shout: introduce pluggable encoder API

I've perhaps gone a bit overboard, but here's the current rundown:

Both Ogg and MP3 use the "shout" audio output plugin.  The shout audio
output plugin itself has two new plugins, one for the Ogg encoder,
and another for the MP3 (LAME) encoder.

Configuration for an Ogg stream doesn't change.  For an MP3 stream,
configuration is the same as Ogg, with two exceptions.  First, you must
specify the optional "encoding" parameter, which should be set to "mp3".
See mpd.conf(5) for more details.  Second, the "quality" parameter is
reversed for LAME, such that 1 is high quality for LAME, whereas 10 is
high quality for Ogg.

I've decomposed the code so that all libshout related operations
are done in audioOutput_shout.c, all Ogg specific functions are in
audioOutput_shout_ogg.c, and of course then all LAME specific functions
are handled in audioOutput_shout_mp3.c.

To develop encoder plugins for the shout audio output plugin, I basically
just mimicked the plugin system used for audio outputs.  This might be
overkill, but hopefully if anyone ever wants to support some other sort
of stream, like maybe AAC, FLAC, or WMA (hey it could happen), they will
hopefully be all set.

The Ogg encoder is slightly less optimal under this configuration.
It used to send shout data directly out of its ogg_page structures.  Now,
in the interest of encapsulation, it copies the data from its ogg_page
structures into a buffer provided by the shout audio output plugin (see
audioOutput_shout_ogg.c, line 77.)  I suspect the performance impact
is negligible.

As for metadata, I'm pretty sure they'll both work.  I wrote up a test
scaffold that would create a fake tag, and tell the plugin to send it
out to the stream every few seconds.  It seemed to work fine.  Of course,
if something does break, I'll be glad to fix it.

Lastly, I've renamed lots of things into snake_case, in keeping with
normalperson's wishes in that regard.

[mk: moved the MP3 patch after this one.  Splitted this patch into
several parts; the others were already applied before this one.  Fixed
a bunch GCC warnings and wrong whitespace modifications.  Made it
compile with mpd-mk by adapting to its prototypes]

1 files changed, 68 insertions, 7 deletions

diff --git a/src/audioOutputs/audioOutput_shout.c b/src/audioOutputs/audioOutput_shout.c
index 5bd2b575c..1e60e3546 100644
--- a/src/audioOutputs/audioOutput_shout.c
+++ b/src/audioOutputs/audioOutput_shout.c
@@ -20,6 +20,7 @@
 
 #ifdef HAVE_SHOUT
 
+#include "../list.h"
 #include "../utils.h"
 
 #define CONN_ATTEMPT_INTERVAL 60
@@ -28,6 +29,33 @@
 #define SHOUT_BUF_SIZE 8192
 
 static int shout_init_count;
+static List *shout_encoder_plugin_list;
+
+mpd_unused
+static void finish_shout_encoder_plugins(void)
+{
+	freeList(shout_encoder_plugin_list);
+}
+
+static void init_shout_encoder_plugins(void)
+{
+	shout_encoder_plugin_list = makeList(NULL, 0);
+}
+
+static void load_shout_encoder_plugin(shout_encoder_plugin * plugin)
+{
+	if (!plugin->name)
+		return;
+	insertInList(shout_encoder_plugin_list, plugin->name, plugin);
+}
+
+mpd_unused
+static void unload_shout_encoder_plugin(shout_encoder_plugin * plugin)
+{
+	if (!plugin->name)
+		return;
+	deleteFromList(shout_encoder_plugin_list, plugin->name);
+}
 
 static void clear_shout_buffer(struct shout_data * sd)
 {
@@ -82,6 +110,12 @@ static void free_shout_data(struct shout_data *sd)
 		}							\
 	}
 
+static void load_shout_plugins(void)
+{
+	init_shout_encoder_plugins();
+	load_shout_encoder_plugin(&shout_ogg_encoder);
+}
+
 static int my_shout_init_driver(struct audio_output *audio_output,
 				ConfigParam * param)
 {
@@ -91,10 +125,14 @@ static int my_shout_init_driver(struct audio_output *audio_output,
 	char *host;
 	char *mount;
 	char *passwd;
+	const char *encoding;
 	const char *user;
 	char *name;
 	BlockParam *block_param;
 	int public;
+	void *data = NULL;
+
+	load_shout_plugins();
 
 	sd = new_shout_data();
 
