Multimedia Streaming Sample Code

This article provides sample code that implements the multimedia streaming interfaces. The video streaming sample code demonstrates how to read a file and render it to a primary Microsoft® DirectDraw® surface. This code has no error checking; see Use Multimedia Streaming in DirectShow Applications for a more thorough, line by line, description of the video streaming code.

The second code sample demonstrates how to use the audio streaming interfaces to stream audio data.

This article contains the following sections.

Video Streaming Sample Code
Audio Streaming Sample Code

Video Streaming Sample Code

This sample code reads a file and renders it to a primary DirectDraw surface.

#include <stdio.h>
#include "ddraw.h"       // DirectDraw interfaces
#include "mmstream.h"    // multimedia stream interfaces
#include "amstream.h"    // DirectShow multimedia stream interfaces
#include "ddstream.h"    // DirectDraw multimedia stream interfaces



void RenderStreamToSurface(IDirectDrawSurface *pSurface, 
    IMultiMediaStream *pMMStream)
{    
    IMediaStream *pPrimaryVidStream;    
    IDirectDrawMediaStream *pDDStream;
    IDirectDrawStreamSample *pSample;
    RECT rect;
    DDSURFACEDESC ddsd;

    pMMStream->GetMediaStream(MSPID_PrimaryVideo, &pPrimaryVidStream);
    pPrimaryVidStream->QueryInterface(IID_IDirectDrawMediaStream, (void **)&pDDStream);
    ddsd.dwSize = sizeof(ddsd);
    pDDStream->GetFormat(&ddsd, NULL, NULL, NULL);
    rect.top = rect.left = 0;
    rect.bottom = ddsd.dwHeight;
    rect.right = ddsd.dwWidth;
    pDDStream->CreateSample(pSurface, &rect, 0, &pSample);

    pMMStream->SetState(STREAMSTATE_RUN);
    while (pSample->Update(0, NULL, NULL, NULL) == S_OK);
    pMMStream->SetState(STREAMSTATE_STOP);

    pSample->Release();    
    pDDStream->Release();
    pPrimaryVidStream->Release();
}

void RenderFileToMMStream(const char * szFileName, 
    IMultiMediaStream **ppMMStream,
    IDirectDraw *pDD)
{    
    IAMMultiMediaStream *pAMStream;
    CoCreateInstance(CLSID_AMMultiMediaStream, NULL, CLSCTX_INPROC_SERVER,
        IID_IAMMultiMediaStream, (void **)&pAMStream);
    WCHAR    wPath[MAX_PATH];        // wide (32-bit) string name
    MultiByteToWideChar(CP_ACP, 0, szFileName, -1, wPath,
        sizeof(wPath)/sizeof(wPath[0]));    

    pAMStream->Initialize(STREAMTYPE_READ, AMMSF_NOGRAPHTHREAD, NULL);
    pAMStream->AddMediaStream(pDD, &MSPID_PrimaryVideo, 0, NULL);
    pAMStream->AddMediaStream(NULL, &MSPID_PrimaryAudio, AMMSF_ADDDEFAULTRENDERER, NULL);
    pAMStream->OpenFile(wPath, 0);    
    *ppMMStream = pAMStream;
}

int _CRTAPI1 main(int argc, char *argv[])    
{    
    if (argc < 2) {
    printf("Usage : showstrm movie.ext\n");
    exit(0);}    

    DDSURFACEDESC ddsd;
    IDirectDraw *pDD;    
    IDirectDrawSurface *pPrimarySurface;
    IMultiMediaStream *pMMStream;

    CoInitialize(NULL);
    
    DirectDrawCreate(NULL, &pDD, NULL);
    pDD->SetCooperativeLevel(GetDesktopWindow(), DDSCL_NORMAL);
    ddsd.dwSize = sizeof(ddsd);
    ddsd.dwFlags = DDSD_CAPS;
    ddsd.ddsCaps.dwCaps = DDSCAPS_PRIMARYSURFACE;
    pDD->CreateSurface(&ddsd, &pPrimarySurface, NULL);
    RenderFileToMMStream(argv[1], &pMMStream, pDD);
    RenderStreamToSurface(pPrimarySurface, pMMStream);    
    pMMStream->Release();
    pPrimarySurface->Release();    
    pDD->Release(); 
    
    CoUninitialize();
    return 0;
}

Audio Streaming Sample Code

The following code sample demonstrates how to stream audio data using the IAudioMediaStream, IAudioStreamSample, IMemoryData, and IAudioData interfaces.

