SnapTimeSyncDynamicSinceStart

Author: pschatzmann

src/api/SnapTime.h

@@ -5,8 +5,9 @@
 #include <sys/time.h>
 
 /**
- * @brief We use the the sys/time functions to represent the server time.
+ * @brief The the sys/time functions are used to represent the server time.
  * The local time will be measured with the help of the Arduino millis() method.
+ * This class provides the basic functionality to translate between local and server time.
  * @author Phil Schatzmann
  * @version 0.1
  * @date 2023-10-28
@@ -16,24 +17,9 @@ class SnapTime {
 public:
   static SnapTime &instance() {
     static SnapTime self;
-
     return self;
   }
 
-  // Calculat the difference between 2 timeval
-  timeval timeDifference(timeval t1, timeval t2) {
-    timeval result;
-    timersub(&t1, &t2, &result);
-    return result;
-  }
-
-  // Calculat the difference between 2 timeval -> result in ms
-  uint32_t timeDifferenceMs(timeval t1, timeval t2) {
-    timeval result;
-    timersub(&t1, &t2, &result);
-    return toMillis(result);
-  }
-
   /// Provides the actual time as timeval
   timeval time() {
     timeval result;
@@ -46,12 +32,6 @@ class SnapTime {
     return result;
   }
 
-  /// Record the last time difference between client and server
-  void setTimeDifferenceClientServerMs(uint32_t diff) {
-    time_diff = diff;
-    time_update_count++;
-  }
-
   /// Provides the current server time in ms
   uint32_t serverMillis() {
     return toMillis(server_time) - server_ms + millis() -
@@ -83,12 +63,32 @@ class SnapTime {
     return true;
   }
 
+  /// Record the last time difference between client and server
+  void setTimeDifferenceClientServerMs(uint32_t diff) {
+    time_diff = diff;
+    time_update_count++;
+  }
+
   // updates the time difference between the local and server time
   void updateServerTime(timeval &server) {
     server_ms = millis();
     server_time = server;
   }
 
+  // Calculat the difference between 2 timeval
+  timeval timeDifference(timeval t1, timeval t2) {
+    timeval result;
+    timersub(&t1, &t2, &result);
+    return result;
+  }
+
+  // Calculat the difference between 2 timeval -> result in ms
+  uint32_t timeDifferenceMs(timeval t1, timeval t2) {
+    timeval result;
+    timersub(&t1, &t2, &result);
+    return toMillis(result);
+  }
+
 #ifdef ESP32
   void setupSNTPTime() {
     ESP_LOGD(TAG, "start");

src/api/SnapTimeSync.h

@@ -4,7 +4,9 @@
 #include "SnapTime.h"
 
 /**
- * @brief Abstract (Common) Time Synchronization Logic
+ * @brief Abstract (Common) Time Synchronization Logic which consists of the
+ * startup synchronization and the local to server clock synchronization which
+ * adjusts the sampling rate.
  * @author Phil Schatzmann
  * @version 0.1
  * @date 2023-10-28
@@ -17,16 +19,19 @@ class SnapTimeSync {
     setProcessingLag(processingLag);
   }
 
+  /// Starts the processing
   void begin(int rate) {
     update_count = 0;
   }
 
+  /// Records the actual server time in millisecondes
   virtual void updateServerTime(uint32_t serverMillis) = 0;
 
   /// Calculate the resampling factor: with a positive delay we play too fast
   /// and need to slow down
   virtual float getFactor() = 0;
 
+  /// Returns true if a synchronization (update of the sampling rate) is needed.
   bool isSync() {
     bool result = active && update_count > 2 && update_count % interval == 0;
     active = false;
@@ -96,7 +101,10 @@ class SnapTimeSyncDynamic : public SnapTimeSync {
     if (last_idx <=1) return 1.0;
     float timespan_local_ms = time_points[last_idx].local_ms - time_points[0].local_ms;
     float timespan_server_ms = time_points[last_idx].server_ms - time_points[0].server_ms;
-    if (timespan_local_ms == 0) return 1.0;
+    if (timespan_local_ms == 0.0 || timespan_server_ms == 0.0) {
+      ESP_LOGE(TAG, "Could not determine clock differences");
+      return 1.0;
+    }
     // if server time span is smaller then local, local runs faster and needs to be slowed down
     float result_factor = timespan_server_ms / timespan_local_ms;    
     ESP_LOGI(TAG, "=> adjusting playback speed by factor: %f", result_factor);
@@ -130,18 +138,18 @@ class SnapTimeSyncDynamicSinceStart : public SnapTimeSync {
   }
 
   float getFactor() {
-    int last_idx = time_points.size()-1;
-    if (last_idx <=1) return 1.0;
     float timespan_local_ms = current_time.local_ms - start_time.local_ms;
     float timespan_server_ms = current_time.server_ms - start_time.server_ms;
-    if (timespan_local_ms == 0) return 1.0;
+    if (timespan_local_ms == 0.0 || timespan_server_ms == 0.0) {
+      ESP_LOGE(TAG, "Could not determine clock differences");
+      return 1.0;
+    }
     // if server time span is smaller then local, local runs faster and needs to be slowed down
     float result_factor = timespan_server_ms / timespan_local_ms;    
     ESP_LOGI(TAG, "=> adjusting playback speed by factor: %f", result_factor);
     return result_factor;
   }
 protected:
-  Vector<SnapTimePoints> time_points;
   SnapTimePoints start_time;
   SnapTimePoints current_time;
 };