+ /* TODO investigate and think:
+ *
+ * Does it makes sense to keep track of notes
+ * that are skipped (because they're either too late
+ * (underrun) or never used (read-ahead, loop) ?
+ *
+ * skip_to() is called on the rinbuffer between
+ * disk and process. it seems wrong to track them
+ * (a potential synth never sees skipped notes, either)
+ * but there may be more to this.
+ */
+