Código de ejemplo de streaming de audio
[La característica asociada a esta página, DirectShow, es una característica heredada. Se ha reemplazado por MediaPlayer, IMFMediaEnginey captura de audio y vídeo en Media Foundation. Esas características se han optimizado para Windows 10 y Windows 11. Microsoft recomienda encarecidamente que el nuevo código use MediaPlayer, IMFMediaEngine y captura de audio y vídeo en Media Foundation en lugar de DirectShow, siempre que sea posible. Microsoft sugiere que el código existente que usa las API heredadas se reescriba para usar las nuevas API si es posible.
Nota
Estas API están en desuso. Las aplicaciones deben usar el filtroSample Grabber o implementar un filtro personalizado para obtener datos de un gráfico de filtros DirectShow.
En el ejemplo de código siguiente se muestra cómo transmitir datos de audio mediante el IAudioMediaStream, IAudioStreamSample, IMemoryDatay interfaces de IAudioData. Por motivos de brevedad, en este ejemplo se realiza una comprobación de errores mínima.
#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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