professionalize peak-meters

The peak meter needs to withstand various test-signals
without visual jitter (in particular 1kHz sine) regardless
of settings (period-size, sample-rate, custom fall-off).

This needs to be done in sync (and not by a random non-rt
‘smoothing’ thread).

On the downside this voids the ‘visual smoothing’ particularly 
with large buffersizes - but then again exactly this “always 
fall-off no matter what [the next real data will be]” is the
problem.

One the upside, there’s one less high-frequency (100Hz) thread
(Yay!) PS. it probably never worked on windows, anyway.

Only peak-meters are affected by his change.
K-meters, IEC I/II and VU were never visually smoothed.

8 files changed, 100 insertions, 232 deletions

diff --git a/libs/ardour/ardour/audioengine.h b/libs/ardour/ardour/audioengine.h
index 445d299f39..330de4e285 100644
--- a/libs/ardour/ardour/audioengine.h
+++ b/libs/ardour/ardour/audioengine.h
@@ -293,12 +293,6 @@ class LIBARDOUR_API AudioEngine : public SessionHandlePtr, public PortManager
 	void do_reset_backend();
 	void do_devicelist_update();
 
-	void meter_thread ();
-	void start_metering_thread ();
-	void stop_metering_thread ();
-
-	static gint      m_meter_exit;
-
 	typedef std::map<std::string,AudioBackendInfo*> BackendMap;
 	BackendMap _backends;
 	AudioBackendInfo* backend_discover (const std::string&);
diff --git a/libs/ardour/ardour/meter.h b/libs/ardour/ardour/meter.h
index d34d5b3710..7539db2140 100644
--- a/libs/ardour/ardour/meter.h
+++ b/libs/ardour/ardour/meter.h
@@ -36,16 +36,6 @@ class BufferSet;
 class ChanCount;
 class Session;
 
-class LIBARDOUR_API Metering {
-  public:
-	static void               update_meters ();
-	static PBD::Signal0<void> Meter;
-
-  private:
-	/* this object is not meant to be instantiated */
-	Metering();
-};
-
 /** Meters peaks on the input and stores them for access.
  */
 class LIBARDOUR_API PeakMeter : public Processor {
@@ -53,7 +43,6 @@ public:
         PeakMeter(Session& s, const std::string& name);
         ~PeakMeter();
 
-	void meter();
 	void reset ();
 	void reset_max ();
 
@@ -64,7 +53,7 @@ public:
 	   number of streams in the route, no matter where we put it.
 	*/
 
-	void reset_max_channels (const ChanCount&);
+	void set_max_channels (const ChanCount&);
 
 	/* tell the meter than no matter how many channels it can handle,
 	   `in' is the number it is actually going be handling from
@@ -83,14 +72,6 @@ public:
 	ChanCount input_streams () const { return current_meters; }
 	ChanCount output_streams () const { return current_meters; }
 
-	float peak_power (uint32_t n) {
-		if (n < _visible_peak_power.size()) {
-			return _visible_peak_power[n];
-		} else {
-			return minus_infinity();
-		}
-	}
-
 	float meter_level (uint32_t n, MeterType type);
 
 	void set_type(MeterType t);
@@ -109,10 +90,13 @@ private:
 	 */
 	ChanCount current_meters;
 
-	std::vector<float> _peak_signal;
-	std::vector<float> _visible_peak_power;
-	std::vector<float> _max_peak_signal;
-	std::vector<float> _max_peak_power;
+	bool               _reset_dpm;
+	bool               _reset_max;
+
+	uint32_t           _bufcnt;
+	std::vector<float> _peak_buffer; // internal, integrate
+	std::vector<float> _peak_power;  // includes accurate falloff, hence dB
+	std::vector<float> _max_peak_signal; // dB calculation is done on demand
 
 	std::vector<Kmeterdsp *> _kmeter;
 	std::vector<Iec1ppmdsp *> _iec1meter;
diff --git a/libs/ardour/ardour/route.h b/libs/ardour/ardour/route.h
index 2d35211f47..fbce3fd3f3 100644
--- a/libs/ardour/ardour/route.h
+++ b/libs/ardour/ardour/route.h
@@ -185,7 +185,6 @@ class LIBARDOUR_API Route : public SessionObject, public Automatable, public Rou
 	bool         apply_processor_changes_rt ();
 	void         emit_pending_signals ();
 	MeterPoint   meter_point() const { return _pending_meter_point; }
-	void         meter ();
 
