# This patch makes it possible to delay either channel. I made this when
# I was working on getting MoC into my car which sadly never happened.
# Anyways, in a car you sit closer to one speaker than the other and
# it isn't just a matter of balancing the sound level as you normally
# do. You also need to adjust the delay so the audio hits your ears
# from both channels at the same time. This affects where the sound
# seems to be coming from and the overall sound image.
# For different reasons this never made it into the official MoC but
# maybe someone will find it cool and take up the project.
#
diff -ru moc-2.4.0/audio.c moc-2.4.0-boost/audio.c
--- moc-2.4.0/audio.c	2006-03-12 01:36:37.000000000 +0100
+++ moc-2.4.0-boost/audio.c	2006-03-12 13:17:53.000000000 +0100
@@ -102,6 +102,13 @@
 #define sample_rate_compat(sound, device) ((device) * 1.05 >= sound \
 		&& (device) * 0.95 <= sound)
 
+#define AUDIO_DELAY_MAX 200
+/* Left channel delay in samples, negative values allowed */
+static int audio_delay = 0;
+static struct fifo_buf audio_delay_fifo = { NULL, 0, 0, 0 };
+static char *audio_delay_buf = NULL;
+static size_t audio_delay_buf_size = (32 * 1024);
+
 /* Make a human readable description of the sound sample format(s).
  * Put the description in msg which is of size buf_size.
  * Return msg. */
@@ -144,6 +151,7 @@
 	return msg;
 }
 
+
 /* Return != 0 if fmt1 and fmt2 have the same sample width. */
 int sfmt_same_bps (const long fmt1, const long fmt2)
 {
@@ -706,7 +714,10 @@
 				driver_sound_params.channels,
 				driver_sound_params.rate);
 	}
-	
+
+	/* Init audio delay buffer */
+	fifo_buf_init (&audio_delay_fifo, sfmt_Bps (driver_sound_params.fmt) * AUDIO_DELAY_MAX / driver_sound_params.channels );
+	audio_delay_buf = xmalloc (audio_delay_buf_size);
 	return res;
 }
 
@@ -746,11 +757,76 @@
 	return hw.get_buff_fill ();
 }
 
+static void process_delay (const char *buf, const size_t size)
+{
+	size_t pos;
+	/* The delay, always positive */
+	int abs_delay = audio_delay >= 0 ?audio_delay : -audio_delay;
+	size_t sample_size = sfmt_Bps (driver_sound_params.fmt);
+	/* Delay this many bytes */
+	int delay_samples = abs_delay * sample_size;
+	/* How many samples to process */
+	size_t samples = size / sample_size;
+	/* Delay left or right? */
+	int delay_left = audio_delay >= 0;
+
+	assert(size>0);
+
+	/* If we have too small buffer, increase it to double the size of 'size' */
+	if (size > audio_delay_buf_size)
+	{
+		audio_delay_buf_size = size * 2;
+		audio_delay_buf = xrealloc (audio_delay_buf, audio_delay_buf_size);
+	}
+	
+	/* We can only handle two channels. If it's not we just copy the inbuffer */
+	if (driver_sound_params.channels != 2)
+	{
+		memcpy (audio_delay_buf, buf, size);
+		return;
+	}
+
+	/* If we have more delay than what is in the buffer we fill with zeroes */
+	if( audio_delay_fifo.fill < delay_samples )
+	{
+		char *tmpbuf = (char *) xcalloc (1, delay_samples-audio_delay_fifo.fill);
+		fifo_buf_put (&audio_delay_fifo, tmpbuf, delay_samples-audio_delay_fifo.fill );
+		free (tmpbuf);
+	}
+	/* If we have less delay than what is in the buffer we throw away the difference */
+	else if( audio_delay_fifo.fill > delay_samples )
+	{
+		char *tmpbuf = (char *) xmalloc (audio_delay_fifo.fill-delay_samples);
+		fifo_buf_get (&audio_delay_fifo, tmpbuf, audio_delay_fifo.fill-delay_samples);
+		free (tmpbuf);
+	}
+
+	/* Copy each sample */
+	for (pos=0; pos < samples; pos += 2)
+	{
+		if (delay_left)
+		{
+			/* Put one in and take one out of the end */
+			fifo_buf_put (&audio_delay_fifo, buf+(pos*sample_size), sample_size);
+			fifo_buf_get (&audio_delay_fifo, audio_delay_buf+(pos*sample_size), sample_size);
+			memcpy (audio_delay_buf + ( (pos + 1) * sample_size), buf + ( (pos + 1) * sample_size), sample_size);
+		}
+		else
+		{
+			memcpy (audio_delay_buf + (pos * sample_size), buf + (pos * sample_size), sample_size);
+			fifo_buf_put (&audio_delay_fifo, buf + ( (pos + 1) * sample_size), sample_size);
+			fifo_buf_get (&audio_delay_fifo, audio_delay_buf + ( (pos + 1) * sample_size), sample_size);
+		}
+	}
+}
+
 int audio_send_pcm (const char *buf, const size_t size)
 {
 	int played;
+
+	process_delay (buf, size),
 	
