Question

我正在尝试使用SDL播放视频。为此，我使用opencv加载视频，并获取帧。然后我只需要将这些帧转换为SDL_Texture*，然后我就可以在屏幕上绘制它们了。

这是我的问题，我将其转换为SDL_Surface*，但转换为SDL_Texture失败了，我不确定原因。这是我的代码：

void Cutscene::play()
{
  this->onLoop();
  this->onRender();

  while(!frameMat.empty())
  {
    this->onLoop();
    this->onRender();
  }
}

void Cutscene::onLoop()
{
  video >> frameMat;

  convertCV_MatToSDL_Texture();
}

void Cutscene::onRender()
{
  Image::onDraw(GameEngine::getInstance()->getRenderer(), frameTexture);

}

void Cutscene::convertCV_MatToSDL_Texture()
{
  IplImage opencvimg2 = (IplImage)frameMat;
  IplImage* opencvimg = &opencvimg2;

  //Convert to SDL_Surface
  frameSurface = SDL_CreateRGBSurfaceFrom((void*)opencvimg->imageData,
                         opencvimg->width, opencvimg->height,
                         opencvimg->depth*opencvimg->nChannels,
                         opencvimg->widthStep,
                         0xff0000, 0x00ff00, 0x0000ff, 0);

  if(frameSurface == NULL)
  {
    SDL_Log("Couldn't convert Mat to Surface.");
    return;
  }

  //Convert to SDL_Texture
  frameTexture = SDL_CreateTextureFromSurface(
                    GameEngine::getInstance()->getRenderer(), frameSurface);
  if(frameTexture == NULL)
  {
    SDL_Log("Couldn't convert Mat(converted to surface) to Texture."); //<- ERROR!!
    return;
  }

  //cvReleaseImage(&opencvimg);
  //MEMORY LEAK?? opencvimg opencvimg2
}

我已在项目的其他部分使用此功能SDL_CreateTextureFromSurface，并且在那里工作。所以问题是：你知道我在代码中做的转换有什么问题吗？如果没有，是否有更好的方法来做我想做的事情？

Answer 1

我得到了它的工作！我认为唯一的问题是我必须使用＆amp; frameMat而不是frameMat。如果有人可能感兴趣，这是我的代码：

SDL_Texture* Cutscene::convertCV_MatToSDL_Texture(const cv::Mat &matImg)
{
    IplImage opencvimg2 = (IplImage)matImg;
    IplImage* opencvimg = &opencvimg2;

     //Convert to SDL_Surface
    frameSurface = SDL_CreateRGBSurfaceFrom(
                         (void*)opencvimg->imageData,
                         opencvimg->width, opencvimg->height,
                         opencvimg->depth*opencvimg->nChannels,
                         opencvimg->widthStep,
                         0xff0000, 0x00ff00, 0x0000ff, 0);

    if(frameSurface == NULL)
    {
        SDL_Log("Couldn't convert Mat to Surface.");
        return NULL;
    }

    //Convert to SDL_Texture
    frameTexture = SDL_CreateTextureFromSurface(
                    GameEngine::getInstance()->getRenderer(), frameSurface);
    if(frameTexture == NULL)
    {
        SDL_Log("Couldn't convert Mat(converted to surface) to Texture.");
        return NULL;
    }
    else
    {
        SDL_Log("SUCCESS conversion");
        return frameTexture;
    }

    cvReleaseImage(&opencvimg);

}

Answer 2

这是没有IplImage的另一种方式：

cv::Mat m ...;
// I'm using SDL_TEXTUREACCESS_STREAMING because it's for a video player, you should
// pick whatever suits you most: https://wiki.libsdl.org/SDL_TextureAccess
// remember to pick the right SDL_PIXELFORMAT_* !
SDL_Texture* tex = SDL_CreateTexture(
        ren, SDL_PIXELFORMAT_BGR24, SDL_TEXTUREACCESS_STREAMING, m.cols,
        m.rows);
SDL_UpdateTexture(tex, NULL, (void*)m.data, m.step1());

// do stuff with texture
SDL_RenderClear(...);
SDL_RenderCopy(...);
SDL_RenderPresent(...);
// cleanup (only after you're done displaying. you can repeatedly call UpdateTexture without destroying it)
SDL_DestroyTexture(tex)

与创建表面方法相比，我更喜欢这样做，因为您不需要释放表面并且它更灵活（例如，您可以轻松地更新纹理，而不是创建/销毁）。我还将注意到，我无法结合使用这些方法：即使用SDL_CreateRGBSurfaceFrom创建纹理，然后再对其进行更新。这导致了灰色条纹，图像被弄乱了。

将cv :: Mat转换为SDL_Texture

2 个答案: