wince下用DirectShow播放音频和视频

//========================================================================
//TITLE:
//    wince下用DirectShow播放音频和视频
//AUTHOR:
//    norains
//DATE:
//    Monday  14-May-2007
//Environment:
//        WinCE 5.0
//========================================================================

        虽然网上关于wince下如何使用DirectShow播放多媒体文件的资料不多,但WinCE毕竟还属于windows,而桌面系统的DirectShow例子网上信手拈来,并且其中DirectShow的功能方法与之WinCE下差别不大,又本人实在没有信心比他们的轮子造得更为华丽,所以这篇文章就直接切入正题,不介绍DirectShow的结构功能,直接来看看怎么用吧.(其实还是自己懒惰的原因大一些,恩,不过这个和本文的主题没多大关系:-)).
      
        为了方便代码的移植,所以我将DirectShow的操作封装成CMedia类,只要直接调用该类,就可以相当简便地调用DirectShow来播放多媒体文件了
       
        好,闲话至此,我们以具体代码看看是如何:

//获取CMedia的实例 CMedia *m_pMedia = CMedia::GetInstance(); //设置播放的窗口 m_pMedia->SetVideoWindow(hWnd); //打开媒体文件 m_pMedia->Open(TEXT("A.AVI")); //播放 m_pMedia->Play(); ... //播放结束后,调用Close释放资源 m_pMedia->Open();

 没错,就是六行代码,就这么简单,可以顺利播放媒体文件.在这里要说一下的是,因为我们播放的是视频,需要有一个窗口显示,所以需要调用SetVideoWindow()函数来设置播放窗口.这个播放视频的窗口,可以是普通的窗口,也可以是Picture控件.当然咯,如果是播放音频文件,那么则完全可以无视这个函数.
       
        还有一个最值得注意的地方,当调用Open()成功之后,一定要调用Close()来释放资源,然后才能打开另一个媒体文件.否则,不释放的资源可能会导致很多莫名其妙的后果哦.
               
        等等,代码似乎还不完美,比如说,我想在文件播放之后再接着播放另外一个文件,那么我如何知道什么时候文件已经播放完毕了呢?这时候我们就需要请出SetNotifyWindow().
       
        该函数的作用是设置一个接受消息的窗口,当DirectShow有事件变更时,就会发送指定的消息到指定的窗口,原型如下:
       
        SetNotifyWindow(HWND hWnd, UINT wMsg,long lInstanceData)
       
        hWnd:接收消息的窗口句柄.
       
        wMsg:指定的自定义消息
       
        lInstanceData:消息的参数.
       
       
        那么,现在以接收一个视频播放结束事件的代码片段为例子:
//自定义一个消息 #define WM_GRAPHNOTIFY (WM_USER + 13) //设置接收消息窗口和消息 m_pMedia->SetVideoWindow(hWnd,WM_GRAPHNOTIFY,NULL); ... //这个是消息循环函数 LRESULT CMainWnd::WndProc(HWND hWnd, UINT wMsg, WPARAM wParam, LPARAM lParam) ...{ switch(wMsg) ...{ ... case WM_GRAPHNOTIFY: ...{ LONG evCode,evParam1,evParam2; //获取此时的DirectShow事件 if(m_pMedia->GetEvent(&evCode,&evParam1,&evParam2) == TRUE) ...{ if(evCode == EC_COMPLETE) ...{ MessageBox(NULL,TEXT("播放完毕"),TEXT(""),MB_OK); } } return 0; } } ... }

 好了,知道播放完毕,就这么简单.恩,还很复杂..?呵呵,我觉得已经很简单了.
       
        文章的最后,让我们再来看看CMedia的其它几个有用的函数吧:
       
        CheckVisibility()
        描述:判断文件的种类
        当返回值为TRUE时,为视频文件;反之为只是音频文件.
       
       
        SetVolume(LONG lVolume, LONG lBalance)
        描述:设置音量.
        lVolume:设置音量的大小,范围为–10,000 到 0.
        lBalance:设置左右音量的均衡,范围是–10,000 到 10,000,默认是0.
       
