A SoundPool is a collection of samples that can be loaded into memory * from a resource inside the APK or from a file in the file system. The * SoundPool library uses the MediaPlayer service to decode the audio * into a raw 16-bit PCM mono or stereo stream. This allows applications * to ship with compressed streams without having to suffer the CPU load * and latency of decompressing during playback.
* *In addition to low-latency playback, SoundPool can also manage the number * of audio streams being rendered at once. When the SoundPool object is * constructed, the maxStreams parameter sets the maximum number of streams * that can be played at a time from this single SoundPool. SoundPool tracks * the number of active streams. If the maximum number of streams is exceeded, * SoundPool will automatically stop a previously playing stream based first * on priority and then by age within that priority. Limiting the maximum * number of streams helps to cap CPU loading and reducing the likelihood that * audio mixing will impact visuals or UI performance.
* *Sounds can be looped by setting a non-zero loop value. A value of -1 * causes the sound to loop forever. In this case, the application must * explicitly call the stop() function to stop the sound. Any other non-zero * value will cause the sound to repeat the specified number of times, e.g. * a value of 3 causes the sound to play a total of 4 times.
* *The playback rate can also be changed. A playback rate of 1.0 causes * the sound to play at its original frequency (resampled, if necessary, * to the hardware output frequency). A playback rate of 2.0 causes the * sound to play at twice its original frequency, and a playback rate of * 0.5 causes it to play at half its original frequency. The playback * rate range is 0.5 to 2.0.
* *Priority runs low to high, i.e. higher numbers are higher priority. * Priority is used when a call to play() would cause the number of active * streams to exceed the value established by the maxStreams parameter when * the SoundPool was created. In this case, the stream allocator will stop * the lowest priority stream. If there are multiple streams with the same * low priority, it will choose the oldest stream to stop. In the case * where the priority of the new stream is lower than all the active * streams, the new sound will not play and the play() function will return * a streamID of zero.
* *Let's examine a typical use case: A game consists of several levels of * play. For each level, there is a set of unique sounds that are used only * by that level. In this case, the game logic should create a new SoundPool * object when the first level is loaded. The level data itself might contain * the list of sounds to be used by this level. The loading logic iterates * through the list of sounds calling the appropriate SoundPool.load() * function. This should typically be done early in the process to allow time * for decompressing the audio to raw PCM format before they are needed for * playback.
* *Once the sounds are loaded and play has started, the application can * trigger sounds by calling SoundPool.play(). Playing streams can be * paused or resumed, and the application can also alter the pitch by * adjusting the playback rate in real-time for doppler or synthesis * effects.
* *Note that since streams can be stopped due to resource constraints, the * streamID is a reference to a particular instance of a stream. If the stream * is stopped to allow a higher priority stream to play, the stream is no * longer be valid. However, the application is allowed to call methods on * the streamID without error. This may help simplify program logic since * the application need not concern itself with the stream lifecycle.
* *In our example, when the player has completed the level, the game * logic should call SoundPool.release() to release all the native resources * in use and then set the SoundPool reference to null. If the player starts * another level, a new SoundPool is created, sounds are loaded, and play * resumes.
*/ public class SoundPool { static { System.loadLibrary("soundpool"); } private final static String TAG = "SoundPool"; private final static boolean DEBUG = false; private int mNativeContext; // accessed by native methods private EventHandler mEventHandler; private OnLoadCompleteListener mOnLoadCompleteListener; private final Object mLock; // SoundPool messages // // must match SoundPool.h private static final int SAMPLE_LOADED = 1; /** * Constructor. Constructs a SoundPool object with the following * characteristics: * * @param maxStreams the maximum number of simultaneous streams for this * SoundPool object * @param streamType the audio stream type as described in AudioManager * For example, game applications will normally use * {@link AudioManager#STREAM_MUSIC}. * @param srcQuality the sample-rate converter quality. Currently has no * effect. Use 0 for the default. * @return a SoundPool object, or null if creation failed */ public SoundPool(int maxStreams, int streamType, int srcQuality) { // do native setup if (native_setup(new WeakReference(this), maxStreams, streamType, srcQuality) != 0) { throw new RuntimeException("Native setup failed"); } mLock = new Object(); } /** * Load the sound from the specified path. * * @param path the path to the audio file * @param priority the priority of the sound. Currently