Jamoma API  0.6.0.a19
AUTimestampGenerator.h
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41 #ifndef __AUTimestampGenerator_h__
42 #define __AUTimestampGenerator_h__
43 
44 #include <math.h>
45 #include "CAHostTimeBase.h"
46 #include <stdio.h>
47 
48 #define TSGFMT "0x%10qx"
49 //#define TSGFMT "%10qd"
50 
51 // This class generates a continuously increasing series of timestamps based
52 // on a series of potentially discontinuous timestamps (as can be delivered from
53 // CoreAudio in the event of an overload or major engine change).
54 // N.B.: "output" = downstream (source) timestamp
55 // "input" = upstream (derived) timestamp
56 class AUTimestampGenerator {
57 public:
58  AUTimestampGenerator(bool hostTimeDiscontinuityCorrection = false) :
59  mStartInputAtZero(true),
60  mBypassed(false),
61  mHostTimeDiscontinuityCorrection(hostTimeDiscontinuityCorrection)
62  {
63 #if DEBUG
64  mVerbosity = 0;
65  sprintf(mDebugName, "tsg @ %p", this);
66 #endif
67  // CAHostTimeBase should be used instead of the calls in <CoreAudio/HostTime.h>
68  // we make this call here to ensure that this is initialized, otherwise the first time
69  // you do actually call CAHostTimeBase to do work, can be on the render thread, and lead to unwanted VM faults
70  CAHostTimeBase::GetFrequency();
71  Reset();
72  }
73 
74  void SetStartInputAtZero(bool b) { mStartInputAtZero = b; }
75  bool GetStartInputAtZero() const { return mStartInputAtZero; }
76 
77  // bypassing is intended for a narrow special case. the upstream sample time will always be the same as the downstream time.
78  void SetBypassed(bool b) { mBypassed = b; }
79  bool GetBypassed() const { return mBypassed; }
80 
81  // Call this to reset the timeline.
82  void Reset()
83  {
84  mCurrentInputTime.mSampleTime = 0.;
85  mNextInputSampleTime = 0.;
86  mCurrentOutputTime.mSampleTime = 0.;
87  mNextOutputSampleTime = 0.;
88  mLastOutputTime.mFlags = 0;
89  mRateScalarAdj = 1.;
90  mFirstTime = true;
91 #if DEBUG
92  if (mVerbosity)
93  printf("%-20.20s: Reset\n", mDebugName);
94 #endif
95  }
96 
97  // Call this once per render cycle with the downstream timestamp.
98  // expectedDeltaFrames is the expected difference between the current and NEXT
99  // downstream timestamps.
100  // sampleRate is the OUTPUT sample rate.
101  void AddOutputTime(const AudioTimeStamp &inTimeStamp, Float64 expectedDeltaFrames, double outputSampleRate, double rateScalarAdj=1.0);
102 
103  // Call this once per render cycle to obtain the upstream timestamp.
104  // framesToAdvance is the number of frames the input timeline is to be
105  // advanced during this render cycle.
106  // sampleRate is the INPUT sample rate.
107  const AudioTimeStamp & GenerateInputTime(Float64 framesToAdvance, double inputSampleRate);
108 
109  // this can be called to override the setting of the next input sample time in GenerateInputTime
110  void Advance(Float64 framesToAdvance)
111  {
112 #if DEBUG
113  if (mVerbosity > 1)
114  printf("%-20.20s: ADVANCE in = "TSGFMT" advance = "TSGFMT"\n", mDebugName, (SInt64)mCurrentInputTime.mSampleTime, (SInt64)framesToAdvance);
115 #endif
116  mNextInputSampleTime = mCurrentInputTime.mSampleTime + framesToAdvance;
117  }
118 
119 
120 private:
121  AudioTimeStamp mCurrentInputTime;
122  Float64 mNextInputSampleTime;
123  Float64 mNextOutputSampleTime;
124 
125  AudioTimeStamp mLastOutputTime;
126  AudioTimeStamp mCurrentOutputTime;
127 
128  bool mFirstTime;
129  bool mStartInputAtZero; // if true, input timeline starts at 0, else it starts
130  // synced with the output timeline
131  bool mDiscontinuous;
132  bool mBypassed;
133  Float64 mDiscontinuityDeltaSamples;
134 
135  double mRateScalarAdj;
136 
137  bool mHostTimeDiscontinuityCorrection; // If true, propagate timestamp discontinuities using host time.
138 
139 
140 #if DEBUG
141 public:
142  int mVerbosity;
143  char mDebugName[64];
144 #endif
145 };
146 
147 
148 #endif // __AUTimestampGenerator_h__