1 /* 2 File: AUTimestampGenerator.h 3 Abstract: Part of CoreAudio Utility Classes 4 Version: 1.1 5 6 Disclaimer: IMPORTANT: This Apple software is supplied to you by Apple 7 Inc. ("Apple") in consideration of your agreement to the following 8 terms, and your use, installation, modification or redistribution of 9 this Apple software constitutes acceptance of these terms. 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APPLE 30 MAKES NO WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION 31 THE IMPLIED WARRANTIES OF NON-INFRINGEMENT, MERCHANTABILITY AND FITNESS 32 FOR A PARTICULAR PURPOSE, REGARDING THE APPLE SOFTWARE OR ITS USE AND 33 OPERATION ALONE OR IN COMBINATION WITH YOUR PRODUCTS. 34 35 IN NO EVENT SHALL APPLE BE LIABLE FOR ANY SPECIAL, INDIRECT, INCIDENTAL 36 OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 37 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 38 INTERRUPTION) ARISING IN ANY WAY OUT OF THE USE, REPRODUCTION, 39 MODIFICATION AND/OR DISTRIBUTION OF THE APPLE SOFTWARE, HOWEVER CAUSED 40 AND WHETHER UNDER THEORY OF CONTRACT, TORT (INCLUDING NEGLIGENCE), 41 STRICT LIABILITY OR OTHERWISE, EVEN IF APPLE HAS BEEN ADVISED OF THE 42 POSSIBILITY OF SUCH DAMAGE. 43 44 Copyright (C) 2014 Apple Inc. All Rights Reserved. 45 46 */ 47 #ifndef __AUTimestampGenerator_h__ 48 #define __AUTimestampGenerator_h__ 49 50 #include <math.h> 51 #include "CAHostTimeBase.h" 52 #include <stdio.h> 53 54 #define TSGFMT "0x%10qx" 55 //#define TSGFMT "%10qd" 56 57 // This class generates a continuously increasing series of timestamps based 58 // on a series of potentially discontinuous timestamps (as can be delivered from 59 // CoreAudio in the event of an overload or major engine change). 60 // N.B.: "output" = downstream (source) timestamp 61 // "input" = upstream (derived) timestamp 62 class AUTimestampGenerator { 63 public: 64 AUTimestampGenerator(bool hostTimeDiscontinuityCorrection = false) 65 { 66 mState.mStartInputAtZero = true; 67 mState.mBypassed = false; 68 mState.mHostTimeDiscontinuityCorrection = hostTimeDiscontinuityCorrection; 69 #if DEBUG 70 mVerbosity = 0; 71 snprintf(mDebugName, sizeof(mDebugName), "tsg @ %p", this); 72 #endif 73 // CAHostTimeBase should be used instead of the calls in <CoreAudio/HostTime.h> 74 // we make this call here to ensure that this is initialized, otherwise the first time 75 // you do actually call CAHostTimeBase to do work, can be on the render thread, and lead to unwanted VM faults 76 CAHostTimeBase::GetFrequency(); 77 Reset(); 78 } 79 SetStartInputAtZero(bool b)80 void SetStartInputAtZero(bool b) { mState.mStartInputAtZero = b; } GetStartInputAtZero()81 bool GetStartInputAtZero() const { return mState.mStartInputAtZero; } 82 83 // bypassing is intended for a narrow special case. the upstream sample time will always be the same as the downstream time. SetBypassed(bool b)84 void SetBypassed(bool b) { mState.mBypassed = b; } GetBypassed()85 bool GetBypassed() const { return mState.mBypassed; } 86 87 // Call this to reset the timeline. Reset()88 void Reset() 89 { 90 mState.mCurrentInputTime.mSampleTime = 0.; 91 mState.mNextInputSampleTime = 0.; 92 mState.mCurrentOutputTime.mSampleTime = 0.; 93 mState.mNextOutputSampleTime = 0.; 94 mState.mLastOutputTime.mFlags = 0; 95 mState.mRateScalarAdj = 1.; 96 97 mFirstTime = true; 98 #if DEBUG 99 if (mVerbosity) 100 printf("%-20.20s: Reset\n", mDebugName); 101 #endif 102 } 103 104 // Call this once per render cycle with the downstream timestamp. 105 // expectedDeltaFrames is the expected difference between the current and NEXT 106 // downstream timestamps. 107 // sampleRate is the OUTPUT sample rate. 108 void AddOutputTime(const AudioTimeStamp &inTimeStamp, Float64 expectedDeltaFrames, double outputSampleRate, double rateScalarAdj=1.0); 109 110 // Call this once per render cycle to obtain the upstream timestamp. 111 // framesToAdvance is the number of frames the input timeline is to be 112 // advanced during this render cycle. 113 // sampleRate is the INPUT sample rate. 114 const AudioTimeStamp & GenerateInputTime(Float64 framesToAdvance, double inputSampleRate, bool advanceHostTime = false); 115 116 // this can be called to override the setting of the next input sample time in GenerateInputTime Advance(Float64 framesToAdvance)117 void Advance(Float64 framesToAdvance) 118 { 119 #if DEBUG 120 if (mVerbosity > 1) 121 printf("%-20.20s: ADVANCE in = " TSGFMT " advance = " TSGFMT "\n", mDebugName, (SInt64)mState.mCurrentInputTime.mSampleTime, (SInt64)framesToAdvance); 122 #endif 123 mState.mNextInputSampleTime = mState.mCurrentInputTime.mSampleTime + framesToAdvance; 124 } 125 126 struct State { 127 AudioTimeStamp mCurrentInputTime; 128 Float64 mNextInputSampleTime; 129 Float64 mNextOutputSampleTime; 130 Float64 mInputSampleTimeForOutputPull; 131 132 AudioTimeStamp mLastOutputTime; 133 AudioTimeStamp mCurrentOutputTime; 134 135 bool mStartInputAtZero; // if true, input timeline starts at 0, else it starts 136 // synced with the output timeline 137 bool mDiscontinuous; 138 bool mBypassed; 139 Float64 mDiscontinuityDeltaSamples; 140 141 double mRateScalarAdj; 142 143 bool mHostTimeDiscontinuityCorrection; // If true, propagate timestamp discontinuities using host time. 144 }; 145 GetState(State & outState)146 void GetState(State& outState) const { outState = mState; } SetState(State const & inState)147 void SetState(State const& inState) { mState = inState; mFirstTime = false; } 148 149 private: 150 151 struct State mState; 152 153 bool mFirstTime; 154 155 #if DEBUG 156 public: 157 int mVerbosity; 158 char mDebugName[64]; 159 #endif 160 }; 161 162 163 #endif // __AUTimestampGenerator_h__ 164