wip: audio meters.

5 files changed, 220 insertions, 0 deletions

diff --git a/src/lib/butler.cc b/src/lib/butler.cc
index 14f342045..57c891404 100644
--- a/src/lib/butler.cc
+++ b/src/lib/butler.cc
@@ -24,6 +24,7 @@
 #include "cross.h"
 #include "dcpomatic_log.h"
 #include "exceptions.h"
+#include "level_calculator.h"
 #include "log.h"
 #include "player.h"
 #include "util.h"
@@ -33,6 +34,7 @@
 using std::cout;
 using std::function;
 using std::make_pair;
+using std::make_shared;
 using std::pair;
 using std::shared_ptr;
 using std::string;
@@ -88,6 +90,7 @@ Butler::Butler(
 	, _alignment(alignment)
 	, _fast(fast)
 	, _prepare_only_proxy(prepare_only_proxy)
+	, _level_calculator(make_shared<LevelCalculator>())
 {
 	_player_video_connection = _player.Video.connect(bind(&Butler::video, this, _1, _2));
 	_player_audio_connection = _player.Audio.connect(bind(&Butler::audio, this, _1, _2, _3));
@@ -312,6 +315,7 @@ Butler::seek_unlocked(DCPTime position, bool accurate)
 
 	_video.clear();
 	_audio.clear();
+	_level_calculator->clear();
 	_closed_caption.clear();
 
 	_summon.notify_all();
@@ -370,6 +374,8 @@ Butler::audio(shared_ptr<AudioBuffers> audio, DCPTime time, int frame_rate)
 		return;
 	}
 
+	_level_calculator->put(audio, time, frame_rate);
+
 	_audio.put(remap(audio, _audio_channels, _audio_mapping), time, frame_rate);
 }
 
@@ -481,3 +487,10 @@ Butler::Error::summary() const
 	return "";
 }
 
+
+shared_ptr<LevelCalculator>
+Butler::level_calculator() const
+{
+	return _level_calculator;
+}
+
diff --git a/src/lib/butler.h b/src/lib/butler.h
index ad2552769..dd04e7b86 100644
--- a/src/lib/butler.h
+++ b/src/lib/butler.h
@@ -37,6 +37,7 @@
 #include <boost/thread/condition.hpp>
 
 
+class LevelCalculator;
 class Player;
 class PlayerVideo;
 
@@ -94,6 +95,8 @@ public:
 	boost::optional<dcpomatic::DCPTime> get_audio(Behaviour behaviour, float* out, Frame frames);
 	boost::optional<TextRingBuffers::Data> get_closed_caption();
 
+	std::shared_ptr<LevelCalculator> level_calculator() const;
+
 	std::pair<size_t, std::string> memory_used() const;
 
 private:
@@ -154,6 +157,8 @@ private:
 	*/
 	boost::optional<dcpomatic::DCPTime> _awaiting;
 
