* fixed bug in Session::follow_slave: average_slave_delta wrapped around to huge positive values when slave lags behind master (ie deltas become negative)

* enabled some debugging output in Session::follow_slave (session_process.cc), beware!


git-svn-id: svn://localhost/ardour2/branches/3.0@4027 d708f5d6-7413-0410-9779-e7cbd77b26cf

2 files changed, 20 insertions, 21 deletions

diff --git a/libs/ardour/ardour/slave.h b/libs/ardour/ardour/slave.h
index 80fac38a2a..8f217d2a46 100644
--- a/libs/ardour/ardour/slave.h
+++ b/libs/ardour/ardour/slave.h
@@ -96,8 +96,6 @@ class Slave {
 	 *   <li>
 	 *     Slave::resolution() should be greater than the maximum distance of 
 	 *     ardours transport position to the slaves requested transport position.
-	 *     (Otherwise Session:average_slave_delta will become negative, and
-	 *      the transport will move silently)
 	 *   </li>
 	 * 	 <li>Slave::locked() should return true, otherwise Session::no_roll will be called</li>
 	 * 	 <li>Slave::starting() should be false, otherwise the transport will not move until it becomes true</li>	 *   
@@ -134,8 +132,7 @@ class Slave {
 	
 	/**
 	 * @return - the timing resolution of the Slave - If the distance of ardours transport
-	 * to the slave becomes negative or greater than the resolution, sound will stop
-	 * (Session::follow_slave label silent_motion)
+	 * to the slave becomes greater than the resolution, sound will stop
 	 */
 	virtual nframes_t resolution() const = 0;
 	
diff --git a/libs/ardour/session_process.cc b/libs/ardour/session_process.cc
index 5a28fd5890..a574b8ce7d 100644
--- a/libs/ardour/session_process.cc
+++ b/libs/ardour/session_process.cc
@@ -487,7 +487,7 @@ Session::follow_slave (nframes_t nframes, nframes_t offset)
 		slave_speed = 0.0f;
 	}
 
-#if 0
+#if 1
 	cerr << "delta = " << (int) (dir * this_delta)
 	     << " speed = " << slave_speed 
 	     << " ts = " << _transport_speed 
@@ -519,18 +519,18 @@ Session::follow_slave (nframes_t nframes, nframes_t offset)
 		}
 
 		if (delta_accumulator_cnt != 0 || this_delta < _current_frame_rate) {
-			delta_accumulator[delta_accumulator_cnt++] = dir*this_delta;
+			delta_accumulator[delta_accumulator_cnt++] = long(dir) * long(this_delta);
 		}
 		
 		if (have_first_delta_accumulator) {
-			average_slave_delta = 0;
+			average_slave_delta = 0L;
 			for (int i = 0; i < delta_accumulator_size; ++i) {
 				average_slave_delta += delta_accumulator[i];
 			}
-			average_slave_delta /= delta_accumulator_size;
-			if (average_slave_delta < 0) {
+			average_slave_delta /= long(delta_accumulator_size);
+			if (average_slave_delta < 0L) {
 				average_dir = -1;
-				average_slave_delta = -average_slave_delta;
+				average_slave_delta = abs(average_slave_delta);
 			} else {
 				average_dir = 1;
 			}
@@ -606,8 +606,8 @@ Session::follow_slave (nframes_t nframes, nframes_t offset)
 					/* XXX what? */
 				}
 
-				memset (delta_accumulator, 0, sizeof (nframes_t) * delta_accumulator_size);
-				average_slave_delta = 0;
+				memset (delta_accumulator, 0, sizeof (long) * delta_accumulator_size);
+				average_slave_delta = 0L;
 				this_delta = 0;
 			}
 		}
@@ -667,18 +667,19 @@ Session::follow_slave (nframes_t nframes, nframes_t offset)
 			float adjusted_speed = slave_speed +
 				(delta / (adjust_seconds * _current_frame_rate));
 			
-			// cerr << "adjust using " << delta
-			// << " towards " << adjusted_speed
-			// << " ratio = " << adjusted_speed / slave_speed
-			// << " current = " << _transport_speed
-			// << " slave @ " << slave_speed
-			// << endl;
-			
+#if 1			
+			cerr << "adjust using " << delta
+			<< " towards " << adjusted_speed
+			<< " ratio = " << adjusted_speed / slave_speed
+			<< " current = " << _transport_speed
+			<< " slave @ " << slave_speed
+			<< endl;
+#endif			
 			request_transport_speed (adjusted_speed);
 			
 #if 1
-			if ((nframes_t) average_slave_delta > _slave->resolution()) {
-				// cerr << "not locked\n";
+			if (abs(average_slave_delta) > (long) _slave->resolution()) {
+				cerr << "average slave delta greater than slave resolution, going to silent motion\n";
 				goto silent_motion;
 			}
 #endif
@@ -733,6 +734,7 @@ Session::follow_slave (nframes_t nframes, nframes_t offset)
 
   noroll:
 	/* don't move at all */
+  cerr << "********* noroll" << endl;
 	no_roll (nframes, 0);
 	return false;
 }