OpenCV:BGR/RGB转I420（颜色失真），再转NV12

RGB转I420由OpenCV实现，I420转NV12，要自己写代码了。

• RGB转I420

  void convert()
  {
  cv::Mat yuv;
  cv::cvtColor(matBgr, yuv, cv::COLOR_RGB2YUV_I420);
  I420_TO_NV12(map_info.data, yuv.data, width, height);
  yuv.release();
  }

• I420转NV12

  static void I420_TO_NV12(uchar* NV12, uchar* I420, const int width, const int height)
  {
  int ySize = width * height;
  int uvSize = ySize / 2;
  memcpy(NV12, I420, ySize);

    int uvIndex = 0;
    for (int i = ySize; i < ySize + uvSize; i += 2) {
        NV12[i+1] = I420[ySize + uvIndex];
        NV12[i  ] = I420[ySize + uvSize/2+uvIndex];
        uvIndex ++;
    }

  }

• 颜色失真参考

https://blog.csdn.net/quantum7/article/details/153632326