C# 实现SDL2进行视频播放窗口截图和字幕添加-C/C++开发

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使用SDL2进行视频播放窗口截图和字幕添加操作

SDL API查看：https://wiki.libsdl.org/APIByCategory

视频截图

我就废话不多说了，大家还是直接看代码吧~


 /// <summary>
 /// SDL2截图操作类
 /// </summary>
 public unsafe class SDLScreenshot
 {
  IntPtr window;// 窗口对象
  IntPtr renderer;// 播放窗口的渲染器（来自于已初始化的播放窗口渲染器） 
  public SDLScreenshot(IntPtr window, IntPtr renderer)
  {
   this.window = window;
   this.renderer = renderer;
  } 
  /// <summary>
  /// 保存截图
  /// </summary>
  /// <param name="width"></param>
  /// <param name="height"></param>
  /// <param name="path"></param>
  public void SaveBMP(int width, int height,string path)
  {
   // 判断渲染器是否初始化
   if (renderer == IntPtr.Zero)
   {
    Console.WriteLine("renderer is null ,please call Init() method.");
    return;
   }
   uint Rmask=0x00FF0000, Gmask = 0x0000FF00, Bmask = 0x000000FF, Amask = 0x00000000;
   // 获取图像数据
   SDL.SDL_Surface* surface= (SDL.SDL_Surface*)SDL.SDL_CreateRGBSurface(0, width, height, 32, Rmask, Gmask, Bmask, Amask);
   //设置纹理的数据
   SDL.SDL_Rect destrect;
   destrect.x = 0;
   destrect.y = 0;
   destrect.w = width;
   destrect.h = height; 
 
   // 读取并渲染图像数据
   SDL.SDL_RenderReadPixels(renderer, ref destrect, SDL.SDL_PIXELFORMAT_ARGB8888, surface->pixels, surface->pitch); 
 
   //保存图片
   int i = SDL.SDL_SaveBMP((IntPtr)surface, path);
   if (i != 0)
   {
    Console.WriteLine("screenshot failed." + SDL.SDL_GetError());
   } 
 
   SDL.SDL_FreeSurface((IntPtr)surface);
   //SDL.SDL_RenderClear(renderer);
   //SDL.SDL_DestroyRenderer(renderer); 
  } 
 
  /// <summary>
  /// 加载截图
  /// </summary>
  /// <param name="width"></param>
  /// <param name="height"></param>
  /// <param name="path"></param>
  public void LoadBMP(int width, int height, string path)
  {
   // 判断渲染器是否初始化
   if (renderer == IntPtr.Zero)
   {
    Console.WriteLine("renderer is null ,please call Init() method.");
    return;
   }
   // 加载图片
   IntPtr surface = SDL.SDL_LoadBMP(path);
   if (surface == IntPtr.Zero)
   {
    Console.WriteLine("load bmp failed." + SDL.SDL_GetError());
    return;
   }
   IntPtr texture = SDL.SDL_CreateTextureFromSurface(renderer, surface);
   if (texture == IntPtr.Zero)
   {
    Console.WriteLine("create texture failed." + SDL.SDL_GetError());
    return;
   }
   SDL.SDL_FreeSurface(surface); 
 
   //设置纹理的数据
   SDL.SDL_Rect destrect;
   destrect.x = 0;
   destrect.y = 0;
   destrect.w = width;
   destrect.h = height; 
 
   SDL.SDL_Rect srcrect = destrect; 
 
   //SDL.SDL_RenderClear(renderer);
   SDL.SDL_RenderCopy(renderer, texture, ref srcrect, ref destrect);
   SDL.SDL_RenderPresent(renderer);
 
 
   //SDL.SDL_Delay(20); 
   SDL.SDL_DestroyTexture(texture);
   //SDL.SDL_DestroyRenderer(renderer);
   //SDL.SDL_DestroyWindow(screen);
   //Quit SDL 
   //SDL.SDL_Quit();
  }
 }

播放测试代码：


 if (isSaveScreenshot)
       {
        SDLScreenshot screenshot = new SDLScreenshot(sdlVideo.window, sdlVideo.sdlrenderer);
        screenshot.SaveBMP(nvVideoframe.VideoFrame->width, nvVideoframe.VideoFrame->height, "screenshot.bmp");
        isSaveScreenshot = false;
     }

测试效果图：

IiBzcmM9

注：此处截图是直接获取的播放窗口的图像像素来实现的。

视频字幕


 /// <summary>
 /// SDL2字幕显示类
 /// </summary>
 public unsafe class SDLTTF
 {
  IntPtr renderer;// 播放窗口的渲染器（来自于已初始化的播放窗口渲染器）
 
  public SDLTTF(IntPtr renderer)
	{
   this.renderer = renderer;
  }
 
  /// <summary>
  /// 展示字幕文字
  /// </summary>
  /// <param name="text"></param>
  public void ShowText(string ttfPath, int fontSize,string text)
  {
   // 初始化 ttf
   if (SDL_ttf.TTF_Init() < 0)
   {
    Console.WriteLine("SDL_ttf.TTF_Init() failed.");
    return;
   }
   // 是否初始化完成
   int was_init = SDL_ttf.TTF_WasInit();
 
   if (was_init == 1)
    // SDL_ttf was already initialized
    Console.WriteLine("SDL_ttf was already initialized");
   else if (was_init == 0)
    // SDL_ttf was not already initialized
    Console.WriteLine("SDL_ttf was not already initialized");
 
