Fixed bug #698

 Hans de Goede      2009-02-13 01:10:52 PST

Since the new "glitch free" version of pulseaudio (used in Fedora 10 amongst
others), the sound of SDL using apps (like a simple playmus call) has been
crackling.

While looking in to fixing this I noticed that the current pulseaudio code in
SDL uses pa_simple. However pa_simple uses a thread to pump pulseaudio events
and ipc, given that SDL already has its own thread for audio handling this is
clearly suboptimal, leading to unnecessary context switching IPC, etc. Also
pa_simple does not allow one to implement the WaitAudio() callback for SDL
audiodrivers properly.

Given that my work is mostly a rewrite (although some original pieces remain)
I'm attaching the new .c and .h file, as that is easier to review then the huge
diff.

Let me know if you also want the diff.

This new version has the following features:
-no longer use an additional thread next to the SDL sound thread
-do not crackle with glitch free audio
-when used with a newer pulse, which does glitch free audio, the total latency
is
 the same as with the alsa driver
-proper WaitAudio() implementation, saving another mixlen worth of latency
-adds a WaitDone() implementation

This patch has been written in consultancy with Lennart Poetering (the
pulseaudio author) and has been reviewed by him for correct use of the pa API.

--HG--
branch : SDL-1.2
extra : convert_revision : svn%3Ac70aab31-4412-0410-b14c-859654838e24/branches/SDL-1.2%403856

src/audio/pulse/SDL_pulseaudio.h

@@ -32,20 +32,38 @@
 #define _THIS	SDL_AudioDevice *this
 
 struct SDL_PrivateAudioData {
-	/* The audio stream handle */
-	pa_simple * stream;
-
-	/* The parent process id, to detect when application quits */
-	pid_t parent;
+	pa_mainloop *mainloop;
+	pa_mainloop_api *mainloop_api;
+	pa_context *context;
+	pa_stream *stream;
 
 	/* Raw mixing buffer */
 	Uint8 *mixbuf;
 	int    mixlen;
 };
 
+#if (PA_API_VERSION < 12)
+/** Return non-zero if the passed state is one of the connected states */
+static inline int PA_CONTEXT_IS_GOOD(pa_context_state_t x) {
+    return
+        x == PA_CONTEXT_CONNECTING ||
+        x == PA_CONTEXT_AUTHORIZING ||
+        x == PA_CONTEXT_SETTING_NAME ||
+        x == PA_CONTEXT_READY;
+}
+/** Return non-zero if the passed state is one of the connected states */
+static inline int PA_STREAM_IS_GOOD(pa_stream_state_t x) {
+    return
+        x == PA_STREAM_CREATING ||
+        x == PA_STREAM_READY;
+}
+#endif	/* pulseaudio <= 0.9.10 */
+
 /* Old variable names */
+#define mainloop		(this->hidden->mainloop)
+#define mainloop_api		(this->hidden->mainloop_api)
+#define context			(this->hidden->context)
 #define stream			(this->hidden->stream)
-#define parent			(this->hidden->parent)
 #define mixbuf			(this->hidden->mixbuf)
 #define mixlen			(this->hidden->mixlen)