 	void         set_meter_type (MeterType t) { _meter_type = t; }
 	MeterType    meter_type() const { return _meter_type; }
diff --git a/libs/ardour/audioengine.cc b/libs/ardour/audioengine.cc
index 6176ebd4df..b18d5e1af2 100644
--- a/libs/ardour/audioengine.cc
+++ b/libs/ardour/audioengine.cc
@@ -61,7 +61,6 @@ using namespace std;
 using namespace ARDOUR;
 using namespace PBD;
 
-gint AudioEngine::m_meter_exit;
 AudioEngine* AudioEngine::_instance = 0;
 
 #ifdef SILENCE_AFTER
@@ -99,7 +98,6 @@ AudioEngine::AudioEngine ()
 	, _silence_hit_cnt (0)
 #endif
 {
-	g_atomic_int_set (&m_meter_exit, 0);
 	reset_silence_countdown ();
 	start_hw_event_processing();
 	discover_backends ();
@@ -108,7 +106,6 @@ AudioEngine::AudioEngine ()
 AudioEngine::~AudioEngine ()
 {
 	_in_destructor = true;
-	stop_metering_thread ();
 	stop_hw_event_processing();
 	drop_backend ();
 	for (BackendMap::const_iterator i = _backends.begin(); i != _backends.end(); ++i) {
@@ -571,40 +568,6 @@ AudioEngine::stop_hw_event_processing()
 }
 
 
-
-void
-AudioEngine::stop_metering_thread ()
-{
-	if (m_meter_thread) {
-		g_atomic_int_set (&m_meter_exit, 1);
-		m_meter_thread->join ();
-		m_meter_thread = 0;
-	}
-}
-
-void
-AudioEngine::start_metering_thread ()
-{
-	if (m_meter_thread == 0) {
-		g_atomic_int_set (&m_meter_exit, 0);
-		m_meter_thread = Glib::Threads::Thread::create (boost::bind (&AudioEngine::meter_thread, this));
-	}
-}
-
-void
-AudioEngine::meter_thread ()
-{
-	pthread_set_name (X_("meter"));
-
-	while (true) {
-		Glib::usleep (10000); /* 1/100th sec interval */
-		if (g_atomic_int_get(&m_meter_exit)) {
-			break;
-		}
-		Metering::Meter ();
-	}
-}
-
 void
 AudioEngine::set_session (Session *s)
 {
@@ -664,11 +627,8 @@ AudioEngine::reconnect_session_routes (bool reconnect_inputs, bool reconnect_out
 void
 AudioEngine::died ()
 {
-        /* called from a signal handler for SIGPIPE */
-
-	stop_metering_thread ();
-
-    _running = false;
+	/* called from a signal handler for SIGPIPE */
+	_running = false;
 }
 
 int
@@ -877,8 +837,6 @@ AudioEngine::start (bool for_latency)
 
 	}
 	
-	start_metering_thread ();
-	
 	if (!for_latency) {
 		Running(); /* EMIT SIGNAL */
 	}
@@ -911,7 +869,6 @@ AudioEngine::stop (bool for_latency)
 	_latency_output_port = 0;
 	_latency_input_port = 0;
 	_started_for_latency = false;
-	stop_metering_thread ();
 	
 	Port::PortDrop ();
 
@@ -1252,7 +1209,6 @@ AudioEngine::halted_callback (const char* why)
 		return;
 	}
 
-    stop_metering_thread ();
 	_running = false;
 
 	Port::PortDrop (); /* EMIT SIGNAL */
diff --git a/libs/ardour/meter.cc b/libs/ardour/meter.cc
index dffefd4a58..60d8b694a8 100644
--- a/libs/ardour/meter.cc
+++ b/libs/ardour/meter.cc
@@ -35,8 +35,6 @@ using namespace std;
 
 using namespace ARDOUR;
 
