Add new "make-centre" processor.make-centre

This just puts L into L, R into R, and (L+R)/2 into C.

4 files changed, 147 insertions, 0 deletions

diff --git a/src/lib/audio_processor.cc b/src/lib/audio_processor.cc
index 6f3b96145..d2215627a 100644
--- a/src/lib/audio_processor.cc
+++ b/src/lib/audio_processor.cc
@@ -21,6 +21,7 @@
 
 #include "audio_processor.h"
 #include "config.h"
+#include "make_centre.h"
 #include "mid_side_decoder.h"
 #include "upmixer_a.h"
 #include "upmixer_b.h"
@@ -39,6 +40,7 @@ void
 AudioProcessor::setup_audio_processors ()
 {
 	_non_experimental.push_back (unique_ptr<AudioProcessor>(new MidSideDecoder()));
+	_non_experimental.push_back (unique_ptr<AudioProcessor>(new MakeCentre()));
 
 	_experimental.push_back (unique_ptr<AudioProcessor>(new UpmixerA(48000)));
 	_experimental.push_back (unique_ptr<AudioProcessor>(new UpmixerB(48000)));
diff --git a/src/lib/make_centre.cc b/src/lib/make_centre.cc
new file mode 100644
index 000000000..39c8451b0
--- /dev/null
+++ b/src/lib/make_centre.cc
@@ -0,0 +1,109 @@
+/*
+    Copyright (C) 2024 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 "audio_mapping.h"
+#include "make_centre.h"
+
+#include "i18n.h"
+
+
+using std::make_shared;
+using std::min;
+using std::shared_ptr;
+using std::string;
+using std::vector;
+
+
+string
+MakeCentre::name() const
+{
+	return _("Centre channel creator");
+}
+
+
+string
+MakeCentre::id() const
+{
+	return N_("make-centre");
+}
+
+
+int
+MakeCentre::out_channels() const
+{
+	return 3;
+}
+
+
+shared_ptr<AudioProcessor>
+MakeCentre::clone(int) const
+{
+	return make_shared<MakeCentre>();
+}
+
+
+shared_ptr<AudioBuffers>
+MakeCentre::run(shared_ptr<const AudioBuffers> in, int channels)
+{
+	int const N = min(channels, 3);
+	auto out = make_shared<AudioBuffers>(channels, in->frames());
+	for (int i = 0; i < in->frames(); ++i) {
+		auto const left = in->data()[0][i];
+		auto const right = in->data()[1][i];
+		auto const centre = (left + right) / 2;
+		if (N > 0) {
+			out->data()[0][i] = left;
+		}
+		if (N > 1) {
+			out->data()[1][i] = right;
+		}
+		if (N > 2) {
+			out->data()[2][i] = centre;
+		}
+	}
+
+	for (int i = N; i < channels; ++i) {
+		out->make_silent(i);
+	}
+
+	return out;
+}
+
+
+void
+MakeCentre::make_audio_mapping_default(AudioMapping& mapping) const
+{
+	mapping.make_zero();
+	for (int i = 0; i < min(2, mapping.input_channels()); ++i) {
+		mapping.set(i, i, 1);
+	}
+}
+
+
+vector<NamedChannel>
+MakeCentre::input_names() const
+{
+	return {
+		NamedChannel(_("Left"), 0),
+		NamedChannel(_("Right"), 1)
+	};
+}
diff --git a/src/lib/make_centre.h b/src/lib/make_centre.h
new file mode 100644
index 000000000..9ce07b81e
--- /dev/null
+++ b/src/lib/make_centre.h
@@ -0,0 +1,35 @@
+/*
+    Copyright (C) 2024 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_processor.h"
+
+
+class MakeCentre : public AudioProcessor
+{
+public:
+	std::string name() const override;
+	std::string id() const override;
+	int out_channels() const override;
+	std::shared_ptr<AudioProcessor> clone(int) const override;
+	std::shared_ptr<AudioBuffers> run(std::shared_ptr<const AudioBuffers>, int channels) override;
+	void make_audio_mapping_default(AudioMapping& mapping) const override;
+	std::vector<NamedChannel> input_names() const override;
+};
diff --git a/src/lib/wscript b/src/lib/wscript
index 0d61d7a69..f36fcb8da 100644
--- a/src/lib/wscript
+++ b/src/lib/wscript
@@ -145,6 +145,7 @@ sources = """
           kdm_util.cc
           log.cc
           log_entry.cc
+          make_centre.cc
           make_dcp.cc
           map_cli.cc
           maths_util.cc