TarsosDSP和SurfaceView多线程问题

Question

我使用TarsosDSP实时计算基音频率。它使用一个AudioDispatcher来实现Runnable，并通过handlePitch方法发布结果，以便在主线程中使用。

当SurfaceView更新时，我使用它来绘制这个值。SurfaceView还需要另一个线程在画布上绘制。所以我有两个可运行的对象。我无法管理如何通过一个线程更新表面视图，同时从另一个线程获得音调值(audiodispatcher)。

我只想使用在handlePitch()方法中得到的分值来更新表面视图上的绘图。但我的应用程序被冻结了。有什么想法吗？

In MainAcitivity.java (onCreate(.))

   myView = (MySurfaceView) findViewById(R.id.myview);

    int sr = 44100;//The sample rate
    int bs = 2048;
    AudioDispatcher d = AudioDispatcherFactory.fromDefaultMicrophone(sr,bs,0);
    PitchDetectionHandler printPitch = new PitchDetectionHandler() {
        @Override
        public void handlePitch(final PitchDetectionResult pitchDetectionResult, AudioEvent audioEvent) {
            final float p = pitchDetectionResult.getPitch();

            runOnUiThread(new Runnable() {
                @Override
                public void run() {

                    if (p != -1){
                        float cent = (float) (1200*Math.log(p/8.176)/Math.log(2)) % 12;
                        System.out.println(cent);
                        myView.setCent(cent);
                    }
                }
            });
        }
    };

    PitchProcessor.PitchEstimationAlgorithm algo = PitchProcessor.PitchEstimationAlgorithm.YIN; //use YIN
    AudioProcessor pitchEstimator = new PitchProcessor(algo, sr,bs,printPitch);
    d.addAudioProcessor(pitchEstimator);
    d.run();//starts the dispatching process
    AudioProcessor p = new PitchProcessor(algo, sr, bs, printPitch);
    d.addAudioProcessor(p);
    new Thread(d,"Audio Dispatcher").start();

In SurfaceView.java (下面的代码是从构造函数触发的)

    myThread = new MyThread(this);
    surfaceHolder = getHolder();
    bmpIcon = BitmapFactory.decodeResource(getResources(),
            R.mipmap.ic_launcher);

    iconWidth = bmpIcon.getWidth();
    iconHeight = bmpIcon.getHeight();
    density = getResources().getDisplayMetrics().scaledDensity;
    setLabelTextSize(Math.round(DEFAULT_LABEL_TEXT_SIZE_DP * density));

    surfaceHolder.addCallback(new SurfaceHolder.Callback(){

        @Override
        public void surfaceCreated(SurfaceHolder holder) {
            myThread.setRunning(true);
            myThread.start();
        }

        @Override
        public void surfaceChanged(SurfaceHolder holder,
                                   int format, int width, int height) {
            // TODO Auto-generated method stub

        }

        @Override
        public void surfaceDestroyed(SurfaceHolder holder) {
            boolean retry = true;
            myThread.setRunning(false);
            while (retry) {
                try {
                    myThread.join();
                    retry = false;
                } catch (InterruptedException e) {
                }
            }
        }});


      protected void drawSomething(Canvas canvas) {

         updateCanvas(canvas, this.cent); //draws some lines depending on the cent value
      }


    public void setCent(double cent) {

        if (this.cent > maxCent)
            this.cent = maxCent;
        this.cent = cent;
    }

更新：

MyThread.java

public class MyThread extends Thread {

    MySurfaceView myView;
    private boolean running = false;

    public MyThread(MySurfaceView view) {
        myView = view;
    }

    public void setRunning(boolean run) {
        running = run;
    }

    @Override
    public void run() {
        while(running){

            Canvas canvas = myView.getHolder().lockCanvas();

            if(canvas != null){
                synchronized (myView.getHolder()) {
                    myView.drawSomething(canvas);
                }
                myView.getHolder().unlockCanvasAndPost(canvas);
            }

            try {
                sleep(1000);
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

        }
    }

Answer 1

如果我正确地理解了您的问题，那么您就有了一个独立的事件源来处理它自己的线程(PitchDetectionHandler)，而当来自源的事件出现时，您希望在它自己的线程上重新绘制一个SurfaceView。如果是这样的话，那么我认为sleep(1000)的整个想法是错误的。你应该跟踪实际事件并对它们做出反应，而不是等着它们睡觉。在Android上，最简单的解决方案似乎是使用HandlerThread/Looper/Handler基础设施，如下所示：

注意以下代码中的but；我不仅没有尝试过它，而且我甚至没有编译它。

import android.graphics.Canvas;
import android.os.Handler;
import android.os.HandlerThread;
import android.os.Message;
import android.view.SurfaceHolder;


public class SurfacePitchDrawingHelper implements Handler.Callback, SurfaceHolder.Callback2 {

    private static final int MSG_DRAW = 100;
    private static final int MSG_FORCE_REDRAW = 101;

    private final Object _lock = new Object();
    private SurfaceHolder _surfaceHolder;
    private HandlerThread _drawingThread;
    private Handler _handler;

    private float _lastDrawnCent;
    private volatile float _lastCent;

    private final boolean _processOnlyLast = true;

    @Override
    public void surfaceCreated(SurfaceHolder holder) {
        synchronized (_lock) {
            _surfaceHolder = holder;

            _drawingThread = new HandlerThread("SurfaceDrawingThread") {
                @Override
                protected void onLooperPrepared() {
                    super.onLooperPrepared();
                }
            };

            _drawingThread.start();
            _handler = new Handler(_drawingThread.getLooper(), this); // <-- this is where bug was
            _lastDrawnCent = Float.NaN;
            //postForceRedraw(); // if needed
        }
    }


