From 9e9cb3bf31a8cbf00ecf43ea0c3acd8b8bb86760 Mon Sep 17 00:00:00 2001
From: Paul Davis <paul@linuxaudiosystems.com>
Date: Tue, 1 Dec 2009 18:32:29 +0000
Subject: adjust to use timestamped MTC messages

git-svn-id: svn://localhost/ardour2/branches/3.0@6255 d708f5d6-7413-0410-9779-e7cbd77b26cf
---
 libs/ardour/ardour/slave.h     |  4 ++--
 libs/ardour/mtc_slave.cc       | 35 ++++++++++++++++++++---------------
 libs/ardour/session_process.cc |  6 ++++--
 3 files changed, 26 insertions(+), 19 deletions(-)

diff --git a/libs/ardour/ardour/slave.h b/libs/ardour/ardour/slave.h
index af69348d4e..16e11097ea 100644
--- a/libs/ardour/ardour/slave.h
+++ b/libs/ardour/ardour/slave.h
@@ -245,8 +245,8 @@ class MTC_Slave : public Slave, public sigc::trackable {
 	bool    have_first_accumulated_speed;
 
 	void reset ();
-	void update_mtc_qtr (MIDI::Parser&, int);
-	void update_mtc_time (const MIDI::byte *, bool);
+	void update_mtc_qtr (MIDI::Parser&, int, nframes_t);
+	void update_mtc_time (const MIDI::byte *, bool, nframes_t);
 	void update_mtc_status (MIDI::Parser::MTC_Status);
 	void read_current (SafeTime *) const;
 	double compute_apparent_speed (nframes64_t);
diff --git a/libs/ardour/mtc_slave.cc b/libs/ardour/mtc_slave.cc
index b8e2693622..4ca86236b7 100644
--- a/libs/ardour/mtc_slave.cc
+++ b/libs/ardour/mtc_slave.cc
@@ -74,10 +74,8 @@ MTC_Slave::rebind (MIDI::Port& p)
 }
 
 void
-MTC_Slave::update_mtc_qtr (Parser& /*p*/, int which_qtr)
+MTC_Slave::update_mtc_qtr (Parser& /*p*/, int which_qtr, nframes_t now)
 {
-	nframes64_t now = session.engine().frame_time();
-
 	DEBUG_TRACE (DEBUG::MTC, string_compose ("qtr frame %1 at %2, valid-for-time? %3\n", which_qtr, now, qtr_frame_messages_valid_for_time));
 
 	if (qtr_frame_messages_valid_for_time) {
@@ -109,9 +107,12 @@ MTC_Slave::update_mtc_qtr (Parser& /*p*/, int which_qtr)
 }
 
 void
-MTC_Slave::update_mtc_time (const byte *msg, bool was_full)
+MTC_Slave::update_mtc_time (const byte *msg, bool was_full, nframes_t now)
 {
-	nframes64_t now = session.engine().frame_time();
+	/* "now" can be zero if this is called from a context where we do not have or do not want
+	   to use a timestamp indicating when this MTC time was received.
+	*/
+
 	Timecode::Time timecode;
 	TimecodeFormat tc_format;
 	bool reset_tc = true;
@@ -201,17 +202,21 @@ MTC_Slave::update_mtc_time (const byte *msg, bool was_full)
 		*/
 		
 		mtc_frame += (long) (1.75 * session.frames_per_timecode_frame()) + session.worst_output_latency();
-		
-		double speed = compute_apparent_speed (now);
-		
-		current.guard1++;
-		current.position = mtc_frame;
-		current.timestamp = now;
-		current.speed = speed;
-		current.guard2++;
+
+		if (now) {
+			double speed = compute_apparent_speed (now);
+			
+			current.guard1++;
+			current.position = mtc_frame;
+			current.timestamp = now;
+			current.speed = speed;
+			current.guard2++;
+		}
 	}
 
-	last_inbound_frame = now;
+	if (now) {
+		last_inbound_frame = now;
+	}
 }
 
 double
@@ -262,7 +267,7 @@ MTC_Slave::handle_locate (const MIDI::byte* mmc_tc)
 	mtc[1] = mmc_tc[2];
 	mtc[0] = mmc_tc[3];
 
-	update_mtc_time (mtc, true);
+	update_mtc_time (mtc, true, 0);
 }
 
 void
diff --git a/libs/ardour/session_process.cc b/libs/ardour/session_process.cc
index d00cad512b..33b24ca95f 100644
--- a/libs/ardour/session_process.cc
+++ b/libs/ardour/session_process.cc
@@ -569,9 +569,11 @@ Session::follow_slave (nframes_t nframes)
 	}
 #endif
 			if (fabs(delta) > 2048) {
+				nframes64_t jump_to = slave_transport_frame + lrintf (_current_frame_rate/5.0f);
 				/* too far off, so locate and keep rolling */
-				DEBUG_TRACE (DEBUG::Slave, string_compose ("slave delta %1 is too big, locate to %2\n", delta, slave_transport_frame));
-				request_locate (slave_transport_frame, true);
+				DEBUG_TRACE (DEBUG::Slave, string_compose ("slave delta %1 is too big, locate to %2\n", 
+									   delta, jump_to));
+				request_locate (jump_to, true);
 				return false;
 			} else {
 				float adjusted_speed = slave_speed + (delta /  float(_current_frame_rate));
-- 
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