Tracks the position of the finger on the screen to generate an audio sample and play it back

This example selects the frequency and generates an audio sample based on the position of the user's finger on the X axis of the screen.

Because the code is relatively simple, you can directly use the Code if you don't need to talk about it.

[Java]
Public class FingerSynthesis extends Activity implements OnTouchListener
{
 
AudioSynthesisTask audioSynth; // specifies the thread used to play the audio sample.
 
Static final float BASE_FREQUENCY = 440; // baseline Audio Frequency
 
 
Float synth_frequency = BASE_FREQUENCY; // 440Hz, changes as your fingers move
Boolean play = false; // determines whether to generate audio samples.
 
@ Override
Public void onCreate (Bundle savedInstanceState)
{
Super. onCreate (savedInstanceState );
 
SetContentView (R. layout. main );
 
View mainView = this. findViewById (R. id. MainView );
MainView. setOnTouchListener (this );
 
AudioSynth = new AudioSynthesisTask ();
AudioSynth.exe cute ();
}
 
@ Override
Public void onPause ()
{
Super. onPause ();
Play = false;
 
Finish ();
}
 
Public boolean onTouch (View v, MotionEvent event)
{
Int action = event. getAction ();
Switch (action)
{
Case MotionEvent. ACTION_DOWN:
Play = true; // set play to true or false based on user operations
Synth_frequency = event. getX () + BASE_FREQUENCY; // tracks the position of the user's finger and changes accordingly
Log. v ("FREQUENCY", "" + synth_frequency );
Break;
Case MotionEvent. ACTION_MOVE:
Play = true;
Synth_frequency = event. getX () + BASE_FREQUENCY;
Log. v ("FREQUENCY", "" + synth_frequency );
Break;
Case MotionEvent. ACTION_UP:
Play = false;
Break;
Case MotionEvent. ACTION_CANCEL:
Break;
Default:
Break;
}
Return true;
}
 
Private class AudioSynthesisTask extends AsyncTask <Void, Void, Void>
{
@ Override
Protected Void doInBackground (Void... params)
{
Final int SAMPLE_RATE = 11025;
 
Int minSize = AudioTrack. getMinBufferSize (SAMPLE_RATE,
AudioFormat. CHANNEL_CONFIGURATION_MONO,
AudioFormat. ENCODING_PCM_16BIT );
 
AudioTrack audioTrack = new AudioTrack (AudioManager. STREAM_MUSIC,
SAMPLE_RATE, AudioFormat. CHANNEL_CONFIGURATION_MONO,
AudioFormat. ENCODING_PCM_16BIT, minSize,
AudioTrack. MODE_STREAM );
 
AudioTrack. play ();
 
Short [] buffer = new short [minSize];
 
Float angle = 0;
 
While (true)
{
 
If (play)
{
For (int I = 0; I <buffer. length; I ++)
{
Float angular_frequency = (float) (2 * Math. PI)
* Synth_frequency/SAMPLE_RATE;
 
Buffer [I] = (short) (Short. MAX_VALUE * (float) Math
. Sin (angle); // generates audio samples.
Angle + = angular_frequency;
}
AudioTrack. write (buffer, 0, buffer. length );
} Else
{
Try
{
Thread. sleep (50 );
} Catch (InterruptedException e)
{
E. printStackTrace ();
}
}
}
}
}
}

Public class FingerSynthesis extends Activity implements OnTouchListener
{

AudioSynthesisTask audioSynth; // specifies the thread used to play the audio sample.

Static final float BASE_FREQUENCY = 440; // baseline Audio Frequency

Float synth_frequency = BASE_FREQUENCY; // 440Hz, changes as your fingers move
Boolean play = false; // determines whether to generate audio samples.

@ Override
Public void onCreate (Bundle savedInstanceState)
{
Super. onCreate (savedInstanceState );

SetContentView (R. layout. main );

View mainView = this. findViewById (R. id. MainView );
MainView. setOnTouchListener (this );

AudioSynth = new AudioSynthesisTask ();
AudioSynth.exe cute ();
}

@ Override
Public void onPause ()
{
Super. onPause ();
Play = false;

Finish ();
}

Public boolean onTouch (View v, MotionEvent event)
{
Int action = event. getAction ();
Switch (action)
{
Case MotionEvent. ACTION_DOWN:
Play = true; // set play to true or false based on user operations
Synth_frequency = event. getX () + BASE_FREQUENCY; // tracks the position of the user's finger and changes accordingly
Log. v ("FREQUENCY", "" + synth_frequency );
Break;
Case MotionEvent. ACTION_MOVE:
Play = true;
Synth_frequency = event. getX () + BASE_FREQUENCY;
Log. v ("FREQUENCY", "" + synth_frequency );
Break;
Case MotionEvent. ACTION_UP:
Play = false;
Break;
Case MotionEvent. ACTION_CANCEL:
Break;
Default:
Break;
}
Return true;
}

Private class AudioSynthesisTask extends AsyncTask <Void, Void, Void>
{
@ Override
Protected Void doInBackground (Void... params)
{
Final int SAMPLE_RATE = 11025;

Int minSize = AudioTrack. getMinBufferSize (SAMPLE_RATE,
AudioFormat. CHANNEL_CONFIGURATION_MONO,
AudioFormat. ENCODING_PCM_16BIT );

AudioTrack audioTrack = new AudioTrack (AudioManager. STREAM_MUSIC,
SAMPLE_RATE, AudioFormat. CHANNEL_CONFIGURATION_MONO,
AudioFormat. ENCODING_PCM_16BIT, minSize,
AudioTrack. MODE_STREAM );

AudioTrack. play ();

Short [] buffer = new short [minSize];

Float angle = 0;

While (true)
{

If (play)
{
For (int I = 0; I <buffer. length; I ++)
{
Float angular_frequency = (float) (2 * Math. PI)
* Synth_frequency/SAMPLE_RATE;

Buffer [I] = (short) (Short. MAX_VALUE * (float) Math
. Sin (angle); // generates audio samples.
Angle + = angular_frequency;
}
AudioTrack. write (buffer, 0, buffer. length );
} Else
{
Try
{
Thread. sleep (50 );
} Catch (InterruptedException e)
{
E. printStackTrace ();
}
}
}
}
}
}