song info: show replay gain info if available (flac/ogg only)

src/song_info.cpp

@@ -22,6 +22,7 @@
 #include "helpers.h"
 #include "song_info.h"
 #include "tag_editor.h"
+#include "tags.h"
 #include "title.h"
 #include "screen_switcher.h"
 
@@ -124,7 +125,17 @@ void SongInfo::PrepareSong(MPD::Song &s)
 			}
 			w << NC::Format::Bold << "Bitrate: " << NC::Format::NoBold << Config.color2 << f.audioProperties()->bitrate() << " kbps\n" << NC::Color::End;
 			w << NC::Format::Bold << "Sample rate: " << NC::Format::NoBold << Config.color2 << f.audioProperties()->sampleRate() << " Hz\n" << NC::Color::End;
-			w << NC::Format::Bold << "Channels: " << NC::Format::NoBold << Config.color2 << channels << '\n' << NC::Color::Default;
+			w << NC::Format::Bold << "Channels: " << NC::Format::NoBold << Config.color2 << channels << NC::Color::End << "\n";
+			
+			auto rginfo = Tags::readReplayGain(f.file());
+			if (!rginfo.empty())
+			{
+				w << NC::Format::Bold << "\nReference loudness: " << NC::Format::NoBold << Config.color2 << rginfo.referenceLoudness() << NC::Color::End << "\n";
+				w << NC::Format::Bold << "Track gain: " << NC::Format::NoBold << Config.color2 << rginfo.trackGain() << NC::Color::End << "\n";
+				w << NC::Format::Bold << "Track peak: " << NC::Format::NoBold << Config.color2 << rginfo.trackPeak() << NC::Color::End << "\n";
+				w << NC::Format::Bold << "Album gain: " << NC::Format::NoBold << Config.color2 << rginfo.albumGain() << NC::Color::End << "\n";
+				w << NC::Format::Bold << "Album peak: " << NC::Format::NoBold << Config.color2 << rginfo.albumPeak() << NC::Color::End << "\n";
+			}
 		}
 	}
 #	endif // HAVE_TAGLIB_H

src/tags.cpp

@@ -187,6 +187,24 @@ void writeXiphComments(const MPD::MutableSong &s, TagLib::Ogg::XiphComment *tag)
 	writeXiph("COMMENT", tagList(s, &MPD::Song::getComment));
 }
 
+Tags::ReplayGainInfo getReplayGain(TagLib::Ogg::XiphComment *tag)
+{
+	auto first_or_empty = [](const TagLib::StringList &list) {
+		std::string result;
+		if (!list.isEmpty())
+			result = list.front().to8Bit(true);
+		return result;
+	};
+	auto &fields = tag->fieldListMap();
+	return Tags::ReplayGainInfo(
+		first_or_empty(fields["REPLAYGAIN_REFERENCE_LOUDNESS"]),
+		first_or_empty(fields["REPLAYGAIN_TRACK_GAIN"]),
+		first_or_empty(fields["REPLAYGAIN_TRACK_PEAK"]),
+		first_or_empty(fields["REPLAYGAIN_ALBUM_GAIN"]),
+		first_or_empty(fields["REPLAYGAIN_ALBUM_PEAK"])
+	);
+}
+
 }
 
 namespace Tags {//
@@ -198,6 +216,22 @@ bool extendedSetSupported(const TagLib::File *f)
 	||     dynamic_cast<const TagLib::FLAC::File *>(f);
 }
 
+ReplayGainInfo readReplayGain(TagLib::File *f)
+{
+	ReplayGainInfo result;
+	if (auto ogg_file = dynamic_cast<TagLib::Ogg::Vorbis::File *>(f))
+	{
+		if (auto xiph = ogg_file->tag())
+			result = getReplayGain(xiph);
+	}
+	else if (auto flac_file = dynamic_cast<TagLib::FLAC::File *>(f))
+	{
+		if (auto xiph = flac_file->xiphComment())
+			result = getReplayGain(xiph);
+	}
+	return result;
+}
+
 void read(MPD::MutableSong &s)
 {
 	TagLib::FileRef f(s.getURI().c_str());

src/tags.h

@@ -30,6 +30,40 @@
 
 namespace Tags {//
 
+struct ReplayGainInfo
+{
+	ReplayGainInfo() { }
+	ReplayGainInfo(std::string reference_loudness, std::string track_gain,
+				   std::string track_peak, std::string album_gain,
+				   std::string album_peak)
+	: m_reference_loudness(reference_loudness), m_track_gain(track_gain)
+	, m_track_peak(track_peak), m_album_gain(album_gain), m_album_peak(album_peak) { }
+	
+	bool empty() const
+	{
+		return m_reference_loudness.empty()
+		    && m_track_gain.empty()
+		    && m_track_peak.empty()
+		    && m_album_gain.empty()
+		    && m_album_peak.empty();
+	}
+	
+	const std::string &referenceLoudness() const { return m_reference_loudness; }
+	const std::string &trackGain() const { return m_track_gain; }
+	const std::string &trackPeak() const { return m_track_peak; }
+	const std::string &albumGain() const { return m_album_gain; }
+	const std::string &albumPeak() const { return m_album_peak; }
+	
+private:
+	std::string m_reference_loudness;
+	std::string m_track_gain;
+	std::string m_track_peak;
+	std::string m_album_gain;
+	std::string m_album_peak;
+};
+
+ReplayGainInfo readReplayGain(TagLib::File *f);
+
 bool extendedSetSupported(const TagLib::File *f);
 
 void read(MPD::MutableSong &);