This document discusses using SoundPool to play sounds in an Android application. It explains how to: 1. Create a SoundPool object specifying the maximum number of streams, stream type, and quality. 2. Load sound files into the SoundPool using load() to get a sound ID. 3. Play sounds using play(), providing the sound ID, left/right volumes, priority, loop setting, and playback speed. The document also notes that sound files should be placed in res/raw and provides an example layout and Java code to load and play a sound when a button is clicked.

1. Develop on Android
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Lesson : The sound, with SoundPool

2. The sound, with SoundPool
• In this lesson, you will learn to play sounds.
• For this, you will use the SoundPool.

3. The sound, with SoundPool
• Create a SoundPool with these parameters :
– the maximum number of streams,
– the type of stream (example : STREAM_MUSIC),
– the quality (not yet used).
SoundPool soundPool;
soundPool = new SoundPool (
2, // max streams
AudioManager.STREAM_MUSIC, // stream type
100 // quality (not used)
);

4. The sound, with SoundPool
• Load the sounds with the method load() with the parameters :
– the context,
– the resource id,
– the priority.
• As result, you get an id (soundId).
soundId = soundPool.load (
this, // context
R.raw.audiofile, // resource id
0 // priority
);

5. The sound, with SoundPool
• Play each sound with the method play() with these parameters :
– the sound id,
– the left and right volumes,
– the priority,
– the status if the sound should be played in loop or not,
– the speed playback.
soundPool.play (
soundId, // sound id
1f, // left volume (0.0-1.0)
1f, // right volume (0.0-1.0)
0, // priority (0 = the lowest)
0, // loop (0 = no, -1 = yes)
1f // rate (0.5-2.0)
);

6. Resources
• An audio file audiofile (any extension) should be present in
the directory resraw of the project.

7. Layout main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<Button
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Play"
android:id="@+id/btnPlay" />
</LinearLayout>

8. File Main.javapublic class Main extends Activity {
SoundPool soundPool;
int soundId;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Button btnPlay = (Button)this.findViewById(R.id.btnPlay);
btnPlay.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
soundPool.play (
soundId, // sound id
1f, // left volume (0.0 à 1.0)
1f, // right volume (0.0 à 1.0)
0, // priority
0, // loop
1f // rate (de 0.5 à 2.0)
);
}
});

9. File Main.java
soundPool = new SoundPool (
2, // max streams
AudioManager.STREAM_MUSIC, // stream type
100 // quality (not used)
);
soundId = soundPool.load (
this, // context
R.raw.audiofile, // resource id
1 // priority
);
}
}

10. Test on your mobile
Media_SoundPool

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