Method Receive

common/baseclasses/vtrans.cpp:91–322

// changes, then this base class code will do everything you need.

HRESULT CVideoTransformFilter::Receive(IMediaSample *pSample)
{
    // If the next filter downstream is the video renderer, then it may
    // be able to operate in DirectDraw mode which saves copying the data
    // and gives higher performance.  In that case the buffer which we
    // get from GetDeliveryBuffer will be a DirectDraw buffer, and
    // drawing into this buffer draws directly onto the display surface.
    // This means that any waiting for the correct time to draw occurs
    // during GetDeliveryBuffer, and that once the buffer is given to us
    // the video renderer will count it in its statistics as a frame drawn.
    // This means that any decision to drop the frame must be taken before
    // calling GetDeliveryBuffer.

    ASSERT(CritCheckIn(&m_csReceive));
    AM_MEDIA_TYPE *pmtOut, *pmt;
#ifdef DEBUG
    FOURCCMap fccOut;
#endif
    HRESULT hr;
    ASSERT(pSample);
    IMediaSample *pOutSample;

    // If no output pin to deliver to then no point sending us data
    ASSERT(m_pOutput != NULL);

    // The source filter may dynamically ask us to start transforming from a
    // different media type than the one we're using now.  If we don't, we'll
    // draw garbage. (typically, this is a palette change in the movie,
    // but could be something more sinister like the compression type changing,
    // or even the video size changing)

#define rcS1 ((VIDEOINFOHEADER *)(pmt->pbFormat))->rcSource
#define rcT1 ((VIDEOINFOHEADER *)(pmt->pbFormat))->rcTarget

    pSample->GetMediaType(&pmt);
    if (pmt != NULL && pmt->pbFormat != NULL)
    {

        // spew some debug output
        ASSERT(!IsEqualGUID(pmt->majortype, GUID_NULL));
#ifdef DEBUG
        fccOut.SetFOURCC(&pmt->subtype);
        LONG lCompression = HEADER(pmt->pbFormat)->biCompression;
        LONG lBitCount = HEADER(pmt->pbFormat)->biBitCount;
        LONG lStride = (HEADER(pmt->pbFormat)->biWidth * lBitCount + 7) / 8;
        lStride = (lStride + 3) & ~3;
        DbgLog((LOG_TRACE, 3, TEXT("*Changing input type on the fly to")));
        DbgLog((LOG_TRACE, 3, TEXT("FourCC: %lx Compression: %lx BitCount: %ld"), fccOut.GetFOURCC(), lCompression,
                lBitCount));
        DbgLog((LOG_TRACE, 3, TEXT("biHeight: %ld rcDst: (%ld, %ld, %ld, %ld)"), HEADER(pmt->pbFormat)->biHeight,
                rcT1.left, rcT1.top, rcT1.right, rcT1.bottom));
        DbgLog((LOG_TRACE, 3, TEXT("rcSrc: (%ld, %ld, %ld, %ld) Stride: %ld"), rcS1.left, rcS1.top, rcS1.right,
                rcS1.bottom, lStride));
#endif

        // now switch to using the new format.  I am assuming that the
        // derived filter will do the right thing when its media type is
        // switched and streaming is restarted.