流式安卓屏幕

Question

我正在尝试闲置Truiton ScreenCapture 示例，以便使用MediaProjection 记录设备屏幕

在本地保存录音时，它可以工作

    mMediaRecorder.setVideoSource(MediaRecorder.VideoSource.SURFACE);
    mMediaRecorder.setOutputFormat(MediaRecorder.OutputFormat.MPEG_4);

    String localFilePath = getLocalFilePath();
    mMediaRecorder.setOutputFile(localFilePath);

    mMediaRecorder.setVideoSize(DISPLAY_WIDTH, DISPLAY_HEIGHT);
    mMediaRecorder.setVideoEncoder(MediaRecorder.VideoEncoder.MPEG_4_SP);
    mMediaRecorder.setVideoFrameRate(30);
    mMediaRecorder.prepare();

当更改为使用 FileDescriptor 时，它不是

    mMediaRecorder.setVideoSource(MediaRecorder.VideoSource.SURFACE);
    mMediaRecorder.setOutputFormat(MediaRecorder.OutputFormat.MPEG_4);

    String hostname = "10.26.100.18";
    int port = 2007;
    Socket socket = new Socket(InetAddress.getByName(hostname), port);
    ParcelFileDescriptor fileDescriptor = ParcelFileDescriptor.fromSocket(socket);
    LocalServerSocket localServerSocket = new LocalServerSocket(fileDescriptor.getFileDescriptor());

    mMediaRecorder.setOutputFile(localServerSocket.getFileDescriptor());

    mMediaRecorder.setVideoSize(DISPLAY_WIDTH, DISPLAY_HEIGHT);
    mMediaRecorder.setVideoEncoder(MediaRecorder.VideoEncoder.MPEG_4_SP);
    mMediaRecorder.setVideoFrameRate(30);
    mMediaRecorder.prepare();

如果不使用LocalServerSocket，那么mMediaRecorder.prepare()会抛出异常，现在我正在使用，在mMediaRecorder.getSurface()下面的方法中获取异常

private VirtualDisplay createVirtualDisplay() {
    return mMediaProjection.createVirtualDisplay("MainActivity",
            DISPLAY_WIDTH, DISPLAY_HEIGHT, mScreenDensity,
            DisplayManager.VIRTUAL_DISPLAY_FLAG_AUTO_MIRROR,
            mMediaRecorder.getSurface(), null /*Callbacks*/, null
            /*Handler*/);
}

例外

Caused by: java.lang.IllegalStateException: failed to get surface
   at android.media.MediaRecorder.getSurface(Native Method)
   at com.truiton.screencapture.MainActivity$override.createVirtualDisplay(MainActivity.java:172)
   at com.truiton.screencapture.MainActivity$override.onActivityResult(MainActivity.java:133)
   at com.truiton.screencapture.MainActivity$override.access$dispatch(MainActivity.java)
   at com.truiton.screencapture.MainActivity.onActivityResult(MainActivity.java:0)
   at android.app.Activity.dispatchActivityResult(Activity.java:6456)
   at android.app.ActivityThread.deliverResults(ActivityThread.java:3695)
   at android.app.ActivityThread.handleSendResult(ActivityThread.java:3742) 
   at android.app.ActivityThread.-wrap16(ActivityThread.java) 
   at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1393) 
   at android.os.Handler.dispatchMessage(Handler.java:102) 
   at android.os.Looper.loop(Looper.java:148) 
   at android.app.ActivityThread.main(ActivityThread.java:5417) 
   at java.lang.reflect.Method.invoke(Native Method) 
   at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 
   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 

这是我的 Java 服务器，在调用 mMediaRecorder.prepare() 后我得到了套接字，并且它卡在了 inputStream.read 上，因为 eccected。当我调用mMediaRecorder.start()时，Android 中的异常发生了

    final byte[] buffer = new byte[1024];
    try {
        ServerSocket serverSocket = new ServerSocket(2007);
        while (!serverSocket.isClosed()) {
            Socket socket = serverSocket.accept();
            File videoFile = createEmptyVideoFile();
            FileOutputStream outputStream = new FileOutputStream(videoFile);
            InputStream inputStream = socket.getInputStream();
            int length = inputStream.read(buffer);
            while (length != -1) {
                outputStream.write(buffer, 0, length);
                length = inputStream.read(buffer);
            }
        }
    } catch (IOException e) {
        e.printStackTrace();
    }

Answer 1

你必须使用 LocalServerSocket，下面是部分对我有用的，我有一个扩展 MediaRecorder 的 MediaStreamer 类。

public class MediaStreamer extends MediaRecorder {

    private LocalServerSocket localServerSocket = null;
    private LocalSocket receiver, sender = null;

    public void prepare() throws IllegalStateException,IOException {

        receiver = new LocalSocket();
        try {
            localServerSocket = new LocalServerSocket("<your_socket_addr>");
            receiver.connect(new LocalSocketAddress("<your_socket_addr>"));
            receiver.setReceiveBufferSize(4096);
            receiver.setSendBufferSize(4096);
            sender = localServerSocket.accept();
            sender.setReceiveBufferSize(4096);
            sender.setSendBufferSize(4096); 
        } catch (IOException e1) {
            throw new IOException("Can't create local socket !");
        }

        setOutputFile(sender.getFileDescriptor());

        try {
            super.prepare();
        } catch (Exception e) {
            closeSockets();
            throw e;
        }           
    }

    public InputStream getInputStream() {

        InputStream out = null;

        try {
            out = receiver.getInputStream();
        } catch (IOException e) {
        }

        return out;

    }


    public void stop() {
        closeSockets();
        super.stop();
    }

    private void closeSockets() {
        if (localServerSocket !=null) {
            try {
                localServerSocket.close();
                sender.close();
                receiver.close();
            }
            catch (IOException e) {

            }
            localServerSocket = null; 
            sender = null; 
            receiver = null;
        }
    }
}

用于录音

video = new MediaStreamer();
video.reset();

video.setVideoSource(MediaRecorder.VideoSource.DEFAULT);
video.setPreviewDisplay(holder.getSurface());
video.setOutputFormat(MediaRecorder.OutputFormat.MPEG_4);
video.setVideoFrameRate(VideoConstants.frameRate);
video.setVideoEncodingBitRate(VideoConstants.bitRate*1000);
video.setVideoSize(VideoConstants.resolationX, VideoConstants.resolationY);
video.setVideoEncoder(MediaRecorder.VideoEncoder.MPEG_4_SP);

try {
   video.prepare();
} catch (IOException e) {
   e.printStackTrace();
}
video.start();

---

但主要问题是 mp4 不是很容易流式传输。基本问题是 MP4 不是实时的、可流式传输的格式，因此即使通过套接字捕获数据，通常在音频或视频捕获结束时写入的关键文件头也会丢失（因为套接字不可搜索，例如本地文件） - 因此无法播放数据（因此，为什么保存为本地文件时它可以正常工作，这是可以理解的）。

没有简单的方法可以对数据进行后处理以手动添加文件头。所以解决办法是要么不使用 MP4 作为录音格式，要么写一个类似于 Spydroid 项目中使用的打包器

希望这会有所帮助！