Refactor/cleanup of SyncTrack and added serialization to/from json.

src/SyncTrack.h

@@ -6,57 +6,62 @@
 #define ANIMTESTBED_SYNCTRACK_H
 
 #include <cassert>
-#include <cmath>
+
-#include <iostream>
+#include "3rdparty/json/json.hpp"
 
 constexpr int cSyncTrackMaxIntervals = 8;
 
+/// Metadata used for synced animation blending.
+//
+// A SyncTrack consists of multiple SyncInterval that are adjacent to each
+// other.
+//
+// Important definitions:
+//
+// - Absolute Time: time within an animation duration in seconds.
+// - Ratio: time relative to the animations duration, e.g. 0.5 corresponds to
+//   50% of the duration.
+// - SyncTime is a floating point value where the integer parts defines the
+//   SyncInterval and the fractional part the fraction within the interval. I.e.
+//   a SyncTime of 5.332 means it is ~33% through interval 5.
+//
+// A SyncInterval is defined by a ratio of the starting point and the ratio of
+// the interval's duration.
 struct SyncTrack {
-  SyncTrack() : m_duration(0.f), m_num_intervals(0) {
+  SyncTrack() : m_duration(0.f), m_num_intervals(1) {
     for (int i = 0; i < cSyncTrackMaxIntervals; i++) {
-      m_sync_markers[i] = 0.f;
+      m_interval_start_ratio[i] = 0.f;
-      m_interval_ratio[i] = 0.f;
+      m_interval_duration_ratio[i] = 0.f;
-      m_interval_ratio[i] = 0.f;
     }
+
+    m_interval_duration_ratio[0] = 1.0f;
   }
 
   float m_duration;
   int m_num_intervals;
-  float m_sync_markers[cSyncTrackMaxIntervals];
+  float m_interval_start_ratio
-  float m_interval_start[cSyncTrackMaxIntervals];
+      [cSyncTrackMaxIntervals];  //< Starting time of interval in absolute time.
-  float m_interval_ratio[cSyncTrackMaxIntervals];
+  float m_interval_duration_ratio[cSyncTrackMaxIntervals];  //<
-
-  void CalcIntervals() {
-    if (m_num_intervals == 0) {
-      m_num_intervals = 1;
-      m_sync_markers[0] = 0.f;
-    }
-    for (int i = 0; i < m_num_intervals; i++) {
-      assert(m_sync_markers[i] >= 0.f && m_sync_markers[i] <= 1.0f);
-
-      int end_index = i < m_num_intervals - 1 ? i + 1 : 0;
-
-      m_interval_start[i] = m_sync_markers[i];
-      float interval_end = m_sync_markers[end_index];
-
-      if (interval_end < m_interval_start[i]) {
-        interval_end += 1.0f;
-      }
-
-      m_interval_ratio[i] = interval_end - m_interval_start[i];
-    }
-  }
 
   float CalcSyncFromAbsTime(float abs_time) {
-    float sync_time = fmodf(abs_time, m_duration) / m_duration;
+    for (int i = 0; i < m_num_intervals; i++) {
+      float query_abs_time = abs_time;
+      float interval_start = m_interval_start_ratio[i] * m_duration;
+      float interval_end =
+          interval_start + m_interval_duration_ratio[i] * m_duration;
 
-    int interval_index = 0;
+      if (query_abs_time < interval_start) {
-    while (sync_time >= m_interval_ratio[interval_index]) {
+        query_abs_time += m_duration;
-      sync_time -= m_interval_ratio[interval_index];
+      }
-      interval_index++;
+      if (query_abs_time >= interval_start && query_abs_time < interval_end) {
+        return float(i)
+               + (query_abs_time - interval_start)
+                     / (interval_end - interval_start);
+      }
     }
 
-    return float(interval_index) + sync_time / m_interval_ratio[interval_index];
+    assert(false && "Invalid absolute time");
+    return -1.f;
   }
 
   float CalcRatioFromSyncTime(float sync_time) {
@@ -64,8 +69,8 @@ struct SyncTrack {
     int interval = int(sync_time - interval_ratio);
 
     return fmodf(
-        m_interval_start[interval]
+        m_interval_start_ratio[interval]
-            + m_interval_ratio[interval] * interval_ratio,
+            + m_interval_duration_ratio[interval] * interval_ratio,
         1.0f);
   }
 
