diff --git a/libs/ardour/ardour/surround_return.h b/libs/ardour/ardour/surround_return.h
index cf559ff948..2e1f28c692 100644
--- a/libs/ardour/ardour/surround_return.h
+++ b/libs/ardour/ardour/surround_return.h
@@ -60,6 +60,19 @@ public:
 		return _surround_processor;
 	}
 
+	enum MainOutputFormat {
+		OUTPUT_FORMAT_5_1 = 2,
+		OUTPUT_FORMAT_7_1_4 = 6
+	};
+
+	MainOutputFormat output_format () const {
+		return _current_output_format;
+	}
+
+	void set_output_format (MainOutputFormat mov) {
+		_target_output_format = mov;
+	}
+
 	/* a value <= -200 indicates that no data is available */
 	float integrated_loudness () const;
 	float max_dbtp () const;
@@ -90,6 +103,8 @@ private:
 	pan_t            _current_value[max_object_id][num_pan_parameters];
 	int              _current_render_mode[max_object_id];
 	size_t           _current_n_objects;
+	MainOutputFormat _target_output_format;
+	MainOutputFormat _current_output_format;
 	BufferSet        _surround_bufs;
 	ChanMapping      _in_map;
 	ChanMapping      _out_map;
diff --git a/libs/ardour/ardour/uri_map.h b/libs/ardour/ardour/uri_map.h
index 35a96450a7..0b4ec4916e 100644
--- a/libs/ardour/ardour/uri_map.h
+++ b/libs/ardour/ardour/uri_map.h
@@ -112,6 +112,7 @@ public:
 		uint32_t surr_BinauralRenderMode;
 		uint32_t surr_ChannelCount;
 		uint32_t surr_DownmixMode;
+		uint32_t surr_OutputFormat;
 		uint32_t surr_WarpMode;
 		uint32_t surr_ExportStart;
 		uint32_t surr_ExportStop;
diff --git a/libs/ardour/surround_return.cc b/libs/ardour/surround_return.cc
index 39c94b45a6..fa5991da93 100644
--- a/libs/ardour/surround_return.cc
+++ b/libs/ardour/surround_return.cc
@@ -34,6 +34,8 @@ SurroundReturn::SurroundReturn (Session& s, Route* r)
 	: Processor (s, _("SurrReturn"), Temporal::TimeDomainProvider (Temporal::AudioTime))
 	, _lufs_meter (s.nominal_sample_rate (), 5)
 	, _current_n_objects (max_object_id)
+	, _target_output_format (OUTPUT_FORMAT_7_1_4)
+	, _current_output_format (OUTPUT_FORMAT_7_1_4)
 	, _in_map (ChanCount (DataType::AUDIO, 128))
 	, _out_map (ChanCount (DataType::AUDIO, 14 + 6 /* Loudness Meter */))
 	, _exporting (false)
@@ -202,6 +204,14 @@ SurroundReturn::run (BufferSet& bufs, samplepos_t start_sample, samplepos_t end_
 #endif
 	}
 
+	if (_current_output_format != _target_output_format) {
+		_current_output_format = _target_output_format;
+#if defined(LV2_EXTENDED) && defined(HAVE_LV2_1_10_0)
+		URIMap::URIDs const& urids = URIMap::instance ().urids;
+		forge_int_msg (urids.surr_Settings, urids.surr_OutputFormat, _target_output_format);
+#endif
+	}
+
 	uint32_t meter_nframes = nframes;
 	uint32_t meter_offset = 0;
 
@@ -386,6 +396,12 @@ SurroundReturn::max_dbtp () const
 int
 SurroundReturn::set_state (XMLNode const& node, int version)
 {
+	int target_output_format;
+	if (node.get_property (X_("output-format"), target_output_format)) {
+		if (target_output_format == OUTPUT_FORMAT_5_1 || target_output_format == OUTPUT_FORMAT_7_1_4) {
+			_target_output_format = (MainOutputFormat) target_output_format;
+		}
+	}
 	return _trim->set_state (node, version);
 }
 
@@ -395,5 +411,6 @@ SurroundReturn::state () const
 	XMLNode& node (_trim->state ());
 	node.set_property ("name", "SurrReturn");
 	node.set_property ("type", "surreturn");
+	node.set_property ("output-format", (int) _current_output_format);
 	return node;
 }
diff --git a/libs/ardour/uri_map.cc b/libs/ardour/uri_map.cc
index 91bec92ddf..00719effcc 100644
--- a/libs/ardour/uri_map.cc
+++ b/libs/ardour/uri_map.cc
@@ -89,6 +89,7 @@ URIMap::URIDs::init(URIMap& uri_map)
 	surr_BinauralRenderMode = uri_map.uri_to_id("urn:ardour:a-vapor#BinauralRenderMode");
 	surr_ChannelCount       = uri_map.uri_to_id("urn:ardour:a-vapor#ChannelCount");
 	surr_DownmixMode        = uri_map.uri_to_id("urn:ardour:a-vapor#DownmixMode");
+	surr_OutputFormat       = uri_map.uri_to_id("urn:ardour:a-vapor#OutputFormat");
 	surr_WarpMode           = uri_map.uri_to_id("urn:ardour:a-vapor#WarpMode");
 	surr_ExportStart        = uri_map.uri_to_id("urn:ardour:a-vapor#ExportStart");
 	surr_ExportStop         = uri_map.uri_to_id("urn:ardour:a-vapor#ExportStop");