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C# 使用SDL2进行视频播放窗口截图和字幕添加

发布2018-03-06浏览4880次

详情内容

使用SDL2进行视频播放窗口截图和字幕添加

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

视频截图

  1.    
  2.  
  3.  
  4.     /// <summary>
  5.     /// SDL2截图操作类
  6.     /// </summary>
  7.     public unsafe class SDLScreenshot
  8.     {
  9.         IntPtr window;// 窗口对象
  10.         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）
  11.  
  12.  
  13.         public SDLScreenshot(IntPtr window, IntPtr renderer)
  14.         {
  15.             this.window = window;
  16.             this.renderer = renderer;
  17.         }
  18.  
  19.  
  20.         /// <summary>
  21.         /// 保存截图
  22.         /// </summary>
  23.         /// <param name="width"></param>
  24.         /// <param name="height"></param>
  25.         /// <param name="path"></param>
  26.         public void SaveBMP(int width, int height,string path)
  27.         {
  28.             // 判断渲染器是否初始化
  29.             if (renderer == IntPtr.Zero)
  30.             {
  31.                 Console.WriteLine("renderer is null ,please call Init() method.");
  32.                 return;
  33.             }
  34.             uint Rmask=0x00FF0000, Gmask = 0x0000FF00, Bmask = 0x000000FF, Amask = 0x00000000;
  35.             // 获取图像数据
  36.             SDL.SDL_Surface* surface= (SDL.SDL_Surface*)SDL.SDL_CreateRGBSurface(0, width, height, 32, Rmask, Gmask, Bmask, Amask);
  37.             //设置纹理的数据
  38.             SDL.SDL_Rect destrect;
  39.             destrect.x = 0;
  40.             destrect.y = 0;
  41.             destrect.w = width;
  42.             destrect.h = height;
  43.  
  44.  
  45.             // 读取并渲染图像数据
  46.             SDL.SDL_RenderReadPixels(renderer, ref destrect, SDL.SDL_PIXELFORMAT_ARGB8888, surface->pixels, surface->pitch);
  47.  
  48.  
  49.             //保存图片
  50.             int i = SDL.SDL_SaveBMP((IntPtr)surface, path);
  51.             if (i != 0)
  52.             {
  53.                 Console.WriteLine("screenshot failed." + SDL.SDL_GetError());
  54.             }
  55.  
  56.  
  57.             SDL.SDL_FreeSurface((IntPtr)surface);
  58.             //SDL.SDL_RenderClear(renderer);
  59.             //SDL.SDL_DestroyRenderer(renderer);
  60.  
  61.  
  62.         }
  63.  
  64.  
  65.         /// <summary>
  66.         /// 加载截图
  67.         /// </summary>
  68.         /// <param name="width"></param>
  69.         /// <param name="height"></param>
  70.         /// <param name="path"></param>
  71.         public void LoadBMP(int width, int height, string path)
  72.         {
  73.             // 判断渲染器是否初始化
  74.             if (renderer == IntPtr.Zero)
  75.             {
  76.                 Console.WriteLine("renderer is null ,please call Init() method.");
  77.                 return;
  78.             }
  79.             // 加载图片
  80.             IntPtr surface = SDL.SDL_LoadBMP(path);
  81.             if (surface == IntPtr.Zero)
  82.             {
  83.                 Console.WriteLine("load bmp failed." + SDL.SDL_GetError());
  84.                 return;
  85.             }
  86.             IntPtr texture = SDL.SDL_CreateTextureFromSurface(renderer, surface);
  87.             if (texture == IntPtr.Zero)
  88.             {
  89.                 Console.WriteLine("create texture failed." + SDL.SDL_GetError());
  90.                 return;
  91.             }
  92.             SDL.SDL_FreeSurface(surface);
  93.  
  94.  
  95.             //设置纹理的数据
  96.             SDL.SDL_Rect destrect;
  97.             destrect.x = 0;
  98.             destrect.y = 0;
  99.             destrect.w = width;
  100.             destrect.h = height;
  101.  
  102.  
  103.             SDL.SDL_Rect srcrect = destrect;
  104.  
  105.  
  106.             //SDL.SDL_RenderClear(renderer);
  107.             SDL.SDL_RenderCopy(renderer, texture, ref srcrect, ref destrect);
  108.             SDL.SDL_RenderPresent(renderer);
  109.  
  110.  
  111.             //SDL.SDL_Delay(20);
  112.  
  113.  
  114.             SDL.SDL_DestroyTexture(texture);
  115.             //SDL.SDL_DestroyRenderer(renderer);
  116.             //SDL.SDL_DestroyWindow(screen);
  117.             //Quit SDL    
  118.             //SDL.SDL_Quit();
  119.         }
  120.     }

