Voorbeeldcode voor audiostreaming

[De functie die is gekoppeld aan deze pagina, DirectShow, is een verouderde functie. Het is vervangen door MediaPlayer, IMFMediaEngineen Audio/Video Capture in Media Foundation. Deze functies zijn geoptimaliseerd voor Windows 10 en Windows 11. Microsoft raadt ten zeerste aan om nieuwe code te gebruiken MediaPlayer, IMFMediaEngine en Audio/Video Capture in Media Foundation in plaats van DirectShow, indien mogelijk. Microsoft stelt voor dat bestaande code die gebruikmaakt van de verouderde API's, indien mogelijk opnieuw worden geschreven om de nieuwe API's te gebruiken.]

In het volgende codevoorbeeld ziet u hoe u audiogegevens streamt met behulp van de IAudioMediaStream, IAudioStreamSample, IMemoryDataen IAudioData interfaces. Voor kortheid voert dit voorbeeld minimale foutcontrole uit.

#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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voorbeeldcode voor multimediastreaming