@@ -173,6 +211,25 @@ static int my_shout_init_driver(struct audio_output *audio_output,
 	check_block_param("format");
 	sd->audio_format = audio_output->reqAudioFormat;
 
+	block_param = getBlockParam(param, "encoding");
+	if (block_param) {
+		if (0 == strncasecmp(block_param->value, "mp3", 3))
+			encoding = block_param->value;
+		else if (0 == strncasecmp(block_param->value, "ogg", 3))
+			encoding = block_param->value;
+		else
+			FATAL("shout encoding \"%s\" is not \"ogg\" or "
+			      "\"mp3\", line %i\n", block_param->value,
+			      block_param->line);
+	} else {
+		encoding = "ogg";
+	}
+	if (!findInList(shout_encoder_plugin_list, encoding, &data)) {
+		FATAL("couldn't find shout encoder plugin for \"%s\" "
+		      "at line %i\n", encoding, block_param->line);
+	}
+	sd->encoder = (shout_encoder_plugin *) data;
+
 	if (shout_set_host(sd->shout_conn, host) != SHOUTERR_SUCCESS ||
 	    shout_set_port(sd->shout_conn, port) != SHOUTERR_SUCCESS ||
 	    shout_set_password(sd->shout_conn, passwd) != SHOUTERR_SUCCESS ||
@@ -181,7 +238,7 @@ static int my_shout_init_driver(struct audio_output *audio_output,
 	    shout_set_user(sd->shout_conn, user) != SHOUTERR_SUCCESS ||
 	    shout_set_public(sd->shout_conn, public) != SHOUTERR_SUCCESS ||
 	    shout_set_nonblocking(sd->shout_conn, 1) != SHOUTERR_SUCCESS ||
-	    shout_set_format(sd->shout_conn, SHOUT_FORMAT_VORBIS)
+	    shout_set_format(sd->shout_conn, sd->encoder->shout_format)
 	    != SHOUTERR_SUCCESS ||
 	    shout_set_protocol(sd->shout_conn, SHOUT_PROTOCOL_HTTP)
 	    != SHOUTERR_SUCCESS ||
@@ -237,7 +294,7 @@ static int my_shout_init_driver(struct audio_output *audio_output,
 
 	audio_output->data = sd;
 
-	return 0;
+	return sd->encoder->init_func(sd);
 }
 
 static int handle_shout_error(struct shout_data *sd, int err)
@@ -278,10 +335,10 @@ static int write_page(struct shout_data *sd)
 	return 0;
 }
 
-static void close_shout_conn(struct shout_data *sd)
+static void close_shout_conn(struct shout_data * sd)
 {
 	if (sd->opened) {
-		if (shout_ogg_encoder_clear_encoder(sd))
+		if (sd->encoder->clear_encoder_func(sd))
 			write_page(sd);
 	}
 
@@ -300,6 +357,7 @@ static void my_shout_finish_driver(struct audio_output *audio_output)
 
 	close_shout_conn(sd);
 
+	sd->encoder->finish_func(sd);
 	free_shout_data(sd);
 
 	shout_init_count--;
@@ -395,7 +453,7 @@ static int open_shout_conn(struct audio_output *audio_output)
 	if (status != 0)
 		return status;
 
-	if (init_encoder(sd) < 0) {
+	if (sd->encoder->init_encoder_func(sd) < 0) {
 		shout_close(sd->shout_conn);
 		return -1;
 	}
@@ -436,7 +494,7 @@ static void send_metadata(struct shout_data * sd)
 	if (!sd->opened || !sd->tag)
 		return;
 
-	if (shout_ogg_encoder_send_metadata(sd, song, size)) {
+	if (sd->encoder->send_metadata_func(sd, song, size)) {
 		shout_metadata_add(sd->shout_meta, "song", song);
 		if (SHOUTERR_SUCCESS != shout_set_metadata(sd->shout_conn,
 							   sd->shout_meta)) {
@@ -473,7 +531,10 @@ static int my_shout_play(struct audio_output *audio_output,
 		}
 	}
 
-	shout_ogg_encoder_encode(sd, chunk, size);
+	if (sd->encoder->encode_func(sd, chunk, size)) {
+		my_shout_close_device(audio_output);
+		return -1;
+	}
 
 	if (write_page(sd) < 0) {
 		my_shout_close_device(audio_output);