播放测试代码：

  1.    if (isSaveScreenshot)
  2.                             {
  3.                                 SDLScreenshot screenshot = new SDLScreenshot(sdlVideo.window, sdlVideo.sdlrenderer);
  4.                                 screenshot.SaveBMP(nvVideoframe.VideoFrame->width, nvVideoframe.VideoFrame->height, "screenshot.bmp");
  5.                                 isSaveScreenshot = false;
  6.                  }

测试效果图：


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

  1.  /// <summary>
  2.     /// SDL2字幕显示类
  3.     /// </summary>
  4.     public unsafe class SDLTTF
  5.     {
  6.         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）
  7.  
  8.         public SDLTTF(IntPtr renderer)
  9.         {
  10.             this.renderer = renderer;
  11.         }
  12.  
  13.         /// <summary>
  14.         /// 展示字幕文字
  15.         /// </summary>
  16.         /// <param name="text"></param>
  17.         public void ShowText(string ttfPath, int fontSize,string text)
  18.         {
  19.             // 初始化 ttf
  20.             if (SDL_ttf.TTF_Init() < 0)
  21.             {
  22.                 Console.WriteLine("SDL_ttf.TTF_Init() failed.");
  23.                 return;
  24.             }
  25.             // 是否初始化完成
  26.             int was_init = SDL_ttf.TTF_WasInit();
  27.  
  28.             if (was_init == 1)
  29.                 // SDL_ttf was already initialized
  30.                 Console.WriteLine("SDL_ttf was already initialized");
  31.             else if (was_init == 0)
  32.                 // SDL_ttf was not already initialized
  33.                 Console.WriteLine("SDL_ttf was not already initialized");
  34.  
  35.             // 判断是否初始化
  36.             if (renderer == IntPtr.Zero)
  37.             {
  38.                 Console.WriteLine("Not initialized by  SDL_ttf.TTF_Init() ,please call Init() method.");
  39.                 return;
  40.             }
  41.  
  42.             //如：打开ttfPath=simfang.ttf 字库，设字体为fontSize=20号
  43.             IntPtr font = SDL_ttf.TTF_OpenFont(ttfPath, fontSize);
  44.             if (font == IntPtr.Zero)
  45.             {
  46.                 Console.WriteLine("open font failed." + SDL.SDL_GetError());
  47.                 return;
  48.             }
  49.  
  50.             // 设置文字颜色
  51.             SDL.SDL_Color color;
  52.             color.a = 255;
  53.             color.r = 255;
  54.             color.g = 255;
  55.             color.b = 255;
  56.  
  57.             // 渲染文字效果
  58.             //IntPtr surface = SDL_ttf.TTF_RenderUTF8_Blended(font, text, color);
  59.             IntPtr surface = SDL_ttf.TTF_RenderUNICODE_Blended(font, text, color);
  60.             if (surface == IntPtr.Zero)
  61.             {
  62.                 Console.WriteLine("show surface failed." + SDL.SDL_GetError());
  63.             }
  64.             IntPtr texture = SDL.SDL_CreateTextureFromSurface(renderer, surface);
  65.             if (texture == IntPtr.Zero)
  66.             {
  67.                 Console.WriteLine("create texture failed." + SDL.SDL_GetError());
  68.             }
  69.             SDL.SDL_FreeSurface(surface);
  70.             // 关闭字体
  71.             SDL_ttf.TTF_CloseFont(font);
  72.  
  73.             // 停止显示
  74.             SDL_ttf.TTF_Quit();
  75.  
  76.             //设置纹理的数据
  77.             SDL.SDL_Rect destrect;
  78.             destrect.x = 0;
  79.             destrect.y = 0;
  80.             destrect.w = text.Length * 20;
  81.             destrect.h = 20;
  82.  
  83.             SDL.SDL_Rect srcrect = destrect;
  84.  
  85.             SDL.SDL_RenderClear(renderer);
  86.             SDL.SDL_RenderCopy(renderer, texture, ref srcrect, ref destrect);
  87.             SDL.SDL_RenderPresent(renderer);
  88.             SDL.SDL_DestroyTexture(texture);
  89.             SDL.SDL_DestroyRenderer(renderer);
  90.         }
  91.     }

