From 5e1f2d21f8acb44928d0e39c05602756d160e5da Mon Sep 17 00:00:00 2001
From: Robin Gareus <robin@gareus.org>
Date: Sat, 7 Aug 2021 23:36:59 +0200
Subject: [PATCH] Fix issues when using MIDI sends with small buffersizes

MIDI data buffers are fixed size, independent of the engine's
buffersize (compare to ThreadBuffers::ensure_buffers)
---
 libs/ardour/ardour/internal_send.h |  1 +
 libs/ardour/internal_send.cc       | 17 +++++++++++++----
 2 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/libs/ardour/ardour/internal_send.h b/libs/ardour/ardour/internal_send.h
index c952b1378f..2ba66ab39a 100644
--- a/libs/ardour/ardour/internal_send.h
+++ b/libs/ardour/ardour/internal_send.h
@@ -83,6 +83,7 @@ private:
 	void init_gain ();
 	int  use_target (boost::shared_ptr<Route>, bool update_name = true);
 	void target_io_changed ();
+	void ensure_mixbufs ();
 
 	void propagate_solo ();
 };
diff --git a/libs/ardour/internal_send.cc b/libs/ardour/internal_send.cc
index 56970eca14..2f2731b714 100644
--- a/libs/ardour/internal_send.cc
+++ b/libs/ardour/internal_send.cc
@@ -159,7 +159,7 @@ InternalSend::use_target (boost::shared_ptr<Route> sendto, bool update_name)
 
 	_send_to->add_send_to_internal_return (this);
 
-	mixbufs.ensure_buffers (_send_to->internal_return ()->input_streams (), _session.get_block_size ());
+	ensure_mixbufs ();
 	mixbufs.set_count (_send_to->internal_return ()->input_streams ());
 
 	_meter->configure_io (ChanCount (DataType::AUDIO, pan_outs ()), ChanCount (DataType::AUDIO, pan_outs ()));
@@ -186,7 +186,7 @@ void
 InternalSend::target_io_changed ()
 {
 	assert (_send_to);
-	mixbufs.ensure_buffers (_send_to->internal_return ()->input_streams (), _session.get_block_size ());
+	ensure_mixbufs ();
 	mixbufs.set_count (_send_to->internal_return ()->input_streams ());
 	reset_panner ();
 }
@@ -344,11 +344,20 @@ out:
 	_active = _pending_active;
 }
 
+void
+InternalSend::ensure_mixbufs ()
+{
+	for (DataType::iterator t = DataType::begin (); t != DataType::end (); ++t) {
+		size_t size = (*t == DataType::MIDI) ? _session.engine ().raw_buffer_size (*t) : _session.get_block_size ();
+		mixbufs.ensure_buffers (*t, _send_to->internal_return ()->input_streams ().get (*t), size);
+	}
+}
+
 int
-InternalSend::set_block_size (pframes_t nframes)
+InternalSend::set_block_size (pframes_t)
 {
 	if (_send_to) {
-		mixbufs.ensure_buffers (_send_to->internal_return ()->input_streams (), nframes);
+		ensure_mixbufs ();
 	}
 
 	return 0;