android/media/MediaPlayer.java

/*
 * Copyright (C) 2006 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.content.ContentResolver;
import android.content.Context;
import android.content.res.AssetFileDescriptor;
import android.net.Uri;
import android.os.Handler;
import android.os.Looper;
import android.os.Message;
import android.os.ParcelFileDescriptor;
import android.os.PowerManager;
import android.util.Log;
import android.view.Surface;
import android.view.SurfaceHolder;
import android.graphics.Bitmap;
import android.media.AudioManager;

import java.io.FileDescriptor;
import java.io.IOException;

import java.lang.ref.WeakReference;

/**
 * MediaPlayer class can be used to control playback
 * of audio/video files and streams. An example on how to use the methods in
 * this class can be found in <a href="../widget/VideoView.html">VideoView</a>.
 * Please see <a href="../../../toolbox/apis/media.html">Android Media APIs</a>
 * for additional help using MediaPlayer.
 *
 * <p>Topics covered are:
 * <ol>
 * <li><a href="#StateDiagram">State Diagram</a>
 * <li><a href="#Valid_and_Invalid_States">Valid and Invalid States</a>
 * <li><a href="#Permissions">Permissions</a>
 * </ol>
 *
 * <a name="StateDiagram"></a>
 * <h3>State Diagram</h3>
 *
 * <p>Playback control of audio/video files and streams is managed as a state
 * machine. The following diagram shows the life cycle and the states of a
 * MediaPlayer object driven by the supported playback control operations.
 * The ovals represent the states a MediaPlayer object may reside
 * in. The arcs represent the playback control operations that drive the object
 * state transition. There are two types of arcs. The arcs with a single arrow
 * head represent synchronous method calls, while those with
 * a double arrow head represent asynchronous method calls.</p>
 *
 * <p><img src="../../../images/mediaplayer_state_diagram.gif"
 *         alt="MediaPlayer State diagram"
 *         border="0" /></p>
 *
 * <p>From this state diagram, one can see that a MediaPlayer object has the
 *    following states:</p>
 * <ul>
 *     <li>When a MediaPlayer object is just created using <code>new</code> or
 *         after {@link #reset()} is called, it is in the <em>Idle</em> state; and after
 *         {@link #release()} is called, it is in the <em>End</em> state. Between these
 *         two states is the life cycle of the MediaPlayer object.
 *         <ul>
 *         <li>There is a subtle but important difference between a newly constructed
 *         MediaPlayer object and the MediaPlayer object after {@link #reset()}
 *         is called. It is a programming error to invoke methods such
 *         as {@link #getCurrentPosition()},
 *         {@link #getDuration()}, {@link #getVideoHeight()},
 *         {@link #getVideoWidth()}, {@link #setAudioStreamType(int)},
 *         {@link #setLooping(boolean)},
 *         {@link #setVolume(float, float)}, {@link #pause()}, {@link #start()},
 *         {@link #stop()}, {@link #seekTo(int)}, {@link #prepare()} or
 *         {@link #prepareAsync()} in the <em>Idle</em> state for both cases. If any of these
 *         methods is called right after a MediaPlayer object is constructed,
 *         the user supplied callback method OnErrorListener.onError() won't be
 *         called by the internal player engine and the object state remains
 *         unchanged; but if these methods are called right after {@link #reset()},
 *         the user supplied callback method OnErrorListener.onError() will be
 *         invoked by the internal player engine and the object will be
 *         transfered to the <em>Error</em> state. </li>
 *         <li>It is also recommended that once
 *         a MediaPlayer object is no longer being used, call {@link #release()} immediately
 *         so that resources used by the internal player engine associated with the
 *         MediaPlayer object can be released immediately. Resource may include
 *         singleton resources such as hardware acceleration components and
 *         failure to call {@link #release()} may cause subsequent instances of
 *         MediaPlayer objects to fallback to software implementations or fail
 *         altogether. Once the MediaPlayer
 *         object is in the <em>End</em> state, it can no longer be used and
 *         there is no way to bring it back to any other state. </li>
 *         <li>Furthermore,
 *         the MediaPlayer objects created using <code>new</code> is in the
 *         <em>Idle</em> state, while those created with one
 *         of the overloaded convenient <code>create</code> methods are <em>NOT</em>
 *         in the <em>Idle</em> state. In fact, the objects are in the <em>Prepared</em>
 *         state if the creation using <code>create</code> method is successful.
 *         </li>
 *         </ul>
 *         </li>
 *     <li>In general, some playback control operation may fail due to various
 *         reasons, such as unsupported audio/video format, poorly interleaved
 *         audio/video, resolution too high, streaming timeout, and the like.
 *         Thus, error reporting and recovery is an important concern under
 *         these circumstances. Sometimes, due to programming errors, invoking a playback
 *         control operation in an invalid state may also occur. Under all these
 *         error conditions, the internal player engine invokes a user supplied
 *         OnErrorListener.onError() method if an OnErrorListener has been
 *         registered beforehand via
 *         {@link #setOnErrorListener(android.media.MediaPlayer.OnErrorListener)}.
