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 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;
}
