Audio Streaming Sample Code
[The feature associated with this page, DirectShow, is a legacy feature. It has been superseded by MediaPlayer, IMFMediaEngine, and Audio/Video Capture in Media Foundation. Those features have been optimized for Windows 10 and Windows 11. Microsoft strongly recommends that new code use MediaPlayer, IMFMediaEngine and Audio/Video Capture in Media Foundation instead of DirectShow, when possible. Microsoft suggests that existing code that uses the legacy APIs be rewritten to use the new APIs if possible.]
Note
These APIs are deprecated. Applications should use the Sample Grabber filter or implement a custom filter to get data from a DirectShow filter graph.
The following code sample demonstrates how to stream audio data using the IAudioMediaStream, IAudioStreamSample, IMemoryData, and IAudioData interfaces. For brevity, this example performs minimal error checking.
#include <windows.h>
#include <stdio.h>
#include <mmsystem.h>
#include <amstream.h>
class CWaveBuffer {
public:
~CWaveBuffer();
BOOL Init(HWAVEOUT hWave, int Size);
BOOL Write(PBYTE pData, int nBytes, int& BytesWritten);
void Flush();
private:
WAVEHDR m_Hdr;
HWAVEOUT m_hWave;
int m_nBytes;
};
class CWaveOut {
public:
CWaveOut(LPCWAVEFORMATEX Format, int nBuffers, int BufferSize);
~CWaveOut();
void Write(PBYTE Data, int nBytes);
void Flush();
void Wait();
void Reset();
private:
const HANDLE m_hSem;
const int m_nBuffers;
int m_CurrentBuffer;
BOOL m_NoBuffer;
CWaveBuffer *m_Hdrs;
HWAVEOUT m_hWave;
};
BOOL CWaveBuffer::Init(HWAVEOUT hWave, int Size)
{
m_hWave = hWave;
m_nBytes = 0;
/* Allocate a buffer and initialize the header. */
m_Hdr.lpData = (LPSTR)LocalAlloc(LMEM_FIXED, Size);
if (m_Hdr.lpData == NULL)
{
return FALSE;
}
m_Hdr.dwBufferLength = Size;
m_Hdr.dwBytesRecorded = 0;
m_Hdr.dwUser = 0;
m_Hdr.dwFlags = 0;
m_Hdr.dwLoops = 0;
m_Hdr.lpNext = 0;
m_Hdr.reserved = 0;
/* Prepare it. */
waveOutPrepareHeader(hWave, &m_Hdr, sizeof(WAVEHDR));
return TRUE;
}
CWaveBuffer::~CWaveBuffer()
{
if (m_Hdr.lpData)
{
waveOutUnprepareHeader(m_hWave, &m_Hdr, sizeof(WAVEHDR));
LocalFree(m_Hdr.lpData);
}
}
void CWaveBuffer::Flush()
{
// ASSERT(m_nBytes != 0);
m_nBytes = 0;
waveOutWrite(m_hWave, &m_Hdr, sizeof(WAVEHDR));
}
BOOL CWaveBuffer::Write(PBYTE pData, int nBytes, int& BytesWritten)
{
// ASSERT((DWORD)m_nBytes != m_Hdr.dwBufferLength);
BytesWritten = min((int)m_Hdr.dwBufferLength - m_nBytes, nBytes);
CopyMemory((PVOID)(m_Hdr.lpData + m_nBytes), (PVOID)pData, BytesWritten);
m_nBytes += BytesWritten;
if (m_nBytes == (int)m_Hdr.dwBufferLength)
{
/* Write it! */
m_nBytes = 0;
waveOutWrite(m_hWave, &m_Hdr, sizeof(WAVEHDR));
return TRUE;
}
return FALSE;
}
void CALLBACK WaveCallback(HWAVEOUT hWave, UINT uMsg, DWORD dwUser,
DWORD dw1, DWORD dw2)
{
if (uMsg == WOM_DONE)
{
ReleaseSemaphore((HANDLE)dwUser, 1, NULL);
}
}
CWaveOut::CWaveOut(LPCWAVEFORMATEX Format, int nBuffers, int BufferSize) :
m_nBuffers(nBuffers),
m_CurrentBuffer(0),
m_NoBuffer(TRUE),
m_hSem(CreateSemaphore(NULL, nBuffers, nBuffers, NULL)),
m_Hdrs(new CWaveBuffer[nBuffers]),
m_hWave(NULL)
{
/* Create wave device. */
waveOutOpen(&m_hWave,
WAVE_MAPPER,
Format,
(DWORD)WaveCallback,
(DWORD)m_hSem,
CALLBACK_FUNCTION);
/* Initialize the wave buffers. */
for (int i = 0; i < nBuffers; i++)
{
m_Hdrs[i].Init(m_hWave, BufferSize);
}
}
CWaveOut::~CWaveOut()
{
/* First, get the buffers back. */
waveOutReset(m_hWave);
/* Free the buffers. */
delete [] m_Hdrs;
/* Close the wave device. */
waveOutClose(m_hWave);
/* Free the semaphore. */
CloseHandle(m_hSem);
}
void CWaveOut::Flush()
{
if (!m_NoBuffer)
{
m_Hdrs[m_CurrentBuffer].Flush();
m_NoBuffer = TRUE;
