Fix MIDI Timestretch

* skip notes outside of region-range (source-start, region-length)
* handle tempo-ramps properly, apply map to stretch-fraction
* fix region properties after stretching
  (position needs to be re-set first, to set a midi-region's
   quarter-note position, which is used by the length calc)

1 files changed, 48 insertions, 7 deletions

diff --git a/libs/ardour/midi_stretch.cc b/libs/ardour/midi_stretch.cc
index 28e4583f2e..f960c10166 100644
--- a/libs/ardour/midi_stretch.cc
+++ b/libs/ardour/midi_stretch.cc
@@ -24,6 +24,8 @@
 #include "ardour/midi_region.h"
 #include "ardour/midi_source.h"
 #include "ardour/midi_stretch.h"
+#include "ardour/session.h"
+#include "ardour/tempo.h"
 #include "ardour/types.h"
 
 #include "pbd/i18n.h"
@@ -53,11 +55,21 @@ MidiStretch::run (boost::shared_ptr<Region> r, Progress*)
 		return -1;
 	}
 
+	const TempoMap& tmap (session.tempo_map ());
+
+	/* Fraction is based on sample-time, while MIDI source
+	 * is always using music-time. This matters in case there is
+	 * a tempo-ramp. So we need to scale the ratio to music-time */
+	const double mtfrac =
+		tmap.framewalk_to_qn (region->position (), region->length () * _request.time_fraction).to_double ()
+		/
+		tmap.framewalk_to_qn (region->position (), region->length ()).to_double ();
+
 	/* the name doesn't need to be super-precise, but allow for 2 fractional
-	   digits just to disambiguate close but not identical stretches.
-	*/
+	 * digits just to disambiguate close but not identical stretches.
+	 */
 
-	snprintf (suffix, sizeof (suffix), "@%d", (int) floor (_request.time_fraction * 100.0f));
+	snprintf (suffix, sizeof (suffix), "@%d", (int) floor (mtfrac * 100.0f));
 
 	string new_name = region->name();
 	string::size_type at = new_name.find ('@');
@@ -95,12 +107,38 @@ MidiStretch::run (boost::shared_ptr<Region> r, Progress*)
 	boost::shared_ptr<MidiModel> new_model = new_src->model();
 	new_model->start_write();
 
+	const double r_start = tmap.quarter_notes_between_samples (region->position () - region->start (), region->position ());
+	const double r_end = r_start + tmap.quarter_notes_between_samples (region->position (), region->position () + region->length ());
+
+#ifdef DEBUG_MIDI_STRETCH
+	printf ("stretch start: %f end: %f  [* %f] * %f\n", r_start, r_end, _request.time_fraction, mtfrac);
+#endif
+
 	/* Note: pass true into force_discrete for the begin() iterator so that the model doesn't
 	 * do interpolation of controller data when we stretch.
 	 */
-	for (Evoral::Sequence<MidiModel::TimeType>::const_iterator i = old_model->begin (MidiModel::TimeType(), true);
-			i != old_model->end(); ++i) {
-		const MidiModel::TimeType new_time = i->time() * (double)_request.time_fraction;
+	for (Evoral::Sequence<MidiModel::TimeType>::const_iterator i = old_model->begin (MidiModel::TimeType(), true); i != old_model->end(); ++i) {
+
+		if (i->time() < r_start) {
+#ifdef DEBUG_MIDI_STRETCH
+			cout << "SKIP EARLY EVENT " << i->time() << "\n";
+#endif
+			continue;
+		}
+		if (i->time() > r_end) {
+#ifdef DEBUG_MIDI_STRETCH
+			cout << "SKIP LATE EVENT " << i->time() << "\n";
+			continue;
+#else
+			break;
+#endif
+		}
+
+#ifdef DEBUG_MIDI_STRETCH
+		cout << "STRETCH " << i->time() << " TO " << (i->time() - r_start) * mtfrac << "\n";
+#endif
+
+		const MidiModel::TimeType new_time = (i->time() - r_start) * mtfrac;
 
 		// FIXME: double copy
 		Evoral::Event<MidiModel::TimeType> ev(*i, true);
@@ -108,13 +146,16 @@ MidiStretch::run (boost::shared_ptr<Region> r, Progress*)
 		new_model->append(ev, Evoral::next_event_id());
 	}
 
-	new_model->end_write (Evoral::Sequence<Temporal::Beats>::DeleteStuckNotes);
+	new_model->end_write (Evoral::Sequence<Temporal::Beats>::ResolveStuckNotes);
 	new_model->set_edited (true);
 
 	new_src->copy_interpolation_from (src);
 
 	const int ret = finish (region, nsrcs, new_name);
+
 	/* non-musical */
+	results[0]->set_start(0);
+	results[0]->set_position (r->position ()); // force updates the region's quarter-note position
 	results[0]->set_length((samplecnt_t) floor (r->length() * _request.time_fraction), 0);
 
 	return ret;