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