wince下用DirectShow播放音频和视频wince下用DirectShow播放音频和视频虽然网上关于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 valueenum 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 propertytypedef 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 videoLONG lWidth;//Height of the videoLONG lHeight;//Approximate bit rateLONG 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 interfacesIGraphBuilder *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 videoHWND m_hWndNotify; //The window notifyBOOL 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//----------------------------------------------------------------------//InitializeCMedia *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 fileif(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 existingHANDLE hdFile =CreateFile(m_szFileName,GENERIC_READ,FILE_SHARE_READ,NULL,OPEN_EXISTING,NULL,NULL);if(hdFile == INVALID_HANDLE_VALUE)...{//The file doesn't existgoto END;}else...{CloseHandle(hdFile);}}// Initialize COMif(CoInitializeEx(NULL, COINIT_MULTITHREADED) != S_OK)...{goto END;}// Get the interface for DirectShow's GraphBuilderif(CoCreateInstance(CLSID_FilterGraph, NULL, CLSCTX_INPROC_SERVER, IID_IGraphBuilder, (void **)&m_pGB) != S_OK)...{goto END;}// Have the graph construct its the appropriate graph automaticallyif(m_pGB->RenderFile(m_szFileName, NULL) != NOERROR)...{goto END;}// QueryInterface for DirectShow interfacesif(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 filesif(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 modeSetDisplayMode(m_DispMode);bResult = TRUE;END:if(bResult == FALSE)...{//Release the resourceClose();}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 hidingif(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 COMmemset(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 propertym_pBA->get_Volume(&prop.lVolume);m_pBA->get_Balance(&prop.lBalance);//Get the video propertyif(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 modem_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 eventsm_pME->FreeEventParams(evCode, evParam1, evParam2);}else...{return FALSE;}return TRUE;}本文来自CSDN博客，转载请标明出处：/norains/archive/2007/05/14/1609118.aspx。
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