-PBD::Signal0<void> Metering::Meter;
-
 PeakMeter::PeakMeter (Session& s, const std::string& name)
     : Processor (s, string_compose ("meter-%1", name))
 {
@@ -46,6 +44,8 @@ PeakMeter::PeakMeter (Session& s, const std::string& name)
 	Vumeterdsp::init(s.nominal_frame_rate());
 	_pending_active = true;
 	_meter_type = MeterPeak;
+	_reset_dpm = true;
+	_reset_max = true;
 }
 
 PeakMeter::~PeakMeter ()
@@ -60,6 +60,11 @@ PeakMeter::~PeakMeter ()
 		_iec2meter.pop_back();
 		_vumeter.pop_back();
 	}
+	while (_peak_power.size() > 0) {
+		_peak_buffer.pop_back();
+		_peak_power.pop_back();
+		_max_peak_signal.pop_back();
+	}
 }
 
 
@@ -76,6 +81,10 @@ PeakMeter::run (BufferSet& bufs, framepos_t /*start_frame*/, framepos_t /*end_fr
 	if (!_active && !_pending_active) {
 		return;
 	}
+	const bool do_reset_max = _reset_max;
+	const bool do_reset_dpm = _reset_dpm;
+	_reset_max = false;
+	_reset_dpm = false;
 
 	// cerr << "meter " << name() << " runs with " << bufs.available() << " inputs\n";
 
@@ -84,6 +93,10 @@ PeakMeter::run (BufferSet& bufs, framepos_t /*start_frame*/, framepos_t /*end_fr
 
 	uint32_t n = 0;
 
+	const float falloff_dB = Config->get_meter_falloff() * nframes / _session.nominal_frame_rate();
+	const int zoh = _session.nominal_frame_rate() * .021;
+	_bufcnt += nframes;
+
 	// Meter MIDI in to the first n_midi peaks
 	for (uint32_t i = 0; i < n_midi; ++i, ++n) {
 		float val = 0.0f;
@@ -103,16 +116,46 @@ PeakMeter::run (BufferSet& bufs, framepos_t /*start_frame*/, framepos_t /*end_fr
 				}
 			}
 		}
-		_peak_signal[n] = max (val, _peak_signal[n]);
+		if (_peak_power[n] < (1.0 / 512.0)) {
+			_peak_power[n] = 0;
+		} else {
+			/* empirical algorithm WRT to audio falloff times */
+			_peak_power[n] -= sqrtf (_peak_power[n]) * falloff_dB * 0.045f;
+		}
+		_peak_power[n] = max(_peak_power[n], val);
+		_max_peak_signal[n] = 0;
 	}
 
 	// Meter audio in to the rest of the peaks
 	for (uint32_t i = 0; i < n_audio; ++i, ++n) {
 		if (bufs.get_audio(i).silent()) {
-			_peak_signal[n] = .0f;
+			;
 		} else {
-			_peak_signal[n] = compute_peak (bufs.get_audio(i).data(), nframes, _peak_signal[n]);
+			_peak_buffer[n] = compute_peak (bufs.get_audio(i).data(), nframes, _peak_buffer[n]);
+			_max_peak_signal[n] = std::max(_peak_buffer[n], _max_peak_signal[n]); // todo sync reset
+		}
+
+		if (do_reset_max) {
+			_max_peak_signal[n] = 0;
 		}
+
+		if (do_reset_dpm) {
+			_peak_buffer[n] = 0;
+			_peak_power[n] = -std::numeric_limits<float>::infinity();
+		} else {
+			// falloff
+			if (_peak_power[n] >  -318.8f) {
+				_peak_power[n] -= falloff_dB;
+			} else {
+				_peak_power[n] = -std::numeric_limits<float>::infinity();
+			}
+			_peak_power[n] = max(_peak_power[n], accurate_coefficient_to_dB(_peak_buffer[n]));
+			// integration buffer, retain peaks > 49Hz
+			if (_bufcnt > zoh) {
+				_peak_buffer[n] = 0;
+			}
+		}
+
 		if (_meter_type & (MeterKrms | MeterK20 | MeterK14 | MeterK12)) {
 			_kmeter[i]->process(bufs.get_audio(i).data(), nframes);
 		}
@@ -128,8 +171,13 @@ PeakMeter::run (BufferSet& bufs, framepos_t /*start_frame*/, framepos_t /*end_fr
 	}
 
