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Using DirectSound to Play Audio Stream Data

, 9 Mar 2005
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An article on how to play audio stream data with DirectSound.

Introduction

This article with its code shows how to play audio stream data with DirectSound. It gives a more flexible method to control the stream data. The demo shows how to play, pause, stop, seek a small or a big WAV file.

Background

Before you read the code, you should know something about DirectSound. You can find the related material in:

MSDN\Graphics and Multimedia\DirectX\SDK Documentation\DiretX8.1(C++)\DirectX Audio

Using the code

The CMyDirectSound has the following public method:

HRESULT SetFormat(const WAVEFORMATEX WFE);
HRESULT SetCallback(LPGETAUDIOSAMPLES_PROGRESS Function_Callback, LPVOID lpData);
typedef HRESULT  (WINAPI *LPGETAUDIOSAMPLES_PROGRESS)(int iAudioChannel, 
                                                      LPBYTE lpDesBuf,
                                                      const DWORD dwRequiredSamples, 
                                                      DWORD &dwRetSamples, 
                                                      LPVOID lpData);
void Play();
void Pause();
void Stop();
void Release();
DWORD GetSamplesPlayed();

First, you should give the information of the audio data you want to play, with "SetFormat":

WAVEFORMATEX formatWav;
m_pWavFile->Open((LPTSTR)(LPCTSTR)m_strFileName, &formatWav, WAVEFILE_READ);
formatWav = *m_pWavFile->GetFormat();

if (NULL == m_pDYDS) {

  m_pDYDS = new CDYDirectSound;
}
m_pDYDS->SetFormat(formatWav);

Second, set the callback function which is to get the audio stream data:

m_pMyDS->SetCallback(GetSamples, this);

Certainly, the body of the callback function should be written by yourself. Then you can play, pause, stop the audio data.

The "GetSamplesPlayed" method will give the number of audio samples played after you begin play. You can use this method to give the playing position.

Points of Interest

I think there're two key points in this class.

1. How to control the DirectSound buffer circle?

I create a second DirectSound buffer with two seconds duration:

//Create Second Sound Buffer
dsbd.dwFlags = DSBCAPS_CTRLPOSITIONNOTIFY;
dsbd.dwBufferBytes = 2*m_WFE.nAvgBytesPerSec; //2-Second Buffer 
dsbd.lpwfxFormat = &m_WFE;

if ( FAILED(m_lpDS->CreateSoundBuffer(&dsbd, &m_lpDSB, NULL)) ) {

  OutputDebugString(_T("Create Second Sound Buffer Failed!"));
  m_strLastError = _T("MyDirectSound SetFormat Failed!");
  return;
}

And I set two DirectSound notify at 0.5 second and 1.5 second:

               (1st Notify)                          (2nd Notify)
0              0.5Second        1Second              1.5Second         2Second
|                  |               |                     |                 |
---------------------------------------------------------------------------
|                                  |                                       |
|--------------------------------------------------------------------------|
//Set Direct Sound Buffer Notify Position
DSBPOSITIONNOTIFY pPosNotify[2];
pPosNotify[0].dwOffset = m_WFE.nAvgBytesPerSec/2 - 1;
pPosNotify[1].dwOffset = 3*m_WFE.nAvgBytesPerSec/2 - 1;  
pPosNotify[0].hEventNotify = m_pHEvent[0];
pPosNotify[1].hEventNotify = m_pHEvent[1];

if ( FAILED(lpDSBNotify->SetNotificationPositions(2, pPosNotify)) ) {

  OutputDebugString(_T("Set NotificationPosition Failed!"));
  m_strLastError = _T("MyDirectSound SetFormat Failed!");
  return;
}

When you call the Play method, a timer will be triggered. The "TimerProcess" function will be called every 300 milliseconds.

