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使用SoundPool 同時播放多個音訊

MediaPlayer 是多媒體包的一個 基本工具,但它一次只能處理一個音訊或 視訊檔案.

如果只有少量的音訊要播放,並且想要快速的效能,SoundPool 類可提供幫助, 它在底層使用了 MediaPlayer API

SoundPool 與 MediaPlayer 之間的一個區別是:  SoundPool 是僅為處理本地媒體檔案而設計的

以下提供一個載入和播放 簡單聲音的示例.

 當示例程式啟動時,建立 SoundPool 並向其中載入音取樣,然後開始播放它們,蟋蟀叫聲不停地迴圈播放,而其他取樣在一定延遲之後播放,然後將自身設定為在相同延遲之後再次播放,

主要程式碼如下:

   @Override
   protected void onResume() {
    soundPool = new SoundPool(4, AudioManager.STREAM_MUSIC, SRC_QUALITY);
    soundPool.setOnLoadCompleteListener(this);
    aMgr = (AudioManager)this.getSystemService(Context.AUDIO_SERVICE);
    sid_background = soundPool.load(this, R.raw.crickets, PRIORITY); //蟋蟀
    sid_chimp = soundPool.load(this, R.raw.chimp, PRIORITY);//黑猩猩
    sid_rooster = soundPool.load(this, R.raw.rooster, PRIORITY);//公雞 
    sid_roar = soundPool.load(this, R.raw.roar, PRIORITY);//怒吼
    try {
		AssetFileDescriptor afd = this.getAssets().openFd("dogbark.mp3"); // 狗叫聲
		sid_bark = soundPool.load(afd.getFileDescriptor(), 0, afd.getLength(), PRIORITY);
		afd.close();
    } catch (IOException e) {
      e.printStackTrace();
    }
    //sid_bark = soundPool.load("/mnt/sdcard/dogbark.mp3", PRIORITY);
    super.onResume();
    }
	
	@Override
	public void onLoadComplete(SoundPool sPool, int sid, int status) {
		Log.v("soundPool", "sid " + sid + " loaded with status " + status);
		final float currentVolume = ((float)aMgr.getStreamVolume(AudioManager.STREAM_MUSIC)) / 
			   ((float)aMgr.getStreamMaxVolume(AudioManager.STREAM_MUSIC));
		if(status != 0)
		return;
		if(sid == sid_background) {
		if(sPool.play(sid, currentVolume, currentVolume, PRIORITY, -1, 1.0f) == 0) {
		   Log.v("soundPool", "Failed to start sound");
		}
		} else if(sid == sid_chimp) {
		queueSound(sid, 5000, currentVolume);
		} else if(sid == sid_rooster) {
		queueSound(sid, 6000, currentVolume);
		} else if(sid == sid_roar) {
		queueSound(sid, 12000, currentVolume);
		} else if(sid == sid_bark) {
		queueSound(sid, 7000, currentVolume);
		}
	}
	private void queueSound(final int sid, final long delay, final float volume) {
		new Handler().postDelayed(new Runnable() {
			@Override
			public void run() {
			if(soundPool == null) return;
				if(soundPool.play(sid, volume, volume,PRIORITY, 0, 1.0f) == 0) {
				   Log.e("soundPool", "Failed to start sound (" + sid + ")");
				}
				queueSound(sid, delay, volume);
			}
		}, delay);
	}