       
        SetDisplayMode(DISPLAYMODE mode)
        描述:设置播放模式.
        DISP_FIT:按比例拉伸至视屏窗口.
        DISP_STRETCH:不按比例拉伸至视屏窗口.
        DISP_NATIVE:如果视频原本尺寸小于屏幕,则以原视频文件大小播放.否则,将和DISP_FIT相同
        DISP_FULLSCREEN:全屏

///////////////////////////////////////////////////////////////////// //Media.h: interface for the CMedia class. // //Version: // 1.2.0 //Date: // 2007.05.08 /**/////////////////////////////////////////////////////////////////////// #ifndef MEDIA_H #define MEDIA_H #include <mmsystem.h> #include <streams.h> //-------------------------------------------------------------------- //Macro define //The volume value #define MAX_VOLUME 0 #define MIN_VOLUME -10000 //The balance value #define MAX_BALANCE 10000 #define MIN_BALANCE -10000 //-------------------------------------------------------------------- //Enum value enum DISPLAYMODE ...{ //Fit to the play window size. How wide (height) the window is, how //is the move. Keep aspect ratio. DISP_FIT, //Stretch to the play window size. Don't keep the aspect ratio. DISP_STRETCH, //Full screen play. DISP_FULLSCREEN, //When the size of video is smaller than the play window, it displayes //as the video size. If it's bigger , it just like the DISP_FIT mode. DISP_NATIVE }; //-------------------------------------------------------------------- //The media file property typedef struct ...{ //The volume range is –10,000 to 0. //Divide by 100 to get equivalent decibel value (for example –10,000 = –100 dB). LONG lVolume; //The value from –10,000 to 10,000 indicating the stereo balance //As with the Volume property, units correspond to .01 decibels (multiplied by –1 when plBalance is a positive value). //For example, a value of 1000 indicates –10 dB on the right channel and –90 dB on the left channel. LONG lBalance; //Width of the video LONG lWidth; //Height of the video LONG lHeight; //Approximate bit rate LONG lBitRate; }MEDIAPROPERTY,*PMEDIAPROPERTY; //-------------------------------------------------------------------- class CMedia ...{ public: BOOL GetEvent(LONG *plEvCode, LONG *plParam1, LONG *plParam2); BOOL SetNotifyWindow(HWND hWnd, UINT wMsg,long lInstanceData); BOOL SetVolume(LONG lVolume, LONG lBalance = 0); BOOL SetDisplayMode(DISPLAYMODE mode); BOOL GetMediaProperty(PMEDIAPROPERTY pOutProperty); static CMedia * GetInstance(); void Close(); BOOL CheckVisibility(); void SetVideoWindow(HWND hWndVideo); BOOL Open(TCHAR * pszFileName); BOOL Stop(); BOOL Pause(); BOOL Play(); virtual ~CMedia(); protected: CMedia(); // Collection of interfaces IGraphBuilder *m_pGB; IMediaControl *m_pMC; IMediaEventEx *m_pME; IVideoWindow *m_pVW; IBasicAudio *m_pBA; IBasicVideo *m_pBV; IMediaSeeking *m_pMS; TCHAR m_szFileName[MAX_PATH]; HWND m_hWndVideo; //The window play video HWND m_hWndNotify; //The window notify BOOL m_bExitThrd; BOOL m_bThrdRunning; static CMedia * m_pInstance; DISPLAYMODE m_DispMode; }; #endif //#ifndef MEDIA_H /**/////////////////////////////////////////////////////////////////////// // Media.cpp: implementation of the CMedia class. // /**/////////////////////////////////////////////////////////////////////// #include "stdafx.h" #include "Media.h" //---------------------------------------------------------------------------------------------- //Macro define //Default play mode #define DEFAULT_DISPLAY_MODE DISP_NATIVE //---------------------------------------------------------------------- //Initialize CMedia *CMedia::m_pInstance = NULL; //------------------------------------------------------------------------ /**/////////////////////////////////////////////////////////////////////// // Construction/Destruction /**/////////////////////////////////////////////////////////////////////// CMedia::CMedia(): m_pGB(NULL), m_pMC(NULL), m_pME(NULL), m_pVW(NULL), m_pBA(NULL), m_pBV(NULL), m_pMS(NULL), m_hWndVideo(NULL), m_bExitThrd(TRUE), m_bThrdRunning(FALSE), m_DispMode(DEFAULT_DISPLAY_MODE), m_hWndNotify(NULL) ...