windows mobile用sdl做視頻顯示(附sdl lib for mobile)

 使用的sdl庫及標頭檔已上傳至http://download.csdn.net/source/1775400

 

sdl是開源的跨平台多媒體開發包， 主要用在快速的視頻格式轉換和顯示，以及封裝了鍵盤/滑鼠/手機按鍵/觸屏等各個平台的使用者互動響應，廣泛應用在遊戲，多媒體播放器等應用中。目前支援windows,linux, wince,mac os,非正式地支援symbian os。

 

  一般視頻解碼器輸出映像的是yuv420格式，而螢幕顯示大都是rgb42規格。 mobile上畫面顯示一般經由decode>>yuv2rgb>>scale>>directDraw直接寫屏。 採用SDL可以加速這一過程，且更方便響應全屏縮放等使用者操作。

 

  下面介紹mobile上用sdl來加速顯示視頻的全過程。

 

  1. 把主對話方塊的視窗控制代碼傳給顯示類。

 

  2. 初始化sdl，設定顯示視頻模式

 

 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);//主視窗控制代碼
   SDL_putenv(sdl_var);

 

   char *myvalue = SDL_getenv("SDL_WINDOWID");

  

   atexit(SDL_Quit);

 

   //根據解碼後的視頻尺寸來初始化sdl

   screen = SDL_SetVideoMode(ImageWidth, ImageHeight, 0,SDL_ANYFORMAT|SDL_RESIZABLE|SDL_DOUBLEBUF|SDL_HWSURFACE);//注意用到的參數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. 在螢幕上繪製像素

 

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存放解碼後yuv資料的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);//顯示圖片到螢幕

}

 

  4. 事件輪詢和按鍵響應

 

void SdlEvent()
{

 SDL_Event event;

 while ( SDL_PollEvent(&event))
 {
  TRACE(L"========SDL VIDEORESIZE EVENT START");
  switch (event.type)
  {
  case SDL_VIDEORESIZE: 
   // 響應映像縮放事件

   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;               
   }

  case SDL_MOUSEBUTTONDOWN:

    //響應觸屏筆點擊事件
     break;
   } 
  case SDL_QUIT:
   //響應退出事件
   break;
  default:
   break;
  }
 }
}