4 files changed, 44 insertions, 23 deletions

diff --git a/src/cpl.cc b/src/cpl.cc
index c862a853..86b738d9 100644
--- a/src/cpl.cc
+++ b/src/cpl.cc
@@ -288,7 +288,16 @@ CPL::read_composition_metadata_asset (cxml::ConstNodePtr node)
 		_luminance = Luminance (lum);
 	}
 
-	_main_sound_configuration = node->optional_string_child("MainSoundConfiguration");
+	if (auto msc = node->optional_string_child("MainSoundConfiguration")) {
+		try {
+			_main_sound_configuration = MainSoundConfiguration(*msc);
+		} catch (MainSoundConfigurationError& e) {
+			/* With Interop DCPs this node may not make any sense, but that's OK */
+			if (_standard == dcp::Standard::SMPTE) {
+				throw e;
+			}
+		}
+	}
 
 	auto sr = node->optional_string_child("MainSoundSampleRate");
 	if (sr) {
@@ -492,7 +501,9 @@ CPL::maybe_write_composition_metadata_asset(xmlpp::Element* node, bool include_m
 		_luminance->as_xml (meta, "meta");
 	}
 
-	meta->add_child("MainSoundConfiguration", "meta")->add_child_text(*_main_sound_configuration);
+	if (_main_sound_configuration) {
+		meta->add_child("MainSoundConfiguration", "meta")->add_child_text(_main_sound_configuration->to_string());
+	}
 	meta->add_child("MainSoundSampleRate", "meta")->add_child_text(raw_convert<string>(*_main_sound_sample_rate) + " 1");
 
 	auto stored = meta->add_child("MainPictureStoredArea", "meta");
diff --git a/src/cpl.h b/src/cpl.h
index 71ac8545..686954b2 100644
--- a/src/cpl.h
+++ b/src/cpl.h
@@ -283,11 +283,11 @@ public:
 		_luminance = l;
 	}
 
-	boost::optional<std::string> main_sound_configuration () const {
+	boost::optional<dcp::MainSoundConfiguration> main_sound_configuration () const {
 		return _main_sound_configuration;
 	}
 
-	void set_main_sound_configuration (std::string c) {
+	void set_main_sound_configuration(dcp::MainSoundConfiguration c) {
 		_main_sound_configuration = c;
 	}
 
@@ -377,7 +377,7 @@ private:
 	boost::optional<std::string> _distributor;
 	boost::optional<std::string> _facility;
 	boost::optional<Luminance> _luminance;
-	boost::optional<std::string> _main_sound_configuration;
+	boost::optional<MainSoundConfiguration> _main_sound_configuration;
 	boost::optional<int> _main_sound_sample_rate;
 	boost::optional<dcp::Size> _main_picture_stored_area;
 	boost::optional<dcp::Size> _main_picture_active_area;
diff --git a/src/types.cc b/src/types.cc
index 153a73af..9b868197 100644
--- a/src/types.cc
+++ b/src/types.cc
@@ -473,8 +473,8 @@ MainSoundConfiguration::MainSoundConfiguration (string s)
 {
 	vector<string> parts;
 	boost::split (parts, s, boost::is_any_of("/"));
-	if (parts.size() != 2) {
-		throw MainSoundConfigurationError (s);
+	if (parts.empty()) {
+		throw MainSoundConfigurationError(s);
 	}
 
 	if (parts[0] == "51") {
@@ -482,7 +482,14 @@ MainSoundConfiguration::MainSoundConfiguration (string s)
 	} else if (parts[0] == "71") {
 		_field = MCASoundField::SEVEN_POINT_ONE;
 	} else {
-		throw MainSoundConfigurationError (s);
+		_field = MCASoundField::OTHER;
+	}
+
+	if (parts.size() < 2) {
+		/* I think it's OK to just have the sound field descriptor with no channels, though
+		 * to me it's not clear and I might be wrong.
+		 */
+		return;
 	}
 
 	vector<string> channels;
@@ -590,31 +597,33 @@ dcp::string_to_status (string s)
 Channel
 dcp::mca_id_to_channel (string id)
 {
-	if (id == "L") {
+	transform(id.begin(), id.end(), id.begin(), ::tolower);
+
+	if (id == "l") {
 		return Channel::LEFT;
-	} else if (id == "R") {
+	} else if (id == "r") {
 		return Channel::RIGHT;
-	} else if (id == "C") {
+	} else if (id == "c") {
 		return Channel::CENTRE;
-	} else if (id == "LFE") {
+	} else if (id == "lfe") {
 		return Channel::LFE;
-	} else if (id == "Ls" || id == "Lss") {
+	} else if (id == "ls" || id == "lss") {
 		return Channel::LS;
-	} else if (id == "Rs" || id == "Rss") {
+	} else if (id == "rs" || id == "rss") {
 		return Channel::RS;
-	} else if (id == "HI") {
+	} else if (id == "hi") {
 		return Channel::HI;
-	} else if (id == "VIN") {
+	} else if (id == "vin") {
 		return Channel::VI;
-	} else if (id == "Lrs") {
+	} else if (id == "lrs") {
 		return Channel::BSL;
-	} else if (id == "Rrs") {
+	} else if (id == "rrs") {
 		return Channel::BSR;
-	} else if (id == "DBOX") {
+	} else if (id == "dbox") {
 		return Channel::MOTION_DATA;
-	} else if (id == "FSKSync") {
+	} else if (id == "sync" || id == "fsksync") {
 		return Channel::SYNC_SIGNAL;
-	} else if (id == "SLVS") {
+	} else if (id == "slvs") {
 		return Channel::SIGN_LANGUAGE;
 	}
 
diff --git a/src/types.h b/src/types.h
index 5f955c4b..a670fdd5 100644
--- a/src/types.h
+++ b/src/types.h
@@ -119,7 +119,8 @@ std::vector<dcp::Channel> used_audio_channels ();
 enum class MCASoundField
 {
 	FIVE_POINT_ONE,
-	SEVEN_POINT_ONE
+	SEVEN_POINT_ONE,
+	OTHER
 };
 
 
@@ -445,7 +446,7 @@ bool operator== (Luminance const& a, Luminance const& b);
 class MainSoundConfiguration
 {
 public:
-	MainSoundConfiguration (std::string);
+	explicit MainSoundConfiguration(std::string);
 	MainSoundConfiguration (MCASoundField field_, int channels);
 
 	MCASoundField field () const {