+	std::shared_ptr<LevelCalculator> _level_calculator;
+
 	boost::signals2::scoped_connection _player_video_connection;
 	boost::signals2::scoped_connection _player_audio_connection;
 	boost::signals2::scoped_connection _player_text_connection;
diff --git a/src/lib/level_calculator.cc b/src/lib/level_calculator.cc
new file mode 100644
index 000000000..0563d4ed8
--- /dev/null
+++ b/src/lib/level_calculator.cc
@@ -0,0 +1,127 @@
+/*
+    Copyright (C) 2025 Carl Hetherington <cth@carlh.net>
+
+    This file is part of DCP-o-matic.
+
+    DCP-o-matic is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    DCP-o-matic is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with DCP-o-matic.  If not, see <http://www.gnu.org/licenses/>.
+
+*/
+
+
+#include "audio_buffers.h"
+#include "level_calculator.h"
+
+
+using std::make_pair;
+using std::shared_ptr;
+using boost::optional;
+
+
+constexpr int frames_per_measurement = 48000 / 30;
+
+
+LevelCalculator::LevelCalculator()
+	: _enabled(false)
+{
+
+}
+
+
+void
+LevelCalculator::put(shared_ptr<const AudioBuffers> audio, dcpomatic::DCPTime time, int frame_rate)
+{
+	if (!_enabled) {
+		std::cout << "no calcs for me.\n";
+		return;
+	}
+
+	boost::mutex::scoped_lock lm(_current_mutex);
+
+	auto const channels = audio->channels();
+
+	if (static_cast<int>(_current_peaks.size()) != channels) {
+		_current_peaks.resize(channels);
+	}
+
+	auto const data = audio->data();
+	auto const frames = audio->frames();
+	for (auto frame = 0; frame < frames; ++frame) {
+		for (auto channel = 0; channel < channels; ++channel) {
+			_current_peaks[channel] = std::max(std::abs(data[channel][frame]), _current_peaks[channel]);
+		}
+
+		++_current_frames;
+		if (_current_frames == frames_per_measurement) {
+			{
+				boost::mutex::scoped_lock lm(_store_mutex);
+				_peaks.emplace_back(time + dcpomatic::DCPTime::from_frames(frame, frame_rate), _current_peaks);
+			}
+			std::fill(_current_peaks.begin(), _current_peaks.end(), 0.0f);
+			_current_frames = 0;
+		}
+	}
+
+}
+
+
+void
+LevelCalculator::clear()
+{
+	boost::mutex::scoped_lock slm(_store_mutex);
+	_peaks.clear();
+
+	boost::mutex::scoped_lock clm(_current_mutex);
+	std::fill(_current_peaks.begin(), _current_peaks.end(), 0.0f);
+	_current_frames = 0;
+}
+
+
+std::vector<float>
+LevelCalculator::get(dcpomatic::DCPTime time)
+{
+	boost::mutex::scoped_lock slm(_store_mutex);
+
+	auto iter = _peaks.begin();
+	optional<dcpomatic::DCPTime> last_delta;
+	std::list<Measurement>::iterator last_iter;
+	while (iter != _peaks.end()) {
+		auto const delta = dcpomatic::DCPTime(time - iter->time).abs();
+		if (last_delta) {
+			if (delta > *last_delta) {
+				/* This is worse than the last - use the last one */
+				return last_iter->value;
+			} else {
+				/* This is better - keep looking */
+				_peaks.erase(last_iter);
+			}
+		}
+		last_delta = delta;
+		last_iter = iter;
+		++iter;
+	}
+
+	if (iter == _peaks.end()) {
+		return {};
+	}
+
+	return iter->value;
+}
+
+
+void
+LevelCalculator::enable(bool e)
+{
+	_enabled = e;
+}
+
diff --git a/src/lib/level_calculator.h b/src/lib/level_calculator.h
new file mode 100644
index 000000000..9eeb5b9b8
--- /dev/null
+++ b/src/lib/level_calculator.h
@@ -0,0 +1,74 @@
+/*
+    Copyright (C) 2025 Carl Hetherington <cth@carlh.net>
+
+    This file is part of DCP-o-matic.
+
+    DCP-o-matic is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    DCP-o-matic is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with DCP-o-matic.  If not, see <http://www.gnu.org/licenses/>.
+
+*/
+
+
+#ifndef DCPOMATIC_LEVEL_CALCULATOR_H
+#define DCPOMATIC_LEVEL_CALCULATOR_H
+
+
+#include "dcpomatic_time.h"
+#include <boost/thread.hpp>
+#include <memory>
+
+
+class AudioBuffers;
+
+
+class LevelCalculator
+{
+public:
+	LevelCalculator();
+
+	LevelCalculator(LevelCalculator const&) = delete;
+	LevelCalculator& operator=(LevelCalculator const&) = delete;
+
+	void put(std::shared_ptr<const AudioBuffers> audio, dcpomatic::DCPTime time, int frame_rate);
+	void clear();
+	std::vector<float> get(dcpomatic::DCPTime time);
+
+	void enable(bool e);
+
+private:
+	boost::mutex _current_mutex;
+	std::vector<float> _current_peaks;
+	int _current_frames = 0;
+
+	struct Measurement
+	{
+		Measurement(dcpomatic::DCPTime t, std::vector<float> v)
+			: time(t)
+			, value(std::move(v))
+		{
+
+		}
+
+		dcpomatic::DCPTime time;
+		std::vector<float> value;
+	};
+
+	mutable boost::mutex _store_mutex;
+	std::list<Measurement> _peaks;
+
+	boost::atomic<bool> _enabled;
+};
+
+
+#endif
+
diff --git a/src/lib/wscript b/src/lib/wscript
index dafd655fe..4b0002f04 100644
--- a/src/lib/wscript
+++ b/src/lib/wscript
@@ -156,6 +156,7 @@ sources = """
           kdm_recipient.cc
           kdm_with_metadata.cc
           kdm_util.cc
+          level_calculator.cc
           log.cc
           log_entry.cc
           make_dcp.cc