旋转时,MediaPlayer向前跳过约6秒

Question

我在片段中有一个MediaPlayer,它在配置更改时保留其实例.播放器正在播放从我的资源目录加载的视频.我设置了方案,目的是重现YouTube应用程序播放,其中音频在配置更改期间继续播放,并且显示器已分离并重新连接到媒体播放器.

当我开始播放并旋转设备时,位置会向前跳跃约6秒,并且(必要时)音频会在发生这种情况时切断.然后,播放继续正常进行.我不知道是什么导致这种情况发生.

根据要求,这是代码:

public class MainFragment extends Fragment implements SurfaceHolder.Callback, MediaController.MediaPlayerControl {

    private static final String TAG = MainFragment.class.getSimpleName();

    AssetFileDescriptor mVideoFd;

    SurfaceView mSurfaceView;
    MediaPlayer mMediaPlayer;
    MediaController mMediaController;
    boolean mPrepared;
    boolean mShouldResumePlayback;
    int mBufferingPercent;
    SurfaceHolder mSurfaceHolder;

    @Override
    public void onInflate(Activity activity, AttributeSet attrs, Bundle savedInstanceState) {
        super.onInflate(activity, attrs, savedInstanceState);
        final String assetFileName = "test-video.mp4";
        try {
            mVideoFd = activity.getAssets().openFd(assetFileName);
        } catch (IOException ioe) {
            Log.e(TAG, "Can't open file " + assetFileName + "!");
        }
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setRetainInstance(true);

        // initialize the media player
        mMediaPlayer = new MediaPlayer();
        try {
            mMediaPlayer.setDataSource(mVideoFd.getFileDescriptor(), mVideoFd.getStartOffset(), mVideoFd.getLength());
        } catch (IOException ioe) {
            Log.e(TAG, "Unable to read video file when setting data source.");
            throw new RuntimeException("Can't read assets file!");
        }

        mMediaPlayer.setOnPreparedListener(new MediaPlayer.OnPreparedListener() {
            @Override
            public void onPrepared(MediaPlayer mp) {
                mPrepared = true;
            }
        });

        mMediaPlayer.setOnBufferingUpdateListener(new MediaPlayer.OnBufferingUpdateListener() {
            @Override
            public void onBufferingUpdate(MediaPlayer mp, int percent) {
                mBufferingPercent = percent;
            }
        });

        mMediaPlayer.prepareAsync();
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        super.onCreateView(inflater, container, savedInstanceState);
        View view = inflater.inflate(R.layout.fragment_main, container, false);
        mSurfaceView = (SurfaceView) view.findViewById(R.id.surface);
        mSurfaceView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                mMediaController.show();
            }
        });

        mSurfaceHolder = mSurfaceView.getHolder();
        if (mSurfaceHolder == null) {
            throw new RuntimeException("SufraceView's holder is null");
        }
        mSurfaceHolder.addCallback(this);
        return view;
    }

    @Override
    public void onViewCreated(View view, Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        mMediaController = new MediaController(getActivity());
        mMediaController.setEnabled(false);
        mMediaController.setMediaPlayer(this);
        mMediaController.setAnchorView(view);
    }

    @Override
    public void onResume() {
        super.onResume();
        if (mShouldResumePlayback) {
            start();
        } else {
            mSurfaceView.post(new Runnable() {
                @Override
                public void run() {
                    mMediaController.show();
                }
            });
        }
    }

    @Override
    public void surfaceCreated(SurfaceHolder holder) {
        mMediaPlayer.setDisplay(mSurfaceHolder);
        mMediaController.setEnabled(true);
    }

    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
        // nothing
    }

    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {
        mMediaPlayer.setDisplay(null);
    }

    @Override
    public void onPause() {
        if (mMediaPlayer.isPlaying() && !getActivity().isChangingConfigurations()) {
            pause();
            mShouldResumePlayback = true;
        }
        super.onPause();
    }

    @Override
    public void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);

    }

    @Override
    public void onDestroyView() {
        mMediaController.setAnchorView(null);
        mMediaController = null;
        mMediaPlayer.setDisplay(null);
        mSurfaceHolder.removeCallback(this);
        mSurfaceHolder = null;
        mSurfaceView = null;
        super.onDestroyView();
    }

    @Override
    public void onDestroy() {
        mMediaPlayer.release();
        mMediaPlayer = null;
        try {
            mVideoFd.close();
        } catch (IOException ioe) {
            Log.e(TAG, "Can't close asset file..", ioe);
        }
        mVideoFd = null;
        super.onDestroy();
    }

    // MediaControler methods:
    @Override
    public void start() {
        mMediaPlayer.start();
    }

    @Override
    public void pause() {
        mMediaPlayer.pause();
    }

    @Override
    public int getDuration() {
        return mMediaPlayer.getDuration();
    }

    @Override
    public int getCurrentPosition() {
        return mMediaPlayer.getCurrentPosition();
    }

    @Override
    public void seekTo(int pos) {
        mMediaPlayer.seekTo(pos);
    }

    @Override
    public boolean isPlaying() {
        return mMediaPlayer.isPlaying();
    }

    @Override
    public int getBufferPercentage() {
        return mBufferingPercent;
    }

    @Override
    public boolean canPause() {
        return true;
    }

    @Override
    public boolean canSeekBackward() {
        return true;
    }

    @Override
    public boolean canSeekForward() {
        return true;
    }

    @Override
    public int getAudioSessionId() {
        return mMediaPlayer.getAudioSessionId();
    }
}

该方法中的if块onPause未被击中.