 *         <ul>
 *         <li>It is important to note that once an error occurs, the
 *         MediaPlayer object enters the <em>Error</em> state (except as noted
 *         above), even if an error listener has not been registered by the application.</li>
 *         <li>In order to reuse a MediaPlayer object that is in the <em>
 *         Error</em> state and recover from the error,
 *         {@link #reset()} can be called to restore the object to its <em>Idle</em>
 *         state.</li>
 *         <li>It is good programming practice to have your application
 *         register a OnErrorListener to look out for error notifications from
 *         the internal player engine.</li>
 *         <li>IlleglStateException is
 *         thrown to prevent programming errors such as calling {@link #prepare()},
 *         {@link #prepareAsync()}, or one of the overloaded <code>setDataSource
 *         </code> methods in an invalid state. </li>
 *         </ul>
 *         </li>
 *     <li>Calling
 *         {@link #setDataSource(FileDescriptor)}, or
 *         {@link #setDataSource(String)}, or
 *         {@link #setDataSource(Context, Uri)}, or
 *         {@link #setDataSource(FileDescriptor, long, long)} transfers a
 *         MediaPlayer object in the <em>Idle</em> state to the
 *         <em>Initialized</em> state.
 *         <ul>
 *         <li>An IllegalStateException is thrown if
 *         setDataSource() is called in any other state.</li>
 *         <li>It is good programming
 *         practice to always look out for <code>IllegalArgumentException</code>
 *         and <code>IOException</code> that may be thrown from the overloaded
 *         <code>setDataSource</code> methods.</li>
 *         </ul>
 *         </li>
 *     <li>A MediaPlayer object must first enter the <em>Prepared</em> state
 *         before playback can be started.
 *         <ul>
 *         <li>There are two ways (synchronous vs.
 *         asynchronous) that the <em>Prepared</em> state can be reached:
 *         either a call to {@link #prepare()} (synchronous) which
 *         transfers the object to the <em>Prepared</em> state once the method call
 *         returns, or a call to {@link #prepareAsync()} (asynchronous) which
 *         first transfers the object to the <em>Preparing</em> state after the
 *         call returns (which occurs almost right way) while the internal
 *         player engine continues working on the rest of preparation work
 *         until the preparation work completes. When the preparation completes or when {@link #prepare()} call returns,
 *         the internal player engine then calls a user supplied callback method,
 *         onPrepared() of the OnPreparedListener interface, if an
 *         OnPreparedListener is registered beforehand via {@link
 *         #setOnPreparedListener(android.media.MediaPlayer.OnPreparedListener)}.</li>
 *         <li>It is important to note that
 *         the <em>Preparing</em> state is a transient state, and the behavior
 *         of calling any method with side effect while a MediaPlayer object is
 *         in the <em>Preparing</em> state is undefined.</li>
 *         <li>An IllegalStateException is
 *         thrown if {@link #prepare()} or {@link #prepareAsync()} is called in
 *         any other state.</li>
 *         <li>While in the <em>Prepared</em> state, properties
 *         such as audio/sound volume, screenOnWhilePlaying, looping can be
 *         adjusted by invoking the corresponding set methods.</li>
 *         </ul>
 *         </li>
 *     <li>To start the playback, {@link #start()} must be called. After
 *         {@link #start()} returns successfully, the MediaPlayer object is in the
 *         <em>Started</em> state. {@link #isPlaying()} can be called to test
 *         whether the MediaPlayer object is in the <em>Started</em> state.
 *         <ul>
 *         <li>While in the <em>Started</em> state, the internal player engine calls
 *         a user supplied OnBufferingUpdateListener.onBufferingUpdate() callback
 *         method if a OnBufferingUpdateListener has been registered beforehand
 *         via {@link #setOnBufferingUpdateListener(OnBufferingUpdateListener)}.
 *         This callback allows applications to keep track of the buffering status
 *         while streaming audio/video.</li>
 *         <li>Calling {@link #start()} has not effect
 *         on a MediaPlayer object that is already in the <em>Started</em> state.</li>
 *         </ul>
 *         </li>
 *     <li>Playback can be paused and stopped, and the current playback position
 *         can be adjusted. Playback can be paused via {@link #pause()}. When the call to
 *         {@link #pause()} returns, the MediaPlayer object enters the
 *         <em>Paused</em> state. Note that the transition from the <em>Started</em>
 *         state to the <em>Paused</em> state and vice versa happens
 *         asynchronously in the player engine. It may take some time before
 *         the state is updated in calls to {@link #isPlaying()}, and it can be
 *         a number of seconds in the case of streamed content.
 *         <ul>
 *         <li>Calling {@link #start()} to resume playback for a paused
 *         MediaPlayer object, and the resumed playback
 *         position is the same as where it was paused. When the call to
 *         {@link #start()} returns, the paused MediaPlayer object goes back to
 *         the <em>Started</em> state.</li>
 *         <li>Calling {@link #pause()} has no effect on
 *         a MediaPlayer object that is already in the <em>Paused</em> state.</li>