#include <windows.h>
#include <mmsystem.h>
#include <amstream.h>

/********************************************************************

   Trivial wave player stuff

 ********************************************************************/

class CWaveBuffer;

class CWaveBuffer {
    public:
        CWaveBuffer();
        ~CWaveBuffer();
        BOOL Init(HWAVEOUT hWave, int Size);
        void Done();
        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;
};

/*
    CWaveBuffer
*/

CWaveBuffer::CWaveBuffer()
{
}

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::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);
}

/************************************************************

  End of wave player stuff

 ************************************************************/


HRESULT RenderStreamToDevice(IMultiMediaStream *pMMStream)
{
    WAVEFORMATEX wfx;
    #define DATA_SIZE 5000
    PBYTE pBuffer = (PBYTE)LocalAlloc(LMEM_FIXED, DATA_SIZE);

    IMediaStream *pStream;
    IAudioStreamSample *pSample;
    IAudioMediaStream *pAudioStream;
    IAudioData *pAudioData;

    pMMStream->GetMediaStream(MSPID_PrimaryAudio, &pStream);
    pStream->QueryInterface(IID_IAudioMediaStream, (void **)&pAudioStream);
    pAudioStream->GetFormat(&wfx);
    CoCreateInstance(CLSID_AMAudioData, NULL, CLSCTX_INPROC_SERVER,
                                    IID_IAudioData, (void **)&pAudioData);
    pAudioData->SetBuffer(DATA_SIZE, pBuffer, 0);
    pAudioData->SetFormat(&wfx);
    pAudioStream->CreateSample(pAudioData, 0, &pSample);
    HANDLE hEvent = CreateEvent(FALSE, NULL, NULL, FALSE);
    CWaveOut WaveOut(&wfx, 4, 2048);
    int iTimes;
    for (iTimes = 0; iTimes < 3; iTimes++) {
        DWORD dwStart = timeGetTime();
        for (; ; ) {
            HRESULT hr = pSample->Update(0, hEvent, NULL, 0);
            if (FAILED(hr) || MS_S_ENDOFSTREAM == hr) {
                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();
    pStream->Release();
    pAudioStream->Release();
    LocalFree((HLOCAL)pBuffer);

    return S_OK;
}

HRESULT RenderFileToMMStream(
    WCHAR * pszFileName, IMultiMediaStream **ppMMStream)
{
    IAMMultiMediaStream *pAMStream;
    CoCreateInstance(CLSID_AMMultiMediaStream, NULL, CLSCTX_INPROC_SERVER,
              IID_IAMMultiMediaStream, (void **)&pAMStream);
    pAMStream->Initialize(STREAMTYPE_READ, AMMSF_NOGRAPHTHREAD, NULL);
    pAMStream->AddMediaStream(NULL, &MSPID_PrimaryAudio, 0, NULL);
    pAMStream->OpenFile(pszFileName, AMMSF_RUN);
    *ppMMStream = pAMStream;
    return S_OK;
}

int _CRTAPI1 main(int argc, char *argv[])
{
    IMultiMediaStream *pMMStream;
    CoInitialize(NULL);
    WCHAR wszName[1000];
    MultiByteToWideChar(CP_ACP, 0, argv[1], -1, wszName,
        sizeof(wszName) / sizeof(wszName[0]));
    RenderFileToMMStream(wszName, &pMMStream);
    RenderStreamToDevice(pMMStream);
    pMMStream->Release();
    CoUninitialize();
    return 0;
}