m_CurrentBuffer = (m_CurrentBuffer + 1) % m_nBuffers;
}
}
void CWaveOut::Reset()
{
waveOutReset(m_hWave);
}
void CWaveOut::Write(PBYTE pData, int nBytes)
{
while (nBytes != 0)
{
/* Get a buffer if necessary. */
if (m_NoBuffer)
{
WaitForSingleObject(m_hSem, INFINITE);
m_NoBuffer = FALSE;
}
/* Write into a buffer. */
int nWritten;
if (m_Hdrs[m_CurrentBuffer].Write(pData, nBytes, nWritten))
{
m_NoBuffer = TRUE;
m_CurrentBuffer = (m_CurrentBuffer + 1) % m_nBuffers;
nBytes -= nWritten;
pData += nWritten;
}
else
{
// ASSERT(nWritten == nBytes);
break;
}
}
}
void CWaveOut::Wait()
{
/* Send any remaining buffers. */
Flush();
/* Wait for the buffers back. */
for (int i = 0; i < m_nBuffers; i++)
{
WaitForSingleObject(m_hSem, INFINITE);
}
LONG lPrevCount;
ReleaseSemaphore(m_hSem, m_nBuffers, &lPrevCount);
}
HRESULT RenderStreamToDevice(IMultiMediaStream *pMMStream)
{
WAVEFORMATEX wfx;
#define DATA_SIZE 5000
IMediaStream *pStream = NULL;
IAudioStreamSample *pSample = NULL;
IAudioMediaStream *pAudioStream = NULL;
IAudioData *pAudioData = NULL;
HRESULT hr = pMMStream->GetMediaStream(MSPID_PrimaryAudio, &pStream);
if (FAILED(hr))
{
return hr;
}
pStream->QueryInterface(IID_IAudioMediaStream, (void **)&pAudioStream);
pStream->Release();
hr = CoCreateInstance(CLSID_AMAudioData, NULL,
CLSCTX_INPROC_SERVER, IID_IAudioData, (void **)&pAudioData);
if (FAILED(hr))
{
pAudioStream->Release();
return hr;
}
PBYTE pBuffer = (PBYTE)LocalAlloc(LMEM_FIXED, DATA_SIZE);
if (pBuffer == NULL)
{
pAudioStream->Release();
pAudioData->Release();
return E_OUTOFMEMORY;
}
pAudioStream->GetFormat(&wfx);
pAudioData->SetBuffer(DATA_SIZE, pBuffer, 0);
pAudioData->SetFormat(&wfx);
hr = pAudioStream->CreateSample(pAudioData, 0, &pSample);
pAudioStream->Release();
if (FAILED(hr))
{
LocalFree((HLOCAL)pBuffer);
pAudioData->Release();
pSample->Release();
return hr;
}
CWaveOut WaveOut(&wfx, 4, 2048);
HANDLE hEvent = CreateEvent(FALSE, NULL, NULL, FALSE);
if (hEvent != 0)
{
int iTimes;
for (iTimes = 0; iTimes < 3; iTimes++)
{
DWORD dwStart = timeGetTime();
for (; ; )
{
hr = pSample->Update(0, hEvent, NULL, 0);
if (FAILED(hr) || hr == MS_S_ENDOFSTREAM)
{
break;
}
WaitForSingleObject(hEvent, INFINITE);
DWORD dwTimeDiff = timeGetTime() - dwStart;
// Limit to 10 seconds
if (dwTimeDiff > 10000) {
break;
}
DWORD dwLength;
pAudioData->GetInfo(NULL, NULL, &dwLength);
WaveOut.Write(pBuffer, dwLength);
}
pMMStream->Seek(0);
}
}
pAudioData->Release();
pSample->Release();
LocalFree((HLOCAL)pBuffer);
return S_OK;
}
HRESULT RenderFileToMMStream(
const char * szFileName,
IMultiMediaStream **ppMMStream)
{
if (strlen(szFileName) > MAX_PATH)
{
return E_INVALIDARG;
}
IAMMultiMediaStream *pAMStream;
HRESULT hr = CoCreateInstance(CLSID_AMMultiMediaStream, NULL,
CLSCTX_INPROC_SERVER, IID_IAMMultiMediaStream,
(void **)&pAMStream);
if (FAILED(hr))
{
return hr;
}
WCHAR wszName[MAX_PATH + 1];
MultiByteToWideChar(CP_ACP, 0, szFileName, -1, wszName,
MAX_PATH + 1);
pAMStream->Initialize(STREAMTYPE_READ, AMMSF_NOGRAPHTHREAD, NULL);
pAMStream->AddMediaStream(NULL, &MSPID_PrimaryAudio, 0, NULL);
hr = pAMStream->OpenFile(wszName, AMMSF_RUN);
{
if (SUCCEEDED(hr))
{
hr = pAMStream->QueryInterface(IID_IMultiMediaStream,
(void**)ppMMStream);
}
}
pAMStream->Release();
return hr;
}
int __cdecl main(int argc, char *argv[])
{
if (argc < 2)
{
printf("Specify a file name.\n");
exit(0);
}
IMultiMediaStream *pMMStream;
CoInitialize(NULL);
HRESULT hr = RenderFileToMMStream(argv[1], &pMMStream);
if (SUCCEEDED(hr))
{
RenderStreamToDevice(pMMStream);
pMMStream->Release();
}
CoUninitialize();
return 0;
}
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