 *         </ul>
 *         </li>
 *     <li>Calling  {@link #stop()} stops playback and causes a
 *         MediaPlayer in the <em>Started</em>, <em>Paused</em>, <em>Prepared
 *         </em> or <em>PlaybackCompleted</em> state to enter the
 *         <em>Stopped</em> state.
 *         <ul>
 *         <li>Once in the <em>Stopped</em> state, playback cannot be started
 *         until {@link #prepare()} or {@link #prepareAsync()} are called to set
 *         the MediaPlayer object to the <em>Prepared</em> state again.</li>
 *         <li>Calling {@link #stop()} has no effect on a MediaPlayer
 *         object that is already in the <em>Stopped</em> state.</li>
 *         </ul>
 *         </li>
 *     <li>The playback position can be adjusted with a call to
 *         {@link #seekTo(int)}.
 *         <ul>
 *         <li>Although the asynchronuous {@link #seekTo(int)}
 *         call returns right way, the actual seek operation may take a while to
 *         finish, especially for audio/video being streamed. When the actual
 *         seek operation completes, the internal player engine calls a user
 *         supplied OnSeekComplete.onSeekComplete() if an OnSeekCompleteListener
 *         has been registered beforehand via
 *         {@link #setOnSeekCompleteListener(OnSeekCompleteListener)}.</li>
 *         <li>Please
 *         note that {@link #seekTo(int)} can also be called in the other states,
 *         such as <em>Prepared</em>, <em>Paused</em> and <em>PlaybackCompleted
 *         </em> state.</li>
 *         <li>Furthermore, the actual current playback position
 *         can be retrieved with a call to {@link #getCurrentPosition()}, which
 *         is helpful for applications such as a Music player that need to keep
 *         track of the playback progress.</li>
 *         </ul>
 *         </li>
 *     <li>When the playback reaches the end of stream, the playback completes.
 *         <ul>
 *         <li>If the looping mode was being set to <var>true</var>with
 *         {@link #setLooping(boolean)}, the MediaPlayer object shall remain in
 *         the <em>Started</em> state.</li>
 *         <li>If the looping mode was set to <var>false
 *         </var>, the player engine calls a user supplied callback method,
 *         OnCompletion.onCompletion(), if a OnCompletionListener is registered
 *         beforehand via {@link #setOnCompletionListener(OnCompletionListener)}.
 *         The invoke of the callback signals that the object is now in the <em>
 *         PlaybackCompleted</em> state.</li>
 *         <li>While in the <em>PlaybackCompleted</em>
 *         state, calling {@link #start()} can restart the playback from the
 *         beginning of the audio/video source.</li>
 * </ul>
 *
 *
 * <a name="Valid_and_Invalid_States"></a>
 * <h3>Valid and invalid states</h3>
 *
 * <table border="0" cellspacing="0" cellpadding="0">
 * <tr><td>Method Name </p></td>
 *     <td>Valid Sates </p></td>
 *     <td>Invalid States </p></td>
 *     <td>Comments </p></td></tr>
 * <tr><td>getCurrentPosition </p></td>
 *     <td>{Idle, Initialized, Prepared, Started, Paused, Stopped,
 *         PlaybackCompleted} </p></td>
 *     <td>{Error}</p></td>
 *     <td>Successful invoke of this method in a valid state does not change the
 *         state. Calling this method in an invalid state transfers the object
 *         to the <em>Error</em> state. </p></td></tr>
 * <tr><td>getDuration </p></td>
 *     <td>{Prepared, Started, Paused, Stopped, PlaybackCompleted} </p></td>
 *     <td>{Idle, Initialized, Error} </p></td>
 *     <td>Successful invoke of this method in a valid state does not change the
 *         state. Calling this method in an invalid state transfers the object
 *         to the <em>Error</em> state. </p></td></tr>
 * <tr><td>getVideoHeight </p></td>
 *     <td>{Idle, Initialized, Prepared, Started, Paused, Stopped,
 *         PlaybackCompleted}</p></td>
 *     <td>{Error}</p></td>
 *     <td>Successful invoke of this method in a valid state does not change the
 *         state. Calling this method in an invalid state transfers the object
 *         to the <em>Error</em> state.  </p></td></tr>
 * <tr><td>getVideoWidth </p></td>
 *     <td>{Idle, Initialized, Prepared, Started, Paused, Stopped,
 *         PlaybackCompleted}</p></td>
 *     <td>{Error}</p></td>
 *     <td>Successful invoke of this method in a valid state does not change
 *         the state. Calling this method in an invalid state transfers the
 *         object to the <em>Error</em> state. </p></td></tr>
 * <tr><td>isPlaying </p></td>
 *     <td>{Idle, Initialized, Prepared, Started, Paused, Stopped,
 *          PlaybackCompleted}</p></td>
 *     <td>{Error}</p></td>
 *     <td>Successful invoke of this method in a valid state does not change
 *         the state. Calling this method in an invalid state transfers the
 *         object to the <em>Error</em> state. </p></td></tr>
 * <tr><td>pause </p></td>
 *     <td>{Started, Paused}</p></td>
 *     <td>{Idle, Initialized, Prepared, Stopped, PlaybackCompleted, Error}</p></td>
 *     <td>Successful invoke of this method in a valid state transfers the
 *         object to the <em>Paused</em> state. Calling this method in an
 *         invalid state transfers the object to the <em>Error</em> state.</p></td></tr>
 * <tr><td>prepare </p></td>
 *     <td>{Initialized, Stopped} </p></td>
 *     <td>{Idle, Prepared, Started, Paused, PlaybackCompleted, Error} </p></td>
 *     <td>Successful invoke of this method in a valid state transfers the
