在UVCCamera Android USB库中从未调用onFrame

我正在我的应用程序中使用UVCCamera。这个库使用了大量线程工作，这让我很困惑，而且我无法跟踪调用回调的位置。例如，我需要在

onFrame

方法中获取预览帧并对其应用效果，但问题是不清楚何时调用onFrame方法。Android线程文档和专业人士说，runnable中的回调集在同一线程中调用。因此，我在启动相机的线程内定义了一个

IFrameCallback

，但Logcat仍然显示从未调用

onFrame

方法

    private final OnDeviceConnectListener mOnDeviceConnectListener = new OnDeviceConnectListener() {
        @Override
        public void onAttach(final UsbDevice device) {
            Toast.makeText(MainActivity.this, "USB_DEVICE_ATTACHED", Toast.LENGTH_SHORT).show();
        }

        @Override
        public void onConnect(final UsbDevice device, final UsbControlBlock ctrlBlock, final boolean createNew) {
            releaseCamera();
            queueEvent(new Runnable() {
                @Override
                public void run() {
                    final UVCCamera camera = new UVCCamera();
                    camera.open(ctrlBlock);
                    camera.setFrameCallback(mIFrameCallback, UVCCamera.PIXEL_FORMAT_YUV);
                    Log.d(TAG, "run: mIFrameCallback set");
                    camera.setStatusCallback(new IStatusCallback() {
                        @Override
                        public void onStatus(final int statusClass, final int event, final int selector,
                                             final int statusAttribute, final ByteBuffer data) {
                            Log.d(TAG, "onStatus: ");
                            runOnUiThread(new Runnable() {
                                @Override
                                public void run() {
                                    final Toast toast = Toast.makeText(MainActivity.this, "onStatus(statusClass=" + statusClass
                                            + "; " +
                                            "event=" + event + "; " +
                                            "selector=" + selector + "; " +
                                            "statusAttribute=" + statusAttribute + "; " +
                                            "data=...)", Toast.LENGTH_SHORT);
                                    synchronized (mSync) {
                                        if (mToast != null) {
                                            mToast.cancel();
                                        }
                                        toast.show();
                                        mToast = toast;
                                    }
                                }
                            });
                        }
                    });
                    camera.setButtonCallback(new IButtonCallback() {
                        @Override
                        public void onButton(final int button, final int state) {
                            Log.d(TAG, "onButton: button callback");
                            runOnUiThread(new Runnable() {
                                @Override
                                public void run() {
                                    final Toast toast = Toast.makeText(MainActivity.this, "onButton(button=" + button + "; " +
                                            "state=" + state + ")", Toast.LENGTH_SHORT);
                                    synchronized (mSync) {
                                        if (mToast != null) {
                                            mToast.cancel();
                                        }
                                        mToast = toast;
                                        toast.show();
                                    }
                                }
                            });
                        }
                    });
//                  camera.setPreviewTexture(camera.getSurfaceTexture());
                    if (mPreviewSurface != null) {
                        mPreviewSurface.release();
                        mPreviewSurface = null;
                    }
                    try {
                        camera.setPreviewSize(UVCCamera.DEFAULT_PREVIEW_WIDTH, UVCCamera.DEFAULT_PREVIEW_HEIGHT, UVCCamera.FRAME_FORMAT_MJPEG);
                    } catch (final IllegalArgumentException e) {
                        // fallback to YUV mode
                        try {
                            camera.setPreviewSize(UVCCamera.DEFAULT_PREVIEW_WIDTH, UVCCamera.DEFAULT_PREVIEW_HEIGHT, UVCCamera.DEFAULT_PREVIEW_MODE);
                        } catch (final IllegalArgumentException e1) {
                            camera.destroy();
                            return;
                        }
                    }
                    final SurfaceTexture st = mUVCCameraView.getSurfaceTexture();
                    if (st != null) {
                        mPreviewSurface = new Surface(st);
                        camera.setPreviewDisplay(mPreviewSurface);
//                      camera.setFrameCallback(mIFrameCallback, UVCCamera.PIXEL_FORMAT_RGB565/*UVCCamera.PIXEL_FORMAT_NV21*/);
                        camera.startPreview();
                    }
                    synchronized (mSync) {
                        mUVCCamera = camera;

                        mUVCCamera.setFrameCallback(mIFrameCallback, UVCCamera.PIXEL_FORMAT_NV21);
                    }
                }
                private final IFrameCallback mIFrameCallback = new IFrameCallback() {
                    @Override
                    public void onFrame(final ByteBuffer frame) {
                        frame.clear();
                        synchronized (bitmap) {
                            bitmap.copyPixelsFromBuffer(frame);
                            Log.d(TAG, "onFrame: frame length: " + frame.array().length);

