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

使用的sdl库及头文件已上传至http://download.csdn.net/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 VIDEORESIZE EVENT START");
  switch (event.type)
  {
  case SDL_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;
   }

  case SDL_MOUSEBUTTONDOWN:

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

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

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