{ memset(m_szFileName,0,sizeof(m_szFileName)); } CMedia::~CMedia() ...{ if(m_pInstance != NULL) ...{ delete m_pInstance; m_pInstance = NULL; } } //------------------------------------------------------------ //Description: // Play the media file // When you call the function,you should call Open() before. // //------------------------------------------------------------- BOOL CMedia::Play() ...{ // Run the graph to play the media file if(m_pMC == NULL) ...{ return FALSE; } m_pMC->Run(); return TRUE; } //------------------------------------------------------------ //Description: // Pause. // When you call the function,you should call Open() before. // //------------------------------------------------------------- BOOL CMedia::Pause() ...{ if(m_pMC == NULL) ...{ return FALSE; } m_pMC->Pause(); return TRUE; } //------------------------------------------------------------ //Description: // Stop. // When you call the function,you should call Open() before. // //------------------------------------------------------------- BOOL CMedia::Stop() ...{ if(m_pMC == NULL || m_pMS == NULL) ...{ return FALSE; } m_pMC->Stop(); m_pMS->SetPositions(0, AM_SEEKING_AbsolutePositioning,NULL,AM_SEEKING_NoPositioning); return TRUE; } //-------------------------------------------------------------------------- //Description: // Open the media file. When succeed in calling the function , //you should call the Close() to release the resource // //------------------------------------------------------------------------- BOOL CMedia::Open(TCHAR *pszFileName) ...{ BOOL bResult = FALSE; if(_tcslen(pszFileName) >= MAX_PATH) ...{ goto END; } else ...{ _tcscpy(m_szFileName,pszFileName); //Check the file existing HANDLE hdFile = CreateFile(m_szFileName,GENERIC_READ,FILE_SHARE_READ,NULL,OPEN_EXISTING,NULL,NULL); if(hdFile == INVALID_HANDLE_VALUE) ...{ //The file doesn't exist goto END; } else ...{ CloseHandle(hdFile); } } // Initialize COM if(CoInitializeEx(NULL, COINIT_MULTITHREADED) != S_OK) ...{ goto END; } // Get the interface for DirectShow's GraphBuilder if(CoCreateInstance(CLSID_FilterGraph, NULL, CLSCTX_INPROC_SERVER, IID_IGraphBuilder, (void **)&m_pGB) != S_OK) ...{ goto END; } // Have the graph construct its the appropriate graph automatically if(m_pGB->RenderFile(m_szFileName, NULL) != NOERROR) ...{ goto END; } // QueryInterface for DirectShow interfaces if(m_pGB->QueryInterface(IID_IMediaControl, (void **)&m_pMC) != NOERROR) ...{ goto END; } if(m_pGB->QueryInterface(IID_IMediaEventEx, (void **)&m_pME) != NOERROR) ...{ goto END; } if(m_pGB->QueryInterface(IID_IMediaSeeking, (void **)&m_pMS) != NOERROR) ...{ goto END; } // Query for video interfaces, which may not be relevant for audio files if(m_pGB->QueryInterface(IID_IVideoWindow, (void **)&m_pVW) != NOERROR) ...{ goto END; } if(m_pGB->QueryInterface(IID_IBasicVideo, (void **)&m_pBV) != NOERROR) ...{ goto END; } // Query for audio interfaces, which may not be relevant for video-only files if(m_pGB->QueryInterface(IID_IBasicAudio, (void **)&m_pBA) != NOERROR) ...{ goto END; } // Is this an audio-only file (no video component)? if (CheckVisibility() == TRUE) ...{ if(m_pVW->put_Owner((OAHWND)m_hWndVideo) != NOERROR) ...