                        }

                        mImageView.post(mUpdateImageTask);
                    }
                };
            }, 0);
        }

        @Override
        public void onDisconnect(final UsbDevice device, final UsbControlBlock ctrlBlock) {
            // XXX you should check whether the coming device equal to camera device that currently using
            releaseCamera();
        }

        @Override
        public void onDettach(final UsbDevice device) {
            Toast.makeText(MainActivity.this, "USB_DEVICE_DETACHED", Toast.LENGTH_SHORT).show();
        }

        @Override
        public void onCancel(final UsbDevice device) {
        }
    };

---

正如您在问题中所看到的，IFrameCallback是在runnable中定义的。这是错误的。它应该在onConnect方法之外定义，然后作为变量传入setFrameCallback。至少，我可以看出这对我来说是有效的：

    private final IFrameCallback mIFrameCallback = new IFrameCallback() {
        @Override
        public void onFrame(final ByteBuffer frame) {
            Log.d("Inside onFrame");
        }
    };


    private final OnDeviceConnectListener mOnDeviceConnectListener = new OnDeviceConnectListener() {
        @Override
        public void onAttach(final UsbDevice device) {
            Toast.makeText(MainActivity.this, "USB_DEVICE_ATTACHED", Toast.LENGTH_SHORT).show();
        }

        @Override
        public void onConnect(final UsbDevice device, final UsbControlBlock ctrlBlock, final boolean createNew) {
            releaseCamera();
            queueEvent(new Runnable() {
                @Override
                public void run() {
                    final UVCCamera camera = new UVCCamera();
                    camera.open(ctrlBlock);
                    camera.setStatusCallback(new IStatusCallback() {
                        @Override
                        public void onStatus(final int statusClass, final int event, final int selector,
                                             final int statusAttribute, final ByteBuffer data) {
                            Log.d(TAG, "onStatus: ");
                            runOnUiThread(new Runnable() {
                                @Override
                                public void run() {
                                    final Toast toast = Toast.makeText(MainActivity.this, "onStatus(statusClass=" + statusClass
                                            + "; " +
                                            "event=" + event + "; " +
                                            "selector=" + selector + "; " +
                                            "statusAttribute=" + statusAttribute + "; " +
                                            "data=...)", Toast.LENGTH_SHORT);
                                    synchronized (mSync) {
                                        if (mToast != null) {
                                            mToast.cancel();
                                        }
//                                        toast.show();
                                        mToast = toast;
                                    }
                                }
                            });
                        }
                    });
                    camera.setButtonCallback(new IButtonCallback() {
                        @Override
                        public void onButton(final int button, final int state) {
                            Log.d(TAG, "onButton: button callback");
                            runOnUiThread(new Runnable() {
                                @Override
                                public void run() {
                                    final Toast toast = Toast.makeText(MainActivity.this, "onButton(button=" + button + "; " +
                                            "state=" + state + ")", Toast.LENGTH_SHORT);
                                    synchronized (mSync) {
                                        if (mToast != null) {
                                            mToast.cancel();
                                        }
                                        mToast = toast;
                                        toast.show();
                                    }
                                }
                            });
                        }
                    });
//                  camera.setPreviewTexture(camera.getSurfaceTexture());
                    if (mPreviewSurface != null) {
                        mPreviewSurface.release();
                        mPreviewSurface = null;
                    }
                    try {
                        camera.setPreviewSize(UVCCamera.DEFAULT_PREVIEW_WIDTH, UVCCamera.DEFAULT_PREVIEW_HEIGHT, UVCCamera.FRAME_FORMAT_MJPEG);
                    } catch (final IllegalArgumentException e) {
                        try {
                            camera.setPreviewSize(UVCCamera.DEFAULT_PREVIEW_WIDTH, UVCCamera.DEFAULT_PREVIEW_HEIGHT, UVCCamera.DEFAULT_PREVIEW_MODE);
                        } catch (final IllegalArgumentException e1) {
                            camera.destroy();
                            return;
                        }
                    }
                    final SurfaceTexture st = mUVCCameraView.getSurfaceTexture();
                    if (st != null) {
                        mPreviewSurface = new Surface(st);
                        camera.setPreviewDisplay(mPreviewSurface);

                        camera.setFrameCallback(mIFrameCallback, UVCCamera.PIXEL_FORMAT_YUV420SP);
                        camera.startPreview();
                    }
                    synchronized (mSync) {
                        mUVCCamera = camera;

                    }
                }
            }, 0);
        }

---

你对这个问题有什么想法吗？