AI 146655: am: CL 146654 Add java docs for SoundPool (cef302d0) · Commits · e / os / android_frameworks_base

media/java/android/media/SoundPool.java

+189 −1

Original line number	Diff line number	Diff line
		@@ -26,8 +26,57 @@ import android.content.Context;
		import android.content.res.AssetFileDescriptor;
		import java.io.IOException;

		/*
		/**
		* 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>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>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
		{
		@@ -37,10 +86,30 @@ public class SoundPool

		private int mNativeContext; // accessed by native methods

		/**
		* 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) {
		native_setup(new WeakReference<SoundPool>(this), maxStreams, streamType, srcQuality);
		}

		/**
		* 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.
		* @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
		@@ -63,6 +132,20 @@ public class SoundPool
		return id;
		}

		/**
		* Load the sound from the specified APK resource
		*
		* <p>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.</p>
		*
		* @param context the application context
		* @param resId the resource ID
		* @param priority the priority of the sound. Currently has no effect.
		* @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;
		@@ -78,6 +161,13 @@ public class SoundPool
		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.
		* @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();
		@@ -90,6 +180,19 @@ public class SoundPool
		}
		}

		/**
		* Load the sound from a FileDescriptor
		*
		* <p>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.</p>
		*
		* @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.
		* @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);
		}
		@@ -98,22 +201,107 @@ public class SoundPool

		private native final int _load(FileDescriptor fd, long offset, long length, int priority);

		/**
		* Unload a sound from a sound ID
		*
		* <p>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.</p>
		*
		* @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
		*
		* <p>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.</p>
		*
		* @param soundID a soundID returned by the load() function
		* @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
		*
		* <p>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.</p>
		*
		* @param streamID a streamID returned by the play() function
		*/
		public native final void pause(int streamID);

		/**
		* Resume a playback stream
		*
		* <p>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.</p>
		*
		* @param streamID a streamID returned by the play() function
		*/
		public native final void resume(int streamID);

		/**
		* Stop a playback stream
		*
		* <p>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.</p>
		*
		* @param streamID a streamID returned by the play() function
		*/
		public native final void stop(int streamID);

		/**
		* Set stream volume
		*
		* <p>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.</p>
		*
		* @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
		*
		* <p>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.
		*
		* @param streamID a streamID returned by the play() function
		*/
		public native final void setPriority(int streamID, int priority);

		/**
		* Change stream priority
		*
		* <p>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.
		*
		* @param streamID a streamID returned by the play() function
		*/
		public native final void setLoop(int streamID, int loop);

		public native final void setRate(int streamID, float rate);