Libsaria: Make alsa controls its own thing

I created a new preference for "Using ALSA" that people can set if they
want to use extra alsa features.  This should allow the UI to provide a
dropdown list of outputs that users can select.  Once a UI is in place,
users can play music either on their computer speakers or pipe it out to
their blu ray players (or other device).

Signed-off-by: Bryan Schumaker <bjschuma@netapp.com>

PKGBUILD

@@ -6,7 +6,7 @@ pkgdesc="A simple GTK and gstreamer based music player."
 url="http://www.ocarinaproject.net/"
 arch=('x86_64' 'i686')
 license=('SimPL')
-depends=('gtk2' 'gstreamer0.10-base' 'taglib')
+depends=('gtk2' 'gstreamer0.10-base' 'gstreamer0.10-base-plugins' 'taglib')
 optdepends=('gstreamer0.10-good-plugins' 'gstreamer0.10-bad-plugins' 'gstreamer0.10-ugly-plugins')
 makedepends=('scons')
 conflicts=()

Sconstruct

@@ -26,6 +26,7 @@ env.Append(CPPPATH = "include")
 
 env.ParseConfig('pkg-config --cflags --libs gtk+-2.0')
 env.ParseConfig('pkg-config --cflags --libs gstreamer-0.10')
+env.ParseConfig('pkg-config --cflags --libs gstreamer-interfaces-0.10')
 env.ParseConfig('pkg-config --cflags --libs taglib')
 
 def version_h(target, source, env):

include/libsaria/audio.h

@@ -5,6 +5,7 @@ extern "C" {
 	#include <gst/gst.h>
 }
 
+#include <list>
 #include <string>
 using namespace std;
 
@@ -13,8 +14,15 @@ namespace libsaria
 	namespace audio
 	{
 		void init(int, char**);
+		void swap();
 		string get_current_file();
 
+		/* Alsa controls */
+		void use_alsa(bool);
+		bool using_alsa();
+		list<string> *get_alsa_devices();
+		void set_device(string &);
+
 		/* Playback control functions */
 		void load_file(string);
 		void load(string);

libsaria/audio/alsa.cpp

@@ -0,0 +1,91 @@
+// Copyright (c) 2012 Bryan Schumaker.
+#include <gst/interfaces/propertyprobe.h>
+#include <libsaria/audio.h>
+#include <libsaria/prefs.h>
+#include <libsaria/print.h>
+#include "audio.h"
+
+#include <list>
+using namespace std;
+
+static GstElement *alsa = NULL;
+static list<string> devices;
+
+static void probe_devices()
+{
+	GValueArray *array;
+	GValue *value;
+
+	devices.clear();
+	array = gst_property_probe_probe_and_get_values_name(GST_PROPERTY_PROBE(alsa), "device");
+
+	devices.push_back("default");
+	for (unsigned int i = 0; i < array->n_values; i++) {
+		value = g_value_array_get_nth(array, i);
+		devices.push_back(g_value_get_string(value));
+	}
+}
+
+static void set_alsa_device(string device)
+{
+	g_object_set(G_OBJECT(alsa), "device", device.c_str(), NULL);
+}
+
+static void add_alsa()
+{
+	println("Adding ALSA");
+	alsa = gst_element_factory_make("alsasink", "alsa");
+	probe_devices();
+	set_audio_sink(alsa);
+}
+
+static void remove_alsa()
+{
+	println("Removing ALSA");
+	set_alsa_device("default");
+	/* Removing the sink will also deallocate it */
+	set_audio_sink(NULL);
+}
+
+namespace libsaria
+{
+
+	void audio::use_alsa(bool use)
+	{
+		struct StoredAudioState state;
+		save_audio_state(&state);
+
+		if (use == true)
+			add_alsa();
+		else
+			remove_alsa();
+
+		load_audio_state(&state);
+		prefs::set("alsa", use);
+	}
+
+	bool audio::using_alsa()
+	{
+		return prefs::get_bool("alsa");
+	}
+
+	void audio::init_alsa()
+	{
+		use_alsa(using_alsa());
+	}
+
+	list<string> *audio::get_alsa_devices()
+	{
+		return &devices;
+	}
+
+	void audio::set_device(string &device)
+	{
+		struct StoredAudioState state;
+
+		save_audio_state(&state);
+		g_object_set(G_OBJECT(alsa), "device", device.c_str(), NULL);
+		load_audio_state(&state);
+	}
+
+}; /* Namespace: libsaria */

libsaria/audio/audio.cpp

@@ -7,8 +7,8 @@
 #include "audio.h"
 
