vtrans.cpp

用DirectX制作高级动画-[Advanced.Animation.with.DirectX]

            pOutSample->Release();
	    AbortPlayback(hr);
            return hr;
	}
    }

    // After a discontinuity, we need to wait for the next key frame
    if (pSample->IsDiscontinuity() == S_OK) {
        DbgLog((LOG_TRACE,3,TEXT("Non-key discontinuity - wait for keyframe")));
	m_nWaitForKey = 30;
    }

    // Start timing the transform (and log it if PERF is defined)

    if (SUCCEEDED(hr)) {
        m_tDecodeStart = timeGetTime();
        MSR_START(m_idTransform);

        // have the derived class transform the data
        hr = Transform(pSample, pOutSample);

        // Stop the clock (and log it if PERF is defined)
        MSR_STOP(m_idTransform);
        m_tDecodeStart = timeGetTime()-m_tDecodeStart;
        m_itrAvgDecode = m_tDecodeStart*(10000/16) + 15*(m_itrAvgDecode/16);

        // Maybe we're waiting for a keyframe still?
        if (m_nWaitForKey)
            m_nWaitForKey--;
        if (m_nWaitForKey && pSample->IsSyncPoint() == S_OK)
	    m_nWaitForKey = FALSE;

        // if so, then we don't want to pass this on to the renderer
        if (m_nWaitForKey && hr == NOERROR) {
            DbgLog((LOG_TRACE,3,TEXT("still waiting for a keyframe")));
	    hr = S_FALSE;
	}
    }

    if (FAILED(hr)) {
        DbgLog((LOG_TRACE,1,TEXT("Error from video transform")));
    } else {
        // the Transform() function can return S_FALSE to indicate that the
        // sample should not be delivered; we only deliver the sample if it's
        // really S_OK (same as NOERROR, of course.)
        // Try not to return S_FALSE to a direct draw buffer (it's wasteful)
        // Try to take the decision earlier - before you get it.

        if (hr == NOERROR) {
    	    hr = m_pOutput->Deliver(pOutSample);
        } else {
            // S_FALSE returned from Transform is a PRIVATE agreement
            // We should return NOERROR from Receive() in this case because returning S_FALSE
            // from Receive() means that this is the end of the stream and no more data should
            // be sent.
            if (S_FALSE == hr) {

                //  We must Release() the sample before doing anything
                //  like calling the filter graph because having the
                //  sample means we may have the DirectDraw lock
                //  (== win16 lock on some versions)
                pOutSample->Release();
                m_bSampleSkipped = TRUE;
                if (!m_bQualityChanged) {
                    m_bQualityChanged = TRUE;
                    NotifyEvent(EC_QUALITY_CHANGE,0,0);
                }
                return NOERROR;
            }
        }
    }

    // release the output buffer. If the connected pin still needs it,
    // it will have addrefed it itself.
    pOutSample->Release();
    ASSERT(CritCheckIn(&m_csReceive));

    return hr;
}



BOOL CVideoTransformFilter::ShouldSkipFrame( IMediaSample * pIn)
{
    REFERENCE_TIME trStart, trStopAt;
    HRESULT hr = pIn->GetTime(&trStart, &trStopAt);

    // Don't skip frames with no timestamps
    if (hr != S_OK)
	return FALSE;

    int itrFrame = (int)(trStopAt - trStart);  // frame duration

    if(S_OK==pIn->IsSyncPoint()) {
        MSR_INTEGER(m_idFrameType, 1);
        if ( m_nKeyFramePeriod < m_nFramesSinceKeyFrame ) {
            // record the max
            m_nKeyFramePeriod = m_nFramesSinceKeyFrame;
        }
        m_nFramesSinceKeyFrame = 0;
        m_bSkipping = FALSE;
    } else {
        MSR_INTEGER(m_idFrameType, 2);
        if (  m_nFramesSinceKeyFrame>m_nKeyFramePeriod
           && m_nKeyFramePeriod>0
           ) {
            // We haven't seen the key frame yet, but we were clearly being
            // overoptimistic about how frequent they are.
            m_nKeyFramePeriod = m_nFramesSinceKeyFrame;
        }
    }


    // Whatever we might otherwise decide,
    // if we are taking only a small fraction of the required frame time to decode
    // then any quality problems are actually coming from somewhere else.
    // Could be a net problem at the source for instance.  In this case there's
    // no point in us skipping frames here.
    if (m_itrAvgDecode*4>itrFrame) {

        // Don't skip unless we are at least a whole frame late.
        // (We would skip B frames if more than 1/2 frame late, but they're safe).
        if ( m_itrLate > itrFrame ) {

            // Don't skip unless the anticipated key frame would be no more than
            // 1 frame early.  If the renderer has not been waiting (we *guess*
            // it hasn't because we're late) then it will allow frames to be
            // played early by up to a frame.

