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Using the Demux with PSI Streams

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[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 It has been superseded by MediaPlayer, IMFMediaEngine, and Audio/Video Capture in Media Foundation.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.]

To get PSI information from an MPEG-2 transport stream using the MPEG-2 demux filter, create an output pin on the demux with the following media type:

  • Major type: KSDATAFORMAT_TYPE_MPEG2_SECTIONS
  • Subtype: MEDIASUBTYPE_None
  • Format type: GUID_NULL

Then call the output pin's IMPEG2PIDMap::MapPID method with the desired PID and the flag MEDIA_MPEG2_PSI.

// Query the demux filter for IMpeg2Demultiplexer.
IMpeg2Demultiplexer *pDemux = NULL;
hr = pFilter->QueryInterface(IID_IMpeg2Demultiplexer, (void**)&pDemux);
if (SUCCEEDED(hr))
{
    // Define the media type.
    AM_MEDIA_TYPE mt;
    ZeroMemory(&mt, sizeof(AM_MEDIA_TYPE));
    mt.majortype = KSDATAFORMAT_TYPE_MPEG2_SECTIONS;
    mt.subtype = MEDIASUBTYPE_None;

    // Create a new output pin.
    IPin *pPin;
    hr = pDemux->CreateOutputPin(&mt, L"PSI Pin", &pPin);
    if (SUCCEEDED(hr))
    {
        // Map the PID.
        IMPEG2PIDMap *pPidMap = NULL;
        hr = pPin->QueryInterface(IID_IMPEG2PIDMap, (void**)&pPidMap);
        if (SUCCEEDED(hr))
        {
            ULONG Pid[] = { 0x00 }; // Map any desired PIDs. 
            ULONG cPid = 1;
            hr = pPidMap->MapPID(cPid, Pid, MEDIA_MPEG2_PSI);
            pPidMap->Release();
        }
        pPin->Release();
    }
    pDemux->Release();
}

Each complete PSI section is delivered in one media sample. To retrieve the PID number associated with a table section, call IMediaSample2::GetProperties on the media sample. The PID is given in the low 13 bits of the dwTypeSpecificFlags flag in the AM_SAMPLE2_PROPERTIES structure. This is useful if you map multiple PSI PIDs to the same output pin.

Using the MPEG-2 Demultiplexer