 GstElement *player = NULL;
-GstElement *alsa = NULL;
 GstBus *bus = NULL;
+static bool restoring_state = false;
 
 static void parse_error(GstMessage *error)
 {
@@ -28,7 +28,8 @@ static void notify_audio_changed()
 		libsaria::audio::pause();
 		libsaria::set_pause_after(false);
 	}
-	trigger_callback(TRACK_LOADED);
+	if (restoring_state == false)
+		trigger_callback(TRACK_LOADED);
 }
 
 static gboolean on_message(GstBus *bus, GstMessage *message, gpointer data)
@@ -59,6 +60,40 @@ static void audio_changed(GstElement *playbin, gpointer data)
 	notify_audio_changed();
 }
 
+/*
+ * Set sink to NULL to use the default sink
+ */
+void set_audio_sink(GstElement *sink)
+{
+	g_object_set(G_OBJECT(player), "audio-sink", sink, NULL);
+}
+
+void save_audio_state(struct StoredAudioState *state)
+{
+	state->cur_file    = libsaria::audio::get_current_file();
+	state->position    = libsaria::audio::position();
+	state->was_playing = libsaria::audio::is_playing();
+}
+
+void load_audio_state(struct StoredAudioState *state)
+{
+	restoring_state = true;
+
+	libsaria::audio::load(state->cur_file);
+	if (state->was_playing == true)
+		libsaria::audio::play();
+	else
+		libsaria::audio::pause();
+	/*
+	 * Wait for async play() or pause() to finish, otherwise
+	 * the seek won't succeed
+	 */
+	gst_element_get_state(GST_ELEMENT(player), NULL, NULL, GST_CLOCK_TIME_NONE);
+	libsaria::audio::seek_to(state->position);
+
+	restoring_state = false;
+}
+
 namespace libsaria
 {
 
@@ -68,18 +103,15 @@ namespace libsaria
 		gst_init(&argc, &argv);
 
 		player = gst_element_factory_make("playbin2", "player");
-		alsa   = gst_element_factory_make("alsasink", "alsa");
 		bus    = gst_pipeline_get_bus(GST_PIPELINE(player));
 
 		gst_bus_add_watch(bus, on_message, NULL);
 
-		/* Without this gapless playback won't work */
-		g_object_set(G_OBJECT(player), "audio-sink", alsa, NULL);
-
 		g_signal_connect(player, "about-to-finish", G_CALLBACK(about_to_finish), NULL);
 		g_signal_connect(player, "audio-changed", G_CALLBACK(audio_changed), NULL);
 
 		init_volume();
+		init_alsa();
 	}
 
 };

libsaria/audio/audio.h

@@ -11,13 +11,25 @@ extern "C" {
 extern GstElement *player;
 extern GstBus *bus;
 
+struct StoredAudioState
+{
+	string cur_file;
+	double position;
+	bool   was_playing;
+};
+
 void load_file(GstElement *, string);
 
+void set_audio_sink(GstElement *);
+void save_audio_state(struct StoredAudioState *);
+void load_audio_state(struct StoredAudioState *);
+
 namespace libsaria
 {
 	namespace audio
 	{
 		void init_volume();
+		void init_alsa();
 	}
 }
 

libsaria/libsaria.cpp

@@ -18,12 +18,12 @@ namespace libsaria
 	{
 		srand( time(NULL) );
 		println("Initializing libsaria");
+		libsaria::prefs::load();
 		audio::init(argc, argv);
 		println("saria dir: %s", get_saria_dir().c_str());
 		make_saria_dir();
 		libsaria::library::load();
 		libsaria::queue::load();
-		libsaria::prefs::load();
 	}
 
 	void quit()