fluidsynth: new decoder plugin for MIDI files

There are a few problems left in this plugin:

- fluidsynth decodes in real time, while MPD prefers to buffer as
  quickly as possible; as a workaround, this plugin uses a timer
  object to synchronize with real-time playback

- I don't know yet how fluidsynth tells me when the song has ended

- the "soundfont" configuration setting is not yet documented, and it
  will likely change soon (in favor of a per-decoder configuration
  block)

3 files changed, 243 insertions, 0 deletions

diff --git a/src/Makefile.am b/src/Makefile.am
index 8170badbe..935f8b3d6 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -12,6 +12,7 @@ mpd_CPPFLAGS = \
 	$(AUDIOFILE_CFLAGS) $(LIBMIKMOD_CFLAGS) \
 	$(MODPLUG_CFLAGS) \
 	$(SIDPLAY_CFLAGS) \
+	$(FLUIDSYNTH_CFLAGS) \
 	$(ID3TAG_CFLAGS) \
 	$(MAD_CFLAGS) \
 	$(FFMPEG_CFLAGS) \
@@ -26,6 +27,7 @@ mpd_LDADD = $(MPD_LIBS) \
 	$(AUDIOFILE_LIBS) $(LIBMIKMOD_LIBS) \
 	$(MODPLUG_LIBS) \
 	$(SIDPLAY_LIBS) \
+	$(FLUIDSYNTH_LIBS) \
 	$(ID3TAG_LIBS) \
 	$(MAD_LIBS) \
 	$(MP4FF_LIBS) \
@@ -317,6 +319,10 @@ if ENABLE_SIDPLAY
 mpd_SOURCES += decoder/sidplay_plugin.cxx
 endif
 
