diff --git a/include/halp/audio.hpp b/include/halp/audio.hpp
index 828ae49a..d2b9a7b3 100644
--- a/include/halp/audio.hpp
+++ b/include/halp/audio.hpp
@@ -201,6 +201,18 @@ struct tick
   int frames{};
 };
 
+/**
+ * Contains the info about the current audio buffer and the bar and quarter notes it's
+ * associated with, so that the musical audio rendering utilities can do their job of
+ * playing back the musical notes, etc.
+ * They need to know when we are in the score.
+ *
+ * The quarter notes have their index starting at 0.
+ * The position of the bars are in quarters. (in 4/4, the first bar has position 0.0 and the
+ * second one has a position of 4.0)
+ *
+ * This struct is usually created and destroyed thousands of times per second.
+ */
 struct tick_musical
 {
   /**
@@ -218,18 +230,41 @@ struct tick_musical
     int denom;
   } signature;
 
+  /** 
+   * The total number of samples since the beginning of the playback of the score.
+   */
   int64_t position_in_frames{};
 
+  /**
+   * Playback time since the beginning of the score.
+   */
   double position_in_nanoseconds{};
 
-  // Quarter note of the first sample in the buffer
+  /**
+   * Quarter note of the first sample in this buffer
+   * This is a double.
+   *
+   * The first quarter note in a score has index 0.
+   *
+   * For example:
+   * - 3.95 would be slightly before the 2nd bar.
+   * - 4.05 would be slightly after the beginning of the 2nd bar.
+   */
   quarter_note start_position_in_quarters{};
 
-  // Quarter note of the first sample in the next buffer
-  // (or one past the last sample of this buffer, e.g. a [closed; open) interval like C++ begin / end)
+  /**
+   * Quarter note of the first sample in the next buffer
+   * (or one past the last sample of this buffer, e.g. a [closed; open) interval like C++ begin / end)
+   */
   quarter_note end_position_in_quarters{};
 
-  // Position of the last signature change in quarter notes (at the start of the tick)
+  /**
+   * Position of the last signature change in quarter notes (at the start of the tick)
+   *
+   * For example: 0.0 if the signature never changes in the score.
+   * If we change the time signature at some, we'll give it the index (in quarter) of the
+   * bar when it last changed.
+   */
   quarter_note last_signature_change{};
 
   // Position of the last bar relative to start in quarter notes
diff --git a/tests/objects/patternal.cpp b/tests/objects/patternal.cpp
index dcac97fc..c04763ff 100644
--- a/tests/objects/patternal.cpp
+++ b/tests/objects/patternal.cpp
@@ -39,9 +39,9 @@ TEST_CASE("The input pattern is stored correctly", "[advanced][patternal]")
 
   // Create the input pattern:
   patternalProcessor.inputs.patterns.value = {
-    (Pattern) {42, {127, 127, 127, 127}}, // hi-hat
-    (Pattern) {38, {0, 127, 0, 127}}, // snare
-    (Pattern) {35, {127, 0, 127, 0}}, // bass drum
+    {42, {127, 127, 127, 127}}, // hi-hat
+    {38, {0, 127, 0, 127}}, // snare
+    {35, {127, 0, 127, 0}}, // bass drum
   };
 
   // Check that the input pattern is stored correctly:
@@ -71,13 +71,13 @@ TEST_CASE("MIDI messages are output properly", "[advanced][patternal]")
   static constexpr double tickDuration = samplingRate / bufferSize; // seconds
   static constexpr double ticksPerSecond = 1.0 / tickDuration;
   static constexpr double testDuration = 3.0; // seconds
-  static constexpr double NS_PER_S = 1000000;
+  static constexpr double NS_PER_S = 1000000000;
 
   Processor patternalProcessor;
   patternalProcessor.inputs.patterns.value = {
-    (Pattern) {noteHiHat, {127, 127, 127, 127}}, // hi-hat
-    (Pattern) {noteSnare, {0, 127, 0, 127}}, // snare
-    (Pattern) {noteBassDrum, {127, 0, 127, 0}}, // bass drum
+    {noteHiHat, {127, 127, 127, 127}}, // hi-hat
+    {noteSnare, {0, 127, 0, 127}}, // snare
+    {noteBassDrum, {127, 0, 127, 0}}, // bass drum
   };
 
   // Check the output on each tick:
@@ -90,16 +90,22 @@ TEST_CASE("MIDI messages are output properly", "[advanced][patternal]")
     // INFO("Test tick " << tickIndex);
     pos_in_frames += bufferSize;
     pos_in_ns += tickDuration / NS_PER_S;
+    double timeNow = tickIndex * tickDuration;
+    double timeAtEndOfTick = (tickIndex + 1) * tickDuration;
+
     tick_musical tk;
-    // TODO tk.start_position_quarter = 
-    // TODO tk.end_position_quarter = 
     tk.tempo = 120; // 120 BPM. One beat lasts 500 ms.
     tk.signature.num = 4;
     tk.signature.denom = 4;
     tk.frames = bufferSize;
-    tk.position_in_nanoseconds = pos_in_ns;
+    tk.position_in_nanoseconds = pos_in_ns; // We don't really need to set this pos in ns.
     tk.position_in_frames = pos_in_frames;
-    double timeNow = tickIndex * tickDuration;
+    tk.last_signature_change = 0; // The signature never changes.
+    tk.start_position_in_quarters = TODO;
+    tk.end_position_in_quarters = TODO;
+    tk.bar_at_start = TODO;
+    tk.bar_at_end = TODO;
+
     patternalProcessor(tk);
 
     // Test the 1st tick:
@@ -140,9 +146,5 @@ TEST_CASE("MIDI messages are output properly", "[advanced][patternal]")
     }
     // TODO: check the other ticks
   }
-
-  // TODO check somethig with:
-  // - start_position_quarter
-  // - last_signature_change
 }