 *         object to the <em>Prepared</em> state. Calling this method in an
 *         invalid state throws an IllegalStateException.</p></td></tr>
 * <tr><td>prepareAsync </p></td>
 *     <td>{Initialized, Stopped} </p></td>
 *     <td>{Idle, Prepared, Started, Paused, PlaybackCompleted, Error} </p></td>
 *     <td>Successful invoke of this method in a valid state transfers the
 *         object to the <em>Preparing</em> state. Calling this method in an
 *         invalid state throws an IllegalStateException.</p></td></tr>
 * <tr><td>release </p></td>
 *     <td>any </p></td>
 *     <td>{} </p></td>
 *     <td>After {@link #release()}, the object is no longer available. </p></td></tr>
 * <tr><td>reset </p></td>
 *     <td>{Idle, Initialized, Prepared, Started, Paused, Stopped,
 *         PlaybackCompleted, Error}</p></td>
 *     <td>{}</p></td>
 *     <td>After {@link #reset()}, the object is like being just created.</p></td></tr>
 * <tr><td>seekTo </p></td>
 *     <td>{Prepared, Started, Paused, PlaybackCompleted} </p></td>
 *     <td>{Idle, Initialized, Stopped, Error}</p></td>
 *     <td>Successful invoke of this method in a valid state does not change
 *         the state. Calling this method in an invalid state transfers the
 *         object to the <em>Error</em> state. </p></td></tr>
 * <tr><td>setAudioStreamType </p></td>
 *     <td>{Idle, Initialized, Stopped, Prepared, Started, Paused,
 *          PlaybackCompleted}</p></td>
 *     <td>{Error}</p></td>
 *     <td>Successful invoke of this method does not change the state.</p></td></tr>
 * <tr><td>setDataSource </p></td>
 *     <td>{Idle} </p></td>
 *     <td>{Initialized, Prepared, Started, Paused, Stopped, PlaybackCompleted,
 *          Error} </p></td>
 *     <td>Successful invoke of this method in a valid state transfers the
 *         object to the <em>Initialized</em> state. Calling this method in an
 *         invalid state throws an IllegalStateException.</p></td></tr>
 * <tr><td>setDisplay </p></td>
 *     <td>any </p></td>
 *     <td>{} </p></td>
 *     <td>This method can be called in any state and calling it does not change
 *         the object state. </p></td></tr>
 * <tr><td>setLooping </p></td>
 *     <td>{Idle, Initialized, Stopped, Prepared, Started, Paused,
 *         PlaybackCompleted}</p></td>
 *     <td>{Error}</p></td>
 *     <td>Successful invoke of this method in a valid state does not change
 *         the state. Calling this method in an
 *         invalid state transfers the object to the <em>Error</em> state.</p></td></tr>
 * <tr><td>isLooping </p></td>
 *     <td>any </p></td>
 *     <td>{} </p></td>
 *     <td>This method can be called in any state and calling it does not change
 *         the object state. </p></td></tr>
 * <tr><td>setOnBufferingUpdateListener </p></td>
 *     <td>any </p></td>
 *     <td>{} </p></td>
 *     <td>This method can be called in any state and calling it does not change
 *         the object state. </p></td></tr>
 * <tr><td>setOnCompletionListener </p></td>
 *     <td>any </p></td>
 *     <td>{} </p></td>
 *     <td>This method can be called in any state and calling it does not change
 *         the object state. </p></td></tr>
 * <tr><td>setOnErrorListener </p></td>
 *     <td>any </p></td>
 *     <td>{} </p></td>
 *     <td>This method can be called in any state and calling it does not change
 *         the object state. </p></td></tr>
 * <tr><td>setOnPreparedListener </p></td>
 *     <td>any </p></td>
 *     <td>{} </p></td>
 *     <td>This method can be called in any state and calling it does not change
 *         the object state. </p></td></tr>
 * <tr><td>setOnSeekCompleteListener </p></td>
 *     <td>any </p></td>
 *     <td>{} </p></td>
 *     <td>This method can be called in any state and calling it does not change
 *         the object state. </p></td></tr>
 * <tr><td>setScreenOnWhilePlaying</></td>
 *     <td>any </p></td>
 *     <td>{} </p></td>
 *     <td>This method can be called in any state and calling it does not change
 *         the object state.  </p></td></tr>
 * <tr><td>setVolume </p></td>
 *     <td>{Idle, Initialized, Stopped, Prepared, Started, Paused,
 *          PlaybackCompleted}</p></td>
 *     <td>{Error}</p></td>
 *     <td>Successful invoke of this method does not change the state.
 * <tr><td>setWakeMode </p></td>
 *     <td>any </p></td>
 *     <td>{} </p></td>
 *     <td>This method can be called in any state and calling it does not change
 *         the object state.</p></td></tr>
 * <tr><td>start </p></td>
 *     <td>{Prepared, Started, Paused, PlaybackCompleted}</p></td>
 *     <td>{Idle, Initialized, Stopped, Error}</p></td>
 *     <td>Successful invoke of this method in a valid state transfers the
 *         object to the <em>Started</em> state. Calling this method in an
 *         invalid state transfers the object to the <em>Error</em> state.</p></td></tr>
 * <tr><td>stop </p></td>
 *     <td>{Prepared, Started, Stopped, Paused, PlaybackCompleted}</p></td>
 *     <td>{Idle, Initialized, Error}</p></td>
 *     <td>Successful invoke of this method in a valid state transfers the
 *         object to the <em>Stopped</em> state. Calling this method in an
 *         invalid state transfers the object to the <em>Error</em> state.</p></td></tr>
 * </table>
 *
 * <a name="Permissions"></a>
 * <h3>Permissions</h3>
 * <p>One may need to declare a corresponding WAKE_LOCK permission {@link
 * android.R.styleable#AndroidManifestUsesPermission &lt;uses-permission&gt;}
 * element.
 *
 */
public class MediaPlayer
{
    static {
        System.loadLibrary("media_jni");
    }