has no effect. Use * a value of 1 for future compatibility. * @return a sound ID. This value can be used to play or unload the sound. */ public int load(String path, int priority) { // pass network streams to player if (path.startsWith("http:")) return _load(path, priority); // try local path int id = 0; try { File f = new File(path); ParcelFileDescriptor fd = ParcelFileDescriptor.open(f, ParcelFileDescriptor.MODE_READ_ONLY); if (fd != null) { id = _load(fd.getFileDescriptor(), 0, f.length(), priority); fd.close(); } } catch (java.io.IOException e) { Log.e(TAG, "error loading " + path); } return id; } /** * Load the sound from the specified APK resource. * * Note that the extension is dropped. For example, if you want to load * a sound from the raw resource file "explosion.mp3", you would specify * "R.raw.explosion" as the resource ID. Note that this means you cannot * have both an "explosion.wav" and an "explosion.mp3" in the res/raw * directory. * * @param context the application context * @param resId the resource ID * @param priority the priority of the sound. Currently has no effect. Use * a value of 1 for future compatibility. * @return a sound ID. This value can be used to play or unload the sound. */ public int load(Context context, int resId, int priority) { AssetFileDescriptor afd = context.getResources().openRawResourceFd(resId); int id = 0; if (afd != null) { id = _load(afd.getFileDescriptor(), afd.getStartOffset(), afd.getLength(), priority); try { afd.close(); } catch (java.io.IOException ex) { //Log.d(TAG, "close failed:", ex); } } return id; } /** * Load the sound from an asset file descriptor. * * @param afd an asset file descriptor * @param priority the priority of the sound. Currently has no effect. Use * a value of 1 for future compatibility. * @return a sound ID. This value can be used to play or unload the sound. */ public int load(AssetFileDescriptor afd, int priority) { if (afd != null) { long len = afd.getLength(); if (len < 0) { throw new AndroidRuntimeException("no length for fd"); } return _load(afd.getFileDescriptor(), afd.getStartOffset(), len, priority); } else { return 0; } } /** * Load the sound from a FileDescriptor. * * This version is useful if you store multiple sounds in a single * binary. The offset specifies the offset from the start of the file * and the length specifies the length of the sound within the file. * * @param fd a FileDescriptor object * @param offset offset to the start of the sound * @param length length of the sound * @param priority the priority of the sound. Currently has no effect. Use * a value of 1 for future compatibility. * @return a sound ID. This value can be used to play or unload the sound. */ public int load(FileDescriptor fd, long offset, long length, int priority) { return _load(fd, offset, length, priority); } private native final int _load(String uri, int priority); private native final int _load(FileDescriptor fd, long offset, long length, int priority); /** * Unload a sound from a sound ID. * * Unloads the sound specified by the soundID. This is the value * returned by the load() function. Returns true if the sound is * successfully unloaded, false if the sound was already unloaded. * * @param soundID a soundID returned by the load() function * @return true if just unloaded, false if previously unloaded */ public native final boolean unload(int soundID); /** * Play a sound from a sound ID. * * Play the sound specified by the soundID. This is the value * returned by the load() function. Returns a non-zero streamID * if successful, zero if it fails. The streamID can be used to * further control playback. Note that calling play() may cause * another sound to stop playing if the maximum number of active * streams is exceeded. A loop value of -1 means loop forever, * a value of 0 means don't loop, other values indicate the * number of repeats, e.g. a value of 1 plays the audio twice. * The playback rate allows the application to vary the playback * rate (pitch) of the sound. A value of 1.0 means play back at * the original frequency. A value of 2.0 means play back twice * as fast, and a value of 0.5 means playback at half speed. * * @param soundID a soundID returned by the load() function * @param leftVolume left volume value (range = 0.0 to 1.0) * @param rightVolume right volume value (range = 0.0 to 1.0) * @param priority stream priority (0 = lowest priority) * @param loop loop mode (0 = no loop, -1 = loop forever) * @param rate playback rate (1.0 = normal playback, range 0.5 to 2.0) * @return non-zero streamID if successful, zero if failed */ public native final int play(int soundID, float leftVolume, float rightVolume, int priority, int loop, float rate); /** * Pause a playback stream. * * Pause the stream specified by the streamID. This is the * value returned by the play() function. If the stream is * playing, it will be paused. If the stream is not playing * (e.g. is stopped or was previously paused), calling this * function will have no effect. * * @param streamID a streamID returned by the play() function */ public native final void pause(int streamID); /** * Resume a playback stream. * * Resume the stream specified by the streamID. This * is the value returned by the play() function. If the stream * is paused, this will resume playback. If the stream was not * previously paused, calling this function