//Beging Play
m_lpDSB->Play(0, 0, DSBPLAY_LOOPING);

//timeSetEvent
m_timerID = timeSetEvent(300, 100, TimerProcess, 
    (DWORD)this, TIME_PERIODIC | TIME_CALLBACK_FUNCTION);

In the "TimerProcess" function, the next second audio stream data will be gotten when the current play cursor arrives the 1st or 2nd notify point.

void CALLBACK TimerProcess(UINT uTimerID, UINT uMsg, 
                           DWORD dwUser, DWORD dw1, DWORD dw2)
{
  CMyDirectSound *pDDS = (CMyDirectSound *)dwUser;
  pDDS->TimerCallback();  
}
//<\TimerProcess>

void CMyDirectSound::TimerCallback()
{
  LPVOID lpvAudio1 = NULL, lpvAudio2 = NULL;
  DWORD dwBytesAudio1 = 0, dwBytesAudio2 = 0;
  DWORD dwRetSamples = 0, dwRetBytes = 0;

  HRESULT hr = WaitForMultipleObjects(2, m_pHEvent, FALSE, 0);
  if(WAIT_OBJECT_0 == hr) {

    m_dwCircles1++;

    //Lock DirectSoundBuffer Second Part
    HRESULT hr = m_lpDSB->Lock(m_WFE.nAvgBytesPerSec, m_WFE.nAvgBytesPerSec,
    &lpvAudio1, &dwBytesAudio1,&lpvAudio2, &dwBytesAudio2, 0);
    if ( FAILED(hr) ) {

      m_strLastError = _T("Lock DirectSoundBuffer Failed!");
      OutputDebugString(m_strLastError);
      return;
    }    
  }
  else if (WAIT_OBJECT_0 + 1 == hr) {    

    m_dwCircles2++;

    //Lock DirectSoundBuffer First Part
    HRESULT hr = m_lpDSB->Lock(0, m_WFE.nAvgBytesPerSec, 
    &lpvAudio1, &dwBytesAudio1, &lpvAudio2, &dwBytesAudio2, 0);
    if ( FAILED(hr) ) {

      m_strLastError = _T("Lock DirectSoundBuffer Failed!");
      OutputDebugString(m_strLastError);
      return;
    }    
  }
  else {

    return;
  }

  //Get 1 Second Audio Buffer 
  m_lpGETAUDIOSAMPLES(m_lpAudioBuf, m_WFE.nSamplesPerSec, dwRetSamples, m_lpData);
  dwRetBytes = dwRetSamples*m_WFE.nBlockAlign;
  
  //If near the end of the audio data
  if (dwRetSamples < m_WFE.nSamplesPerSec) {

    DWORD dwRetBytes = dwRetSamples*m_WFE.nBlockAlign;
    memset(m_lpAudioBuf+dwRetBytes, 0, m_WFE.nAvgBytesPerSec - dwRetBytes);        
  }
  
  //Copy AudioBuffer to DirectSoundBuffer
  if (NULL == lpvAudio2) {

    memcpy(lpvAudio1, m_lpAudioBuf, dwBytesAudio1);
  }
  else {

    memcpy(lpvAudio1, m_lpAudioBuf, dwBytesAudio1);
    memcpy(lpvAudio2, m_lpAudioBuf + dwBytesAudio1, dwBytesAudio2);
  }
  
  //Unlock DirectSoundBuffer
  m_lpDSB->Unlock(lpvAudio1, dwBytesAudio1, lpvAudio2, dwBytesAudio2);
}
//<\TimerCallback>

2. How the following callback function works?

//Get Audio Buffer
  m_lpGETAUDIOSAMPLES(m_lpAudioBuf, m_WFE.nSamplesPerSec, dwRetSamples, m_lpData);

Do you remember what you have done when you set the callback function?

void CDYDirectSound::SetCallback(LPGETAUDIOSAMPLES_PROGRESS Function_Callback, 
                                 LPVOID lpData)
{
  m_lpGETAUDIOSAMPLES = Function_Callback;
  m_lpData = lpData;
}
//<\SetCallback>

Yes, you transfer the GETAUDIOSAMPLES_PROGRESS function's pointer to m_lpGETAUDIOSAMPLES.

