Fix MIDI loop capture alignment

Loop recording creates a single long source, regions have to be
"split" from this source, using "start" as offset.

Since MIDI uses absolute timestamps, offsetting this by accumulating
 buffer_position += (*ci)->samples;
like Track::use_captured_audio_sources() does, is not correct.

Furthermore, record_enabled() may be off when stopping recording,
MIDI needs to be flushed regardless.

3 files changed, 17 insertions, 4 deletions

diff --git a/libs/ardour/ardour/types.h b/libs/ardour/ardour/types.h
index 3db1a34dc9..3a991aa81a 100644
--- a/libs/ardour/ardour/types.h
+++ b/libs/ardour/ardour/types.h
@@ -783,6 +783,7 @@ enum MidiTempoMapDisposition {
 struct CaptureInfo {
 	samplepos_t start;
 	samplecnt_t samples;
+	samplecnt_t loop_offset;
 };
 
 enum LoopFadeChoice {
diff --git a/libs/ardour/disk_writer.cc b/libs/ardour/disk_writer.cc
index aafdcc5dcd..6e13da644b 100644
--- a/libs/ardour/disk_writer.cc
+++ b/libs/ardour/disk_writer.cc
@@ -463,6 +463,7 @@ DiskWriter::run (BufferSet& bufs, samplepos_t start_sample, samplepos_t end_samp
 				*/
 				_capture_captured     = start_sample - loop_start;
 				_capture_start_sample = loop_start;
+				_first_recordable_sample = loop_start;
 				if (_capture_captured > 0) {
 					/* when enabling record while already looping,
 					 * zero fill region back to loop-start.
@@ -695,6 +696,16 @@ DiskWriter::finish_capture (boost::shared_ptr<ChannelList> c)
 	ci->start =  _capture_start_sample;
 	ci->samples = _capture_captured;
 
+	if (_loop_location) {
+		samplepos_t loop_start  = 0;
+		samplepos_t loop_end    = 0;
+		samplepos_t loop_length = 0;
+		get_location_times (_loop_location, &loop_start, &loop_end, &loop_length);
+		ci->loop_offset = _num_captured_loops * loop_length;
+	} else {
+		ci->loop_offset = 0;
+	}
+
 	DEBUG_TRACE (DEBUG::CaptureAlignment, string_compose ("Finish capture, add new CI, %1 + %2\n", ci->start, ci->samples));
 
 	/* XXX theoretical race condition here. Need atomic exchange ?
@@ -1024,7 +1035,7 @@ DiskWriter::do_flush (RunContext ctxt, bool force_flush)
 			to_write = _chunk_samples;
 		}
 
-		if (record_enabled() && ((total > _chunk_samples) || force_flush)) {
+		if ((total > _chunk_samples) || force_flush) {
 			Source::Lock lm(_midi_write_source->mutex());
 			if (_midi_write_source->midi_write (lm, *_midi_buf, get_capture_start_sample (0), to_write) != to_write) {
 				error << string_compose(_("MidiDiskstream %1: cannot write to disk"), id()) << endmsg;
@@ -1348,7 +1359,6 @@ DiskWriter::transport_looped (samplepos_t transport_sample)
 	if (_capture_captured) {
 		_transport_looped = true;
 		_transport_loop_sample = transport_sample;
-		_first_recordable_sample = transport_sample;
 	}
 }
 
diff --git a/libs/ardour/track.cc b/libs/ardour/track.cc
index 87c9aedabb..a4c26a7ffb 100644
--- a/libs/ardour/track.cc
+++ b/libs/ardour/track.cc
@@ -977,15 +977,17 @@ Track::use_captured_midi_sources (SourceList& srcs, CaptureInfos const & capture
 		                                                      _name, (*ci)->start, (*ci)->samples, region_name));
 
 
-		// cerr << _name << ": based on ci of " << (*ci)->start << " for " << (*ci)->samples << " add a region\n";
+		// cerr << _name << ": based on ci of " << (*ci)->start << " for " << (*ci)->samples << " start: " << (*ci)->loop_offset << " add MIDI region\n";
 
 		try {
 			PropertyList plist;
 
 			/* start of this region is the offset between the start of its capture and the start of the whole pass */
-			plist.add (Properties::start, (*ci)->start - initial_capture);
+			samplecnt_t start_off = (*ci)->start - initial_capture + (*ci)->loop_offset;
+			plist.add (Properties::start, start_off);
 			plist.add (Properties::length, (*ci)->samples);
 			plist.add (Properties::length_beats, converter.from((*ci)->samples).to_double());
+			plist.add (Properties::start_beats, converter.from(start_off).to_double());
 			plist.add (Properties::name, region_name);
 
 			boost::shared_ptr<Region> rx (RegionFactory::create (srcs, plist));