Ongoing work on latency compensation

[ardour.git] / libs / ardour / session_transport.cc

diff --git a/libs/ardour/session_transport.cc b/libs/ardour/session_transport.cc
index bb89ff57d4178b88caf9a8f41c80c54274ca59ba..07782750e3e18efd66c8ff7b0625ab7d9cbd06c6 100644 (file)
--- a/libs/ardour/session_transport.cc
+++ b/libs/ardour/session_transport.cc
@@ -1171,6 +1171,12 @@ Session::start_locate (samplepos_t target_sample, bool with_roll, bool with_flus
        }
 }
 
+samplecnt_t
+Session::worst_latency_preroll () const
+{
+       return _worst_output_latency + _worst_input_latency;
+}
+
 int
 Session::micro_locate (samplecnt_t distance)
 {
@@ -1250,15 +1256,16 @@ Session::locate (samplepos_t target_sample, bool with_roll, bool with_flush, boo
        // thread(s?) can restart.
        g_atomic_int_inc (&_seek_counter);
        _last_roll_or_reversal_location = target_sample;
-       timecode_time(_transport_sample, transmitting_timecode_time);
+       _remaining_latency_preroll = worst_latency_preroll ();
+       timecode_time(_transport_sample, transmitting_timecode_time); // XXX here?
 
        /* do "stopped" stuff if:
         *
         * we are rolling AND
-        *    no autoplay in effect AND
-         *       we're not going to keep rolling after the locate AND
-         *           !(playing a loop with JACK sync)
-         *
+        * no autoplay in effect AND
+        * we're not going to keep rolling after the locate AND
+        * !(playing a loop with JACK sync)
+        *
         */
 
        bool transport_was_stopped = !transport_rolling();
@@ -1492,6 +1499,9 @@ Session::set_transport_speed (double speed, samplepos_t destination_sample, bool
 
                /* not zero, not 1.0 ... varispeed */
 
+               // TODO handled transport start..  _remaining_latency_preroll
+               // and reversal of playback direction.
+
                if ((synced_to_engine()) && speed != 0.0 && speed != 1.0) {
                        warning << string_compose (
                                _("Global varispeed cannot be supported while %1 is connected to JACK transport control"),
@@ -1659,6 +1669,7 @@ Session::start_transport ()
 
        _last_roll_location = _transport_sample;
        _last_roll_or_reversal_location = _transport_sample;
+       _remaining_latency_preroll = worst_latency_preroll ();
 
        have_looped = false;
 
@@ -1728,13 +1739,22 @@ Session::start_transport ()
                                _count_in_samples *= 1. + bar_fract;
                        }
 
+                       if (_count_in_samples > _remaining_latency_preroll) {
+                               _remaining_latency_preroll = _count_in_samples;
+                       }
+
                        int clickbeat = 0;
                        samplepos_t cf = _transport_sample - _count_in_samples;
-                       while (cf < _transport_sample) {
-                               add_click (cf - _worst_track_latency, clickbeat == 0);
+                       samplecnt_t offset = _click_io->connected_latency (true);
+                       while (cf < _transport_sample + offset) {
+                               add_click (cf, clickbeat == 0);
                                cf += dt;
                                clickbeat = fmod (clickbeat + 1, num);
                        }
+
+                       if (_count_in_samples < _remaining_latency_preroll) {
+                               _count_in_samples = _remaining_latency_preroll;
+                       }
                }
        }