Telechips 8902 & WinCE6.0 平台下 overlay 使用冲突现象的分析

最近在分析播放视频(mkv 格式)引起显示异常的问题。
平台为： WinCE6.0；CPU 为 Telechips8902.
发现在主菜单/设置/多媒体类型选择等界面会出现问题；但在导航界面不会出现问题。所以分析问题的原因与主菜单等界面的显示方式有关，查看代码发现主菜单等界面使用 overlay 显示。
由于视频显示也采用 overlay 方式(怀疑 mkv 格式视频的显示比其它格式显示多使用一层 overlay 表面)，可能是因为 overlay 表面使用冲突引起主菜单等显示异常的问题。需要分析视频显示的实现过程与 UI 的实现过程来确认是否是此原因？
UI 代码中 overlay 的实现是通过 IOCtrl 来实现的，没有通过系统标准的 overlay 访问接口。

Telechips 8902 共 2 层 overlay surface，视频播放使用一层（YUV）；UI 的显示采用 IOCtrl 直接通过 OS 写屏操作，经测试发现使用一层 overlay(RGB) surface；此时如果视频播放的视频文件格式需要需要通过 overlay 显示 SUB-TITLE 时，与 UI 显示使用的 overlay 表面资源冲突。这样导致了如上问题的产生。

为了排除 UI 实现对上述结果的影响，采用 DirectDraw 示例工程 mosquito 与视频一起运行，看是否可以重现上述问题：
先运行 mosquito，界面出现蚊子飞的动画效果。此时，再运行 Telechips 的示例工程 TCMovieManager。先选择一首没有字幕的视频播放，发现视频与  mosquito 的效果（蚊子飞的动画）同时存在。此时将视频切换到带有字幕的视频，开始视频播放后，发现 mosquito 的效果（蚊子飞的动画）消失。这样就重现了 UI 界面与视频冲突的现象！

此问题，单独从应用层来分析比较难解决。
个人建议的方法：
(1)从 OS 入手，修改视频播放时对字幕（SUB-TITLE）的处理，字幕（SUB-TITLE）要不不显示、要不显示在视频 overlay 层上；
(2)考虑不再实现视频后台播放的功能。

附部分 mosquito 的源代码，主要包括 overlay 层格式与初始化：

/* 
 * Telechips 8902 支持 2 层 overlay 
 * 只能创建一层 YUYV 的 overlay (可以再创建一层 RGB overlay) 
 * RGB 模式可以创建多个，模式与顺序没有不影响创建 
*/  
static DDPIXELFORMAT ddpfOverlayFormats[] = {  
    //{sizeof(DDPIXELFORMAT), DDPF_FOURCC, MAKEFOURCC('Y','U','Y','V'),0,0,0,0,0},  // YUYV - Leo.Zheng Telechips 8902 可以支持  
    //{sizeof(DDPIXELFORMAT), DDPF_FOURCC, MAKEFOURCC('U','Y','V','Y'),0,0,0,0,0},  // UYVY - Leo.Zheng Telechips 8902:Create No.1 surface return: 0x88760218  
    // {sizeof(DDPIXELFORMAT), DDPF_RGB, 0, 16,  0x7C00, 0x03e0, 0x001F, 0},        // 16-bit RGB 5:5:5  
    {sizeof(DDPIXELFORMAT), DDPF_RGB, 0, 16,  0xF800, 0x07e0, 0x001F, 0},        // 16-bit RGB 5:6:5  
};  
  
#define PF_TABLE_SIZE (sizeof(ddpfOverlayFormats) / sizeof(ddpfOverlayFormats[0]))  
  
  
  
//-----------------------------------------------------------------------------  
// Name: InitApp()  
// Desc: Do work required for every instance of the application:  
//          Create the window, initialize data  
//-----------------------------------------------------------------------------  
static HRESULT InitApp(HINSTANCE hInstance, int nCmdShow)  
{  
    HWND                        hWnd;  
    WNDCLASS                    wc;  
    DDSURFACEDESC               ddsd;  
    DDCAPS                      ddcaps;  
    HRESULT                     hRet;  
    DWORD                       dwUpdateFlags = 0;  
    DDOVERLAYFX                 ovfx;  
    DEVMODE                     DevMode;  
  