@@ -78,8 +83,11 @@ struct SyncTrack {
     }
 
     for (int i = 0; i < m_num_intervals; i++) {
-      if ((fabsf(m_interval_start[i] - other.m_interval_start[i]) > 1.0e-5)
+      if ((fabsf(m_interval_start_ratio[i] - other.m_interval_start_ratio[i])
-          || (fabsf(m_interval_ratio[i] - other.m_interval_ratio[i])
+           > 1.0e-5)
+          || (fabsf(
+                  m_interval_duration_ratio[i]
+                  - other.m_interval_duration_ratio[i])
               > 1.0e-5)) {
         return false;
       }
@@ -88,18 +96,40 @@ struct SyncTrack {
     return true;
   }
 
+  /** Constructs SyncTrack from markers.
+   *
+   * Markers are specified in absolute time and must be >= 0 and <= duration.
+   * They define the start of the interval. The last marker is implicitly the
+   * (possibly looped) first marker.
+   */
   static SyncTrack CreateFromMarkers(
       float duration,
-      int n_markers,
+      const std::vector<float>& markers) {
-      float markers[cSyncTrackMaxIntervals]) {
+    assert(markers.size() > 0);
+    assert(markers.size() < cSyncTrackMaxIntervals);
+
     SyncTrack result;
     result.m_duration = duration;
-    result.m_num_intervals = n_markers;
+    result.m_num_intervals = markers.size();
-    for (int i = 0; i < n_markers; i++) {
-      result.m_sync_markers[i] = markers[i];
-    }
 
-    result.CalcIntervals();
+    for (int i = 0; i < markers.size(); i++) {
+      assert(markers[i] >= 0.f && markers[i] <= duration);
+
+      int end_index = i == (markers.size() - 1) ? 0 : i + 1;
+
+      float interval_start = markers[i];
+      float interval_end = markers[end_index];
+
+      if (interval_end == interval_start) {
+        interval_end = interval_start + duration;
+      } else if (interval_end < interval_start) {
+        interval_end += duration;
+      }
+
+      result.m_interval_start_ratio[i] = interval_start / duration;
+      result.m_interval_duration_ratio[i] =
+          (interval_end - interval_start) / duration;
+    }
 
     return result;
   }
@@ -115,41 +145,62 @@ struct SyncTrack {
         (1.0f - weight) * track_A.m_duration + weight * track_B.m_duration;
 
     float interval_0_offset =
-        track_B.m_interval_start[0] - track_A.m_interval_start[0];
+        track_B.m_interval_start_ratio[0] - track_A.m_interval_start_ratio[0];
     if (interval_0_offset > 0.5f) {
       interval_0_offset = -fmodf(1.f - interval_0_offset, 1.0f);
     } else if (interval_0_offset < -0.5) {
       interval_0_offset = fmodf(1.f + interval_0_offset, 1.0f);
     }
 
-    result.m_interval_start[0] = fmodf(
+    result.m_interval_start_ratio[0] = fmodf(
-        1.0 + (1.0f - weight) * track_A.m_interval_start[0]
+        1.0 + (1.0f - weight) * track_A.m_interval_start_ratio[0]
-            + weight * (track_A.m_interval_start[0] + interval_0_offset),
+            + weight * (track_A.m_interval_start_ratio[0] + interval_0_offset),
         1.0f);
-    result.m_sync_markers[0] = result.m_interval_start[0];
 
     for (int i = 0; i < result.m_num_intervals; i++) {
-      float interval_duration_A = track_A.m_interval_ratio[i];
+      float interval_duration_A = track_A.m_interval_duration_ratio[i];
-      float interval_duration_B = track_B.m_interval_ratio[i];
+      float interval_duration_B = track_B.m_interval_duration_ratio[i];
-      result.m_interval_ratio[i] =
+      result.m_interval_duration_ratio[i] =
           (1.0f - weight) * interval_duration_A + weight * interval_duration_B;
 
