libyuv库函数实现RGBA8888转I420S-P

        i420buf = webrtc::I420Buffer::Create(w,h);
        uint8_t* yplane=i420buf->MutableDataY();
        uint8_t* uplane=i420buf->MutableDataU();
        uint8_t* vplane=i420buf->MutableDataV();

        libyuv::ConvertToI420(reinterpret_cast<uint8_t *>(base),0,//源buff指针
                                  yplane,w,//y分量和长度
                                  uplane,(w+1)/2,//u分量和长度
                                  vplane,(w+1)/2,//v分量和长度
                                  0,0,//处理x，y坐标
                                  w,h,//源宽高
                                  w,h,//目标宽高
                                  libyuv::kRotate0,//旋转
                                  libyuv::FOURCC_ARGB);//类型

上面这个函数处理有色差,下面这个接口则没有

        libyuv::ABGRToI420(reinterpret_cast<uint8_t *>(base),
                           s*4,
                           yplane,w,
                           uplane,(w+1)/2,
                           vplane,(w+1)/2,
                           w,h);