src/filters/BaseClasses/vtrans.h

   1 //------------------------------------------------------------------------------
   2 // File: VTrans.h
   3 //
   4 // Desc: DirectShow base classes - defines a video transform class.
   5 //
   6 // Copyright (c) 1992-2002 Microsoft Corporation.  All rights reserved.
   7 //------------------------------------------------------------------------------
   8
   9
  10 // This class is derived from CTransformFilter, but is specialised to handle
  11 // the requirements of video quality control by frame dropping.
  12 // This is a non-in-place transform, (i.e. it copies the data) such as a decoder.
  13
  14 class CVideoTransformFilter : public CTransformFilter
  15 {
  16   public:
  17
  18     CVideoTransformFilter(TCHAR *, LPUNKNOWN, REFCLSID clsid);
  19     ~CVideoTransformFilter();
  20     HRESULT EndFlush();
  21
  22     // =================================================================
  23     // ----- override these bits ---------------------------------------
  24     // =================================================================
  25     // The following methods are in CTransformFilter which is inherited.
  26     // They are mentioned here for completeness
  27     //
  28     // These MUST be supplied in a derived class
  29     //
  30     // NOTE:
  31     // virtual HRESULT Transform(IMediaSample * pIn, IMediaSample *pOut);
  32     // virtual HRESULT CheckInputType(const CMediaType* mtIn) PURE;
  33     // virtual HRESULT CheckTransform
  34     //     (const CMediaType* mtIn, const CMediaType* mtOut) PURE;
  35     // static CCOMObject * CreateInstance(LPUNKNOWN, HRESULT *);
  36     // virtual HRESULT DecideBufferSize
  37     //     (IMemAllocator * pAllocator, ALLOCATOR_PROPERTIES *pprop) PURE;
  38     // virtual HRESULT GetMediaType(int iPosition, CMediaType *pMediaType) PURE;
  39     //
  40     // These MAY also be overridden
  41     //
  42     // virtual HRESULT StopStreaming();
  43     // virtual HRESULT SetMediaType(PIN_DIRECTION direction,const CMediaType *pmt);
  44     // virtual HRESULT CheckConnect(PIN_DIRECTION dir,IPin *pPin);
  45     // virtual HRESULT BreakConnect(PIN_DIRECTION dir);
  46     // virtual HRESULT CompleteConnect(PIN_DIRECTION direction,IPin *pReceivePin);
  47     // virtual HRESULT EndOfStream(void);
  48     // virtual HRESULT BeginFlush(void);
  49     // virtual HRESULT EndFlush(void);
  50     // virtual HRESULT NewSegment
  51     //     (REFERENCE_TIME tStart,REFERENCE_TIME tStop,double dRate);
  52 #ifdef PERF
  53
  54     // If you override this - ensure that you register all these ids
  55     // as well as any of your own,
  56     virtual void RegisterPerfId() {
  57         m_idSkip        = MSR_REGISTER(TEXT("Video Transform Skip frame"));
  58         m_idFrameType   = MSR_REGISTER(TEXT("Video transform frame type"));
  59         m_idLate        = MSR_REGISTER(TEXT("Video Transform Lateness"));
  60         m_idTimeTillKey = MSR_REGISTER(TEXT("Video Transform Estd. time to next key"));
  61         CTransformFilter::RegisterPerfId();
  62     }
  63 #endif
  64
  65   protected:
  66
  67     // =========== QUALITY MANAGEMENT IMPLEMENTATION ========================
  68     // Frames are assumed to come in three types:
  69     // Type 1: an AVI key frame or an MPEG I frame.
  70     //        This frame can be decoded with no history.
  71     //        Dropping this frame means that no further frame can be decoded
  72     //        until the next type 1 frame.
  73     //        Type 1 frames are sync points.
  74     // Type 2: an AVI non-key frame or an MPEG P frame.
  75     //        This frame cannot be decoded unless the previous type 1 frame was
  76     //        decoded and all type 2 frames since have been decoded.
  77     //        Dropping this frame means that no further frame can be decoded
  78     //        until the next type 1 frame.
  79     // Type 3: An MPEG B frame.
  80     //        This frame cannot be decoded unless the previous type 1 or 2 frame
  81     //        has been decoded AND the subsequent type 1 or 2 frame has also
  82     //        been decoded.  (This requires decoding the frames out of sequence).
  83     //        Dropping this frame affects no other frames.  This implementation
  84     //        does not allow for these.  All non-sync-point frames are treated
  85     //        as being type 2.
  86     //
  87     // The spacing of frames of type 1 in a file is not guaranteed.  There MUST
  88     // be a type 1 frame at (well, near) the start of the file in order to start
  89     // decoding at all.  After that there could be one every half second or so,
  90     // there could be one at the start of each scene (aka "cut", "shot") or
  91     // there could be no more at all.
  92     // If there is only a single type 1 frame then NO FRAMES CAN BE DROPPED
  93     // without losing all the rest of the movie.  There is no way to tell whether
  94     // this is the case, so we find that we are in the gambling business.
  95     // To try to improve the odds, we record the greatest interval between type 1s
  96     // that we have seen and we bet on things being no worse than this in the
  97     // future.
  98
  99     // You can tell if it's a type 1 frame by calling IsSyncPoint().
 100     // there is no architected way to test for a type 3, so you should override
 101     // the quality management here if you have B-frames.
 102
 103     int m_nKeyFramePeriod; // the largest observed interval between type 1 frames
 104                            // 1 means every frame is type 1, 2 means every other.
 105
 106     int m_nFramesSinceKeyFrame; // Used to count frames since the last type 1.
 107                                 // becomes the new m_nKeyFramePeriod if greater.
 108
 109     BOOL m_bSkipping;           // we are skipping to the next type 1 frame
 110
 111 #ifdef PERF
 112     int m_idFrameType;          // MSR id Frame type.  1=Key, 2="non-key"
 113     int m_idSkip;               // MSR id skipping
 114     int m_idLate;               // MSR id lateness
 115     int m_idTimeTillKey;        // MSR id for guessed time till next key frame.
 116 #endif
 117
 118     virtual HRESULT StartStreaming();
 119
 120     HRESULT AbortPlayback(HRESULT hr);  // if something bad happens
 121
 122     HRESULT Receive(IMediaSample *pSample);
 123
 124     HRESULT AlterQuality(Quality q);
 125
 126     BOOL ShouldSkipFrame(IMediaSample * pIn);
 127
 128     int m_itrLate;              // lateness from last Quality message
 129                                 // (this overflows at 214 secs late).
 130     int m_tDecodeStart;         // timeGetTime when decode started.
 131     int m_itrAvgDecode;         // Average decode time in reference units.
 132
 133     BOOL m_bNoSkip;             // debug - no skipping.
 134
 135     // We send an EC_QUALITY_CHANGE notification to the app if we have to degrade.
 136     // We send one when we start degrading, not one for every frame, this means
 137     // we track whether we've sent one yet.
 138     BOOL m_bQualityChanged;
 139
 140     // When non-zero, don't pass anything to renderer until next keyframe
 141     // If there are few keys, give up and eventually draw something
 142     int m_nWaitForKey;
 143 };