如何播放大型 WAV 文件
2006-07-23 11:31:41 来源:WEB开发网核心提示: //建立Cwave类,放在Wave.h文件中:class CWave:public CObject{//Constructionpublic:CWave();virtual ~CWave();//Operationspublic:DWORD OpenDevice();DWORD Close
//建立Cwave类,放在Wave.h文件中:
class CWave:public CObject
{
//Construction
public:
CWave();
virtual ~CWave();
//Operations
public:
DWORD OpenDevice();
DWORD CloseDevice();
DWORD Play(CWnd *pParentWnd,LPCSTR pFileName);
DWORD Stop();
//Implementation
protected:
void DisplayErrorMsg(DWORD dwError);
//Members
protected:
MCIDEVICEID m_nDeviceID;
MCIDEVICEID m_nElementID;
};
//Cwave类的实现代码,Cwave.cpp
#include <stdafx.h>
#include "cwave.h"
CWave::CWave()
{
m_nDeviceID=0;
m_nElementID=0;
}
CWave::~CWave()
{
if(m_nElementID)
Stop();
if(m_nDeviceID)
CloseDevice();
}
DWORD CWave::OpenDevice()
{
DWORD dwResult=0;
if (m_nDeviceID)
{
MCI_OPEN_PARMS mciOpenParms;
mciOpenParms.lpstrDeviceType=(LPSTR)MCI_DEVTYPE_WAVEFORM_AUDIO;
//open the wave device
dwResult = mciSendCommand(NULL,
MCI_OPEN,
MCI_OPEN_TYPE|MCI_OPEN_TYPE_ID|MCI_WAIT,
(DWORD)(LPVOID)&mciOpenParms);
//save device identifier,will use eith other MCI commands
m_nDeviceID = mciOpenParms.wDeviceID;
//display error message if failed
if(dwResult)
DisplayErrorMsg(dwResult);
}
//return result of MCI operation
return dwResult;
}
DWORD CWave::CloseDevice()
{
DWORD dwResult=0;
//close if currently open
if(m_nDeviceID)
{
//close the MCI device
dwResult=mciSendCommand(m_nDeviceID,MCI_CLOSE,NULL,NULL);
//display error message if failed
if(dwResult)
DisplayErrorMsg(dwResult);
//set identifier to close state
else
m_nDeviceID=0;
}
//return result of MCI operation
return dwResult;
}
DWORD CWave::Play(CWnd* pWnd,LPCSTR pFileName)
{
MCI_OPEN_PARMS mciOpenParms;
//initialize structure
memset(&mciOpenParms,0,sizeof(MCI_OPEN_PARMS));
//set the WAV file name to be played
mciOpenParms.lpstrElementName=pFileName;
//first open the device
DWORD dwResult=mciSendCommand(m_nDeviceID,MCI_OPEN,
MCI_OPEN_ELEMENT,(DWORD)(LPVOID)&mciOpenParms);
//display error message if failed
if(dwResult)
DisplayErrorMsg(dwResult);
//if successful,instruct the device to play the WAV file
else
{
//save element indentifier
m_nElementID=mciOpenParms.wDeviceID;
MCI_PLAY_PARMS mciPlayParms;
//set the window that will receive notification message
mciPlayParms.dwCallback=(DWORD)pWnd->m_hWnd;
//instruct device to play file
dwResult=mciSendCommand(m_nElementID,MCI_PLAY,
MCI_NOTIFY,(DWORD)(LPVOID)&mciPlayParms);
//display error and close element if failed
if(dwResult)
{
DisplayErrorMsg(dwResult);
Stop();
}
}
//return result of MCI operation
return dwResult;
}
DWORD CWave::Stop()
{
DWORD dwResult=0;
//close if element is currently open
if(m_nElementID)
{
dwResult=mciSendCommand(m_nElementID,MCI_CLOSE,NULL,NULL);
//display error message if failed
if(dwResult)
DisplayErrorMsg(dwResult);
//set identifier to closed state
else
m_nElementID=0;
}
return dwResult;
}
void CWave::DisplayErrorMsg(DWORD dwError)
{
//check if there was an error
if(dwError)
{
//character string that contains error message
char szErrorMsg[MAXERRORLENGTH];
//retrieve string associated error message
if(!mciGetErrorString(dwError,szErrorMsg,sizeof(szErrorMsg)))
strcpy(szErrorMsg,"Unknown Error");
//display error string in message box
AfxMessageBox(szErrorMsg);
}
}
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