Android 一分钟了解简单原生FaceDetector人脸识别，解决SurfaceView+MediaRecorder录制视频不清晰

近来，发现登入后台管理系统，发现上传上来的认证视频太模糊了，于是乎，发现没有给MediaRecorder设置帧频率。

// 设置帧频率，录制视频会更加清晰
mRecorder.setVideoEncodingBitRate(5*1024*1024);

1.直接开撸，先打开相机，来获取想要的bitmap，关于为什么用到YuvImage：https://blog.csdn.net/illidantao/article/details/51366047

    try {
                    camera = Camera.open(Camera.CameraInfo.CAMERA_FACING_FRONT);
                } catch (Exception e) {
                    e.printStackTrace();
                }

              
                try {
                    camera = Camera.open(Camera.CameraInfo.CAMERA_FACING_FRONT);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
                camera.setDisplayOrientation(90);
                camera.startPreview();
            }
            camera.setPreviewCallback(new Camera.PreviewCallback() {

                @Override
                public void onPreviewFrame(final byte[] data, Camera camera) {
                    Camera.Size size = camera.getParameters().getPreviewSize();
                    YuvImage image = new YuvImage(data, ImageFormat.NV21, size.width,
                            size.height, null);
                    if (image != null) {
                        ByteArrayOutputStream stream = new ByteArrayOutputStream();
                        image.compressToJpeg(new Rect(0, 0, size.width, size.height),
                                80, stream);
                        Bitmap bmp = BitmapFactory.decodeByteArray(
                                stream.toByteArray(), 0, stream.size());
                        Matrix matrix = new Matrix();
                        matrix.reset();
                        matrix.setRotate(-90);
                        bmp = Bitmap.createBitmap(bmp, 0, 0, bmp.getWidth(), bmp.getHeight(), matrix, true);
                        Bitmap bitmap = bmp.copy(Bitmap.Config.RGB_565, true);
                        findFace(bitmap);
                        try {
                            stream.close();
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    }
                }

            });

安卓原生SDK中有个FaceDetector类，传入一个Bitmap 格式的数据；B，只能识别双眼距离大于20 像素的人脸像（当然，这个可在framework层中修改）；C，只能检测出人脸的位置（双眼的中心点及距离），不能对人脸进行匹配（查找指定的脸谱）。下面的坐标实现具体的获取人脸的中心点坐标，通过FaceDetector.Face[1]传入要抓取的个数，如果想抓去多个的话Face[*]就可以了，findFaces(bitmap,face)得到一个int值，如果其大于1则代表成功那么就开始接下来的操作了。 

public void findFace(Bitmap bitmap) {
    FaceDetector faceDetector = new FaceDetector(bitmap.getWidth(), bitmap.getHeight(), 1);
    FaceDetector.Face[] face = new FaceDetector.Face[1];
    int faces = faceDetector.findFaces(bitmap, face);
    if (faces > 0) {
        camera.stopPreview();
        preview = false;
        camera.setPreviewCallback(null);
        camera.release();
        initMediaRecorder();
    }
}

 2.当获取验证成功以后，实现6秒录制视频。

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    getWindow().setFormat(PixelFormat.TRANSLUCENT);
    setContentView(R.layout.activity_uservideo);
    
    surfaceview.getHolder().setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
    surfaceview.getHolder().setFixedSize(200, 200);
    surfaceview.getHolder().addCallback(new SurfaceViewCallback());
}

 public void initMediaRecorder() {
        if (mRecorder == null) {
            mRecorder = new MediaRecorder(); // Create MediaRecorder
        }

        try {
            initCamera();

            // 这两项需要放在setOutputFormat之前
            mRecorder.setCamera(videocamera);
            mRecorder.setVideoSource(MediaRecorder.VideoSource.CAMERA);
            // Set output file format
            mRecorder.setOutputFormat(MediaRecorder.OutputFormat.MPEG_4);
            // 这两项需要放在setOutputFormat之后
            mRecorder.setVideoEncoder(MediaRecorder.VideoEncoder.H264);
//            mRecorder.setOrientationHint(90);
//            mRecorder.setVideoSize(320, 240);
            CamcorderProfile profile = CamcorderProfile.get(CamcorderProfile.QUALITY_1080P);
            mRecorder.setVideoSize(profile.videoFrameWidth, profile.videoFrameHeight);
            // 设置帧频率，录制视频会更加清晰
            mRecorder.setVideoEncodingBitRate(5*1024*1024);
            // mRecorder.setVideoFrameRate(20);
            mRecorder.setPreviewDisplay(mSurfaceHolder.getSurface());
            file = Constants.FOLDER_PHOTO + System.currentTimeMillis() + ".mp4";
            mRecorder.setOutputFile(file);

            mRecorder.prepare();
            mRecorder.start();   // Recording is now started
            setCountBack();
        } catch (IOException e1) {
            e1.printStackTrace();
        }
    }

private void initCamera() {
    Camera.CameraInfo cameraInfo = new Camera.CameraInfo();
    cameraCount = Camera.getNumberOfCameras(); // get cameras number

    for (int camIdx = 0; camIdx < cameraCount; camIdx++) {
        Camera.getCameraInfo(camIdx, cameraInfo); // get camerainfo
        if (cameraInfo.facing == Camera.CameraInfo.CAMERA_FACING_FRONT) {
            // 代表摄像头的方位，目前有定义值两个分别为CAMERA_FACING_FRONT前置和CAMERA_FACING_BACK后置
            try {
                videocamera = Camera.open(camIdx);
                videocamera.setDisplayOrientation(90);
                videocamera.cancelAutoFocus();
            } catch (RuntimeException e) {
                e.printStackTrace();
            }
        }
    }
    videocamera.unlock();
}

void setCountBack() {
    timeCount = 5;
    timetext.setText(timeCount + "秒");
    handler.postDelayed(new Runnable() {
        @Override
        public void run() {
            if (timeCount > 0) {
                timetext.setText(--timeCount + "秒");
                handler.postDelayed(this, 1000);
                return;
            }

            timetext.setText("");

            if (mRecorder == null) {
                return;
            }

            try {
                mRecorder.stop();
                //上传视频
                uploadVideo();
            } catch (Exception e) {
                ToastUtil.showToast(AuthRecordingVideoActivity.this, getString(R.string.error_recoder));
            }
        }
    }, 1000);


}

关于SurfaceView预览Camera拉伸问题：https://blog.csdn.net/illidantao/article/details/51366047