事件测试字幕添加：

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

  1.   /// <summary>
  2.         /// 字幕叠加****需要添加三个dll库：SDL2_ttf.dll 、libfreetype-6.dll 、zlib1.dll
  3.         /// </summary>
  4.         /// <param name="sender"></param>
  5.         /// <param name="e"></param>
  6.         private void mbtnAddFontText_Click(object sender, EventArgs e)
  7.         {
  8.             Console.WriteLine("叠加字幕...............");
  9.  
  10.             sdlTTF = new SDLTTF(sdlVideo.sdlrenderer);
  11.             // 中英文都需要兼容
  12.             string text = "Hello 世界!";
  13.             // 设置一个字体库并设置字体大小和显示文字内容
  14.             sdlTTF.ShowText("simkai.ttf",12, text);
  15.         }

测试效果图：


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：

  1. /// <summary>
  2.         /// 播放视频
  3.         /// </summary>
  4.         /// <param name="width"></param>
  5.         /// <param name="height"></param>
  6.         /// <param name="pixels"></param>
  7.         /// <param name="pixelsSize"></param>
  8.         /// <param name="pitch"></param>
  9.         /// <returns></returns>
  10.         public int SDL_Display(int width, int height, IntPtr pixels, int pixelsSize,
  11.             int pitch)
  12.         {
  13.             lock (this)
  14.             {
  15.                 while (isPause)
  16.                 {
  17.                     SDL.SDL_Delay(20);//延迟播放
  18.                 }
  19.  
  20.                 #region SDL 视频数据渲染播放
  21.                 //设置纹理的数据
  22.                 sdlrect.x = 0;
  23.                 sdlrect.y = 0;
  24.                 sdlrect.w = width;
  25.                 sdlrect.h = height;
  26.                 SDL.SDL_UpdateTexture(sdltexture, ref sdlrect, pixels, pitch);
  27.                 //SDL.SDL_UpdateTexture(sdltexture, IntPtr.Zero, pixels, pitch);//此处代码导致播放窗口绿色阴影
  28.                 //复制纹理信息到渲染器目标
  29.                 SDL.SDL_RenderClear(sdltexture);
  30.                 //SDL.SDL_Rect srcRect = sdlrect;
  31.                 //SDL.SDL_RenderCopy(sdlrenderer, sdltexture, ref srcRect, ref sdlrect);
  32.  
  33.                 SDL.SDL_RenderCopy(sdlrenderer, sdltexture, IntPtr.Zero, IntPtr.Zero);
  34.                 //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
  35.                 if (ttfText!=null&&!ttfText.Equals(""))
  36.                 {
  37.                     RenderToShowTTF(ttfText);
  38.                 }
  39.                 //else
  40.                 //{
  41.                 //    RenderToShowTTF( "未设置字幕内容");
  42.                 //}
  43.                 //视频渲染显示
  44.                 SDL.SDL_RenderPresent(sdlrenderer);
  45.                 //SDL.SDL_Delay(40);
  46.                 //SDL.SDL_PollEvent(out sdlevent);
  47.                 //switch (sdlevent.type)
  48.                 //{
  49.                 //    case SDL.SDL_EventType.SDL_QUIT:
  50.                 //        SDL.SDL_Quit();
  51.                 //        return -1;
  52.                 //    default:
  53.                 //        break;
  54.                 //}
  55.                 return 0;
  56.             }
  57.  
  58.  
  59.             //SDL.SDL_RenderClear(sdlrenderer);
  60.             //SDL.SDL_RenderCopy(sdlrenderer, sdltexture, ref srcRect, ref sdlrect);
  61.             //SDL.SDL_RenderPresent(sdlrenderer);
  62.             Delay 40ms  
  63.             //SDL.SDL_Delay(40);
  64.             #endregion
  65.  
  66.  
  67.             //#region SDL 视频数据渲染播放
  68.             //设置纹理的数据
  69.             sdlrect.x = 0;
  70.             sdlrect.y = 0;
  71.             sdlrect.w = width;
  72.             sdlrect.h = height;
  73.             SDL.SDL_UpdateTexture(sdltexture, ref sdlrect, pixels, pitch);
  74.             //复制纹理信息到渲染器目标
  75.             SDL.SDL_Rect srcRect = sdlrect;
  76.             SDL.SDL_RenderCopy(sdlrenderer, sdltexture, ref srcRect, ref sdlrect);
  77.             //视频渲染显示
  78.             SDL.SDL_RenderPresent(sdlrenderer);
  79.             //SDL.SDL_Delay(40);
