windows mobile用sdl做视频显示(附sdl lib for mobile)(转)

http://blog.youkuaiyun.com/lius1984/article/details/4420786?

使用的sdl库及头文件已上传至 http://download.youkuaiyun.com/source/1775400

sdl是开源的跨平台多媒体开发包，主要用在快速的视频格式转换和显示，以及封装了键盘/鼠标/手机按键/触屏等各个平台的用户交互响应，广泛应用在游戏，多媒体播放器等应用中。目前支持windows,linux, wince,mac os,非正式地支持symbian os。

  一般视频解码器输出图像的是yuv420格式，而屏幕显示大都是rgb42规格。mobile上画面显示一般经由decode>>yuv2rgb>>scale>>directDraw直接写屏。采用SDL可以加速这一过程，且更方便响应全屏缩放等用户操作。

  下面介绍mobile上用sdl来加速显示视频的全过程。

 

  1. 把主对话框的窗口句柄传给显示类。

  2. 初始化sdl，设置显示视频模式

 SDL_Surface    *screen;
 SDL_Rect       sdl_rect;
 SDL_Overlay    *bmp;

bool InitSdl()

{

   char sdl_var[64]; 
   sprintf(sdl_var,"SDL_WINDOWID=0x%lx", m_hWnd);//主窗口句柄
  SDL_putenv(sdl_var);

   char *myvalue =SDL_getenv("SDL_WINDOWID");

   atexit(SDL_Quit);

   //根据解码后的视频尺寸来初始化sdl

   screen =SDL_SetVideoMode(ImageWidth, ImageHeight, 0,SDL_ANYFORMAT|SDL_RESIZABLE|SDL_DOUBLEBUF|SDL_HWSURFACE);//注意用到的参数flags
 if(!screen)
 {
     TRACE(L"error SDL SetVideoMode!");
     return false;
 }

 bmp = SDL_CreateYUVOverlay(ImageWidth,ImageHeight, ,SDL_YV12_OVERLAY,screen);
 if(!bmp)
 { 
     TRACE(L"error SDL CreateYUVOverlay!");
     return false; 
 }

 return TRUE;

}

  3. 在屏幕上绘制像素

void SdlDisplayFrame()
{
 AVPicture pict;

 pict.data[0] = bmp->pixels[0];
 pict.data[1] = bmp->pixels[2];
 pict.data[2] = bmp->pixels[1];

 pict.linesize[0] = bmp->pitches[0];
 pict.linesize[1] = bmp->pitches[2];
 pict.linesize[2] = bmp->pitches[1];

 //pFrame是ffmpeg存放解码后yuv数据的struct

 img_convert(&pict, PIX_FMT_YUV420P,(AVPicture *)pFrame,pContext->pix_fmt, iImage_Width, iImage_Height);

 SDL_LockSurface(screen);                 
 SDL_LockYUVOverlay(bmp);
 {
  sdl_rect.x = 0;
  sdl_rect.y = 0;
  sdl_rect.w =m_width;  //pContext->width;
  sdl_rect.h =m_height;  //pContext->height;

 }

 SDL_UnlockYUVOverlay(bmp);                     
 SDL_UnlockSurface(screen);               

 SDL_DisplayYUVOverlay(bmp,&sdl_rect);//显示图片到屏幕
}

  4. 事件轮询和按键响应

void SdlEvent()
{

 SDL_Event event;

 while ( SDL_PollEvent(&event))
 {
  TRACE(L"========SDL VIDEORESIZEEVENT START");
  switch (event.type)
  {
  caseSDL_VIDEORESIZE: 
   // 响应图像缩放事件

   if(m_iImage_Width == Image_Primary_Width && m_iImage_Height == Image_Primary_Height)
   {
    TRACE(L"event.resize.w= %d",event.resize.w);
    TRACE(L"event.resize.h= %d",event.resize.h);
    m_width=event.resize.w;        
    m_height= event.resize.h;

    SDL_FreeYUVOverlay(bmp);
    bmp= NULL;
    SDL_FreeSurface(screen);
    screen= NULL;

    if(!IsQcif)
    {
     m_height=  m_height * 2;
     m_width= m_width * 2;
     screen=SDL_SetVideoMode(MobileFullScreenWidth,MobileFullScreenHeight,
      0,SDL_ANYFORMAT|SDL_RESIZABLE|SDL_DOUBLEBUF|SDL_HWSURFACE);
       if(screen == NULL)
     {
      TRACE(L"screen=NULL");
      return;
     }

     bmp=SDL_CreateYUVOverlay(MobileFullScreenWidth,MobileFullScreenHeight,
      SDL_YV12_OVERLAY,screen);
     if(bmp == NULL)
     {
      TRACE(L"bm1= NULL");
      return;
     }
     IsQcif= true;
    }
    else
    {
     screen= SDL_SetVideoMode(Image_Primary_Width,Image_Primary_Height,
      0,SDL_ANYFORMAT|SDL_RESIZABLE|SDL_DOUBLEBUF|SDL_HWSURFACE);
     if(screen == NULL)
     {
      TRACE(L"screen1=NULL");
      return;
     }

     bmp=SDL_CreateYUVOverlay(Image_Primary_Width,Image_Primary_Height,
      SDL_YV12_OVERLAY,screen);
     if(bmp == NULL)
     {
      TRACE(L"bm1= NULL");
      return;
     }

     IsQcif= false;
    }

    break;               
   }

  caseSDL_MOUSEBUTTONDOWN:

   //响应触屏笔点击事件
     break;
   } 
  case SDL_QUIT:
   //响应退出事件
   break;
  default:
   break;
  }
 }
}