design: Add in gstreamer thoughts

Because a music player should be able to play music :)

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

design.txt

@@ -17,6 +17,7 @@ Files:
 		design.txt
 	ocarina/gui/
 	ocarina/include/
+		audio.h
 		database.h
 		database.hpp
 		file.h
@@ -26,6 +27,7 @@ Files:
 		playlist.h
 		prefs.h
 	ocarina/lib/
+		audio.cpp
 		database.cpp
 		file.cpp
 		group.cpp
@@ -45,6 +47,47 @@ Files:
 
 
 
+Audio: (lib/audio.cpp)
+	This file will introduce an "audio" namespace containing all of the
+	functions interacting with gstreamer.  This will create a wrapper
+	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.
+
+- Internal:
+	Set up a message bus to look for end-of-stream and error messages so
+	the next song can be played.  This function should call the play
+	function after loading a track and after checking the "pause after N"
+	count.
+
+- API:
+	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.
+	audio :: load_file(filepath)
+		Loads a file path but does not begin playback.
+	audio :: play()
+		Begin playback
+	audio :: pause()
+		Pause playback
+	audio :: seek_to(X)
+		Seek to a position X seconds into the track
+	audio :: stop()
+		pause()
+		seek_to(0)
+	audio :: pause_after(N)
+		Pause after N tracks, pass a negative number to disable.
+	audio :: position()
+		Return the number of seconds that the song has played
+	audio :: duration()
+		Return the duration of the current song in seconds
+
+
+
 On-disk files: (lib/file.cpp)
 	I use the disk to store data between sessions, this could include
 	library state and user preferences.  In theory, file formats do not
@@ -449,3 +492,11 @@ Future work:
 
 		To help with fixing groups, a mapping of (old values) ->
 		(new values) should be kept.
+
+	- Fix track durations: (6.1)
+		Some tracks in my library are tagged with the wrong duration,
+		so fix them as they are played.
+
+	- Track tag editor: (6.2)
+		Make a pop-up window for editing the tags of a track.  Be sure
+		to update the library information and the on-disk file.