m_pMyDS->SetCallback(GetSamples, this);

And the GetSamples is defined as:

HRESULT CALLBACK GetSamples(LPBYTE lpDesBuf, 
                            const DWORD dwRequiredSamples, 
                            DWORD &dwRetSamples, 
                            LPVOID lpData)
{
  CDirectSoundTestDlg *pDlg = (CDirectSoundTestDlg *)lpData;
  pDlg->GetAudioSamples(lpDesBuf, dwRequiredSamples, dwRetSamples);
  return 0;
}
//<\GetSamples>

HRESULT CDirectSoundTestDlg::GetAudioSamples(LPBYTE lpDesBuf,
                                             const DWORD dwRequiredSamples,
                                             DWORD &dwRetSamples)
{
  DWORD dwRequiredBytes = 0, dwRetBytes = 0;
  WAVEFORMATEX *pWFE = m_pWavFile->GetFormat();
  dwRequiredBytes = dwRequiredSamples*pWFE->nBlockAlign;
  m_pWavFile->Read(lpDesBuf, dwRequiredBytes, &dwRetBytes);
  dwRetSamples = dwRetBytes/pWFE->nBlockAlign;
  return dwRetBytes;
}
//<\GetAudioSamples>

You can write your own "GetAudioSamples" to get the audio stream data.

License

This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

A list of licenses authors might use can be found here

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About the Author

Cai Tao

China China
No Biography provided

Comments and Discussions

 
GeneralUsing DirectSound to Play Audio Stream Data Pinmemberkhosrow parizi31-Aug-12 2:52 
QuestionLarger buffer Pinmemberrahnz29-May-12 15:17 
Buga little bug during play/pause switch Pinmembertonyjiang8821519-Dec-11 2:17 
Questiona small problem with slider-position Pinmemberdumbledorehoho25-Jan-10 18:14 
Generalit is no good when work with windows media palyer 10 Pinmembernofengyu23-Jan-10 20:22 
Generalthanks Pinmembergj_code13-Aug-09 4:55 
Generala few question about play wave file with DirectSound and display spectrum. Pinmemberjacky_zz4-Sep-08 15:02 
QuestionAbout "GetAudioSamples" PinmemberHuangAnbang10-Sep-07 18:16 
GeneralUnresolved Error for Release Build PinmemberSeenu Reddi21-Feb-07 15:03 
QuestionThe Primary buffer is redundant???? Pinmembercnxhwy23-Nov-06 16:11 
QuestionHow do handle block mode audio ? PinmemberMusong22-Aug-06 16:54 
QuestionCalculation error in GetSamplesPlayed() ? PinmemberAzonacun8-May-06 8:38 
AnswerRe: Calculation error in GetSamplesPlayed() ? PinmemberKedzo6-Jul-06 11:51 
Question'dmusici.h' missing! PinmemberWilliamZhou24-Mar-06 5:29 
AnswerRe: 'dmusici.h' missing! PinmemberSreekanth Muralidharan27-Apr-06 19:49 
GeneralMeasuring the sound level Pinmembermsorc24-Feb-06 6:08 
QuestionUsing a Stream in stead of of File ? PinmemberYossef30-Nov-05 23:07 
GeneralBug report and my fixes PinsussIKedzo25-Oct-05 1:54 
GeneralConflicts with other applications PinmemberStevenDorning6-Oct-05 22:19 
GeneralSomething wrong when load different BitsPerSample WAV file! Pinmemberikkiu200130-Jun-05 23:51 
Generalabout mfc42u.lib Pinmembercaoxiang31-May-05 18:10 
GeneralRe: about mfc42u.lib PinmemberYesterdayOncemore13-Feb-06 20:13 
GeneralRe: about mfc42u.lib PinmemberDuncan1234529-Mar-06 21:59 
GeneralAudio Format.. Pinmembermpallavi28-Apr-05 18:08 
GeneralRe: Audio Format.. PinmemberCai Tao28-Apr-05 21:27 

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