Android example source code file (SoundPool.java)
The SoundPool.java Android example source code/*
* Copyright (C) 2007 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package android.media;
import android.util.AndroidRuntimeException;
import android.util.Log;
import java.io.File;
import java.io.FileDescriptor;
import android.os.ParcelFileDescriptor;
import java.lang.ref.WeakReference;
import android.content.Context;
import android.content.res.AssetFileDescriptor;
import java.io.IOException;
import android.os.Handler;
import android.os.Looper;
import android.os.Message;
/**
* The SoundPool class manages and plays audio resources for applications.
*
* <p>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.</p>
*
* <p>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.</p>
*
* <p>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.</p>
*
* <p>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.</p>
*
* <p>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.</p>
*
* <p>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.</p>
*
* <p>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.</p>
*
* <p>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.</p>
*
* <p>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.</p>
*/
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();
// 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;
}
}
/**
* 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);
if (f != null) {
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);
/**
* 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) {
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(); }
}
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