       if (i < cSyncTrackMaxIntervals) {
-        result.m_interval_start[i + 1] =
+        result.m_interval_start_ratio[i + 1] =
-            result.m_interval_start[i] + result.m_interval_ratio[i];
+            result.m_interval_start_ratio[i]
-        if (result.m_interval_start[i + 1] > 1.0f) {
+            + result.m_interval_duration_ratio[i];
-          result.m_interval_start[i + 1] =
+        if (result.m_interval_start_ratio[i + 1] > 1.0f) {
-              fmodf(result.m_interval_start[i + 1], 1.0f);
+          result.m_interval_start_ratio[i + 1] =
+              fmodf(result.m_interval_start_ratio[i + 1], 1.0f);
         }
-
-        result.m_sync_markers[i + 1] = result.m_interval_start[i + 1];
       }
     }
 
-    assert (result.m_num_intervals < cSyncTrackMaxIntervals);
+    assert(result.m_num_intervals < cSyncTrackMaxIntervals);
 
     return result;
   }
 };
 
+inline void to_json(nlohmann::json& j, const SyncTrack& sync_track) {
+  j["type"] = "SyncTrack";
+  j["duration"] = sync_track.m_duration;
+  for (int i = 0; i < sync_track.m_num_intervals; i++) {
+    j["interval"][i]["start"] = sync_track.m_interval_start_ratio[i];
+    j["interval"][i]["ratio"] = sync_track.m_interval_duration_ratio[i];
+  }
+}
+
+inline void from_json(const nlohmann::json& j, SyncTrack& sync_track) {
+  assert(j["type"] == "SyncTrack");
+
+  sync_track.m_duration = j["duration"];
+
+  sync_track.m_num_intervals = j["interval"].size();
+  assert(sync_track.m_num_intervals < cSyncTrackMaxIntervals);
+
+  for (int i = 0; i < sync_track.m_num_intervals; i++) {
+    sync_track.m_interval_start_ratio[i] = j["interval"][i]["start"];
+    sync_track.m_interval_duration_ratio[i] = j["interval"][i]["ratio"];
+  }
+}
+
 #endif  //ANIMTESTBED_SYNCTRACK_H

tests/SyncTrackTests.cc

@@ -6,197 +6,228 @@
 #include "catch.hpp"
 
 TEST_CASE("Basic", "[SyncTrack]") {
-  SyncTrack track_A;
+  SyncTrack track_a;
-  track_A.m_num_intervals = 2;
+  track_a.m_num_intervals = 2;
-  track_A.m_duration = 2.0;
+  track_a.m_duration = 2.0;
-  track_A.m_interval_start[0] = 0.f;
+  track_a.m_interval_start_ratio[0] = 0.f;
-  track_A.m_interval_ratio[0] = 0.7;
+  track_a.m_interval_duration_ratio[0] = 0.7;
-  track_A.m_interval_start[1] = 0.7f;
+  track_a.m_interval_start_ratio[1] = 0.7f;
-  track_A.m_interval_ratio[1] = 0.3;
+  track_a.m_interval_duration_ratio[1] = 0.3;
 
-  SyncTrack track_B;
+  SyncTrack track_b;
-  track_B.m_num_intervals = 2;
+  track_b.m_num_intervals = 2;
-  track_B.m_duration = 1.5;
+  track_b.m_duration = 1.5;
-  track_B.m_interval_start[0] = 0.0f;
+  track_b.m_interval_start_ratio[0] = 0.0f;
-  track_B.m_interval_ratio[0] = 0.6;
+  track_b.m_interval_duration_ratio[0] = 0.6;
-  track_B.m_interval_start[1] = 0.6f;
+  track_b.m_interval_start_ratio[1] = 0.6f;
-  track_B.m_interval_ratio[1] = 0.4;
+  track_b.m_interval_duration_ratio[1] = 0.4;
 