更新:

在进行了一些调试之后,删除与SurfaceHolder的交互会导致问题消失.换句话说,如果我没有在MediaPlayer上设置显示,则在配置更改期间音频将正常工作:无暂停,无跳过.看起来设置MediaPlayer上的显示有一些时间问题会让玩家感到困惑.

此外,我发现hide()在配置更改期间删除它之前必须使用MediaController.这样可以提高稳定性,但不能解决跳过问题.

另一个更新:

如果您在意,Android媒体堆栈如下所示:

MediaPlayer.java 
 -> android_media_MediaPlayer.cpp 
 -> MediaPlayer.cpp
 -> IMediaPlayer.cpp 
 -> MediaPlayerService.cpp 
 -> BnMediaPlayerService.cpp 
 -> IMediaPlayerService.cpp 
 -> *ConcreteMediaPlayer*
 -> *BaseMediaPlayer* (Stagefright, NuPlayerDriver, Midi, etc) 
 -> *real MediaPlayerProxy* (AwesomePlayer, NuPlayer, etc) 
 -> *RealMediaPlayer* (AwesomePlayerSource, NuPlayerDecoder, etc) 
  -> Codec
  -> HW/SW decoder

在检查AwesomePlayer时,看起来这个很棒的玩家可以在以下情况下自行暂停setSurface():

status_t AwesomePlayer::setNativeWindow_l(const sp<ANativeWindow> &native) {
    mNativeWindow = native;

    if (mVideoSource == NULL) {
        return OK;
    }

    ALOGV("attempting to reconfigure to use new surface");

    bool wasPlaying = (mFlags & PLAYING) != 0;

    pause_l();
    mVideoRenderer.clear();

    shutdownVideoDecoder_l();

    status_t err = initVideoDecoder();

    if (err != OK) {
        ALOGE("failed to reinstantiate video decoder after surface change.");
        return err;
    }

    if (mLastVideoTimeUs >= 0) {
        mSeeking = SEEK;
        mSeekTimeUs = mLastVideoTimeUs;
        modifyFlags((AT_EOS | AUDIO_AT_EOS | VIDEO_AT_EOS), CLEAR);
    }

    if (wasPlaying) {
        play_l();
    }

    return OK;
}

这表明设置表面将导致玩家破坏以前使用的任何表面以及视频解码器.将曲面设置为null不应导致音频停止,将其设置为新曲面需要重新初始化视频解码器并且播放器要搜索视频中的当前位置.按照惯例,寻求永远不会超过你的要求,也就是说,如果你在寻求时超过一个关键帧,你应该落在你超越的框架上(而不是下一个).

因此,我的假设是,Android MediaPlayer不遵守此约定,并在搜索时跳转到下一个关键帧.这与具有稀疏关键帧的视频源相结合,可以解释我正在经历的跳跃.不过,我没有看过AwesomePlayer的搜索实现.有人提到,跳过下一个关键帧是需要发生的事情,如果您的MediaPlayer开发时考虑了流式传输,因为流可以在消费后立即丢弃.重点是,可能不会认为MediaPlayer会选择向前跳而不是向后跳.

最后更新:

虽然我仍然不知道为什么当连接一个新Surface的显示器时播放跳过MediaPlayer,由于接受的答案,我已经让旋转期间的播放无缝.

Answer 1

感谢natez0r的回答,我设法让设置描述起作用.但是,我使用的方法略有不同.我将在此详细介绍以供参考.

我有一个Fragment标记在配置更改中保留的标记.此片段处理媒体播放(MediaPlayer)和标准TextureView(提供SurfaceTexture视频缓冲区转储的位置).只有在我的Activity完成onResume()并且SurfaceTexture可用后,我才会初始化媒体播放.一旦我收到对SurfaceTexture的引用,我只是在我的片段中调用setSurfaceTexture(因为它是公共的)而不是子类化TextureView.配置更改发生时保留的唯一两件事是MediaPlayer引用和SurfaceTexture引用.

我已将示例项目的源代码上传到Github.随意看看!

Answer 2

我知道这个问题现在有点老了,但我能够在没有跳过的情况下在我的应用程序中使用它.问题是表面被破坏(杀死它里面的任何缓冲区).这可能无法解决您的所有问题,因为它针对API 16,但您可以SurfaceTexture在自定义内部管理自己TextureView的视频:

private SurfaceTexture mTexture;

    private TextureView.SurfaceTextureListener mSHCallback =
            new TextureView.SurfaceTextureListener() {
                @Override
                public void onSurfaceTextureAvailable(SurfaceTexture surface, int width,
                        int height) {
                    mTexture = surface;
                    mPlayer.setSurface(new Surface(mTexture));
                }

                @Override
                public void onSurfaceTextureSizeChanged(SurfaceTexture surface, int width,
                        int height) {
                    mTexture = surface;
                }

                @Override
                public boolean onSurfaceTextureDestroyed(SurfaceTexture surface) {
                    mTexture = surface;
                    return false;
                }

                @Override
                public void onSurfaceTextureUpdated(SurfaceTexture surface) {
                    mTexture = surface;
                }
            };

关键是返回false onSurfaceTextureDestroyed并保持mTexture.当视图重新附加到窗口时,您可以设置surfaceTexture:

    @Override
    protected void onAttachedToWindow() {
        super.onAttachedToWindow();
        if (mTexture != null) {
            setSurfaceTexture(mTexture);
        }
    }

这使我的视图可以从完全停止的位置继续播放视频.