changeset 150:ebbfb154351a ClockSync

Now leveraging BBB's lock between xenomai clock and audio clock for ultra-accurate, low-latency clocking. CAVEAT: fractions of samples drifts will occurr every time the clock is changed

--- a/core/VirtualClock.cpp	Mon Sep 21 03:12:21 2015 +0100
+++ b/core/VirtualClock.cpp	Tue Sep 22 04:09:13 2015 +0100
@@ -10,41 +10,47 @@
 	double coefficients[IIR_FILTER_STAGE_COEFFICIENTS] = {
 			0.000241359049041961, 0.000482718098083923, 0.000241359049041961, -1.95557824031504, 0.956543676511203
 	};
-	iir.setNumberOfStages(4);
+	double states[4];
+	for(int n = 0; n < 4; n++){
+		states[n] = initialValueUs;
+	}
+	iir.setNumberOfStages(2);
 	iir.setCoefficients(coefficients);
-	printf("kalmanInit=%f\n",initialValueUs);
-	kalman.init(0.01, 158575.715009816 /*measured var() */,
-			initialValueUs
-//#ifdef USE_JUCE
-//			5804.98866213152 /*blockSize/Fs*1e6*/
-//#else
-//			5804.98866213152 /*blockSize/Fs*1e6*/
-//#endif
-			);
+	iir.setStates(states);
+//	printf("kalmanInit=%f\n",initialValueUs);
+//	kalman.init(0.01, 158575.715009816 /*measured var() */,	initialValueUs);
+	kalman.init(10, 1588.715009816 /*measured var() */,	initialValueUs);
 }
 	
 VirtualClock::VirtualClock(){}
 void VirtualClock::sync(){
 	sync(1);
 }
+
 void VirtualClock::sync(double numPeriods){
 	myClock_t currentTime = Clock::getTimeUs();
 	elapsedPeriods += numPeriods;
 	static int calls = 0;
 	if(calls == 0){
 		startTime = currentTime;
-//AA		lastSyncEstimatedTime = startTime;
 		lastSyncEstimatedTime = 0;
 	} else {
 		double newBlockPeriod = (currentTime - lastSyncTime);
-//		period = iir.process(movingAverage.add(newPeriod)); //TODO: replace with Kalman filter
+#ifdef USE_JUCE
 		blockPeriod = iir.process(kalman.process(newBlockPeriod));
-//		period = 22.6760958210091;
+#else
+		// this leverages the fact that on the Beaglebone the audio clock
+		// is synced to the xenomai clock.
+		// CAVEAT: we are actually drifting by fractions of a sample everytime
+		// there is a clock adjustment because we do not know exactly at what point
+		// time the clock change actually takes place
+		// Avoiding this would actually require a redesign and would anyhow produce overall
+		// less accurate results.
+		blockPeriod = numPeriods/gAudioCodec->getAudioSamplingRate()*1e6;
+#endif /* USE_JUCE */
+		//		printf("%f %f\n", blockPeriod, newBlockPeriod);
 		period = blockPeriod / numPeriods;
 		lastSyncEstimatedTime += (period * numPeriods);
-//		if(calls == 800)
-//			lastSyncEstimatedTime = lastSyncTime;
-//		printf("%lld, %lld\n", lastSyncTime, lastSyncEstimatedTime);
 	}
 	lastSyncTime = currentTime;
 //	printf("%lld\n", lastSyncTime);
@@ -79,7 +85,6 @@
 		printf("ERROR: periodOffset adjustment of %f resulted in elapsedPeriods=%f\n", periodOffset, elapsedPeriods);
 		exit(1);
 	}
-	printf("this is not called\n");
 	movingAverage.reset();
 }
 double VirtualClock::getPeriod(){

--- a/include/VirtualClock.h	Mon Sep 21 03:12:21 2015 +0100
+++ b/include/VirtualClock.h	Tue Sep 22 04:09:13 2015 +0100
@@ -9,6 +9,8 @@
 #ifdef USE_JUCE
 #else
 #include <BeagleRT.h>
+#include <I2c_Codec.h>
+extern I2c_Codec* gAudioCodec;
 #endif /* USE_JUCE */
 
 class VirtualClock{