Srnd: expose the momentary loudness value in addtion to integrated loudness

libs/ardour/ardour/lufs_meter.h

@@ -39,6 +39,7 @@ public:
 	void reset ();
 
 	float integrated_loudness () const;
+	float momentary () const;
 	float max_momentary () const;
 	float dbtp () const;
 
@@ -74,6 +75,8 @@ private:
 	uint32_t _pow_idx;
 	float    _thresh_rel;
 
+	float    _momentary_l;
+
 	float    _maxloudn_M;
 	float    _integrated;
 	float    _dbtp;

libs/ardour/ardour/surround_return.h

@@ -76,6 +76,8 @@ public:
 
 	/* a value <= -200 indicates that no data is available */
 	float integrated_loudness () const;
+	float max_momentary () const;
+	float momentary () const;
 	float max_dbtp () const;
 
 	samplecnt_t signal_latency () const;

libs/ardour/lufs_meter.cc

@@ -173,6 +173,8 @@ LUFSMeter::run (float const** data, uint32_t n_samples)
 			const float sum_m      = sumfrag (4); // 400ms
 			const float loudness_m = -0.691f + 10.f * log10f (sum_m);
 
+			_momentary_l = loudness_m;
+
 			_maxloudn_M = std::max<float> (_maxloudn_M, loudness_m);
 
 			/* observe 400ms window every 100ms */
@@ -256,6 +258,12 @@ LUFSMeter::integrated_loudness () const
 	return _integrated;
 }
 
+float
+LUFSMeter::momentary () const
+{
+	return _momentary_l;
+}
+
 float
 LUFSMeter::max_momentary () const
 {

libs/ardour/surround_return.cc

@@ -395,6 +395,18 @@ SurroundReturn::finalize_export ()
 	_export_start = _export_end = 0;
 }
 
+float
+SurroundReturn::momentary () const
+{
+	return _lufs_meter.momentary ();
+}
+
+float
+SurroundReturn::max_momentary () const
+{
+	return _lufs_meter.max_momentary ();
+}
+
 float
 SurroundReturn::integrated_loudness () const
 {