   WHEN("Calculating sync time of track_B at 0.5 duration") {
     float sync_time_at_0_75 =
-        track_B.CalcSyncFromAbsTime(0.5 * track_B.m_duration);
+        track_b.CalcSyncFromAbsTime(0.5 * track_b.m_duration);
     REQUIRE(sync_time_at_0_75 == Catch::Detail::Approx(0.83333));
   }
 
   WHEN("Calculating sync time of track_B at 0.6 duration") {
     float sync_time_at_0_6 =
-        track_B.CalcSyncFromAbsTime(0.6 * track_B.m_duration);
+        track_b.CalcSyncFromAbsTime(0.6 * track_b.m_duration);
     REQUIRE(sync_time_at_0_6 == Catch::Detail::Approx(1.0));
   }
 
   WHEN("Calculating sync time of track_B at 0.7 duration") {
     float sync_time_at_0_7 =
-        track_B.CalcSyncFromAbsTime(0.7 * track_B.m_duration);
+        track_b.CalcSyncFromAbsTime(0.7 * track_b.m_duration);
     REQUIRE(sync_time_at_0_7 == Catch::Detail::Approx(1.25));
   }
 
   WHEN("Calculating sync time of track_B at 0.0 duration") {
     float sync_time_at_1_0 =
-        track_B.CalcSyncFromAbsTime(0.0 * track_B.m_duration);
+        track_b.CalcSyncFromAbsTime(0.0 * track_b.m_duration);
     REQUIRE(sync_time_at_1_0 == Catch::Detail::Approx(0.0));
   }
 
   WHEN("Calculating sync time of track_B at 1.0 duration") {
     float sync_time_at_1_0 =
-        track_B.CalcSyncFromAbsTime(0.9999 * track_B.m_duration);
+        track_b.CalcSyncFromAbsTime(0.9999 * track_b.m_duration);
     REQUIRE(sync_time_at_1_0 == Catch::Detail::Approx(2.0).epsilon(0.001f));
   }
 
   WHEN("Calculating ratio from sync time on track_A at 0.83333") {
-    float ratio = track_A.CalcRatioFromSyncTime(0.83333333);
+    float ratio = track_a.CalcRatioFromSyncTime(0.83333333);
     REQUIRE(ratio == Catch::Detail::Approx(0.5833333));
   }
 
   WHEN("Calculating ratio from sync time on track_A at 0.83333") {
-    float ratio = track_A.CalcRatioFromSyncTime(1.25);
+    float ratio = track_a.CalcRatioFromSyncTime(1.25);
     REQUIRE(ratio == Catch::Detail::Approx(0.775));
   }
 
   WHEN("Blending two synctracks with weight 0.") {
-    SyncTrack blended = SyncTrack::Blend(0.f, track_A, track_B);
+    SyncTrack blended = SyncTrack::Blend(0.f, track_a, track_b);
 
-    THEN("Result must equal track_A") { REQUIRE(track_A == blended); }
+    THEN("Result must equal track_A") { REQUIRE(track_a == blended); }
   }
 
   WHEN("Blending two synctracks with weight 1.") {
-    SyncTrack blended = SyncTrack::Blend(1.f, track_A, track_B);
+    SyncTrack blended = SyncTrack::Blend(1.f, track_a, track_b);
 
-    THEN("Result must equal track_B") { REQUIRE(track_B == blended); }
+    THEN("Result must equal track_B") { REQUIRE(track_b == blended); }
   }
 }
 
-TEST_CASE("Sync Marker Interval Calculation", "[SyncTrack]") {
+TEST_CASE("Sync Track From Marker", "[SyncTrack]") {
-  SyncTrack track_A;
+  SyncTrack track = SyncTrack::CreateFromMarkers(2.0f, {0.9f, 0.2f});
-  track_A.m_num_intervals = 2;
-  track_A.m_duration = 2.0;
-  track_A.m_sync_markers[0] = 0.9;
-  track_A.m_sync_markers[1] = 0.2;
 
-  WHEN("Calculating intervals") {
+  WHEN("Querying Ratios") {
-    track_A.CalcIntervals();
+    CHECK(track.m_interval_start_ratio[0] == Catch::Detail::Approx(0.45f));
+    CHECK(track.m_interval_duration_ratio[0] == Catch::Detail::Approx(0.65f));
 