+if ENABLE_FLUIDSYNTH
+mpd_SOURCES += decoder/fluidsynth_plugin.c
+endif
+
 if HAVE_FFMPEG
 mpd_SOURCES += decoder/ffmpeg_plugin.c
 endif
diff --git a/src/decoder/fluidsynth_plugin.c b/src/decoder/fluidsynth_plugin.c
new file mode 100644
index 000000000..3a744d2f9
--- /dev/null
+++ b/src/decoder/fluidsynth_plugin.c
@@ -0,0 +1,233 @@
+/*
+ * Copyright (C) 2003-2009 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include "../decoder_api.h"
+#include "../timer.h"
+#include "../conf.h"
+
+#include <glib.h>
+
+#include <fluidsynth.h>
+
+#undef G_LOG_DOMAIN
+#define G_LOG_DOMAIN "fluidsynth"
+
+/**
+ * Convert a fluidsynth log level to a GLib log level.
+ */
+static GLogLevelFlags
+fluidsynth_level_to_glib(enum fluid_log_level level)
+{
+	switch (level) {
+	case FLUID_PANIC:
+	case FLUID_ERR:
+		return G_LOG_LEVEL_CRITICAL;
+
+	case FLUID_WARN:
+		return G_LOG_LEVEL_WARNING;
+
+	case FLUID_INFO:
+		return G_LOG_LEVEL_INFO;
+
+	case FLUID_DBG:
+	case LAST_LOG_LEVEL:
+		return G_LOG_LEVEL_DEBUG;
+	}
+
+	/* invalid fluidsynth log level */
+	return G_LOG_LEVEL_MESSAGE;
+}
+
+/**
+ * The fluidsynth logging callback.  It forwards messages to the GLib
+ * logging library.
+ */
+static void
+fluidsynth_mpd_log_function(int level, char *message, G_GNUC_UNUSED void *data)
+{
+	g_log(G_LOG_DOMAIN, fluidsynth_level_to_glib(level), "%s", message);
+}
+
+static bool
+fluidsynth_init(void)
+{
+	fluid_set_log_function(LAST_LOG_LEVEL,
+			       fluidsynth_mpd_log_function, NULL);
+
+	return true;
+}
+
+static void
+fluidsynth_file_decode(struct decoder *decoder, const char *path_fs)
+{
+	static const struct audio_format audio_format = {
+		.sample_rate = 48000,
+		.bits = 16,
+		.channels = 2,
+	};
+	char setting_sample_rate[] = "synth.sample-rate";
+	/*
+	char setting_verbose[] = "synth.verbose";
+	char setting_yes[] = "yes";
+	*/
+	const char *soundfont_path;
+	fluid_settings_t *settings;
+	fluid_synth_t *synth;
+	fluid_player_t *player;
+	char *path_dup;
+	int ret;
+	Timer *timer;
+	enum decoder_command cmd;
+
+	soundfont_path =
+		config_get_string("soundfont",
+				  "/usr/share/sounds/sf2/FluidR3_GM.sf2");
+
+	/* set up fluid settings */
+
+	settings = new_fluid_settings();
+	if (settings == NULL)
+		return;
+
+	fluid_settings_setnum(settings, setting_sample_rate, 48000);
+
+	/*
+	fluid_settings_setstr(settings, setting_verbose, setting_yes);
+	*/
+
+	/* create the fluid synth */
+
+	synth = new_fluid_synth(settings);
+	if (synth == NULL) {
+		delete_fluid_settings(settings);
+		return;
+	}
+
+	ret = fluid_synth_sfload(synth, soundfont_path, true);
+	if (ret < 0) {
+		g_warning("fluid_synth_sfload() failed");
+		delete_fluid_synth(synth);
+		delete_fluid_settings(settings);
+		return;
+	}
+
+	/* create the fluid player */
+
+	player = new_fluid_player(synth);
+	if (player == NULL) {
+		delete_fluid_synth(synth);
+		delete_fluid_settings(settings);
+		return;
+	}
+
+	/* temporarily duplicate the path_fs string, because
+	   fluidsynth wants a writable string */
+	path_dup = g_strdup(path_fs);
+	ret = fluid_player_add(player, path_dup);
+	g_free(path_dup);
+	if (ret != 0) {
+		g_warning("fluid_player_add() failed");
+		delete_fluid_player(player);
+		delete_fluid_synth(synth);
+		delete_fluid_settings(settings);
+		return;
+	}
+
+	/* start the player */
+
+	ret = fluid_player_play(player);
+	if (ret != 0) {
+		g_warning("fluid_player_play() failed");
+		delete_fluid_player(player);
+		delete_fluid_synth(synth);
+		delete_fluid_settings(settings);
+		return;
+	}
+
+	/* set up a timer for synchronization; fluidsynth always
+	   decodes in real time, which forces us to synchronize */
+	/* XXX is there any way to switch off real-time decoding? */
+
+	timer = timer_new(&audio_format);
+	timer_start(timer);
+
+	/* initialization complete - announce the audio format to the
+	   MPD core */
+
+	decoder_initialized(decoder, &audio_format, false, -1);
+
+	do {
+		int16_t buffer[2048];
+		const unsigned max_frames = G_N_ELEMENTS(buffer) / 2;
+
+		/* synchronize with the fluid player */
+
+		timer_add(timer, sizeof(buffer));
+		timer_sync(timer);
+
+		/* read samples from fluidsynth and send them to the
+		   MPD core */
+
+		ret = fluid_synth_write_s16(synth, max_frames,
+					    buffer, 0, 2,
+					    buffer, 1, 2);
+		/* XXX how do we see whether the player is done?  We
+		   can't access the private attribute
+		   player->status */
+		if (ret != 0)
+			break;
+
+		cmd = decoder_data(decoder, NULL, buffer, sizeof(buffer),
+				   0, 0, NULL);
+	} while (cmd == DECODE_COMMAND_NONE);
+
+	/* clean up */
+
+	timer_free(timer);
+
+	fluid_player_stop(player);
+	fluid_player_join(player);
+
+	delete_fluid_player(player);
+	delete_fluid_synth(synth);
+	delete_fluid_settings(settings);
+}
+
+static struct tag *
+fluidsynth_tag_dup(const char *file)
+{
+	struct tag *tag = tag_new();
+
+	/* to be implemented */
+	(void)file;
+
+	return tag;
+}
+
+static const char *const fluidsynth_suffixes[] = {
+	"mid",
+	NULL
+};
+
+const struct decoder_plugin fluidsynth_decoder_plugin = {
+	.name = "fluidsynth",
+	.init = fluidsynth_init,
+	.file_decode = fluidsynth_file_decode,
+	.tag_dup = fluidsynth_tag_dup,
+	.suffixes = fluidsynth_suffixes,
+};
diff --git a/src/decoder_list.c b/src/decoder_list.c
index 96429067c..e7f757e71 100644
--- a/src/decoder_list.c
+++ b/src/decoder_list.c
@@ -35,6 +35,7 @@ extern const struct decoder_plugin wavpack_plugin;
 extern const struct decoder_plugin modplug_plugin;
 extern const struct decoder_plugin mikmod_decoder_plugin;
 extern const struct decoder_plugin sidplay_decoder_plugin;
+extern const struct decoder_plugin fluidsynth_decoder_plugin;
 extern const struct decoder_plugin ffmpeg_plugin;
 
 static const struct decoder_plugin *const decoder_plugins[] = {
@@ -74,6 +75,9 @@ static const struct decoder_plugin *const decoder_plugins[] = {
 #ifdef ENABLE_SIDPLAY
 	&sidplay_decoder_plugin,
 #endif
+#ifdef ENABLE_FLUIDSYNTH
+	&fluidsynth_decoder_plugin,
+#endif
 #ifdef HAVE_FFMPEG
 	&ffmpeg_plugin,
 #endif