 	// Zero any excess peaks
-	for (uint32_t i = n; i < _peak_signal.size(); ++i) {
-		_peak_signal[i] = 0.0f;
+	for (uint32_t i = n; i < _peak_power.size(); ++i) {
+		_peak_power[i] = -std::numeric_limits<float>::infinity();
+		_max_peak_signal[n] = 0;
+	}
+
+	if (_bufcnt > zoh) {
+		_bufcnt = 0;
 	}
 
 	_active = _pending_active;
@@ -138,10 +186,16 @@ PeakMeter::run (BufferSet& bufs, framepos_t /*start_frame*/, framepos_t /*end_fr
 void
 PeakMeter::reset ()
 {
-	for (size_t i = 0; i < _peak_signal.size(); ++i) {
-		_peak_signal[i] = 0.0f;
+	if (_active || _pending_active) {
+		_reset_dpm = true;
+	} else {
+		for (size_t i = 0; i < _peak_power.size(); ++i) {
+			_peak_power[i] = -std::numeric_limits<float>::infinity();
+			_peak_buffer[i] = 0;
+		}
 	}
 
+	// these are handled async just fine.
 	for (size_t n = 0; n < _kmeter.size(); ++n) {
 		_kmeter[n]->reset();
 		_iec1meter[n]->reset();
@@ -153,19 +207,13 @@ PeakMeter::reset ()
 void
 PeakMeter::reset_max ()
 {
-	for (size_t i = 0; i < _max_peak_power.size(); ++i) {
-		_max_peak_power[i] = -std::numeric_limits<float>::infinity();
-		_max_peak_signal[i] = 0;
+	if (_active || _pending_active) {
+		_reset_max = true;
+		return;
 	}
-
-	const size_t n_midi  = min (_peak_signal.size(), (size_t) current_meters.n_midi());
-
-	for (size_t n = 0; n < _peak_signal.size(); ++n) {
-		if (n < n_midi) {
-			_visible_peak_power[n] = 0;
-		} else {
-			_visible_peak_power[n] = -std::numeric_limits<float>::infinity();
-		}
+	for (size_t i = 0; i < _max_peak_signal.size(); ++i) {
+		_max_peak_signal[i] = 0;
+		_peak_buffer[i] = 0;
 	}
 }
 
@@ -185,7 +233,7 @@ PeakMeter::configure_io (ChanCount in, ChanCount out)
 
 	current_meters = in;
 
-	reset_max_channels (in);
+	set_max_channels (in);
 
 	return Processor::configure_io (in, out);
 }
@@ -193,22 +241,9 @@ PeakMeter::configure_io (ChanCount in, ChanCount out)
 void
 PeakMeter::reflect_inputs (const ChanCount& in)
 {
-	for (uint32_t i = in.n_total(); i < current_meters.n_total(); ++i) {
-		if (i < _peak_signal.size()) {
-			_peak_signal[i] = 0.0f;
-		}
-	}
-	for (uint32_t i = in.n_audio(); i < current_meters.n_audio(); ++i) {
-		if (i >= _kmeter.size()) continue;
-		_kmeter[i]->reset();
-		_iec1meter[i]->reset();
-		_iec2meter[i]->reset();
-		_vumeter[i]->reset();
-	}
-
+	reset();
 	current_meters = in;
 	reset_max();
-
 	// ConfigurationChanged() postponed
 }
 
@@ -218,29 +253,26 @@ PeakMeter::emit_configuration_changed () {
 }
 
 void
-PeakMeter::reset_max_channels (const ChanCount& chn)
+PeakMeter::set_max_channels (const ChanCount& chn)
 {
 	uint32_t const limit = chn.n_total();
 	const size_t n_audio = chn.n_audio();
 