-    CHECK(track_A.m_interval_start[0] == Catch::Detail::Approx(0.9f));
+    CHECK(track.m_interval_start_ratio[1] == Catch::Detail::Approx(0.1f));
-    CHECK(track_A.m_interval_ratio[0] == Catch::Detail::Approx(0.3f));
+    CHECK(track.m_interval_duration_ratio[1] == Catch::Detail::Approx(0.35f));
 
-    CHECK(track_A.m_interval_start[1] == Catch::Detail::Approx(0.2f));
+    WHEN("Querying ratio at sync time at 0.001") {
-    CHECK(track_A.m_interval_ratio[1] == Catch::Detail::Approx(0.7f));
+      float ratio = track.CalcRatioFromSyncTime(0.0001f);
+      CHECK(ratio == Catch::Detail::Approx(0.45).epsilon(0.001));
+    }
 
-    WHEN("Querying ratio at sync time at 1.001") {
+    WHEN("Querying ratio at sync time at 0.9999") {
-      float ratio = track_A.CalcRatioFromSyncTime(1.0001f);
+      float ratio = track.CalcRatioFromSyncTime(0.9999f);
-      CHECK(ratio == Catch::Detail::Approx(0.2).epsilon(0.001));
+      CHECK(ratio == Catch::Detail::Approx(0.1).epsilon(0.001));
     }
 
     WHEN("Querying ratio at sync time at 1.001") {
-      float ratio = track_A.CalcRatioFromSyncTime(0.0001f);
+      float ratio = track.CalcRatioFromSyncTime(1.0001f);
-      CHECK(ratio == Catch::Detail::Approx(0.9).epsilon(0.001));
+      CHECK(ratio == Catch::Detail::Approx(0.1).epsilon(0.001));
     }
 
     WHEN("Querying ratio at sync time at 1.9999") {
-      float ratio = track_A.CalcRatioFromSyncTime(0.9999f);
+      float ratio = track.CalcRatioFromSyncTime(1.9999f);
-      CHECK(ratio == Catch::Detail::Approx(0.2).epsilon(0.001));
+      CHECK(ratio == Catch::Detail::Approx(0.45).epsilon(0.001));
     }
   }
 
-  WHEN("Blending sync track with 3 events") {
+  WHEN("Querying SyncTime from Absolute Time") {
-    track_A.m_num_intervals = 3;
+    WHEN("Querying absolute time at 0.9001s") {
-    track_A.m_duration = 2.0;
+      float sync_time = track.CalcSyncFromAbsTime(0.9001f);
-    track_A.m_sync_markers[0] = 0.;
+      CHECK_THAT(sync_time, Catch::WithinAbs(0.0, 0.001));
-    track_A.m_sync_markers[1] = 0.3;
-    track_A.m_sync_markers[2] = 0.9;
-    track_A.CalcIntervals();
-
-    SyncTrack track_B;
-    track_B.m_num_intervals = 3;
-    track_B.m_duration = 1.5;
-    track_B.m_sync_markers[0] = 0.7;
-    track_B.m_sync_markers[1] = 0.9;
-    track_B.m_sync_markers[2] = 0.2;
-    track_B.CalcIntervals();
-
-    WHEN("Calculating A's durations") {
-      CHECK(track_A.m_interval_ratio[0] == Catch::Detail::Approx(0.3));
-      CHECK(track_A.m_interval_ratio[1] == Catch::Detail::Approx(0.6));
-      CHECK(track_A.m_interval_ratio[2] == Catch::Detail::Approx(0.1));
     }
 
-    WHEN("Calculating B's durations") {
+    WHEN("Querying absolute time at 0.2001s") {
-      CHECK(track_B.m_interval_ratio[0] == Catch::Detail::Approx(0.2));
+      float sync_time = track.CalcSyncFromAbsTime(0.2001f);
-      CHECK(track_B.m_interval_ratio[1] == Catch::Detail::Approx(0.3));
+      CHECK_THAT(sync_time, Catch::WithinAbs(1.0, 0.001));
-      CHECK(track_B.m_interval_ratio[2] == Catch::Detail::Approx(0.5));
     }
 
