Android MediaPlayer setNextMediaPlayer 不工作

Question

我的目标是创建一个VideoView 可以播放pre-defined 播放列表中的视频。

我正在尝试使用MediaPlayer.setNextMediaPlayer(...) 来实现两个视频之间的无缝过渡。但是，当第一个视频播放完毕后，第二个视频不会按照文档所述自动启动。

Xamarin Android 代码：

    Queue<MediaPlayer> MediaPlayerList = null;
    private void PlayVideo()
    {
        MediaPlayerList = new Queue<MediaPlayer>();

        //Let's go ahead and create all media players
        VideoView_CurrentVideoView = new VideoView(this);

        VideoView_CurrentVideoView.Completion += mVideoView_Completion;
        VideoView_CurrentVideoView.Prepared += mVideoView_Prepared;

        //Let's prepare all MediaPlayer
        for (int i = 0; i < VideoView_CurrentVideoChannel.VideoAssetList.Count; i++)
        {
            string filePath = FilePath[i];
            if (i == 0)
            {
                VideoView_CurrentVideoView.SetVideoPath(filePath);
                VideoContainer.AddView(VideoView_CurrentVideoView);
            }
            else
            {
                MediaPlayer mpNew = new MediaPlayer();
                mpNew.SetDataSource(filePath);
                MediaPlayerList.Enqueue(mpNew);
            }
        }

        VideoView_CurrentVideoView.Start();
    }

    void mVideoView_Completion(object sender, EventArgs e)
    {
        MediaPlayer mp = (MediaPlayer)sender;
        mp.Release();
    }

    void mVideoView_Prepared(object sender, EventArgs e)
    {
        MediaPlayer mp = (MediaPlayer)sender;

        //Take the next available MediaPlayer from the queue
        MediaPlayer nextMediaPlayer = MediaPlayerList.Dequeue();

        //Put the current MediaPlayer at the end of the queue
        MediaPlayerList.Enqueue(mp);


        nextMediaPlayer.Prepare();
        mp.SetNextMediaPlayer(nextMediaPlayer);
    }

任何帮助或建议将不胜感激。这是在Xamarin Android 中编码的。

更新 #1：将 .Prepare() 远离 Prepared() 事件后

    Queue<string> VideoListQueue = null;
    MediaPlayer NextMediaPlayer = null;
    private void PlayVideo()
    {
        string filePath = FilePath[0];


        //Create video view
        if (VideoContainer.ChildCount == 0)
        {
            //setup the videoview container
            VideoView_CurrentVideoView = new VideoView(this);
            VideoView_CurrentVideoView.Info += VideoView_CurrentVideoView_Info;
            VideoView_CurrentVideoView.Error += VideoView_CurrentVideoView_Error;

            LinearLayout.LayoutParams param = new LinearLayout.LayoutParams(ViewGroup.LayoutParams.FillParent, ViewGroup.LayoutParams.FillParent);
            param.LeftMargin = 0;
            param.RightMargin = 0;
            param.BottomMargin = 0;
            param.TopMargin = 0;

            VideoView_CurrentVideoView.LayoutParameters = param;
            VideoView_CurrentVideoView.LayoutParameters.Width = ViewGroup.LayoutParams.FillParent;
            VideoView_CurrentVideoView.LayoutParameters.Height = ViewGroup.LayoutParams.FillParent;

            VideoView_CurrentVideoView.Completion += VideoView_CurrentVideoView_Completion;
            VideoView_CurrentVideoView.Prepared += VideoView_CurrentVideoView_Prepared;
            VideoContainer.AddView(VideoView_CurrentVideoView);
        }

        VideoView_CurrentVideoView.SetVideoPath(filePath);
        VideoView_CurrentVideoView.SeekTo(0);
        VideoView_CurrentVideoView.Start();
    }

    void VideoView_CurrentVideoView_Prepared(object sender, EventArgs e)
    {
        //Do nothing at this moment
        MediaPlayer mp = (MediaPlayer)sender;
    }

    void VideoView_CurrentVideoView_Completion(object sender, EventArgs e)
    {
        //GC the finished MediaPlayer
        MediaPlayer mp = (MediaPlayer)sender;
        mp.Reset();
        mp.Release();
        mp = null;


        //Preparing the next MediaPlayer
        MediaPlayer currentPlayer = NextMediaPlayer;
        NextMediaPlayer = SetupNextMediaPlayer();
        currentPlayer.SetNextMediaPlayer(NextMediaPlayer);
    }


    MediaPlayer SetupNextMediaPlayer()
    {
        MediaPlayer mp = new MediaPlayer();
        //When the video start playing, let's get ready for next one
        string sourceURL = VideoListQueue.Dequeue();
        VideoListQueue.Enqueue(sourceURL);

        string filePath = sourceURL;


        mp = new MediaPlayer();
        mp.Info += VideoView_CurrentVideoView_Info;
        mp.Completion += VideoView_CurrentVideoView_Completion;
        mp.Prepared += VideoView_CurrentVideoView_Prepared;

        mp.SetDataSource(filePath);
        mp.Prepare();


        //Fire back the created MediaPlayer object to the caller
        return mp;
    }

    void VideoView_CurrentVideoView_Info(object sender, MediaPlayer.InfoEventArgs e)
    {
        Console.WriteLine("What = " + e.What);

        switch (e.What)
        {
            case MediaInfo.VideoRenderingStart:
                {
                    //This is only happening on video first started
                    NextMediaPlayer = SetupNextMediaPlayer();
                    e.Mp.SetNextMediaPlayer(NextMediaPlayer);
                    break;
                }
        }

    }

    void VideoView_CurrentVideoView_Error(object sender, MediaPlayer.ErrorEventArgs e)
    {
        e.Handled = true;
    }

此时，媒体播放器将在第一个视频播放完毕后开始播放第二个视频。但是，第二个视频只有声音，没有视频显示。

谁知道我做错了什么？我有一种感觉，它必须与未附加到 SurfaceView 的 MediaPlayer 做一些事情。但是，我使用 VideoView 创建了视图，如何从 VideoView 获取 Surface？

Answer 1

关于仅用声音播放第二个视频：尝试使用以下方法为每个 MediaPlayer 实现 OnCompletionListener 侦听器：

mediaPlayer.setOnCompletionListener(new OnCompletionListener() {

    @Override
    public void onCompletion(MediaPlayer mp) {
        mp.setDisplay(null); //for current mediaPlayer
        nextMediaPlayer.setDisplay(getHolder()); //for next video
    }
});

我不能说它是无间隙的，但它以某种方式起作用。为了存档，我不使用标准的 VideoView，而是使用从 SurfaceView 扩展而来的自定义 View。

Answer 2

如果您在 .Completion 事件中准备并播放下一个媒体播放器会怎样？你试过吗？虽然可能会有一点延迟

Answer 3

经过多年的测试，并非所有硬件都会出现此问题。例如，我在 Nexus7 上运行相同的 APK，它看起来是无缝的，并且一切正常。相反，如果我在 Amlogic 媒体播放板上运行它，就会出现上述问题。

我决定结束这篇文章，得出的结论是它与硬件有关。我知道有人通过在 OpenGL 中运行所有东西来克服这个限制，但这完全是一个单独的野兽来处理。

结论

如果您遇到与上述类似的问题，那么您无能为力，因为它严重依赖于硬件。