{ goto END; } if(m_pVW->put_WindowStyle(WS_CHILD | WS_CLIPSIBLINGS | WS_CLIPCHILDREN) != NOERROR) ...{ goto END; } } //Set play mode SetDisplayMode(m_DispMode); bResult = TRUE; END: if(bResult == FALSE) ...{ //Release the resource Close(); } return bResult; } //------------------------------------------------------------ //Description: // This method sets an owning parent for the video window. // //Parameters: // hWnd : [in] Handle of new owner window. // //---------------------------------------------------------- void CMedia::SetVideoWindow(HWND hWndVideo) ...{ m_hWndVideo = hWndVideo; } //------------------------------------------------------------ //Description: // Check the file visibility // When you call the function,you should call Open() before. // //Parameters: // TRUE: Video // FALSE: It's not the video // //------------------------------------------------------------ BOOL CMedia::CheckVisibility() ...{ if (!m_pVW) ...{ //No VideoWindow interface. Assuming audio/MIDI file or unsupported video codec return FALSE; } if (!m_pBV) ...{ //No BasicVideo interface. Assuming audio/MIDI file or unsupported video codec. return FALSE; } // If this is an audio-only clip, get_Visible() won't work. // // Also, if this video is encoded with an unsupported codec, // we won't see any video, although the audio will work if it is // of a supported format. long lVisible; if(m_pVW->get_Visible(&lVisible) != NOERROR) ...{ return FALSE; } return TRUE; } //------------------------------------------------------------ //Description: // Release the resource which opened in the Open() // //------------------------------------------------------------ void CMedia::Close() ...{ // Relinquish ownership (IMPORTANT!) after hiding if(m_pVW) ...{ m_pVW->put_Visible(OAFALSE); m_pVW->put_Owner(NULL); } if(m_pMC != NULL) ...{ m_pMC->Release(); m_pMC = NULL; } if(m_pME != NULL) ...{ m_pME->SetNotifyWindow(NULL,NULL,NULL); m_pME->Release(); m_pME = NULL; } if(m_pMS != NULL) ...{ m_pMS->Release(); m_pMS = NULL; } if(m_pBV != NULL) ...{ m_pBV->Release(); m_pBV = NULL; } if(m_pBA != NULL) ...{ m_pBA->Release(); m_pBA = NULL; } if(m_pVW != NULL) ...{ m_pVW->Release(); m_pVW = NULL; } if(m_pGB != NULL) ...{ m_pGB->Release(); m_pGB = NULL; } // Finished with COM memset(m_szFileName,0,sizeof(m_szFileName)); CoUninitialize(); } //------------------------------------------------------------ //Description: // Get the instance of object // //------------------------------------------------------------ CMedia * CMedia::GetInstance() ...{ if(m_pInstance == NULL) ...{ m_pInstance = new CMedia(); } return m_pInstance; } //------------------------------------------------------------ //Description: // Get the media file property. // When you call the function,you should call Open() before. // //------------------------------------------------------------ BOOL CMedia::GetMediaProperty(PMEDIAPROPERTY pOutProperty) ...{ MEDIAPROPERTY prop = ...{0}; if(m_pBA == NULL || m_pBV == NULL) ...{ return FALSE; } //Get the audio property m_pBA->get_Volume(&prop.lVolume); m_pBA->get_Balance(&prop.lBalance); //Get the video property if(CheckVisibility() == TRUE) ...{ m_pBV->get_BitRate(&prop.lBitRate); m_pBV->GetVideoSize(&prop.lWidth,&prop.lHeight); } *pOutProperty = prop; return TRUE; } //------------------------------------------------------------ //Description: // Set the display mode. // When you call the function,you should call Open() before. // //------------------------------------------------------------ BOOL CMedia::SetDisplayMode(DISPLAYMODE mode) ...{ if(m_pVW == NULL) ...