From daccb8378485bed273db268cc08160be17164338 Mon Sep 17 00:00:00 2001
From: Philip Rosedale <philip@coffeeandpower.com>
Date: Mon, 4 Feb 2013 12:49:12 -0800
Subject: [PATCH] Added Stdev class to until

---
 Source/Audio.cpp | 33 ++++++++++++++++++++++-----------
 Source/Util.cpp  | 45 +++++++++++++++++++++++++++++++++++++++++++--
 Source/Util.h    | 13 +++++++++++++
 3 files changed, 78 insertions(+), 13 deletions(-)

diff --git a/Source/Audio.cpp b/Source/Audio.cpp
index 700ed438b4..37c2e9b69a 100644
--- a/Source/Audio.cpp
+++ b/Source/Audio.cpp
@@ -41,10 +41,7 @@ const int AUDIO_UDP_LISTEN_PORT = 55444;
 
 int starve_counter = 0;
 
-//  Stuff used to compute the standard deviation of the sample
-int stdev_counter = 0;
-float stdev_variance[1000];                    //  Difference between when last two packets received
-float stdev_value;
+StDev stdev;
 
 #define LOG_SAMPLE_DELAY 1
 
@@ -226,14 +223,28 @@ void *receiveAudioViaUDP(void *args) {
     
     while (true) {
         if (sharedAudioData->audioSocket->receive((void *)receivedData, receivedBytes)) {
-            gettimeofday(&currentReceiveTime, NULL);
-            
-            
-            if (LOG_SAMPLE_DELAY) {
-                // write time difference (in microseconds) between packet receipts to file
-                double timeDiff = diffclock(previousReceiveTime, currentReceiveTime);
 
-                logFile << timeDiff << std::endl;
+            bool firstSample = (currentReceiveTime.tv_sec == 0);
+            
+            gettimeofday(&currentReceiveTime, NULL);
+
+            if (LOG_SAMPLE_DELAY) {
+                if (!firstSample) {
+                    // write time difference (in microseconds) between packet receipts to file
+                    double timeDiff = diffclock(previousReceiveTime, currentReceiveTime);
+                    logFile << timeDiff << std::endl;
+                }
+            }
+            
+            //  Compute standard deviation for jitter
+            if (firstSample) {
+                stdev.reset();
+            } else {
+                stdev.addValue(diffclock(previousReceiveTime, currentReceiveTime));
+                if (stdev.getSamples() > 300) {
+                    printf("Avg: %4.2f, Stdev: %4.2f\n", stdev.getAverage(), stdev.getStDev());
+                    stdev.reset();
+                }
             }
             
             AudioRingBuffer *ringBuffer = sharedAudioData->ringBuffer;
diff --git a/Source/Util.cpp b/Source/Util.cpp
index 74cfb4b41d..6eedd863b8 100644
--- a/Source/Util.cpp
+++ b/Source/Util.cpp
@@ -14,6 +14,47 @@
 #include <iostream>
 #include "world.h"
 #include "glm.hpp"
+#include "util.h"
+
+
+const int MAX_STDEV_SAMPLES = 1000;
+
+StDev::StDev() {
+    data = new float[MAX_STDEV_SAMPLES];
+    sampleCount = 0;
+}
+
+void StDev::reset() {
+    sampleCount = 0;
+}
+
+void StDev::addValue(float v) {
+    data[sampleCount++] = v;
+    if (sampleCount == MAX_STDEV_SAMPLES) sampleCount = 0;
+}
+
+float StDev::getAverage() {
+    float average = 0;
+    for (int i = 0; i < sampleCount; i++) {
+        average += data[i];
+    }
+    if (sampleCount > 0)
+        return average/(float)sampleCount;
+    else return 0;
+}
+
+float StDev::getStDev() {
+    float average = getAverage();
+    float stdev = 0;
+    for (int i = 0; i < sampleCount; i++) {
+        stdev += powf(data[i] - average, 2);
+    }
+    if (sampleCount > 0)
+        return sqrt(stdev/(float)sampleCount);
+    else
+        return 0;
+}
+
 
 float randFloat () {
     return (rand()%10000)/10000.f;
@@ -101,7 +142,7 @@ double diffclock(timeval clock1,timeval clock2)
 }
 
 void drawtext(int x, int y, float scale, float rotate, float thick, int mono, char *string, 
-              float r=1.0, float g=1.0, float b=1.0)
+              float r, float g, float b)
 {
     //
     //  Draws text on screen as stroked so it can be resized
@@ -126,7 +167,7 @@ void drawtext(int x, int y, float scale, float rotate, float thick, int mono, ch
 
 
 void drawvec3(int x, int y, float scale, float rotate, float thick, int mono, glm::vec3 vec, 
-              float r=1.0, float g=1.0, float b=1.0)
+              float r, float g, float b)
 {
     //
     //  Draws text on screen as stroked so it can be resized
diff --git a/Source/Util.h b/Source/Util.h
index 0074ff9994..594983972b 100644
--- a/Source/Util.h
+++ b/Source/Util.h
@@ -24,4 +24,17 @@ void drawvec3(int x, int y, float scale, float rotate, float thick, int mono, gl
               float r=1.0, float g=1.0, float b=1.0);
 double diffclock(timeval clock1,timeval clock2);
 
+class StDev {
+public:
+    StDev();
+    void reset();
+    void addValue(float v);
+    float getAverage();
+    float getStDev();
+    int getSamples() {return sampleCount;};
+private:
+    float * data;
+    int sampleCount = 0;
+};
+
 #endif