audio: Begin implementing audio code

I have written play(), pause(), next() and seek_to() so far.

Signed-off-by: Anna Schumaker <schumaker.anna@gmail.com>

config

@@ -34,6 +34,7 @@ class Config:
 		if self.TEST: env.Append( CCFLAGS = [ "-DCONFIG_TEST" ])
 
 	def reset(self, TEST = False):
+		self.AUDIO    = False
 		self.DATABASE = False
 		self.DECK     = False
 		self.FILE     = False

design/audio.txt

@@ -13,11 +13,12 @@ Audio: (lib/audio.cpp)
 	namespace that will be easier to work with than using raw gstreamer
 	functions.
 
-	The audio layer will also control the "pause after N tracks" feature
-	so songs can be loaded without neeting to pass in a "begin playback"
-	flag every time.  The remaining tracks counter will only be decremented
-	when a song finishes through the end-of-stream message passed by the
-	gst pipeline.
+	The audio layer is meant to be an interface used by the front end to
+	control most features of the backend library.  This means implementing
+	next track, previous track, and so on here.
+
+	Gstreamer options passed to audio :: init() can be found by running
+	`gst-inspect-1.0 --help-gst` on the command line.
 
 - Internal:
 	Set up a message bus to look for end-of-stream and error messages so
@@ -28,27 +29,30 @@ Audio: (lib/audio.cpp)
 - API:
 	void audio :: init(argc, argv)
 		Initialize the gstreamer layer and reload the track that was
-		last loaded before shutdown.  Please only pass --gst-* options
-		for argv.
+		last loaded before shutdown.  Gstreamer is supposed to remove
+		options from the argv array as they are processed, so pass
+		pointers to argc and argv to this function.
 
-	void audio :: play()
-		Begin or resume playback.
+	bool audio :: play()
+	bool audio :: pause()
+		Change the gstreamer state to either GST_STATE_PLAYING or
+		GST_STATE_PAUSED.  Return true on success and false otherwise.
 
-	void audio :: pause()
-		Pause playback.
-
-	void audio :: seek_to(int)
-		Seek to a position X seconds into the track
+	bool audio :: seek_to(int)
+		Seek to a position X seconds into the track.  Return true if
+		a track is loaded and the seek isn't out of bounds.  False
+		otherwise.
 
 	void audio :: stop()
 		pause()
 		seek_to(0)
 
-	void audio :: next()
-		Call the playlist :: next() function to get the next trackid,
+	bool audio :: next()
+		Call the deck :: next() function to get the next trackid,
 		and load that file into the gstreamer pipeline.  Do not change
 		the state of the pipeline (if nothing is playing yet, don't
-		call play()).
+		call play()).  Return true if a track has been loaded into the
+		pipeline, false otherwise.
 
 	void audio :: previous()
 		Call the playlist :: previous() function to iterate backwards
@@ -65,7 +69,9 @@ Audio: (lib/audio.cpp)
 		Return the duration of the current song in seconds.
 
 	void audio :: pause_after(unsigned int)
-		Pause after N tracks, pass a negative number to disable.
+		Pause after N tracks, pass a negative number to disable.  The
+		count will only be decremented when an end-of-stream message
+		is received by the gstreamer pipeline.
 
 	unsigned int audio :: pause_count()
 		Return the number of tracks that will be played before

include/audio.h

@@ -0,0 +1,23 @@
+/*
+ * Copyright 2013 (c) Anna Schumaker.
+ */
+#ifndef OCARINA_AUDIO_H
+#define OCARINA_AUDIO_H
+
+extern "C" {
+	#include <gst/gst.h>
+}
+
+namespace audio
+{
+
+	void init(int *, char ***);
+
+	bool play();
+	bool pause();
+	bool seek_to(double);
+	bool next();
+
+};
+
+#endif /* OCARINA_AUDIO_H */

lib/Sconscript

@@ -15,6 +15,7 @@ modules = {
 #                         #
 ###########################
 
+	"AUDIO"    : Module("audio.cpp", package = "gstreamer-1.0", depends = [ "DECK", "LIBRARY" ]),
 	"DATABASE" : Module("database.cpp", depends = [ "FILE" ]),
 	"DECK"     : Module("deck.cpp", depends = [ "PLAYLIST" ]),
 	"FILE"     : Module("file.cpp", package = "glib-2.0"),

