Reproduce MCA subdescriptors when writing XML without the assets being present.

This assumes that we don't read a CPL, modify the sound assets, then
write it out again.  Maybe we should make that possible (e.g. by
invalidating the CPL's MCA subdescriptors list when changing sound).

1 files changed, 84 insertions, 0 deletions

diff --git a/src/mca_sub_descriptor.cc b/src/mca_sub_descriptor.cc
new file mode 100644
index 00000000..34bde9f8
--- /dev/null
+++ b/src/mca_sub_descriptor.cc
@@ -0,0 +1,84 @@
+/*
+    Copyright (C) 2026 Carl Hetherington <cth@carlh.net>
+
+    This file is part of libdcp.
+
+    libdcp 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.
+
+    libdcp 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 libdcp.  If not, see <http://www.gnu.org/licenses/>.
+
+    In addition, as a special exception, the copyright holders give
+    permission to link the code of portions of this program with the
+    OpenSSL library under certain conditions as described in each
+    individual source file, and distribute linked combinations
+    including the two.
+
+    You must obey the GNU General Public License in all respects
+    for all of the code used other than OpenSSL.  If you modify
+    file(s) with this exception, you may extend this exception to your
+    version of the file(s), but you are not obligated to do so.  If you
+    do not wish to do so, delete this exception statement from your
+    version.  If you delete this exception statement from all source
+    files in the program, then also delete it here.
+*/
+
+
+#include "dcp_assert.h"
+#include "mca_sub_descriptor.h"
+#include "util.h"
+LIBDCP_DISABLE_WARNINGS
+#include <libxml++/libxml++.h>
+LIBDCP_ENABLE_WARNINGS
+
+
+using std::string;
+using namespace dcp;
+
+
+MCASubDescriptor::MCASubDescriptor(cxml::ConstNodePtr node)
+{
+	tag = node->name();
+	instance_id = remove_urn_uuid(node->string_child("InstanceID"));
+	mca_label_dictionary_id = node->string_child("MCALabelDictionaryID");
+        mca_link_id = remove_urn_uuid(node->string_child("MCALinkID"));
+        mca_tag_symbol = node->string_child("MCATagSymbol");
+        mca_tag_name = node->optional_string_child("MCATagName");
+        mca_channel_id = node->optional_string_child("MCAChannelID");
+        rfc5646_spoken_language = node->optional_string_child("RFC5646SpokenLanguage");
+	if (auto id = node->optional_string_child("SoundfieldGroupLinkID")) {
+		soundfield_group_link_id = remove_urn_uuid(*id);
+	}
+}
+
+
+void
+MCASubDescriptor::as_xml(xmlpp::Element* parent) const
+{
+	auto node = cxml::add_child(parent, tag, string("r0"));
+	cxml::add_child(node, "InstanceID", string("r1"))->add_child_text("urn:uuid:" + instance_id);
+	cxml::add_child(node, "MCALabelDictionaryID", string("r1"))->add_child_text(mca_label_dictionary_id);
+	cxml::add_child(node, "MCALinkID", string("r1"))->add_child_text("urn:uuid:" + mca_link_id);
+	cxml::add_child(node, "MCATagSymbol", string("r1"))->add_child_text(mca_tag_symbol);
+	if (mca_tag_name) {
+		cxml::add_child(node, "MCATagName", string("r1"))->add_child_text(*mca_tag_name);
+	}
+	if (mca_channel_id) {
+		cxml::add_child(node, "MCAChannelID", string("r1"))->add_child_text(*mca_channel_id);
+	}
+	if (rfc5646_spoken_language) {
+		cxml::add_child(node, "RFC5646SpokenLanguage", string("r1"))->add_child_text(*rfc5646_spoken_language);
+	}
+	if (soundfield_group_link_id) {
+		cxml::add_child(node, "SoundfieldGroupLinkID", string("r1"))->add_child_text("urn:uuid:" + *soundfield_group_link_id);
+	}
+}
+