   // 判断是否初始化
   if (renderer == IntPtr.Zero)
   {
    Console.WriteLine("Not initialized by SDL_ttf.TTF_Init() ,please call Init() method.");
    return;
   }
 
   //如：打开ttfPath=simfang.ttf 字库，设字体为fontSize=20号
   IntPtr font = SDL_ttf.TTF_OpenFont(ttfPath, fontSize);
   if (font == IntPtr.Zero)
   {
    Console.WriteLine("open font failed." + SDL.SDL_GetError());
    return;
   }
 
   // 设置文字颜色
   SDL.SDL_Color color;
   color.a = 255;
   color.r = 255;
   color.g = 255;
   color.b = 255;
 
   // 渲染文字效果
   //IntPtr surface = SDL_ttf.TTF_RenderUTF8_Blended(font, text, color);
   IntPtr surface = SDL_ttf.TTF_RenderUNICODE_Blended(font, text, color);
   if (surface == IntPtr.Zero)
   {
    Console.WriteLine("show surface failed." + SDL.SDL_GetError());
   }
   IntPtr texture = SDL.SDL_CreateTextureFromSurface(renderer, surface);
   if (texture == IntPtr.Zero)
   {
    Console.WriteLine("create texture failed." + SDL.SDL_GetError());
   }
   SDL.SDL_FreeSurface(surface);
   // 关闭字体
   SDL_ttf.TTF_CloseFont(font);
 
   // 停止显示
   SDL_ttf.TTF_Quit();
 
   //设置纹理的数据
   SDL.SDL_Rect destrect;
   destrect.x = 0;
   destrect.y = 0;
   destrect.w = text.Length * 20;
   destrect.h = 20;
 
   SDL.SDL_Rect srcrect = destrect; 
   SDL.SDL_RenderClear(renderer);
   SDL.SDL_RenderCopy(renderer, texture, ref srcrect, ref destrect);
   SDL.SDL_RenderPresent(renderer);
   SDL.SDL_DestroyTexture(texture);
   SDL.SDL_DestroyRenderer(renderer);
  }
 }

事件测试字幕添加：

需要的引用库下载：https://www.libsdl.org/projects/SDL_ttf/


 /// <summary>
  /// 字幕叠加****需要添加三个dll库：SDL2_ttf.dll 、libfreetype-6.dll 、zlib1.dll
  /// </summary>
  /// <param name="sender"></param>
  /// <param name="e"></param>
  private void mbtnAddFontText_Click(object sender, EventArgs e)
  {
   Console.WriteLine("叠加字幕...............");
 
   sdlTTF = new SDLTTF(sdlVideo.sdlrenderer);
   // 中英文都需要兼容
   string text = "Hello 世界!";
   // 设置一个字体库并设置字体大小和显示文字内容
   sdlTTF.ShowText("simkai.ttf",12, text);
  }

测试效果图：

IiBzcmM9

如果是播放过程中显示字幕一定要在视频渲染完成后渲染字幕，如下面工具类的方法：


/// <summary>
  /// 播放视频
  /// </summary>
  /// <param name="width"></param>
  /// <param name="height"></param>
  /// <param name="pixels"></param>
  /// <param name="pixelsSize"></param>
  /// <param name="pitch"></param>
  /// <returns></returns>
  public int SDL_Display(int width, int height, IntPtr pixels, int pixelsSize,
   int pitch)
  {
   lock (this)
   {
    while (isPause)
    {
     SDL.SDL_Delay(20);//延迟播放
    }
 
    #region SDL 视频数据渲染播放
    //设置纹理的数据
    sdlrect.x = 0;
    sdlrect.y = 0;
    sdlrect.w = width;
    sdlrect.h = height;
    SDL.SDL_UpdateTexture(sdltexture, ref sdlrect, pixels, pitch);
    //SDL.SDL_UpdateTexture(sdltexture, IntPtr.Zero, pixels, pitch);//此处代码导致播放窗口绿色阴影
    //复制纹理信息到渲染器目标
    SDL.SDL_RenderClear(sdltexture);
    //SDL.SDL_Rect srcRect = sdlrect;
    //SDL.SDL_RenderCopy(sdlrenderer, sdltexture, ref srcRect, ref sdlrect);
 
    SDL.SDL_RenderCopy(sdlrenderer, sdltexture, IntPtr.Zero, IntPtr.Zero);
    //字幕渲染显示-特别提醒：此处必须放置于视频渲染之后，否则字幕不会显示
    if (ttfText!=null&&!ttfText.Equals(""))
    {
     RenderToShowTTF(ttfText);
    }
    //else
    //{
    // RenderToShowTTF( "未设置字幕内容");
    /