-	while (_peak_signal.size() > limit) {
-		_peak_signal.pop_back();
-		_visible_peak_power.pop_back();
+	while (_peak_power.size() > limit) {
+		_peak_buffer.pop_back();
+		_peak_power.pop_back();
 		_max_peak_signal.pop_back();
-		_max_peak_power.pop_back();
 	}
 
-	while (_peak_signal.size() < limit) {
-		_peak_signal.push_back(0);
-		_visible_peak_power.push_back(minus_infinity());
+	while (_peak_power.size() < limit) {
+		_peak_buffer.push_back(0);
+		_peak_power.push_back(-std::numeric_limits<float>::infinity());
 		_max_peak_signal.push_back(0);
-		_max_peak_power.push_back(minus_infinity());
 	}
 
-	assert(_peak_signal.size() == limit);
-	assert(_visible_peak_power.size() == limit);
+	assert(_peak_buffer.size() == limit);
+	assert(_peak_power.size() == limit);
 	assert(_max_peak_signal.size() == limit);
-	assert(_max_peak_power.size() == limit);
 
 	/* alloc/free other audio-only meter types. */
 	while (_kmeter.size() > n_audio) {
@@ -273,80 +305,6 @@ PeakMeter::reset_max_channels (const ChanCount& chn)
  * of meter size during this call.
  */
 
-void
-PeakMeter::meter ()
-{
-	if (!_active) {
-		return;
-	}
-
-	// TODO block this thread while PeakMeter::reset_max_channels() is
-	// reallocating channels.
-	// (may happen with Session > New: old session not yet closed,
-	// meter-thread still active while new one is initializing and
-	// maybe on other occasions, too)
-	if (   (_visible_peak_power.size() != _peak_signal.size())
-			|| (_max_peak_power.size()     != _peak_signal.size())
-			|| (_max_peak_signal.size()    != _peak_signal.size())
-			 ) {
-		return;
-	}
-
-	const size_t limit = min (_peak_signal.size(), (size_t) current_meters.n_total ());
-	const size_t n_midi  = min (_peak_signal.size(), (size_t) current_meters.n_midi());
-
-	/* 0.01f ^= 100 Hz update rate */
-	const float midi_meter_falloff = Config->get_meter_falloff() * 0.01f;
-	/* kmeters: 24dB / 2 sec */
-	const float audio_meter_falloff = (_meter_type & (MeterK20 | MeterK14 | MeterK12)) ? 0.12f : midi_meter_falloff;
-
-	for (size_t n = 0; n < limit; ++n) {
-
-		/* grab peak since last read */
-
-		float new_peak = _peak_signal[n]; /* XXX we should use atomic exchange from here ... */
-		_peak_signal[n] = 0;              /* ... to here */
-
-		if (n < n_midi) {
-			_max_peak_power[n] = -std::numeric_limits<float>::infinity(); // std::max (new_peak, _max_peak_power[n]); // XXX
-			_max_peak_signal[n] = 0;
-			if (midi_meter_falloff == 0.0f || new_peak > _visible_peak_power[n]) {
-				;
-			} else {
-				/* empirical algorithm WRT to audio falloff times */
-				new_peak = _visible_peak_power[n] - sqrt(_visible_peak_power[n] * midi_meter_falloff * 0.0002f);
-				if (new_peak < (1.0 / 512.0)) new_peak = 0;
-			}
-			_visible_peak_power[n] = new_peak;
-			continue;
-		}
-
-		/* AUDIO */
-
-		/* compute new visible value using falloff */
-
-		_max_peak_signal[n] = std::max(new_peak, _max_peak_signal[n]);
-
-		if (new_peak > 0.0) {
-			new_peak = accurate_coefficient_to_dB (new_peak);
-		} else {
-			new_peak = minus_infinity();
-		}
-
-		/* update max peak */
-
-		_max_peak_power[n] = std::max (new_peak, _max_peak_power[n]);
-
-		if (audio_meter_falloff == 0.0f || new_peak > _visible_peak_power[n]) {
-			_visible_peak_power[n] = new_peak;
-		} else {
-			// do falloff
-			new_peak = _visible_peak_power[n] - (audio_meter_falloff);
-			_visible_peak_power[n] = std::max (new_peak, -std::numeric_limits<float>::infinity());
-		}
-	}
-}
-
 #define CHECKSIZE(MTR) (n < MTR.size() + n_midi && n >= n_midi)
 
