diff --git a/libs/ardour/ardour/region.h b/libs/ardour/ardour/region.h
index af50f1949b..615bce86d6 100644
--- a/libs/ardour/ardour/region.h
+++ b/libs/ardour/ardour/region.h
@@ -126,8 +126,8 @@ public:
 	timepos_t nt_last()    const { return end().decrement(); }
 
 	timepos_t source_position () const;
-	timepos_t source_relative_position (Temporal::timepos_t const &) const;
-	timepos_t region_relative_position (Temporal::timepos_t const &) const;
+	timecnt_t source_relative_position (Temporal::timepos_t const &) const;
+	timecnt_t region_relative_position (Temporal::timepos_t const &) const;
 
 	samplepos_t position_sample ()  const { return position().samples(); }
 	samplecnt_t start_sample ()     const { return _start.val().samples(); }
@@ -311,9 +311,7 @@ public:
 	/** Convert a timestamp in absolute time to beats measured from source start*/
 	Temporal::Beats absolute_time_to_source_beats(Temporal::timepos_t const &) const;
 
-	Temporal::Beats absolute_time_to_region_beats (Temporal::timepos_t const & b) const {
-		return position().distance (b+start()).beats ();
-	}
+	Temporal::Beats absolute_time_to_region_beats (Temporal::timepos_t const &) const;
 
 	int apply (Filter &, Progress* progress = 0);
 
diff --git a/libs/ardour/region.cc b/libs/ardour/region.cc
index 7db3cae691..07b84a84fa 100644
--- a/libs/ardour/region.cc
+++ b/libs/ardour/region.cc
@@ -2071,6 +2071,12 @@ Region::source_beats_to_absolute_beats (Temporal::Beats beats) const
 	return source_position().beats() + beats;
 }
 
+Temporal::Beats
+Region::absolute_time_to_region_beats(timepos_t const & b) const
+{
+	 return (position().distance (b)).beats () + start().beats();;
+}
+
 Temporal::timepos_t
 Region::region_beats_to_absolute_time (Temporal::Beats beats) const
 {
@@ -2087,47 +2093,41 @@ Region::source_beats_to_absolute_time (Temporal::Beats beats) const
 	return source_position() + timepos_t (beats);
 }
 
+/** Calculate  (time - source_position) in Beats
+ *
+ * Measure the distance between the absolute time and the position of
+ * the source start, in beats. The result is positive if time is later
+ * than source position.
+ *
+ * @param p is an absolute time
+ * @returns time offset from p to the region's source position as the origin in Beat units
+ */
 Temporal::Beats
-Region::absolute_time_to_source_beats(timepos_t const & time) const
+Region::absolute_time_to_source_beats(timepos_t const& p) const
 {
-	/* measure the distance between the absolute time and the position of
-	   the source start, in beats. positive if time is later than source
-	   position.
-	*/
-
-	return source_position().distance (time).beats();
+	return source_position().distance (p).beats();
 }
 
-timepos_t
+/** Calculate (pos - source-position)
+ *
+ * @param p is an absolute time
+ * @returns time offset from p to the region's source position as the origin.
+ */
+timecnt_t
 Region::source_relative_position (timepos_t const & p) const
 {
-	/* p is an absolute time, return the time with the source position as
-	   the origin.
-
-	   Note that conventionally we would return a timecnt_t, expressing a
-	   distance from the source position. But we return timepos_t for which
-	   the origin is implicit, and in this case, the origin is the region
-	   position, not zero.
-
-	   XXX this seems likely to cause problems.
-	*/
-	return p.earlier (source_position());
+	return source_position().distance (p);
 }
 
-timepos_t
+/** Calculate (p - region-position)
+ *
+ * @param p is an absolute time
+ * @returns the time offset using the region (timeline) position as origin
+ */
+timecnt_t
 Region::region_relative_position (timepos_t const & p) const
 {
-	/* p is an absolute time, return the time with the region position as
-	   the origin.
-
-	   Note that conventionally we would return a timecnt_t, expressing a
-	   distance from the region position. But we return timepos_t for which
-	   the origin is implicit, and in this case, the origin is the region
-	   position, not zero.
-
-	   XXX this seems likely to cause problems.
-	*/
-	return p.earlier (position());
+	return position().distance (p);
 }
 
 Temporal::TimeDomain