Forward midi feedback from LV2 plugins and allow to chain LV2 midi plugins.

3 files changed, 44 insertions, 2 deletions

diff --git a/libs/ardour/ardour/buffer_set.h b/libs/ardour/ardour/buffer_set.h
index 3cb6cbdbd9..1a1d564288 100644
--- a/libs/ardour/ardour/buffer_set.h
+++ b/libs/ardour/ardour/buffer_set.h
@@ -122,6 +122,9 @@ public:
 
 	/** Flush modified LV2 event output buffers back to Ardour buffers */
 	void flush_lv2_midi(bool input, size_t i);
+
+	/** Forward plugin MIDI output to to Ardour buffers */
+	void forward_lv2_midi(LV2_Evbuf*, size_t, bool purge_ardour_buffer = true);
 #endif
 
 #if defined VST_SUPPORT || defined LXVST_SUPPORT
diff --git a/libs/ardour/buffer_set.cc b/libs/ardour/buffer_set.cc
index 1f8317ffe2..c231a8f402 100644
--- a/libs/ardour/buffer_set.cc
+++ b/libs/ardour/buffer_set.cc
@@ -266,6 +266,25 @@ BufferSet::get_lv2_midi(bool input, size_t i, bool old_api)
 }
 
 void
+BufferSet::forward_lv2_midi(LV2_Evbuf* buf, size_t i, bool purge_ardour_buffer)
+{
+	MidiBuffer& mbuf  = get_midi(i);
+	if (purge_ardour_buffer) {
+		mbuf.silence(0, 0);
+	}
+	for (LV2_Evbuf_Iterator i = lv2_evbuf_begin(buf);
+			 lv2_evbuf_is_valid(i);
+			 i = lv2_evbuf_next(i)) {
+		uint32_t frames, subframes, type, size;
+		uint8_t* data;
+		lv2_evbuf_get(i, &frames, &subframes, &type, &size, &data);
+		if (type == LV2Plugin::urids.midi_MidiEvent) {
+			mbuf.push_back(frames, size, data);
+		}
+	}
+}
+
+void
 BufferSet::flush_lv2_midi(bool input, size_t i)
 {
 	MidiBuffer&            mbuf  = get_midi(i);
diff --git a/libs/ardour/lv2_plugin.cc b/libs/ardour/lv2_plugin.cc
index c900a21176..0389a33c69 100644
--- a/libs/ardour/lv2_plugin.cc
+++ b/libs/ardour/lv2_plugin.cc
@@ -1640,8 +1640,28 @@ LV2Plugin::connect_and_run(BufferSet& bufs,
 		PortFlags flags = _port_flags[port_index];
 		bool      valid = false;
 
-		// Flush MIDI (write back to Ardour MIDI buffers)
-		if ((flags & PORT_OUTPUT) && (flags & (PORT_EVENT|PORT_SEQUENCE))) {
+		/* TODO ask drobilla about comment
+		 * "Make Ardour event buffers generic so plugins can communicate"
+		 * in libs/ardour/buffer_set.cc:310
+		 *
+		 * ideally the user could choose which of the following two modes
+		 * to use (e.g. instrument/effect chains  MIDI OUT vs MIDI TRHU).
+		 *
+		 * This implementation follows the discussion on IRC Mar 16 2013 16:47 UTC
+		 * 16:51 < drobilla> rgareus: [..] i.e always replace with MIDI output [of LV2 plugin] if it's there
+		 * 16:52 < drobilla> rgareus: That would probably be good enough [..] to make users not complain
+		 *                            for quite a while at least ;)
+		 */
+		// copy output of LV2 plugin's MIDI port to Ardour MIDI buffers -- MIDI OUT
+		if ((flags & PORT_OUTPUT) && (flags & (PORT_EVENT|PORT_SEQUENCE|PORT_MIDI))) {
+			const uint32_t buf_index = out_map.get(
+				DataType::MIDI, midi_out_index++, &valid);
+			if (valid) {
+				bufs.forward_lv2_midi(_ev_buffers[port_index], buf_index);
+			}
+		}
+		// Flush MIDI (write back to Ardour MIDI buffers) -- MIDI THRU
+		else if ((flags & PORT_OUTPUT) && (flags & (PORT_EVENT|PORT_SEQUENCE))) {
 			const uint32_t buf_index = out_map.get(
 				DataType::MIDI, midi_out_index++, &valid);
 			if (valid) {