playlist/flac: re-add the plugin

This reverts commit d7d9dbd2c2 by
reimplementing it with the current MPD API.

3 years ago, I was wrong about the "embcue" plugin being able to
replace this one, because "embcue" reads a tag named "CUESHEET", while
this plugin reads the "CUESHEET" FLAC metablock.  There's an important
difference between those two!

Makefile.am

@@ -1479,6 +1479,12 @@ PLAYLIST_LIBS = \
 	$(EXPAT_LIBS) \
 	$(FLAC_LIBS)
 
+if ENABLE_FLAC
+libplaylist_plugins_a_SOURCES += \
+	src/playlist/plugins/FlacPlaylistPlugin.cxx \
+	src/playlist/plugins/FlacPlaylistPlugin.hxx
+endif
+
 if ENABLE_CUE
 libplaylist_plugins_a_SOURCES += \
 	src/playlist/cue/CueParser.cxx src/playlist/cue/CueParser.hxx \

NEWS

@@ -19,6 +19,7 @@ ver 0.20 (not yet released)
 * playlist
   - cue: don't skip pregap
   - embcue: fix last track
+  - flac: new plugin which reads the "CUESHEET" metadata block
 * output
   - jack: reduce CPU usage
   - pulse: set channel map to WAVE-EX

src/playlist/PlaylistRegistry.cxx

@@ -27,6 +27,7 @@
 #include "plugins/PlsPlaylistPlugin.hxx"
 #include "plugins/AsxPlaylistPlugin.hxx"
 #include "plugins/RssPlaylistPlugin.hxx"
+#include "plugins/FlacPlaylistPlugin.hxx"
 #include "plugins/CuePlaylistPlugin.hxx"
 #include "plugins/EmbeddedCuePlaylistPlugin.hxx"
 #include "input/InputStream.hxx"
@@ -53,6 +54,9 @@ const struct playlist_plugin *const playlist_plugins[] = {
 #ifdef ENABLE_SOUNDCLOUD
 	&soundcloud_playlist_plugin,
 #endif
+#ifdef ENABLE_FLAC
+	&flac_playlist_plugin,
+#endif
 #ifdef ENABLE_CUE
 	&cue_playlist_plugin,
 	&embcue_playlist_plugin,

src/playlist/plugins/FlacPlaylistPlugin.cxx

@@ -0,0 +1,135 @@
+/*
+ * Copyright (C) 2003-2015 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program 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.
+ *
+ * This program 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 this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/** \file
+ *
+ * Playlist plugin that reads embedded cue sheets from the "CUESHEET"
+ * tag of a music file.
+ */
+
+#include "config.h"
+#include "FlacPlaylistPlugin.hxx"
+#include "../PlaylistPlugin.hxx"
+#include "../SongEnumerator.hxx"
+#include "DetachedSong.hxx"
+#include "fs/Traits.hxx"
+#include "fs/AllocatedPath.hxx"
+#include "fs/NarrowPath.hxx"
+
+#include <FLAC/metadata.h>
+
+#include <string.h>
+
+class FlacPlaylist final : public SongEnumerator {
+	const char *const uri;
+
+	FLAC__StreamMetadata *const cuesheet;
+	const unsigned sample_rate;
+	const FLAC__uint64 total_samples;
+
+	unsigned next_track = 0;
+
+public:
+	FlacPlaylist(const char *_uri,
+		     FLAC__StreamMetadata *_cuesheet,
+		     const FLAC__StreamMetadata &streaminfo)
+		:uri(_uri), cuesheet(_cuesheet),
+		 sample_rate(streaminfo.data.stream_info.sample_rate),
+		 total_samples(streaminfo.data.stream_info.total_samples) {
+	}
+
+	virtual ~FlacPlaylist() {
+		FLAC__metadata_object_delete(cuesheet);
+	}
+
+	virtual DetachedSong *NextSong() override;
+};
+
+DetachedSong *
+FlacPlaylist::NextSong()
+{
+	const FLAC__StreamMetadata_CueSheet &c = cuesheet->data.cue_sheet;
+
+	/* find the next audio track */
+
+	while (next_track < c.num_tracks &&
+	       (c.tracks[next_track].number > c.num_tracks ||
+		c.tracks[next_track].type != 0))
+		++next_track;
+
+	if (next_track >= c.num_tracks)
+		return nullptr;
+
+	FLAC__uint64 start = c.tracks[next_track].offset;
+	++next_track;
+	FLAC__uint64 end = next_track < c.num_tracks
+		? c.tracks[next_track].offset
+		: total_samples;
+
+	auto *song = new DetachedSong(uri);
+	song->SetStartTime(SongTime::FromScale(start, sample_rate));
+	song->SetEndTime(SongTime::FromScale(end, sample_rate));
+	return song;
+}
+
+static SongEnumerator *
+flac_playlist_open_uri(const char *uri,
+		       gcc_unused Mutex &mutex, gcc_unused Cond &cond)
+{
+	if (!PathTraitsUTF8::IsAbsolute(uri))
+		/* only local files supported */
+		return nullptr;
+
+	const auto path_fs = AllocatedPath::FromUTF8(uri);
+	if (path_fs.IsNull())
+		return nullptr;
+
+	const NarrowPath narrow_path_fs(path_fs);
+
+	FLAC__StreamMetadata *cuesheet;
+	if (!FLAC__metadata_get_cuesheet(narrow_path_fs, &cuesheet))
+		return nullptr;
+
+	FLAC__StreamMetadata streaminfo;
+	if (!FLAC__metadata_get_streaminfo(uri, &streaminfo) ||
+	    streaminfo.data.stream_info.sample_rate == 0) {
+		FLAC__metadata_object_delete(cuesheet);
+		return nullptr;
+	}
+
+	return new FlacPlaylist(uri, cuesheet, streaminfo);
+}
+
+static const char *const flac_playlist_suffixes[] = {
+	"flac",
+	nullptr
+};
+
+const struct playlist_plugin flac_playlist_plugin = {
+	"flac",
+
+	nullptr,
+	nullptr,
+	flac_playlist_open_uri,
+	nullptr,
+
+	nullptr,
+	flac_playlist_suffixes,
+	nullptr,
+};

src/playlist/plugins/FlacPlaylistPlugin.hxx

@@ -0,0 +1,25 @@
+/*
+ * Copyright (C) 2003-2015 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program 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.
+ *
+ * This program 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 this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef MPD_FLAC_PLAYLIST_PLUGIN_HXX
+#define MPD_FLAC_PLAYLIST_PLUGIN_HXX
+
+extern const struct playlist_plugin flac_playlist_plugin;
+
+#endif