    private final static String TAG = "MediaPlayer";

    private int mNativeContext; // accessed by native methods
    private int mListenerContext; // accessed by native methods
    private Surface mSurface; // accessed by native methods
    private SurfaceHolder  mSurfaceHolder;
    private EventHandler mEventHandler;
    private PowerManager.WakeLock mWakeLock = null;
    private boolean mScreenOnWhilePlaying;
    private boolean mStayAwake;

    /**
     * Default constructor. Consider using one of the create() methods for
     * synchronously instantiating a MediaPlayer from a Uri or resource.
     * <p>When done with the MediaPlayer, you should call  {@link #release()},
     * to free the resources. If not released, too many MediaPlayer instances may
     * result in an exception.</p>
     */
    public MediaPlayer() {

        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;
        }

        /* Native setup requires a weak reference to our object.
         * It's easier to create it here than in C++.
         */
        native_setup(new WeakReference<MediaPlayer>(this));
    }

    /**
     * Sets the SurfaceHolder to use for displaying the video portion of the media.
     * This call is optional. Not calling it when playing back a video will
     * result in only the audio track being played.
     *
     * @param sh the SurfaceHolder to use for video display
     */
    public void setDisplay(SurfaceHolder sh) {
        mSurfaceHolder = sh;
        mSurface = sh.getSurface();
        updateSurfaceScreenOn();
    }

    /**
     * Convenience method to create a MediaPlayer for a given Uri.
     * On success, {@link #prepare()} will already have been called and must not be called again.
     * <p>When done with the MediaPlayer, you should call  {@link #release()},
     * to free the resources. If not released, too many MediaPlayer instances will
     * result in an exception.</p>
     *
     * @param context the Context to use
     * @param uri the Uri from which to get the datasource
     * @return a MediaPlayer object, or null if creation failed
     */
    public static MediaPlayer create(Context context, Uri uri) {
        return create (context, uri, null);
    }

    /**
     * Convenience method to create a MediaPlayer for a given Uri.
     * On success, {@link #prepare()} will already have been called and must not be called again.
     * <p>When done with the MediaPlayer, you should call  {@link #release()},
     * to free the resources. If not released, too many MediaPlayer instances will
     * result in an exception.</p>
     *
     * @param context the Context to use
     * @param uri the Uri from which to get the datasource
     * @param holder the SurfaceHolder to use for displaying the video
     * @return a MediaPlayer object, or null if creation failed
     */
    public static MediaPlayer create(Context context, Uri uri, SurfaceHolder holder) {

        try {
            MediaPlayer mp = new MediaPlayer();
            mp.setDataSource(context, uri);
            if (holder != null) {
                mp.setDisplay(holder);
            }
            mp.prepare();
            return mp;
        } catch (IOException ex) {
            Log.d(TAG, "create failed:", ex);
            // fall through
        } catch (IllegalArgumentException ex) {
            Log.d(TAG, "create failed:", ex);
            // fall through
        } catch (SecurityException ex) {
            Log.d(TAG, "create failed:", ex);
            // fall through
        }

        return null;
    }

    /**
     * Convenience method to create a MediaPlayer for a given resource id.
     * On success, {@link #prepare()} will already have been called and must not be called again.
     * <p>When done with the MediaPlayer, you should call  {@link #release()},
     * to free the resources. If not released, too many MediaPlayer instances will
     * result in an exception.</p>
     *
     * @param context the Context to use
     * @param resid the raw resource id (<var>R.raw.&lt;something></var>) for
     *              the resource to use as the datasource
     * @return a MediaPlayer object, or null if creation failed
     */
    public static MediaPlayer create(Context context, int resid) {
        try {
            AssetFileDescriptor afd = context.getResources().openRawResourceFd(resid);
            if (afd == null) return null;

            MediaPlayer mp = new MediaPlayer();
            mp.setDataSource(afd.getFileDescriptor(), afd.getStartOffset(), afd.getLength());
            afd.close();
            mp.prepare();
            return mp;
        } catch (IOException ex) {
            Log.d(TAG, "create failed:", ex);
            // fall through
        } catch (IllegalArgumentException ex) {
            Log.d(TAG, "create failed:", ex);
           // fall through
        } catch (SecurityException ex) {
            Log.d(TAG, "create failed:", ex);
            // fall through
        }
        return null;
    }

    /**
     * Sets the data source as a content Uri.
     *
     * @param context the Context to use when resolving the Uri
     * @param uri the Content URI of the data you want to play
     * @throws IllegalStateException if it is called in an invalid state
     */
    public void setDataSource(Context context, Uri uri)
        throws IOException, IllegalArgumentException, SecurityException, IllegalStateException {

        String scheme = uri.getScheme();
        if(scheme == null || scheme.equals("file")) {
            setDataSource(uri.getPath());
            return;
        }

        ParcelFileDescriptor fd = null;
        try {
            ContentResolver resolver = context.getContentResolver();
            fd = resolver.openFileDescriptor(uri, "r");
            if (fd == null) {
                return;
            }
            setDataSource(fd.getFileDescriptor());
            return;
        } catch (SecurityException ex) {
        } catch (IOException ex) {
        } finally {
            if (fd != null) {
                fd.close();
            }
        }
        setDataSource(uri.toString());
        return;
    }

    /**
     * Sets the data source (file-path or http/rtsp URL) to use.
     *
     * @param path the path of the file, or the http/rtsp URL of the stream you want to play
     * @throws IllegalStateException if it is called in an invalid state
     */
    public native void setDataSource(String path) throws IOException, IllegalArgumentException, IllegalStateException;

    /**
     * Sets the data source (FileDescriptor) to use. It is the caller's responsibility
     * to close the file descriptor. It is safe to do so as soon as this call returns.
     *
     * @param fd the FileDescriptor for the file you want to play
     * @throws IllegalStateException if it is called in an invalid state
     */
    public void setDataSource(FileDescriptor fd)
            throws IOException, IllegalArgumentException, IllegalStateException {
        // intentionally less than LONG_MAX
        setDataSource(fd, 0, 0x7ffffffffffffffL);
    }

    /**
     * Sets the data source (FileDescriptor) to use.  It is the caller's responsibility
     * to close the file descriptor. It is safe to do so as soon as this call returns.
     *
     * @param fd the FileDescriptor for the file you want to play
     * @param offset the offset into the file where the data to be played starts, in bytes
     * @param length the length in bytes of the data to be played
     * @throws IllegalStateException if it is called in an invalid state
     */
    public native void setDataSource(FileDescriptor fd, long offset, long length)
            throws IOException, IllegalArgumentException, IllegalStateException;