{ return FALSE; } m_DispMode = mode; if(mode == DISP_FULLSCREEN) ...{ m_pVW->put_FullScreenMode(OATRUE); } else ...{ //Restore to the normal mode m_pVW->put_FullScreenMode(OAFALSE); RECT rcWnd = ...{0}; GetClientRect(m_hWndVideo,&rcWnd); LONG lWndWidth = rcWnd.right - rcWnd.left; LONG lWndHeight = rcWnd.bottom - rcWnd.top; MEDIAPROPERTY prop = ...{0}; GetMediaProperty(&prop); if(mode == DISP_FIT || mode == DISP_NATIVE) ...{ LONG lDispLeft,lDispTop,lDispWidth,lDispHeight; if(mode == DISP_NATIVE && lWndWidth >= prop.lWidth && lWndHeight >= prop.lHeight) ...{ lDispLeft = (lWndWidth - prop.lWidth) / 2; lDispTop = (lWndHeight - prop.lHeight) / 2; lDispWidth = prop.lWidth; lDispHeight = prop.lHeight; } else ...{ if(prop.lWidth * lWndHeight > lWndWidth * prop.lHeight) ...{ lDispWidth = lWndWidth; lDispHeight = (LONG)((float)lDispWidth / (float)prop.lWidth * prop.lHeight); lDispLeft = 0; lDispTop = (lWndHeight - lDispHeight) / 2; } else if(prop.lWidth * lWndHeight < lWndWidth * prop.lHeight) ...{ lDispHeight = lWndHeight; lDispWidth = (LONG)((float)lDispHeight / (float)prop.lHeight * prop.lWidth); lDispLeft = (lWndWidth - lDispWidth) / 2; lDispTop = 0; } else ...{ lDispWidth = lWndWidth; lDispHeight = lWndHeight; lDispLeft = 0; lDispTop = 0; } } m_pVW->put_Left(lDispLeft); m_pVW->put_Top(lDispTop); m_pVW->put_Width(lDispWidth); m_pVW->put_Height(lDispHeight); } else if(mode == DISP_STRETCH) ...{ m_pVW->put_Left(0); m_pVW->put_Top(0); m_pVW->put_Width(lWndWidth); m_pVW->put_Height(lWndHeight); } } return TRUE; } //------------------------------------------------------------ //Description: // Set the volume. // When you call the function,you should call Open() before. // //Parameters: // lVolume:[in] The volume (amplitude) of the audio signal. // Range is –10,000 to 0. // lBalance:[in] The balance for the audio signal. Default value is 0. // The value from –10,000 to 10,000 indicating the stereo balance. // //------------------------------------------------------------ BOOL CMedia::SetVolume(LONG lVolume, LONG lBalance) ...{ if(m_pBA == NULL) ...{ return FALSE; } if(lVolume < MIN_VOLUME && lVolume > MAX_VOLUME && lBalance < MIN_BALANCE && lBalance > MAX_BALANCE) ...{ return FALSE; } m_pBA->put_Volume(lVolume); m_pBA->put_Balance(lBalance); return TRUE; } //---------------------------------------------------------------------- //Description: // Registers a window that will handle messages when a specified event occurs. // //Parameters: // hWnd:[in] Handle of window to notify. Pass NULL to stop notification. // wMsg:[in] Window message to be passed as the notification. // lInstanceData:[in] Value (instance data) to be passed as the lParam parameter for the lMsg message. // //----------------------------------------------------------------------------- BOOL CMedia::SetNotifyWindow(HWND hWnd, UINT wMsg,long lInstanceData) ...{ if(m_pME == NULL) ...{ return FALSE; } m_pME->SetNotifyWindow((OAHWND)hWnd,wMsg,lInstanceData); return TRUE; } //---------------------------------------------------------------------- //Description: // This method retrieves the notification event. // //----------------------------------------------------------------------- BOOL CMedia::GetEvent(LONG *plEvCode, LONG *plParam1, LONG *plParam2) ...{ if(m_pME == NULL) ...{ return FALSE; } LONG evCode, evParam1, evParam2; if(m_pME->GetEvent(&evCode, &evParam1, &evParam2, 0) == NOERROR) ...{ *plEvCode = evCode; *plParam1 = evParam1; *plParam2 = evParam2; // Spin through the events m_pME->FreeEventParams(evCode, evParam1, evParam2); } else ...{ return FALSE; } return TRUE; }