OboeTester: add sine wave oscillator as a reference for input

This will prevent glitches caused by the number of input and
output frames being different in the full duplex callback.

Fixes #2068

apps/OboeTester/app/src/main/cpp/FullDuplexAnalyzer.h

@@ -29,10 +29,6 @@ class FullDuplexAnalyzer : public FullDuplexStreamWithConversion {
 public:
     FullDuplexAnalyzer(LoopbackProcessor *processor)
             : mLoopbackProcessor(processor) {
-        // If we are measuring glitches then we should set this >1 to avoid input underruns.
-        // Underruns are more common when doing sample rate conversion because of the variable
-        // callback sizes.
-        setNumInputBurstsCushion(3);
     }
 
     /**

apps/OboeTester/app/src/main/cpp/analyzer/BaseSineAnalyzer.h

@@ -74,6 +74,14 @@ class BaseSineAnalyzer : public LoopbackProcessor {
         mTolerance = tolerance;
     }
 
+    // advance and wrap phase
+    void incrementInputPhase() {
+        mInputPhase += mPhaseIncrement;
+        if (mInputPhase > M_PI) {
+            mInputPhase -= (2.0 * M_PI);
+        }
+    }
+
     // advance and wrap phase
     void incrementOutputPhase() {
         mOutputPhase += mPhaseIncrement;
@@ -82,6 +90,7 @@ class BaseSineAnalyzer : public LoopbackProcessor {
         }
     }
 
+
     /**
      * @param frameData upon return, contains the reference sine wave
      * @param channelCount
@@ -142,11 +151,12 @@ class BaseSineAnalyzer : public LoopbackProcessor {
      * @param referencePhase
      * @return true if magnitude and phase updated
      */
-    bool transformSample(float sample, float referencePhase) {
-        // Track incoming signal and slowly adjust magnitude to account
-        // for drift in the DRC or AGC.
-        mSinAccumulator += static_cast<double>(sample) * sinf(referencePhase);
-        mCosAccumulator += static_cast<double>(sample) * cosf(referencePhase);
+    bool transformSample(float sample) {
+        // Compare incoming signal with the reference input sine wave.
+        mSinAccumulator += static_cast<double>(sample) * sinf(mInputPhase);
+        mCosAccumulator += static_cast<double>(sample) * cosf(mInputPhase);
+        incrementInputPhase();
+
         mFramesAccumulated++;
         // Must be a multiple of the period or the calculation will not be accurate.
         if (mFramesAccumulated == mSinePeriod) {
@@ -181,6 +191,7 @@ class BaseSineAnalyzer : public LoopbackProcessor {
     void prepareToTest() override {
         LoopbackProcessor::prepareToTest();
         mSinePeriod = getSampleRate() / kTargetGlitchFrequency;
+        mInputPhase = 0.0f;
         mOutputPhase = 0.0f;
         mInverseSinePeriod = 1.0 / mSinePeriod;
         mPhaseIncrement = 2.0 * M_PI * mInverseSinePeriod;
@@ -193,9 +204,13 @@ class BaseSineAnalyzer : public LoopbackProcessor {
     int32_t mSinePeriod = 1; // this will be set before use
     double  mInverseSinePeriod = 1.0;
     double  mPhaseIncrement = 0.0;
+    // Use two sine wave phases, input and output.
+    // This is because the number of input and output samples may differ
+    // in a callback and the output frame count may advance ahead of the input, or visa versa.
+    double  mInputPhase = 0.0;
     double  mOutputPhase = 0.0;
     double  mOutputAmplitude = 0.75;
-    // This is the phase offset between the output sine wave and the recorded
+    // This is the phase offset between the mInputPhase sine wave and the recorded
     // signal at the tuned frequency.
     // If this jumps around then we are probably just hearing noise.
     // Noise can cause the magnitude to be high but mPhaseOffset will be pretty random.

apps/OboeTester/app/src/main/cpp/analyzer/DataPathAnalyzer.h

@@ -63,7 +63,7 @@ class DataPathAnalyzer : public BaseSineAnalyzer {
         float sample = frameData[getInputChannel()];
         mInfiniteRecording.write(sample);
 
-        if (transformSample(sample, mOutputPhase)) {
+        if (transformSample(sample)) {
             // Analyze magnitude and phase on every period.
             if (mPhaseOffset != kPhaseInvalid) {
                 double diff = fabs(calculatePhaseError(mPhaseOffset, mPreviousPhaseOffset));

apps/OboeTester/app/src/main/cpp/analyzer/GlitchAnalyzer.h

@@ -229,7 +229,7 @@ class GlitchAnalyzer : public BaseSineAnalyzer {
                     // Track incoming signal and slowly adjust magnitude to account
                     // for drift in the DRC or AGC.
                     // Must be a multiple of the period or the calculation will not be accurate.
-                    if (transformSample(sample, mInputPhase)) {
+                    if (transformSample(sample)) {
                         // Adjust phase to account for sample rate drift.
                         mInputPhase += mPhaseOffset;
 
@@ -249,7 +249,6 @@ class GlitchAnalyzer : public BaseSineAnalyzer {
                         }
                     }
                 }
-                incrementInputPhase();
             } break;
 
             case STATE_GLITCHING: {
@@ -288,14 +287,6 @@ class GlitchAnalyzer : public BaseSineAnalyzer {
 
     int maxMeasurableGlitchLength() const { return 2 * mSinePeriod; }
 
-    // advance and wrap phase
-    void incrementInputPhase() {
-        mInputPhase += mPhaseIncrement;
-        if (mInputPhase > M_PI) {
-            mInputPhase -= (2.0 * M_PI);
-        }
-    }
-
     bool isOutputEnabled() override { return mState != STATE_IDLE; }
 
     void onGlitchStart() {
@@ -399,7 +390,6 @@ class GlitchAnalyzer : public BaseSineAnalyzer {
     sine_state_t  mState = STATE_IDLE;
     int64_t       mLastGlitchPosition;
 
-    double  mInputPhase = 0.0;
     double  mMaxGlitchDelta = 0.0;
     int32_t mGlitchCount = 0;
     int32_t mConsecutiveBadFrames = 0;