    // Check for rotation support by getting the rotation angles supported.  
    memset(&DevMode, 0, sizeof(DevMode));  
    DevMode.dmSize = sizeof(DevMode);  
    DevMode.dmFields = DM_DISPLAYQUERYORIENTATION;  
    if(DISP_CHANGE_SUCCESSFUL == ChangeDisplaySettingsEx(NULL, &DevMode, NULL, CDS_TEST, NULL))  
    {  
        g_RotationAngles = DevMode.dmDisplayOrientation;  
    }  
    else  
    {  
        OutputDebugString(L"MOSQUITO: Device does not support any rotation modes. Rotation disabled.");  
        g_RotationAngles = -1;  
    }  
  
    // Get the current rotation angle.  
    memset(&DevMode, 0, sizeof (DevMode));  
    DevMode.dmSize = sizeof (DevMode);  
    DevMode.dmFields = DM_DISPLAYORIENTATION;  
    if (DISP_CHANGE_SUCCESSFUL == ChangeDisplaySettingsEx(NULL, &DevMode, NULL, CDS_TEST, NULL))  
    {  
        g_CurrentAngle = DevMode.dmDisplayOrientation;  
    }  
    else  
    {  
        OutputDebugString(L"MOSQUITO: Unable to read current rotation. Rotation disabled.");  
        g_CurrentAngle = -1;  
    }  
  
    // Set up and register window class.  
    ......  
  
    // Create the main DirectDraw object  
    hRet = DirectDrawCreate(NULL, &g_pDD, NULL);  
    if(hRet != DD_OK)  
        return InitFail(hWnd, hRet, TEXT("DirectDrawCreate FAILED"));  
  
    // Get normal mode.  
    hRet = g_pDD->SetCooperativeLevel(hWnd, DDSCL_NORMAL);  
    if (hRet != DD_OK)  
        return InitFail(hWnd, hRet, TEXT("SetCooperativeLevel FAILED"));  
  
    // Get a primary surface interface pointer (only needed for init.)  
    memset(&ddsd, 0, sizeof(ddsd));  
    ddsd.dwSize = sizeof(ddsd);  
    ddsd.dwFlags = DDSD_CAPS;  
    ddsd.ddsCaps.dwCaps = DDSCAPS_PRIMARYSURFACE;  
    hRet = g_pDD->CreateSurface(&ddsd, &g_pDDSPrimary, NULL);  
    if (hRet != DD_OK)  
        return InitFail(hWnd, hRet, TEXT("CreateSurface FAILED"));  
  
    // See if we can support overlays.  
    memset(&ddcaps, 0, sizeof(ddcaps));  
    ddcaps.dwSize = sizeof(ddcaps);  
    hRet = g_pDD->GetCaps(&ddcaps, NULL);  
    if (hRet != DD_OK)  
        return InitFail(hWnd, hRet, TEXT("GetCaps FAILED"));  
  
    if (ddcaps.dwOverlayCaps == 0)  
        return InitFail(hWnd, hRet, TEXT("Overlays are not supported in hardware!"));  
    /* // Leo.Zheng Add 
    if(!(capsDrv.dwCaps & DDCAPS_OVERLAY)) 
        return FALSE; 
    */  
  
    // Get alignment info to compute our overlay surface size.  
    rs.left = 0;  
    rs.top = 0;  
    rs.right = BUG_WIDTH;  
    rs.bottom = BUG_HEIGHT;  
    if (ddcaps.dwAlignSizeSrc != 0)  
        rs.right += rs.right % ddcaps.dwAlignSizeSrc;  
      
    // Create the overlay flipping surface. We will attempt the pixel formats  
    // in our table one at a time until we find one that jives.  
    int i = 0;  
    memset(&ddsd, 0, sizeof(ddsd));  
    ddsd.dwSize = sizeof(ddsd);  
    ddsd.ddsCaps.dwCaps = DDSCAPS_OVERLAY | DDSCAPS_FLIP;  
    ddsd.dwFlags = DDSD_CAPS | DDSD_HEIGHT | DDSD_WIDTH | DDSD_BACKBUFFERCOUNT | DDSD_PIXELFORMAT;  
    ddsd.dwWidth = rs.right;  
    ddsd.dwHeight = rs.bottom;  
    ddsd.dwBackBufferCount = 1;  
    do  
    {   // Leo.Zheng MStar 2521 只创建 16-bit RGB 5:6:5 成功; 创建 16-bit RGB 5:5:5 失败.  
        ddsd.ddpfPixelFormat = ddpfOverlayFormats[i];  
        hRet = g_pDD->CreateSurface(&ddsd, &g_pDDSOverlay, NULL);            // Leo.Zheng 此处调用后引起使用 IOCtrl 显示在 LCD 上的消失  
        RETAILMSG(1,(L"[mosquito]Create No.%d surface return: 0x%X
",i + 1,hRet));  
    }while(hRet != DD_OK && (++i < PF_TABLE_SIZE));  
    if(hRet != DD_OK)  
        return InitFail(hWnd, hRet, TEXT("Unable to create overlay surface!"));  
  
