Question

I’m trying to develop a spectrum based live wallpaper, which will change when the music plays or someone touches the screen, for android 2.3 and up. The problem is that I need to get the session id to initialise the Visualizer so…

How can I get the sessionId from android

And it would be good if you could show me how I need to init the Visualizer properly to get FFT data, or alternative ways to get fft data.

Answer 1

The default audio session id is 0 (It will react on all sound output-music,system sounds).

And to init Visualizer to get FFT one way is:

Visualizer viz = new Visualizer(0);
 viz.setCaptureSize(Visualizer.getCaptureSizeRange()[1]);

        viz.setDataCaptureListener(new OnDataCaptureListener() {

            @Override
            public void onWaveFormDataCapture(Visualizer arg0, byte[] arg1, int arg2) {
                //Wave procesing here

            }
            @Override
            public void onFftDataCapture(Visualizer arg0, byte[] arg1, int arg2) {
                //FFT procesing here!
                }


        }, Visualizer.getMaxCaptureRate(), true, true);
        viz.setEnabled(true);

And the other one would look like this:

    Visualizer viz = new Visualizer(0);
         viz.setCaptureSize(Visualizer.getCaptureSizeRange()[1]);
    viz.setEnabled(true);
//to get data use viz.getFft(fftdata);
    viz.getFft(fftdata);

And in manifest you need to add some premisions:

 <uses-permission android:name="android.permission.RECORD_AUDIO"/>
<uses-permission android:name="android.permission.MODIFY_AUDIO_SETTINGS"/>