    /**
     * Prepares the player for playback, synchronously.
     *
     * After setting the datasource and the display surface, you need to either
     * call prepare() or prepareAsync(). For files, it is OK to call prepare(),
     * which blocks until MediaPlayer is ready for playback.
     *
     * @throws IllegalStateException if it is called in an invalid state
     */
    public native void prepare() throws IOException, IllegalStateException;

    /**
     * Prepares the player for playback, asynchronously.
     *
     * After setting the datasource and the display surface, you need to either
     * call prepare() or prepareAsync(). For streams, you should call prepareAsync(),
     * which returns immediately, rather than blocking until enough data has been
     * buffered.
     *
     * @throws IllegalStateException if it is called in an invalid state
     */
    public native void prepareAsync() throws IllegalStateException;

    /**
     * Starts or resumes playback. If playback had previously been paused,
     * playback will continue from where it was paused. If playback had
     * been stopped, or never started before, playback will start at the
     * beginning.
     *
     * @throws IllegalStateException if it is called in an invalid state
     */
    public  void start() throws IllegalStateException {
        stayAwake(true);
        _start();
    }

    private native void _start() throws IllegalStateException;

    /**
     * Stops playback after playback has been stopped or paused.
     *
     * @throws IllegalStateException if the internal player engine has not been
     * initialized.
     */
    public void stop() throws IllegalStateException {
        stayAwake(false);
        _stop();
    }

    private native void _stop() throws IllegalStateException;

    /**
     * Pauses playback. Call start() to resume.
     *
     * @throws IllegalStateException if the internal player engine has not been
     * initialized.
     */
    public void pause() throws IllegalStateException {
        stayAwake(false);
        _pause();
    }

    private native void _pause() throws IllegalStateException;

    /**
     * Set the low-level power management behavior for this MediaPlayer.  This
     * can be used when the MediaPlayer is not playing through a SurfaceHolder
     * set with {@link #setDisplay(SurfaceHolder)} and thus can use the
     * high-level {@link #setScreenOnWhilePlaying(boolean)} feature.
     *
     * <p>This function has the MediaPlayer access the low-level power manager
     * service to control the device's power usage while playing is occurring.
     * The parameter is a combination of {@link android.os.PowerManager} wake flags.
     * Use of this method requires {@link android.Manifest.permission#WAKE_LOCK}
     * permission.
     * By default, no attempt is made to keep the device awake during playback.
     *
     * @param context the Context to use
     * @param mode    the power/wake mode to set
     * @see android.os.PowerManager
     */
    public void setWakeMode(Context context, int mode) {
        boolean washeld = false;
        if (mWakeLock != null) {
            if (mWakeLock.isHeld()) {
                washeld = true;
                mWakeLock.release();
            }
            mWakeLock = null;
        }

        PowerManager pm = (PowerManager)context.getSystemService(Context.POWER_SERVICE);
        mWakeLock = pm.newWakeLock(mode|PowerManager.ON_AFTER_RELEASE, MediaPlayer.class.getName());
        mWakeLock.setReferenceCounted(false);
        if (washeld) {
            mWakeLock.acquire();
        }
    }

    /**
     * Control whether we should use the attached SurfaceHolder to keep the
     * screen on while video playback is occurring.  This is the preferred
     * method over {@link #setWakeMode} where possible, since it doesn't
     * require that the application have permission for low-level wake lock
     * access.
     *
     * @param screenOn Supply true to keep the screen on, false to allow it
     * to turn off.
     */
    public void setScreenOnWhilePlaying(boolean screenOn) {
        if (mScreenOnWhilePlaying != screenOn) {
            mScreenOnWhilePlaying = screenOn;
            updateSurfaceScreenOn();
        }
    }

    private void stayAwake(boolean awake) {
        if (mWakeLock != null) {
            if (awake && !mWakeLock.isHeld()) {
                mWakeLock.acquire();
            } else if (!awake && mWakeLock.isHeld()) {
                mWakeLock.release();
            }
        }
        mStayAwake = awake;
        updateSurfaceScreenOn();
    }

    private void updateSurfaceScreenOn() {
        if (mSurfaceHolder != null) {
            mSurfaceHolder.setKeepScreenOn(mScreenOnWhilePlaying && mStayAwake);
        }
    }

    /**
     * Returns the width of the video.
     *
     * @return the width of the video, or 0 if there is no video,
     * no display surface was set, or prepare()/prepareAsync()
     * have not completed yet
     */
    public native int getVideoWidth();

    /**
     * Returns the height of the video.
     *
     * @return the height of the video, or 0 if there is no video,
     * no display surface was set, or prepare()/prepareAsync()
     * have not completed yet
     */
    public native int getVideoHeight();

    /**
     * Checks whether the MediaPlayer is playing.
     *
     * @return true if currently playing, false otherwise
     */
    public native boolean isPlaying();

    /**
     * Seeks to specified time position.
     *
     * @param msec the offset in milliseconds from the start to seek to
     * @throws IllegalStateException if the internal player engine has not been
     * initialized
     */
    public native void seekTo(int msec) throws IllegalStateException;

    /**
     * Gets the current playback position.
     *
     * @return the current position in milliseconds
     */
    public native int getCurrentPosition();

    /**
     * Gets the duration of the file.
     *
     * @return the duration in milliseconds
     */
    public native int getDuration();

