Add an option to preserve tags when transcoding

src/av/AvTranscoder.cpp

@@ -158,9 +158,12 @@ Transcoder::start()
 		args.push_back("0:" + std::to_string(*_parameters.stream));
 	}
 
-	// Strip metadata
-	args.push_back("-map_metadata");
-	args.push_back("-1");
+	if (_parameters.stripMetadata)
+	{
+		// Strip metadata
+		args.push_back("-map_metadata");
+		args.push_back("-1");
+	}
 
 	// Skip video flows (including covers)
 	args.push_back("-vn");

src/av/AvTranscoder.hpp

@@ -47,8 +47,9 @@ struct TranscodeParameters
 {
 	Encoding	encoding {Encoding::MP3};
 	std::size_t	bitrate {128000};
-	boost::optional<std::size_t> stream {boost::none}; // Id of the stream to be transcoded (auto detect by default)
-	boost::optional<std::chrono::seconds> offset {boost::none};
+	boost::optional<std::size_t> stream; // Id of the stream to be transcoded (auto detect by default)
+	boost::optional<std::chrono::seconds> offset;
+	bool stripMetadata {true};
 };
 
 class Transcoder