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Android -- 获取摄像头帧数据解码

由于Android下摄像头预览数据只能  ImageFormat.NV21 格式的,所以解码时要经过一翻周折.

Camera mCamera = Camera.open();Camera.Parameters p = mCamera.getParameters();p.setPreviewFormat(ImageFormat.NV21);/*这是唯一值,也可以不设置。有些同学可能设置成 PixelFormat 下面的一个值,其实是不对的,具体的可以看官方文档*/mCamera.setParameters(p);mCamera.startPreview();

下面是解码核心部分:

@Override  public void onPreviewFrame(byte[] data, Camera camera) {              Size size = camera.getParameters().getPreviewSize();              try{          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());                    stream.close();          }      }catch(Exception ex){          Log.e("Sys","Error:"+ex.getMessage());      }  }

代码很简单。就是把YUV数据转成 Bitmap 就行了,系统提供 YuvImage 类。

yuv420sp转RGB                                                                       

/**         * 解码         *          * @param rgb         * @param yuv420sp         * @param width         * @param height         */        static public void decodeYUV420SP(int[] rgb, byte[] yuv420sp, int width, int height) {                final int frameSize = width * height;                for (int j = 0, yp = 0; j < height; j++) {                        int uvp = frameSize + (j >> 1) * width, u = 0, v = 0;                        for (int i = 0; i < width; i++, yp++) {                                int y = (0xff & ((int) yuv420sp[yp])) - 16;                                if (y < 0)                                        y = 0;                                if ((i & 1) == 0) {                                        v = (0xff & yuv420sp[uvp++]) - 128;                                        u = (0xff & yuv420sp[uvp++]) - 128;                                }                                int y1192 = 1192 * y;                                int r = (y1192 + 1634 * v);                                int g = (y1192 - 833 * v - 400 * u);                                int b = (y1192 + 2066 * u);                                if (r < 0)                                        r = 0;                                else if (r > 262143)                                        r = 262143;                                if (g < 0)                                        g = 0;                                else if (g > 262143)                                        g = 262143;                                if (b < 0)                                        b = 0;                                else if (b > 262143)                                        b = 262143;                                rgb[yp] = 0xff000000 | ((r << 6) & 0xff0000) | ((g >> 2) & 0xff00) | ((b >> 10) & 0xff);                        }                }        }

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