    /**
     * Releases resources associated with this MediaPlayer object.
     * It is considered good practice to call this method when you're
     * done using the MediaPlayer.
     */
    public void release() {
        if (mWakeLock != null) mWakeLock.release();
        updateSurfaceScreenOn();
        mOnPreparedListener = null;
        mOnBufferingUpdateListener = null;
        mOnCompletionListener = null;
        mOnSeekCompleteListener = null;
        mOnErrorListener = null;
        mOnVideoSizeChangedListener = null;
        _release();
    }

    private native void _release();

    /**
     * Resets the MediaPlayer to its uninitialized state. After calling
     * this method, you will have to initialize it again by setting the
     * data source and calling prepare().
     */
    public void reset() {
        _reset();
        // make sure none of the listeners get called anymore
        mEventHandler.removeCallbacksAndMessages(null);
    }

    private native void _reset();

    /**
     * Sets the audio stream type for this MediaPlayer. See {@link AudioManager}
     * for a list of stream types.
     *
     * @param streamtype the audio stream type
     * @see android.media.AudioManager
     */
    public native void setAudioStreamType(int streamtype);

    /**
     * Sets the player to be looping or non-looping.
     *
     * @param looping whether to loop or not
     */
    public native void setLooping(boolean looping);

    /**
     * Checks whether the MediaPlayer is looping or non-looping.
     *
     * @return true if the MediaPlayer is currently looping, false otherwise
     */
    public native boolean isLooping();

    /**
     * Sets the volume on this player.
     * This API is recommended for balancing the output of audio streams
     * within an application. Unless you are writing an application to
     * control user settings, this API should be used in preference to
     * {@link AudioManager#setStreamVolume(int, int, int)} which sets the volume of ALL streams of
     * a particular type. Note that the passed volume values are raw scalars.
     * UI controls should be scaled logarithmically.
     *
     * @param leftVolume left volume scalar
     * @param rightVolume right volume scalar
     */
    public native void setVolume(float leftVolume, float rightVolume);

    /**
     * Currently not implemented, returns null.
     * @deprecated
     * @hide
     */
    public native Bitmap getFrameAt(int msec) throws IllegalStateException;

    private native final void native_setup(Object mediaplayer_this);
    private native final void native_finalize();
    @Override
    protected void finalize() { native_finalize(); }

    /* Do not change these values without updating their counterparts
     * in include/media/mediaplayer.h!
     */
    private static final int MEDIA_NOP = 0; // interface test message
    private static final int MEDIA_PREPARED = 1;
    private static final int MEDIA_PLAYBACK_COMPLETE = 2;
    private static final int MEDIA_BUFFERING_UPDATE = 3;
    private static final int MEDIA_SEEK_COMPLETE = 4;
    private static final int MEDIA_SET_VIDEO_SIZE = 5;
    private static final int MEDIA_ERROR = 100;

    // error codes from framework that indicate content issues
    // contained in arg1 of error message

    // Seek not supported - live stream
    private static final int ERROR_SEEK_NOT_SUPPORTED = 42;

    // A/V interleave exceeds the progressive streaming buffer
    private static final int ERROR_CONTENT_IS_POORLY_INTERLEAVED = 43;

    // video decoder is falling behind - content is too complex
    private static final int ERROR_VIDEO_TRACK_IS_FALLING_BEHIND = 44;

    private class EventHandler extends Handler
    {
        private MediaPlayer mMediaPlayer;

        public EventHandler(MediaPlayer mp, Looper looper) {
            super(looper);
            mMediaPlayer = mp;
        }

        @Override
        public void handleMessage(Message msg) {
            if (mMediaPlayer.mNativeContext == 0) {
                Log.w(TAG, "mediaplayer went away with unhandled events");
                return;
            }
            switch(msg.what) {
            case MEDIA_PREPARED:
                if (mOnPreparedListener != null)
                    mOnPreparedListener.onPrepared(mMediaPlayer);
                return;

            case MEDIA_PLAYBACK_COMPLETE:
                if (mOnCompletionListener != null)
                    mOnCompletionListener.onCompletion(mMediaPlayer);
                stayAwake(false);
                return;

            case MEDIA_BUFFERING_UPDATE:
                if (mOnBufferingUpdateListener != null)
                    mOnBufferingUpdateListener.onBufferingUpdate(mMediaPlayer, msg.arg1);
                return;

            case MEDIA_SEEK_COMPLETE:
              if (mOnSeekCompleteListener != null)
                  mOnSeekCompleteListener.onSeekComplete(mMediaPlayer);
              return;

            case MEDIA_SET_VIDEO_SIZE:
              if (mOnVideoSizeChangedListener != null)
                  mOnVideoSizeChangedListener.onVideoSizeChanged(mMediaPlayer, msg.arg1, msg.arg2);
              return;

            case MEDIA_ERROR:
                Log.e(TAG, "Error (" + msg.arg1 + "," + msg.arg2 + ")");
                boolean error_was_handled = false;
                if (mOnErrorListener != null) {
                    error_was_handled = mOnErrorListener.onError(mMediaPlayer, msg.arg1, msg.arg2);
                }
                if (mOnCompletionListener != null && ! error_was_handled) {
                    mOnCompletionListener.onCompletion(mMediaPlayer);
                }
                stayAwake(false);
                return;
            case MEDIA_NOP: // interface test message - ignore
                break;

            default:
                Log.e(TAG, "Unknown message type " + msg.what);
                return;
            }
        }
    }

