Update the Metronome, align to output

diff --git a/libs/ardour/session_click.cc b/libs/ardour/session_click.cc
index b4b5283fd855d271532615f3aaf61e03625a73d7..3f3976a944508959353f9ccbcafa397f594a5249 100644 (file)
--- a/libs/ardour/session_click.cc
+++ b/libs/ardour/session_click.cc
@@ -54,23 +54,27 @@ Session::add_click (samplepos_t pos, bool emphasis)
 }
 
 void
-Session::click (samplepos_t start, samplecnt_t nframes)
+Session::click (samplepos_t cycle_start, samplecnt_t nframes)
 {
-       vector<TempoMap::BBTPoint> points;
-       samplecnt_t click_distance;
+       vector<TempoMap::BBTPoint> points; // TODO use mempool allocator
 
        if (_click_io == 0) {
                return;
        }
 
-       Glib::Threads::RWLock::WriterLock clickm (click_lock, Glib::Threads::TRY_LOCK);
-
-       /* how far have we moved since the last time the clicks got cleared
+       /* transport_frame is audible-frame (what you hear,
+        * incl output latency). So internally we're ahead,
+        * we need to prepare frames that the user will hear
+        * in "output latency's" worth of time.
         */
+       samplecnt_t offset = _click_io->connected_latency (true);
+
+       Glib::Threads::RWLock::WriterLock clickm (click_lock, Glib::Threads::TRY_LOCK);
 
-       click_distance = start - _clicks_cleared;
+       /* how far have we moved since the last time the clicks got cleared */
+       const samplecnt_t click_distance = cycle_start + offset - _clicks_cleared;
 
-       if (!clickm.locked() || !_clicking || click_data == 0 || ((click_distance + nframes) < _worst_track_latency)) {
+       if (!clickm.locked() || !_clicking || click_data == 0 || ((click_distance + nframes) < 0)) {
                _click_io->silence (nframes);
                return;
        }
@@ -79,18 +83,15 @@ Session::click (samplepos_t start, samplecnt_t nframes)
                return;
        }
 
-       start -= _worst_track_latency;
-#ifdef MIXBUS
-       if (_master_out) {
-               start -= _master_out->signal_latency (); // delay signal by mixbus' internal latency
-       }
-#endif
-       /* start could be negative at this point */
+       /* range to check for clicks */
+       samplepos_t start = cycle_start + offset;
        const samplepos_t end = start + nframes;
        /* correct start, potentially */
        start = max (start, (samplepos_t) 0);
 
-       _tempo_map->get_grid (points, start, end);
+       if (end > start) {
+               _tempo_map->get_grid (points, start, end);
+       }
 
        if (distance (points.begin(), points.end()) == 0) {
                goto run_clicks;
@@ -102,7 +103,7 @@ Session::click (samplepos_t start, samplecnt_t nframes)
                        add_click ((*i).sample, true);
                        break;
                default:
-                       if (click_emphasis_data == 0 || (Config->get_use_click_emphasis () == false) || (click_emphasis_data && (*i).beat != 1)) { // XXX why is this check needed ??
+                       if (click_emphasis_data == 0 || (Config->get_use_click_emphasis () == false) || (click_emphasis_data && (*i).beat != 1)) { // XXX why is this check needed ??  (*i).beat !=1 must be true here
                                add_click ((*i).sample, false);
                        }
                        break;
@@ -111,7 +112,7 @@ Session::click (samplepos_t start, samplecnt_t nframes)
 
   run_clicks:
        clickm.release ();
-       run_click (start, nframes);
+       run_click (cycle_start, nframes);
 }
 
 void
@@ -119,6 +120,9 @@ Session::run_click (samplepos_t start, samplepos_t nframes)
 {
        Glib::Threads::RWLock::ReaderLock clickm (click_lock, Glib::Threads::TRY_LOCK);
 
+       /* align to output */
+       start += _click_io->connected_latency (true);
+
        if (!clickm.locked() || click_data == 0) {
                _click_io->silence (nframes);
                return;