            // Let T = Stream time from now to anticipated next key frame
            // = (frame duration) * (KeyFramePeriod - FramesSinceKeyFrame)
            // So we skip if T - Late < one frame  i.e.
            //   (duration) * (freq - FramesSince) - Late < duration
            // or (duration) * (freq - FramesSince - 1) < Late

            // We don't dare skip until we have seen some key frames and have
            // some idea how often they occur and they are reasonably frequent.
            if (m_nKeyFramePeriod>0) {
                // It would be crazy - but we could have a stream with key frames
                // a very long way apart - and if they are further than about
                // 3.5 minutes apart then we could get arithmetic overflow in
                // reference time units.  Therefore we switch to mSec at this point
                int it = (itrFrame/10000)
                         * (m_nKeyFramePeriod-m_nFramesSinceKeyFrame -  1);
                MSR_INTEGER(m_idTimeTillKey, it);

                // For debug - might want to see the details - dump them as scratch pad
#ifdef VTRANSPERF
                MSR_INTEGER(0, itrFrame);
                MSR_INTEGER(0, m_nFramesSinceKeyFrame);
                MSR_INTEGER(0, m_nKeyFramePeriod);
#endif
                if (m_itrLate/10000 > it) {
                    m_bSkipping = TRUE;
                    // Now we are committed.  Once we start skipping, we
                    // cannot stop until we hit a key frame.
                } else {
#ifdef VTRANSPERF
                    MSR_INTEGER(0, 777770);  // not near enough to next key
#endif
                }
            } else {
#ifdef VTRANSPERF
                MSR_INTEGER(0, 777771);  // Next key not predictable
#endif
            }
        } else {
#ifdef VTRANSPERF
            MSR_INTEGER(0, 777772);  // Less than one frame late
            MSR_INTEGER(0, m_itrLate);
            MSR_INTEGER(0, itrFrame);
#endif
        }
    } else {
#ifdef VTRANSPERF
        MSR_INTEGER(0, 777773);  // Decode time short - not not worth skipping
        MSR_INTEGER(0, m_itrAvgDecode);
        MSR_INTEGER(0, itrFrame);
#endif
    }

    ++m_nFramesSinceKeyFrame;

    if (m_bSkipping) {
        // We will count down the lateness as we skip each frame.
        // We re-assess each frame.  The key frame might not arrive when expected.
        // We reset m_itrLate if we get a new Quality message, but actually that's
        // not likely because we're not sending frames on to the Renderer.  In
        // fact if we DID get another one it would mean that there's a long
        // pipe between us and the renderer and we might need an altogether
        // better strategy to avoid hunting!
        m_itrLate = m_itrLate - itrFrame;
    }

    MSR_INTEGER(m_idLate, (int)m_itrLate/10000 ); // Note how late we think we are
    if (m_bSkipping) {
        if (!m_bQualityChanged) {
            m_bQualityChanged = TRUE;
            NotifyEvent(EC_QUALITY_CHANGE,0,0);
        }
    }
    return m_bSkipping;
}


HRESULT CVideoTransformFilter::AlterQuality(Quality q)
{
    // to reduce the amount of 64 bit arithmetic, m_itrLate is an int.
    // +, -, >, == etc  are not too bad, but * and / are painful.
    if (m_itrLate>300000000) {
        // Avoid overflow and silliness - more than 30 secs late is already silly
        m_itrLate = 300000000;
    } else {
        m_itrLate = (int)q.Late;
    }
    // We ignore the other fields

    // We're actually not very good at handling this.  In non-direct draw mode
    // most of the time can be spent in the renderer which can skip any frame.
    // In that case we'd rather the renderer handled things.
    // Nevertheless we will keep an eye on it and if we really start getting
    // a very long way behind then we will actually skip - but we'll still tell
    // the renderer (or whoever is downstream) that they should handle quality.

    return E_FAIL;     // Tell the renderer to do his thing.

}



// This will avoid several hundred useless warnings if compiled -W4 by MS VC++ v4
#pragma warning(disable:4514)