    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {
        synchronized (_lock) {
            // clean queue and kill looper
            _handler.removeCallbacksAndMessages(null);
            _drawingThread.getLooper().quit();

            while (true) {
                try {
                    _drawingThread.join();
                    break;
                } catch (InterruptedException e) {
                }
            }

            _handler = null;
            _drawingThread = null;
            _surfaceHolder = null;
        }
    }

    @Override
    public void surfaceRedrawNeeded(SurfaceHolder holder) {
        postForceRedraw();
    }


    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
        synchronized (_lock) {
            _surfaceHolder = holder;
        }
        postForceRedraw();
    }

    private void postForceRedraw() {
        _handler.sendEmptyMessage(MSG_FORCE_REDRAW);
    }

    public void postRedraw(float cent) {
        if (_processOnlyLast) {
            _lastCent = cent;
            _handler.sendEmptyMessage(MSG_DRAW);
        } else {
            Message message = _handler.obtainMessage(MSG_DRAW);
            message.obj = Float.valueOf(cent);
            _handler.sendMessage(message);
        }
    }


    private void doRedraw(Canvas canvas, float cent) {
        // put actual painting logic here
    }

    @Override
    public boolean handleMessage(Message msg) {
        float lastCent = _processOnlyLast ? _lastCent : ((Float) msg.obj).floatValue();
        boolean shouldRedraw = (MSG_FORCE_REDRAW == msg.what)
                || ((MSG_DRAW == msg.what) && (_lastDrawnCent != lastCent));

        if (shouldRedraw) {
            Canvas canvas = null;
            synchronized (_lock) {
                if (_surfaceHolder != null)
                    canvas =_surfaceHolder.lockCanvas();
            }
            if (canvas != null) {
                doRedraw(canvas, lastCent);
                _surfaceHolder.unlockCanvasAndPost(canvas);
                _lastDrawnCent = lastCent;
            }

            return true;
        }

        return false;
    }
}

然后在你的活动课上你会做一些类似的事情

private SurfaceView surfaceView;
private SurfacePitchDrawingHelper surfacePitchDrawingHelper = new SurfacePitchDrawingHelper();

...

@Override
protected void onCreate(Bundle savedInstanceState) {

    ...

    surfaceView = (SurfaceView) findViewById(R.id.surfaceView);
    surfaceView.getHolder().addCallback(surfacePitchDrawingHelper);

    int sr = 44100;//The sample rate
    int bs = 2048;
    AudioDispatcher d = AudioDispatcherFactory.fromDefaultMicrophone(sr, bs, 0);
    PitchDetectionHandler printPitch = new PitchDetectionHandler() {
        @Override
        public void handlePitch(final PitchDetectionResult pitchDetectionResult, AudioEvent audioEvent) {
            final float p = pitchDetectionResult.getPitch();
            float cent = (float) (1200 * Math.log(p / 8.176) / Math.log(2)) % 12;
            System.out.println(cent);
            surfacePitchDrawingHelper.postRedraw(cent);
        }
    };

    PitchProcessor.PitchEstimationAlgorithm algo = PitchProcessor.PitchEstimationAlgorithm.YIN; //use YIN
    AudioProcessor pitchEstimator = new PitchProcessor(algo, sr, bs, printPitch);
    d.addAudioProcessor(pitchEstimator);
    // d.run();//starts the dispatching process <-- this was another bug in the original code (see update)!
    AudioProcessor p = new PitchProcessor(algo, sr, bs, printPitch);
    d.addAudioProcessor(p);
    new Thread(d, "Audio Dispatcher").start();

    ...

}

请注意，SurfacePitchDrawingHelper封装了大部分与绘图相关的逻辑，您的子类MySurfaceView中没有必要(我认为这是个坏主意)。

主要思想是，当创建新的SurfacePitchDrawingHelper时，Surface创建是专用的Surface。HandlerThread + Looper + Handler提供了一个有用的基础结构，可以(以高效的方式)在单独的线程上运行一个无限循环，等待传入的消息并逐一处理它们。因此，除了SurfaceHolder.Callback2之外，它的有效公共API由单个postRedraw方法组成，该方法可用于要求绘图线程进行另一次重绘，这正是自定义PitchDetectionHandler所使用的。“询问”是通过将一条消息放入要由绘图线程处理的队列中来完成的(更具体地说，我们在该线程上的自定义Handler )。我没有费心地将真正的公共API简化为“有效的”API，因为它使代码更加复杂，而且我太懒了。当然，这两个“实现”都可以转移到内部类中。

您需要做出一个重要的决定:绘图线程是否应该生成每个入站消息(所有cent值)，以便在当前发生绘图。如果PitchDetectionHandler生成的事件比“绘图线程”更新Surface的速度快得多，这可能变得特别重要。我相信，在大多数情况下，只处理PitchDetectionHandler的最后一个值是可以的，但我将这两个版本留在代码中进行说明。这一区别目前由_processOnlyLast字段在代码中实现。最有可能的是，您应该做出这个决定，只需去掉这个几乎不变的字段和不相关分支中的代码。

当然，不要忘记将实际的绘图逻辑放在doRedraw中

更新(为什么后退按钮不能工作)

TLDR版本

令人反感的是

 d.run();//starts the dispatching process

评论一下吧！

更长版本

查看您的示例，我们可以看到d是AudioDispatcher，哪个implements Runnable，因此run方法是一个在新线程上被调用的方法。您可能会注意到这一点很重要，因为在此方法中会执行一些IO操作，并阻塞它运行的线程。因此，在您的情况下，它阻塞了主UI线程。往下走几行就行了

new Thread(d, "Audio Dispatcher").start();

这似乎是使用AudioDispatcher的正确方法

从我在注释中询问的堆栈跟踪可以很容易地看出这一点。

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