  80.             SDL.SDL_PollEvent(out sdlevent);
  81.             switch (sdlevent.type)
  82.             {
  83.                 case SDL.SDL_EventType.SDL_QUIT:
  84.                     SDL.SDL_Quit();
  85.                     return -1;
  86.                 default:
  87.                     break;
  88.             }
  89.             return 0;
  90.             //#endregion
  91.         }
  92.  
  93.         /// <summary>
  94.         ///  设置字幕显示内容
  95.         /// </summary>
  96.         /// <param name="ttfPath"></param>
  97.         /// <param name="fontSize"></param>
  98.         public void SDL_TTF_TEXT(string ttfPath, string text, int fontSize)
  99.         {
  100.             this.ttfPath = ttfPath;
  101.             this.ttfText = text;
  102.             this.ttfFontSize = fontSize;
  103.         }
  104.  
  105.         /// <summary>
  106.         /// 渲染字幕
  107.         /// </summary>
  108.         /// <param name="text"></param>
  109.         private void RenderToShowTTF(string text)
  110.         {
  111.             // 初始化 ttf
  112.             if (SDL_ttf.TTF_Init() < 0)
  113.             {
  114.                 Console.WriteLine("SDL_ttf.TTF_Init() failed.");
  115.                 return;
  116.             }
  117.             // 是否初始化完成
  118.             int was_init = SDL_ttf.TTF_WasInit();
  119.  
  120.             if (was_init == 1)
  121.                 // SDL_ttf was already initialized
  122.                 Console.WriteLine("SDL_ttf was already initialized");
  123.             else if (was_init == 0)
  124.                 // SDL_ttf was not already initialized
  125.                 Console.WriteLine("SDL_ttf was not already initialized");
  126.  
  127.             //如：打开ttfPath=simfang.ttf 字库，设字体为fontSize=20号
  128.             IntPtr font = SDL_ttf.TTF_OpenFont(ttfPath, ttfFontSize);
  129.             if (font == IntPtr.Zero)
  130.             {
  131.                 Console.WriteLine("open font failed." + SDL.SDL_GetError());
  132.                 return;
  133.             }
  134.  
  135.             // 设置文字字体
  136.             SDL_ttf.TTF_SetFontStyle(font, SDL_ttf.TTF_STYLE_BOLD);
  137.  
  138.             // 设置文字颜色
  139.             SDL.SDL_Color color;
  140.             color.a = 255;
  141.             color.r = 255;
  142.             color.g = 255;
  143.             color.b = 255;
  144.  
  145.             // 渲染文字效果
  146.             //IntPtr surface = SDL_ttf.TTF_RenderText_Blended(font, text, color);
  147.             IntPtr surface = SDL_ttf.TTF_RenderUTF8_Blended(font, text, color);
  148.             //IntPtr surface = SDL_ttf.TTF_RenderUNICODE_Blended(font, text, color);
  149.             if (surface == IntPtr.Zero)
  150.             {
  151.                 Console.WriteLine("show surface failed." + SDL.SDL_GetError());
  152.             }
  153.             IntPtr texture = SDL.SDL_CreateTextureFromSurface(sdlrenderer, surface);
  154.             if (texture == IntPtr.Zero)
  155.             {
  156.                 Console.WriteLine("create texture failed." + SDL.SDL_GetError());
  157.             }
  158.  
  159.             SDL.SDL_FreeSurface(surface);
  160.             // 关闭字体
  161.             SDL_ttf.TTF_CloseFont(font);
  162.  
  163.             // 停止显示
  164.             SDL_ttf.TTF_Quit();
  165.  
  166.             // 计算合适的宽度和高度
  167.             int texWidth = 0;
  168.             int texHeight = 0;
  169.             uint format = 0;
  170.             int access = 0;
  171.             // 下面这行代码解决字体虚浮不清问题
  172.             SDL.SDL_QueryTexture(texture, out format, out access, out texWidth, out texHeight);
  173.             //设置纹理的数据
  174.             SDL.SDL_Rect destrect;
  175.             destrect.x = 0;
  176.             destrect.y = 0;
  177.             destrect.w = texWidth;
  178.             destrect.h = texHeight;
  179.  
  180.             SDL.SDL_Rect srcrect = destrect;
  181.             SDL.SDL_RenderCopy(sdlrenderer, texture, ref srcrect, ref destrect);
  182.         }