    /**
     * Called from native code when an interesting event happens.  This method
     * just uses the EventHandler system to post the event back to the main app thread.
     * We use a weak reference to the original MediaPlayer object so that the native
     * code is safe from the object disappearing from underneath it.  (This is
     * the cookie passed to native_setup().)
     */
    private static void postEventFromNative(Object mediaplayer_ref,
                                            int what, int arg1, int arg2, Object obj)
    {
        MediaPlayer mp = (MediaPlayer)((WeakReference)mediaplayer_ref).get();
        if (mp == null) {
            return;
        }

        if (mp.mEventHandler != null) {
            Message m = mp.mEventHandler.obtainMessage(what, arg1, arg2, obj);
            mp.mEventHandler.sendMessage(m);
        }
    }

    /**
     * Interface definition for a callback to be invoked when the media
     * source is ready for playback.
     */
    public interface OnPreparedListener
    {
        /**
         * Called when the media file is ready for playback.
         *
         * @param mp the MediaPlayer that is ready for playback
         */
        void onPrepared(MediaPlayer mp);
    }

    /**
     * Register a callback to be invoked when the media source is ready
     * for playback.
     *
     * @param l the callback that will be run
     */
    public void setOnPreparedListener(OnPreparedListener l)
    {
        mOnPreparedListener = l;
    }

    private OnPreparedListener mOnPreparedListener;

    /**
     * Interface definition for a callback to be invoked when playback of
     * a media source has completed.
     */
    public interface OnCompletionListener
    {
        /**
         * Called when the end of a media source is reached during playback.
         *
         * @param mp the MediaPlayer that reached the end of the file
         */
        void onCompletion(MediaPlayer mp);
    }

    /**
     * Register a callback to be invoked when the end of a media source
     * has been reached during playback.
     *
     * @param l the callback that will be run
     */
    public void setOnCompletionListener(OnCompletionListener l)
    {
        mOnCompletionListener = l;
    }

    private OnCompletionListener mOnCompletionListener;

    /**
     * Interface definition of a callback to be invoked indicating buffering
     * status of a media resource being streamed over the network.
     */
    public interface OnBufferingUpdateListener
    {
        /**
         * Called to update status in buffering a media stream.
         *
         * @param mp      the MediaPlayer the update pertains to
         * @param percent the percentage (0-100) of the buffer
         *                that has been filled thus far
         */
        void onBufferingUpdate(MediaPlayer mp, int percent);
    }

    /**
     * Register a callback to be invoked when the status of a network
     * stream's buffer has changed.
     *
     * @param l the callback that will be run
     */
    public void setOnBufferingUpdateListener(OnBufferingUpdateListener l)
    {
        mOnBufferingUpdateListener = l;
    }

    private OnBufferingUpdateListener mOnBufferingUpdateListener;

    /**
     * Interface definition of a callback to be invoked indicating
     * the completion of a seek operation.
     */
    public interface OnSeekCompleteListener
    {
        /**
         * Called to indicate the completion of a seek operation.
         *
         * @param mp the MediaPlayer that issued the seek operation
         */
        public void onSeekComplete(MediaPlayer mp);
    }

    /**
     * Register a callback to be invoked when a seek operation has been
     * completed.
     *
     * @param l the callback that will be run
     */
    public void setOnSeekCompleteListener(OnSeekCompleteListener l)
    {
        mOnSeekCompleteListener = l;
    }

    private OnSeekCompleteListener mOnSeekCompleteListener;

    /**
     * Interface definition of a callback to be invoked when the
     * video size is first known or updated
     * FIXME: Unhide this API after approval
     * @hide
     */
    public interface OnVideoSizeChangedListener
    {
        /**
         * Called to indicate the video size
         *
         * @param mp        the MediaPlayer associated with this callback
         * @param width     the width of the video
         * @param height    the height of the video
         * @hide
         */
        public void onVideoSizeChanged(MediaPlayer mp, int width, int height);
    }

    /**
     * Register a callback to be invoked when the video size is
     * known or updated.
     *
     * @param l the callback that will be run
     * @hide
     */
    public void setOnVideoSizeChangedListener(OnVideoSizeChangedListener l)
    {
        mOnVideoSizeChangedListener = l;
    }

    private OnVideoSizeChangedListener mOnVideoSizeChangedListener;

    /* Do not change these values without updating their counterparts
     * in include/media/mediaplayer.h!
     */
    /** Unspecified media player error.
     * @see android.media.MediaPlayer.OnErrorListener
     */
    public static final int MEDIA_ERROR_UNKNOWN = 1;
    /** Media server died. In this case, the application must release the
     * MediaPlayer object and instantiate a new one.
     * @see android.media.MediaPlayer.OnErrorListener
     */
    public static final int MEDIA_ERROR_SERVER_DIED = 100;


    /**
     * Interface definition of a callback to be invoked when there
     * has been an error during an asynchronous operation (other errors
     * will throw exceptions at method call time).
     */
    public interface OnErrorListener
    {
        /**
         * Called to indicate an error.
         *
         * @param mp      the MediaPlayer the error pertains to
         * @param what    the type of error that has occurred:
         * <ul>
         * <li>{@link #MEDIA_ERROR_UNKNOWN}
         * <li>{@link #MEDIA_ERROR_SERVER_DIED}
         * </ul>
         * @param extra   an extra code, specific to the error type
         * @return True if the method handled the error, false if it didn't.
         * Returning false, or not having an OnErrorListener at all, will
         * cause the OnCompletionListener to be called.
         */
        boolean onError(MediaPlayer mp, int what, int extra);
    }

    /**
     * Register a callback to be invoked when an error has happened
     * during an asynchronous operation.
     *
     * @param l the callback that will be run
     */
    public void setOnErrorListener(OnErrorListener l)
    {
        mOnErrorListener = l;
    }

    private OnErrorListener mOnErrorListener;
}