 float
@@ -391,16 +349,17 @@ PeakMeter::meter_level(uint32_t n, MeterType type) {
 			break;
 		case MeterPeak:
 		case MeterPeak0dB:
-			return peak_power(n);
-		case MeterMaxSignal:
-			if (n < _max_peak_signal.size()) {
-				return _max_peak_signal[n];
+			if (n < _peak_power.size()) {
+				return _peak_power[n];
 			}
 			break;
+		case MeterMaxSignal:
+			assert(0);
+			break;
 		default:
 		case MeterMaxPeak:
-			if (n < _max_peak_power.size()) {
-				return _max_peak_power[n];
+			if (n < _max_peak_signal.size()) {
+				return accurate_coefficient_to_dB(_max_peak_signal[n]);
 			}
 			break;
 	}
diff --git a/libs/ardour/route.cc b/libs/ardour/route.cc
index b28f83c477..4b4e450c34 100644
--- a/libs/ardour/route.cc
+++ b/libs/ardour/route.cc
@@ -206,8 +206,6 @@ Route::init ()
 
 	/* now that we have _meter, its safe to connect to this */
 
-	Metering::Meter.connect_same_thread (*this, (boost::bind (&Route::meter, this)));
-
 	{
 		Glib::Threads::Mutex::Lock lx (AudioEngine::instance()->process_lock ());
 		configure_processors (0);
@@ -1915,7 +1913,7 @@ Route::configure_processors_unlocked (ProcessorStreams* err)
 
 
 	if (_meter) {
-		_meter->reset_max_channels (processor_max_streams);
+		_meter->set_max_channels (processor_max_streams);
 	}
 
 	/* make sure we have sufficient scratch buffers to cope with the new processor
@@ -4021,28 +4019,6 @@ Route::set_active (bool yn, void* src)
 	}
 }
 
-void
-Route::meter ()
-{
-	Glib::Threads::RWLock::ReaderLock rm (_processor_lock);
-
-	assert (_meter);
-
-	_meter->meter ();
-
-	for (ProcessorList::iterator i = _processors.begin(); i != _processors.end(); ++i) {
-
-		boost::shared_ptr<Send> s;
-		boost::shared_ptr<Return> r;
-
-		if ((s = boost::dynamic_pointer_cast<Send> (*i)) != 0) {
-			s->meter()->meter();
-		} else if ((r = boost::dynamic_pointer_cast<Return> (*i)) != 0) {
-			r->meter()->meter ();
-		}
-	}
-}
-
 boost::shared_ptr<Pannable>
 Route::pannable() const
 {
diff --git a/libs/surfaces/control_protocol/control_protocol.cc b/libs/surfaces/control_protocol/control_protocol.cc
index cd379b10dc..71cae36086 100644
--- a/libs/surfaces/control_protocol/control_protocol.cc
+++ b/libs/surfaces/control_protocol/control_protocol.cc
@@ -281,7 +281,7 @@ ControlProtocol::route_get_peak_input_power (uint32_t table_index, uint32_t whic
 		return 0.0f;
 	}
 
-	return r->peak_meter().peak_power (which_input);
+	return r->peak_meter().meter_level (which_input, MeterPeak);
 }
 
 
diff --git a/libs/surfaces/mackie/strip.cc b/libs/surfaces/mackie/strip.cc
index 23624d12cf..3d3a92987a 100644
--- a/libs/surfaces/mackie/strip.cc
+++ b/libs/surfaces/mackie/strip.cc
@@ -719,7 +719,7 @@ void
 Strip::update_meter ()
 {
 	if (_meter && _transport_is_rolling && _metering_active) {
-		float dB = const_cast<PeakMeter&> (_route->peak_meter()).peak_power (0);
+		float dB = const_cast<PeakMeter&> (_route->peak_meter()).meter_level (0, MeterPeak);
 		_meter->send_update (*_surface, dB);
 	}
 }