效果就会好很多：

，请看这里的“中华人民共和国”

注意：常用中英文ttf字体包中包含了：times new roman，中山行书百年纪念版，calibri，Christopherhand，DejaVuSansMono，方正兰亭黑，James Fajardo，Monaco，微软雅黑，仿宋，黑体，楷体，宋体，yahei_mono，仿宋_GB2312，楷体_GB2312，迷你简行楷碑等。本文使用的是simkai.ttf。下面是部分字体文件名：

bb1550.ttf
calibri.ttf
calibrib.ttf
calibrii.ttf
calibriz.ttf
comesinhandy.ttf
DejaVuSansMono-Bold.ttf
DejaVuSansMono-BoldOblique.ttf
DejaVuSansMono-Oblique.ttf
DejaVuSansMono.ttf
DroidSansFallback.ttf
James_Fajardo.ttf
Monaco.ttf
msyh.ttf
msyhbd.ttf
simfang.ttf
simhei.ttf
simkai.ttf
simsun.ttc
times.ttf
timesbd.ttf
timesbi.ttf
timesi.ttf
yahei_mono.ttf

如果懒得下载，Windows里面有字体，在C:\Windows\Fonts目录下。

参考资料

sdl2.0 如何才能实现截图功能：http://tieba.baidu.com/p/5214857530

True type fonts with SDL_ttf  : http://www.willusher.io/sdl2%20tutorialshttps://cdn.jxasp.com:9143/image/2013/12/18/lesson-6-true-type-fonts-with-sdl_ttf

SDL TTF:    http://www.sdltutorials.com/sdl-ttf

SDL 使用SDL_ttf显示文字: http://blog.csdn.net/rankun1/article/details/51393732

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