-    WHEN("Blending two synctracks with weight 0.") {
+    WHEN("Querying absolute time at 0.8999s") {
-      SyncTrack blended = SyncTrack::Blend(0.f, track_A, track_B);
+      float sync_time = track.CalcSyncFromAbsTime(0.8999f);
-
+      CHECK_THAT(sync_time, Catch::WithinAbs(1.999, 0.001));
-      THEN("Result must equal track_A") { REQUIRE(track_A == blended); }
     }
 
-    WHEN("Blending two synctracks with weight 1.") {
+    WHEN("Querying absolute time at 1.9999s") {
-      SyncTrack blended = SyncTrack::Blend(1.f, track_A, track_B);
+      float sync_time = track.CalcSyncFromAbsTime(1.9999f);
-
+      CHECK_THAT(sync_time, Catch::WithinAbs(0.84615384, 0.001));
-      THEN("Result must equal track_B") { REQUIRE(track_B == blended); }
     }
+  }
+}
 
-    WHEN("Blending with weight 0.2") {
+TEST_CASE("Sync Track Blending", "[SyncTrack]") {
-      float weight = 0.2f;
+  SyncTrack track_a = SyncTrack::CreateFromMarkers(2.0, {0., 0.6, 1.8});
-      SyncTrack blended = SyncTrack::Blend(weight, track_A, track_B);
+  SyncTrack track_b = SyncTrack::CreateFromMarkers(1.5f, {1.05, 1.35, 0.3});
 
-      REQUIRE(
+  WHEN("Calculating A's durations") {
-          blended.m_duration
+    CHECK(track_a.m_interval_duration_ratio[0] == Catch::Detail::Approx(0.3));
-          == (1.0f - weight) * track_A.m_duration
+    CHECK(track_a.m_interval_duration_ratio[1] == Catch::Detail::Approx(0.6));
-                 + weight * track_B.m_duration);
+    CHECK(track_a.m_interval_duration_ratio[2] == Catch::Detail::Approx(0.1));
-      REQUIRE(
+  }
-          blended.m_interval_start[0]
-          == fmodf(
-              (1.0f - weight) * (track_A.m_interval_start[0] + 1.0f)
-                  + weight * (track_B.m_interval_start[0]),
-              1.0f));
-      REQUIRE(
-          blended.m_interval_ratio[1]
-          == (1.0f - weight) * (track_A.m_interval_ratio[1])
-                  + weight * (track_B.m_interval_ratio[1])
-              );
-      REQUIRE(
-          blended.m_interval_ratio[2]
-          == (1.0f - weight) * (track_A.m_interval_ratio[2])
-                 + weight * (track_B.m_interval_ratio[2])
-      );
-    }
 
-    WHEN("Inverted blending with weight 0.2") {
+  WHEN("Calculating B's durations") {
-      float weight = 0.2f;
+    CHECK(track_b.m_interval_duration_ratio[0] == Catch::Detail::Approx(0.2));
-      SyncTrack blended = SyncTrack::Blend(weight, track_B, track_A);
+    CHECK(track_b.m_interval_duration_ratio[1] == Catch::Detail::Approx(0.3));
+    CHECK(track_b.m_interval_duration_ratio[2] == Catch::Detail::Approx(0.5));
+  }
 