lib/audio.cpp

@@ -0,0 +1,100 @@
+/*
+ * Copyright 2013 (c) Anna Schumaker.
+ */
+#include <audio.h>
+#include <deck.h>
+#include <library.h>
+
+#include <string.h>
+
+static GstElement *ocarina_player;
+static bool track_loaded = false;
+
+static gboolean on_message(GstBus *bus, GstMessage *message, gpointer data)
+{
+	return TRUE;
+}
+
+static bool change_state(GstState state)
+{
+	GstStateChangeReturn ret;
+
+	ret = gst_element_set_state(GST_ELEMENT(ocarina_player), state);
+	switch (ret) {
+	case GST_STATE_CHANGE_SUCCESS:
+	case GST_STATE_CHANGE_ASYNC:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static bool load_song(library :: Song &song)
+{
+	GstState state;
+	gchar *escaped;
+	std::string filepath = song.library->root_path + "/" + song.track->filepath;
+
+	gst_element_get_state(GST_ELEMENT(ocarina_player), &state,
+			      NULL, GST_CLOCK_TIME_NONE);
+
+	escaped = gst_filename_to_uri(filepath.c_str(), NULL);
+	g_object_set(G_OBJECT(ocarina_player), "uri", escaped, NULL);
+	g_free(escaped);
+
+	return change_state(state);
+}
+
+void audio :: init(int *argc, char ***argv)
+{
+	GstBus *bus;
+
+	gst_init(argc, argv);
+
+	ocarina_player = gst_element_factory_make("playbin", "ocarina_player");
+	bus = gst_pipeline_get_bus(GST_PIPELINE(ocarina_player));
+
+	gst_bus_add_watch(bus, on_message, NULL);
+}
+
+bool audio :: play()
+{
+	if (track_loaded == false)
+		return false;
+	return change_state(GST_STATE_PLAYING);
+}
+
+bool audio :: pause()
+{
+	if (track_loaded == false)
+		return false;
+	return change_state(GST_STATE_PAUSED);
+}
+
+bool audio :: seek_to(double pos)
+{
+	if (track_loaded == false)
+		return false;
+	return gst_element_seek_simple(GST_ELEMENT(ocarina_player),
+					GST_FORMAT_TIME,
+					GST_SEEK_FLAG_FLUSH,
+					pos);
+	return true;
+}
+
+bool audio :: next()
+{
+	unsigned int id;
+	library :: Song song;
+
+	try {
+		id = deck :: next();
+		if (library :: lookup(id, &song) == false)
+			track_loaded = false;
+		else
+			track_loaded = load_song(song);
+	} catch (int) {
+		track_loaded = false;
+	}
+	return track_loaded;
+}

tests/Sconscript

@@ -57,8 +57,8 @@ rm_test_dir(xdg.BaseDirectory.xdg_data_home);
 #
 # Read SConscript files
 #
-scripts = [ "database", "deck", "file", "filter", "group", "idle", "index",
-            "library", "playlist", "print" ]
+scripts = [ "audio", "database", "deck", "file", "filter", "group", "idle",
+            "index", "library", "playlist", "print" ]
 for s in scripts:
 	CONFIG.reset(TEST = True)
 	SConscript("%s/Sconscript" % s)

tests/audio/Sconscript

@@ -0,0 +1,6 @@
+#!/usr/bin/python
+Import("Test", "CONFIG")
+
+CONFIG.AUDIO = True
+
+Test("audio", "audio.cpp")

tests/audio/audio.cpp

@@ -0,0 +1,65 @@
+/*
+ * Copyright 2013 (c) Anna Schumaker.
+ */
+#include <audio.h>
+#include <deck.h>
+#include <library.h>
+#include <print.h>
+
+#include <stdlib.h>
+#include <string>
+#include <unistd.h>
+
+void gen_library()
+{
+	system("tests/library/gen_library.sh");
+	print("\n");
+}
+
+void check_ret(const std :: string &test, bool ret, bool expected)
+{
+	print("Test %s: ", test.c_str());
+	if (ret == expected)
+		print("Success!\n");
+	else
+		print("Failed.\n");
+}
+
+/* Call various functions without a track loaded */
+void test_0()
+{
+	check_ret("0a", audio :: play(), false);
+	check_ret("0b", audio :: pause(), false);
+	check_ret("0c", audio :: seek_to(10), false);
+	check_ret("0d", audio :: next(), false);
+	print("\n");
+}
+
+void test_1()
+{
+	check_ret("1a", audio :: next(), true);
+	check_ret("1b", audio :: play(), true);
+	check_ret("1c", audio :: pause(), true);
+	check_ret("1c", audio :: seek_to(10), true);
+}
+
+int main(int argc, char **argv)
+{
+	Playlist *plist;
+
+	gen_library();
+
+	/* Initialize before testing */
+	audio :: init(&argc, &argv);
+	test_0();
+
+	/* Read in library, set up a playlist */
+	library :: add_path("/tmp/library/0");
+	plist = deck :: create();
+	for (unsigned int i = 0; i < 150; i++)
+		plist->add(i);
+
+	test_1();
+
+	return 0;
+}