    // Load the images.  
    if (LoadBugImages() != DD_OK)  
        return InitFail(hWnd, hRet, TEXT("Unable to load images to overlay surface!"));  
  
    // Finish setting up the overlay.  
    int StretchFactor1000 = ddcaps.dwMinOverlayStretch > 1000 ? ddcaps.dwMinOverlayStretch : 1000;  
  
    rd.left=0;   
    rd.top=0;  
    // Adding 999 takes care of integer truncation problems.  
    rd.right  = (rs.right * StretchFactor1000 + 999) / 1000;  
    rd.bottom = rs.bottom * StretchFactor1000 / 1000;  
    if (ddcaps.dwAlignSizeDest != 0)  
        rd.right = (int)((rd.right + ddcaps.dwAlignSizeDest - 1)/ ddcaps.dwAlignSizeDest) * ddcaps.dwAlignSizeDest;  
  
    // Set the flags we'll send to UpdateOverlay  
    dwUpdateFlags = DDOVER_SHOW;  
    // dwUpdateFlags = DDOVER_SHOW | DDOVER_DDFX;           // Leo.Zheng DDOVER_DDFX WinCE 不支持  
  
    // Does the overlay hardware support source color keying?  
    // If so, we can hide the black background around the image.  
    // This probably won't work with YUV formats  
    memset(&ovfx, 0, sizeof(ovfx));  
    ovfx.dwSize = sizeof(ovfx);  
    if (ddcaps.dwOverlayCaps & DDOVERLAYCAPS_CKEYSRC)           // MStar2521 不支持 color key  
    {  
        dwUpdateFlags |= DDOVER_KEYSRCOVERRIDE;  
  
        // Create an overlay FX structure so we can specify a source color key.  
        // This information is ignored if the DDOVER_SRCKEYOVERRIDE flag   
        // isn't set.  
        ovfx.dckSrcColorkey.dwColorSpaceLowValue=0; // black as the color key  
        ovfx.dckSrcColorkey.dwColorSpaceHighValue=0;  
    }  
    else  
    {  
        RETAILMSG(1,(L"[mosquito]cannot support color key: 0x%X(0x%x)
",ddcaps.dwOverlayCaps,DDOVERLAYCAPS_CKEYSRC));  
    }  
  
    // Update the overlay parameters.  
    hRet = g_pDDSOverlay->UpdateOverlay(&rs, g_pDDSPrimary, &rd, dwUpdateFlags, &ovfx);  
    if (hRet != DD_OK)  
    {  
        // 在 MStar 2521 设备上运行第二个此程序实例时出错。  
        // 在 TeleChips 8902 设备上运行第三个此程序实例时出错。  
        return InitFail(hWnd, hRet, TEXT("Unable to show overlay surface: 0x%x!"),hRet);  
    }  
  
    // Set a bunch of position and velocity module vars.  
    g_nOverlayXPos = 0;  
    g_nOverlayYPos = 0;  
    g_nOverlayXVel = RANDOM_VELOCITY();  
    g_nOverlayYVel = RANDOM_VELOCITY();  
    g_nOverlayWidth = rd.right - rd.left;  
    g_nOverlayHeight = rd.bottom - rd.top;  
      
    // Set the "destination position alignment" global so we won't have to  
    // keep calling GetCaps() everytime we move the overlay surface.  
    g_dwOverlayXPositionAlignment = ddcaps.dwAlignBoundaryDest;  
  
    // Create a timer to flip the pages.  
    if (TIMER_ID != SetTimer(hWnd, TIMER_ID, TIMER_RATE, NULL))  
        return InitFail(hWnd, hRet, TEXT("SetTimer FAILED"));  
  
    return DD_OK;  
}