-      REQUIRE(
+  WHEN("Blending two synctracks with weight 0.") {
-          blended.m_duration
+    SyncTrack blended = SyncTrack::Blend(0.f, track_a, track_b);
-          == (1.0f - weight) * track_B.m_duration
+
-                 + weight * track_A.m_duration);
+    THEN("Result must equal track_A") { REQUIRE(track_a == blended); }
-      REQUIRE(
+  }
-          blended.m_interval_start[0]
+
-          == fmodf(
+  WHEN("Blending two synctracks with weight 1.") {
-              (1.0f - weight) * (track_B.m_interval_start[0])
+    SyncTrack blended = SyncTrack::Blend(1.f, track_a, track_b);
-                  + weight * (track_A.m_interval_start[0] + 1.0f),
+
-              1.0f));
+    THEN("Result must equal track_B") { REQUIRE(track_b == blended); }
-      REQUIRE(
+  }
-          blended.m_interval_ratio[1]
+
-          == (1.0f - weight) * (track_B.m_interval_ratio[1])
+  WHEN("Blending with weight 0.2") {
-                 + weight * (track_A.m_interval_ratio[1])
+    float weight = 0.2f;
-      );
+    SyncTrack blended = SyncTrack::Blend(weight, track_a, track_b);
-      REQUIRE(
+
-          blended.m_interval_ratio[2]
+    REQUIRE(
-          == (1.0f - weight) * (track_B.m_interval_ratio[2])
+        blended.m_duration
-                 + weight * (track_A.m_interval_ratio[2])
+        == (1.0f - weight) * track_a.m_duration + weight * track_b.m_duration);
-      );
+    REQUIRE(
-    }
+        blended.m_interval_start_ratio[0]
+        == fmodf(
+            (1.0f - weight) * (track_a.m_interval_start_ratio[0] + 1.0f)
+                + weight * (track_b.m_interval_start_ratio[0]),
+            1.0f));
+    REQUIRE(
+        blended.m_interval_duration_ratio[1]
+        == (1.0f - weight) * (track_a.m_interval_duration_ratio[1])
+               + weight * (track_b.m_interval_duration_ratio[1]));
+    REQUIRE(
+        blended.m_interval_duration_ratio[2]
+        == (1.0f - weight) * (track_a.m_interval_duration_ratio[2])
+               + weight * (track_b.m_interval_duration_ratio[2]));
+  }
+
+  WHEN("Inverted blending with weight 0.2") {
+    float weight = 0.2f;
+    SyncTrack blended = SyncTrack::Blend(weight, track_b, track_a);
+
+    REQUIRE(
+        blended.m_duration
+        == (1.0f - weight) * track_b.m_duration + weight * track_a.m_duration);
+    REQUIRE(
+        blended.m_interval_start_ratio[0]
+        == fmodf(
+            (1.0f - weight) * (track_b.m_interval_start_ratio[0])
+                + weight * (track_a.m_interval_start_ratio[0] + 1.0f),
+            1.0f));
+    REQUIRE(
+        blended.m_interval_duration_ratio[1]
+        == (1.0f - weight) * (track_b.m_interval_duration_ratio[1])
+               + weight * (track_a.m_interval_duration_ratio[1]));
+    REQUIRE(
+        blended.m_interval_duration_ratio[2]
+        == (1.0f - weight) * (track_b.m_interval_duration_ratio[2])
+               + weight * (track_a.m_interval_duration_ratio[2]));
+  }
+}
+
+TEST_CASE("Serialization", "[SyncTrack]") {
+  SyncTrack track;
+  track.m_num_intervals = 3;
+  track.m_duration = 2.0;
+  track.m_interval_start_ratio[0] = 0.f;
+  track.m_interval_duration_ratio[0] = 0.7;
+  track.m_interval_start_ratio[1] = 0.7f;
+  track.m_interval_duration_ratio[1] = 0.3;
+  track.m_interval_start_ratio[2] = 0.7f;
+  track.m_interval_duration_ratio[2] = 0.3;
+
+  nlohmann::json synctrack_json = track;
+
+  const SyncTrack synctrack_deserialized = synctrack_json;
+
+  CHECK(synctrack_deserialized.m_duration == track.m_duration);
+  CHECK(synctrack_deserialized.m_num_intervals == track.m_num_intervals);
+
+  for (int i = 0; i < track.m_num_intervals; i++) {
+    CHECK(
+        synctrack_deserialized.m_interval_start_ratio[i]
+        == track.m_interval_start_ratio[i]);
+    CHECK(
+        synctrack_deserialized.m_interval_duration_ratio[i]
+        == track.m_interval_duration_ratio[i]);
   }
 }