will have no effect. * * @param streamID a streamID returned by the play() function */ public native final void resume(int streamID); /** * Pause all active streams. * * Pause all streams that are currently playing. This function * iterates through all the active streams and pauses any that * are playing. It also sets a flag so that any streams that * are playing can be resumed by calling autoResume(). */ public native final void autoPause(); /** * Resume all previously active streams. * * Automatically resumes all streams that were paused in previous * calls to autoPause(). */ public native final void autoResume(); /** * Stop a playback stream. * * Stop the stream specified by the streamID. This * is the value returned by the play() function. If the stream * is playing, it will be stopped. It also releases any native * resources associated with this stream. If the stream is not * playing, it will have no effect. * * @param streamID a streamID returned by the play() function */ public native final void stop(int streamID); /** * Set stream volume. * * Sets the volume on the stream specified by the streamID. * This is the value returned by the play() function. The * value must be in the range of 0.0 to 1.0. If the stream does * not exist, it will have no effect. * * @param streamID a streamID returned by the play() function * @param leftVolume left volume value (range = 0.0 to 1.0) * @param rightVolume right volume value (range = 0.0 to 1.0) */ public native final void setVolume(int streamID, float leftVolume, float rightVolume); /** * Similar, except set volume of all channels to same value. * @hide */ public void setVolume(int streamID, float volume) { setVolume(streamID, volume, volume); } /** * Change stream priority. * * Change the priority of the stream specified by the streamID. * This is the value returned by the play() function. Affects the * order in which streams are re-used to play new sounds. If the * stream does not exist, it will have no effect. * * @param streamID a streamID returned by the play() function */ public native final void setPriority(int streamID, int priority); /** * Set loop mode. * * Change the loop mode. A loop value of -1 means loop forever, * a value of 0 means don't loop, other values indicate the * number of repeats, e.g. a value of 1 plays the audio twice. * If the stream does not exist, it will have no effect. * * @param streamID a streamID returned by the play() function * @param loop loop mode (0 = no loop, -1 = loop forever) */ public native final void setLoop(int streamID, int loop); /** * Change playback rate. * * The playback rate allows the application to vary the playback * rate (pitch) of the sound. A value of 1.0 means playback at * the original frequency. A value of 2.0 means playback twice * as fast, and a value of 0.5 means playback at half speed. * If the stream does not exist, it will have no effect. * * @param streamID a streamID returned by the play() function * @param rate playback rate (1.0 = normal playback, range 0.5 to 2.0) */ public native final void setRate(int streamID, float rate); /** * Interface definition for a callback to be invoked when all the * sounds are loaded. */ public interface OnLoadCompleteListener { /** * Called when a sound has completed loading. * * @param soundPool SoundPool object from the load() method * @param soundPool the sample ID of the sound loaded. * @param status the status of the load operation (0 = success) */ public void onLoadComplete(SoundPool soundPool, int sampleId, int status); } /** * Sets the callback hook for the OnLoadCompleteListener. */ public void setOnLoadCompleteListener(OnLoadCompleteListener listener) { synchronized(mLock) { if (listener != null) { // setup message handler Looper looper; if ((looper = Looper.myLooper()) != null) { mEventHandler = new EventHandler(this, looper); } else if ((looper = Looper.getMainLooper()) != null) { mEventHandler = new EventHandler(this, looper); } else { mEventHandler = null; } } else { mEventHandler = null; } mOnLoadCompleteListener = listener; } } private class EventHandler extends Handler { private SoundPool mSoundPool; public EventHandler(SoundPool soundPool, Looper looper) { super(looper); mSoundPool = soundPool; } @Override public void handleMessage(Message msg) { switch(msg.what) { case SAMPLE_LOADED: if (DEBUG) Log.d(TAG, "Sample " + msg.arg1 + " loaded"); synchronized(mLock) { if (mOnLoadCompleteListener != null) { mOnLoadCompleteListener.onLoadComplete(mSoundPool, msg.arg1, msg.arg2); } } break; default: Log.e(TAG, "Unknown message type " + msg.what); return; } } } // post event from native code to message handler private static void postEventFromNative(Object weakRef, int msg, int arg1, int arg2, Object obj) { SoundPool soundPool = (SoundPool)((WeakReference)weakRef).get(); if (soundPool == null) return; if (soundPool.mEventHandler != null) { Message m = soundPool.mEventHandler.obtainMessage(msg, arg1, arg2, obj); soundPool.mEventHandler.sendMessage(m); } } /** * Release the SoundPool resources. * * Release all memory and native resources used by the SoundPool * object. The SoundPool can no longer be used and the reference * should be set to null. */ public native final void release(); private native final int native_setup(Object weakRef, int maxStreams, int streamType, int srcQuality); protected void finalize() { release(); } }