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// File: VTrans.h
// Desc: DirectShow base classes - defines a video transform class.
// Copyright (c) 1992-2001 Microsoft Corporation. All rights reserved.
// This class is derived from CTransformFilter, but is specialised to handle
// the requirements of video quality control by frame dropping.
// This is a non-in-place transform, (i.e. it copies the data) such as a decoder.
class CVideoTransformFilter : public CTransformFilter
CVideoTransformFilter(__in_opt LPCTSTR, __inout_opt LPUNKNOWN, REFCLSID clsid);
HRESULT EndFlush();
// =================================================================
// ----- override these bits ---------------------------------------
// =================================================================
// The following methods are in CTransformFilter which is inherited.
// They are mentioned here for completeness
// These MUST be supplied in a derived class
// NOTE:
// virtual HRESULT Transform(IMediaSample * pIn, IMediaSample *pOut);
// virtual HRESULT CheckInputType(const CMediaType* mtIn) PURE;
// virtual HRESULT CheckTransform
// (const CMediaType* mtIn, const CMediaType* mtOut) PURE;
// static CCOMObject * CreateInstance(LPUNKNOWN, HRESULT *);
// virtual HRESULT DecideBufferSize
// (IMemAllocator * pAllocator, ALLOCATOR_PROPERTIES *pprop) PURE;
// virtual HRESULT GetMediaType(int iPosition, CMediaType *pMediaType) PURE;
// These MAY also be overridden
// virtual HRESULT StopStreaming();
// virtual HRESULT SetMediaType(PIN_DIRECTION direction,const CMediaType *pmt);
// virtual HRESULT CheckConnect(PIN_DIRECTION dir,IPin *pPin);
// virtual HRESULT BreakConnect(PIN_DIRECTION dir);
// virtual HRESULT CompleteConnect(PIN_DIRECTION direction,IPin *pReceivePin);
// virtual HRESULT EndOfStream(void);
// virtual HRESULT BeginFlush(void);
// virtual HRESULT EndFlush(void);
// virtual HRESULT NewSegment
// (REFERENCE_TIME tStart,REFERENCE_TIME tStop,double dRate);
#ifdef PERF
// If you override this - ensure that you register all these ids
// as well as any of your own,
virtual void RegisterPerfId() {
m_idSkip = MSR_REGISTER(TEXT("Video Transform Skip frame"));
m_idFrameType = MSR_REGISTER(TEXT("Video transform frame type"));
m_idLate = MSR_REGISTER(TEXT("Video Transform Lateness"));
m_idTimeTillKey = MSR_REGISTER(TEXT("Video Transform Estd. time to next key"));
// =========== QUALITY MANAGEMENT IMPLEMENTATION ========================
// Frames are assumed to come in three types:
// Type 1: an AVI key frame or an MPEG I frame.
// This frame can be decoded with no history.
// Dropping this frame means that no further frame can be decoded
// until the next type 1 frame.
// Type 1 frames are sync points.
// Type 2: an AVI non-key frame or an MPEG P frame.
// This frame cannot be decoded unless the previous type 1 frame was
// decoded and all type 2 frames since have been decoded.
// Dropping this frame means that no further frame can be decoded
// until the next type 1 frame.
// Type 3: An MPEG B frame.
// This frame cannot be decoded unless the previous type 1 or 2 frame
// has been decoded AND the subsequent type 1 or 2 frame has also
// been decoded. (This requires decoding the frames out of sequence).
// Dropping this frame affects no other frames. This implementation
// does not allow for these. All non-sync-point frames are treated
// as being type 2.
// The spacing of frames of type 1 in a file is not guaranteed. There MUST
// be a type 1 frame at (well, near) the start of the file in order to start
// decoding at all. After that there could be one every half second or so,
// there could be one at the start of each scene (aka "cut", "shot") or
// there could be no more at all.
// If there is only a single type 1 frame then NO FRAMES CAN BE DROPPED
// without losing all the rest of the movie. There is no way to tell whether
// this is the case, so we find that we are in the gambling business.
// To try to improve the odds, we record the greatest interval between type 1s
// that we have seen and we bet on things being no worse than this in the
// future.
// You can tell if it's a type 1 frame by calling IsSyncPoint().
// there is no architected way to test for a type 3, so you should override
// the quality management here if you have B-frames.
int m_nKeyFramePeriod; // the largest observed interval between type 1 frames
// 1 means every frame is type 1, 2 means every other.
int m_nFramesSinceKeyFrame; // Used to count frames since the last type 1.
// becomes the new m_nKeyFramePeriod if greater.
BOOL m_bSkipping; // we are skipping to the next type 1 frame
#ifdef PERF
int m_idFrameType; // MSR id Frame type. 1=Key, 2="non-key"
int m_idSkip; // MSR id skipping
int m_idLate; // MSR id lateness
int m_idTimeTillKey; // MSR id for guessed time till next key frame.
virtual HRESULT StartStreaming();
HRESULT AbortPlayback(HRESULT hr); // if something bad happens
HRESULT Receive(IMediaSample *pSample);
HRESULT AlterQuality(Quality q);
BOOL ShouldSkipFrame(IMediaSample * pIn);
int m_itrLate; // lateness from last Quality message
// (this overflows at 214 secs late).
int m_tDecodeStart; // timeGetTime when decode started.
int m_itrAvgDecode; // Average decode time in reference units.
BOOL m_bNoSkip; // debug - no skipping.
// We send an EC_QUALITY_CHANGE notification to the app if we have to degrade.
// We send one when we start degrading, not one for every frame, this means
// we track whether we've sent one yet.
BOOL m_bQualityChanged;
// When non-zero, don't pass anything to renderer until next keyframe
// If there are few keys, give up and eventually draw something
int m_nWaitForKey;