - how can i translate byte[] buffer to amplitude level -

i working library records audio , can listen each time new byte array if buffer if filled callback :

public void onvoicereceived(byte[] buffer) {  } 

now want take buffer , translate level can draw amplitude meter. how can translate data? dont want create recorder , use read() command.

this drawing code

    private void drawcircleview(canvas canvas, double ampvalue) {     // paint background color     canvas.drawcolor(android.r.color.holo_blue_bright);      // paint rectangular shape fill surface.     int border = 0;     rectf r = new rectf(border, border, canvas.getwidth(), canvas.getheight());     paint paint = new paint();     paint.setargb(255, 100, 0, 0); // paint color gray+semy transparent     canvas.drawrect(r, paint);      /*      * want paint circles, black , white. 1 of circles bounce, tile button 'swap' pressed , other circle begin bouncing.      */     calculateradiuses();     // paint left circle(black)     paint.setstrokewidth(0);     paint.setcolor(getresources().getcolor(android.r.color.holo_blue_light));     canvas.drawcircle(canvas.getwidth() / 2, canvas.getheight() / 2, ampvalue, paint); } 

thanks!

the byte[] buffer raw unformatted data. move forward, you'll need know format of data. how many bits per sample, endianness, , how many channels of data. 16 bits per sample common. assuming there 2 channels of data , 16 bits, bytes going arranged [ch1 hi byte, ch1 lo byte, ch2 hi byte, ch2 lo byte, ...] , on.

once information known can convert double. typically, double amplitude kept in range (-1.0, 1.0).

double[] samples = new double[buffer.length]; (int = 0; < buffer.length; ++i) {     int intsample = ((buffer[i*2] << 8) | buffer[i*2 + 1]) << 16;      samples[i] = intsample * (1/4294967296.0); // scale double (-1.0,1.0) } 

now crude level meter, first need decide if want peak meter or rms meter. peak meter find max of abs of samples.