-	played = hw.play (buf, size);
+	played = hw.play (audio_delay_buf, size);
 
 	if (played == 0)
 		fatal ("Audio output error.");
@@ -774,6 +850,10 @@
 			audio_conv_destroy (&sound_conv);
 			need_audio_conversion = 0;
 		}
+
+		free (audio_delay_buf);
+		fifo_buf_destroy( &audio_delay_fifo );
+
 		audio_opened = 0;
 	}
 }
@@ -947,6 +1027,37 @@
 		logit ("Tried to set mixer to volume out of range.");
 }
 
+/* Set the amount of delay in samples between channels. 
+ * Positivei values delays left, negative values delays right */
+void audio_set_delay (const int val)
+{
+	if (val >= -AUDIO_DELAY_MAX && val <= AUDIO_DELAY_MAX)
+	{
+		audio_delay=val;
+	}
+	else
+		logit ("Tried to set delay to value out of range.");
+}
+
+int audio_get_delay ()
+{
+	return audio_delay;
+}
+
+/* Returns the delay in milimetres */
+int audio_get_mm ()
+{
+	int mm;
+	/* Velocity of sound can be calculated roughly with the formula
+	 * c = 331.5 + (0.6 * temperature in degrees Celsius).
+	 * In 22 degrees that's 334.7. We use fixed point calculation for this
+	 */
+	mm = 3347000 * audio_delay / driver_sound_params.rate;
+	if (audio_delay >= 0) mm += 5;
+	else mm -= 5;
+	return mm / 10; /* One decimal precision */
+}
+
 void audio_plist_delete (const char *file)
 {
 	int num;
diff -ru moc-2.4.0/audio.h moc-2.4.0-boost/audio.h
--- moc-2.4.0/audio.h	2006-02-12 12:55:10.000000000 +0100
+++ moc-2.4.0-boost/audio.h	2006-03-12 01:19:15.000000000 +0100
@@ -250,5 +250,7 @@
 char *audio_get_mixer_channel_name ();
 void audio_toggle_mixer_channel ();
 void audio_plist_move (const char *file1, const char *file2);
-
+void audio_set_delay (const int val);
+int audio_get_delay ();
+int audio_get_mm ();
 #endif
Endast i moc-2.4.0-boost: gdb.cmds
diff -ru moc-2.4.0/interface.c moc-2.4.0-boost/interface.c
--- moc-2.4.0/interface.c	2006-02-12 12:55:10.000000000 +0100
+++ moc-2.4.0-boost/interface.c	2006-03-12 01:23:03.000000000 +0100
@@ -1613,6 +1613,36 @@
 	set_mixer (get_mixer_value() + diff);
 }
 
+static int get_delay_value ()
+{
+	send_int_to_srv (CMD_GET_DELAY);
+	return get_data_int ();
+}
+
+static int get_delay_mm ()
+{
+	send_int_to_srv (CMD_GET_MM);
+	return get_data_int ();
+}
+
+static void set_delay (int val)
+{
+	if (val < -200)
+		val = -200;
+	else if (val > 200)
+		val = 200;
+	
+	send_int_to_srv (CMD_SET_DELAY);
+	send_int_to_srv (val);
+
+	interface_message ("Differance between left and right: %d mm", get_delay_mm ());
+}
+
+static void adjust_delay (const int diff)
+{
+	set_delay (get_delay_value() + diff);
+}
+
 /* Add the currently selected file to the playlist. */
 static void add_file_plist ()
 {
@@ -3151,6 +3181,12 @@
 			case KEY_CMD_EXEC10:
 				exec_custom_command ("ExecCommand10");
 				break;
+			case KEY_CMD_DELAY_LEFT:
+				adjust_delay(1);
+				break;
+			case KEY_CMD_DELAY_RIGHT:
+				adjust_delay(-1);
+				break;
 			default:
 				abort ();
 		}
diff -ru moc-2.4.0/keys.c moc-2.4.0-boost/keys.c
--- moc-2.4.0/keys.c	2006-02-12 12:55:10.000000000 +0100
+++ moc-2.4.0-boost/keys.c	2006-03-11 23:49:36.000000000 +0100
@@ -719,7 +719,23 @@
  		CON_MENU,
  		{ KEY_F(10), -1 },
  		1
-  	}
+  	},
+	{
+		KEY_CMD_DELAY_LEFT,
+		"delay_left",
+		"Move audio position to the left",
+		CON_MENU,
+		{ 'O', -1 },
+		1
+	},
+	{
+		KEY_CMD_DELAY_RIGHT,
+		"delay_right",
+		"Move audio position to the right",
+		CON_MENU,
+		{ 'P', -1 },
+		1
+	}
 };
 
 static struct special_keys
diff -ru moc-2.4.0/keys.h moc-2.4.0-boost/keys.h
--- moc-2.4.0/keys.h	2006-02-12 12:55:10.000000000 +0100
+++ moc-2.4.0-boost/keys.h	2006-03-11 23:49:36.000000000 +0100
@@ -86,6 +86,8 @@
 	KEY_CMD_EXEC8,
 	KEY_CMD_EXEC9,
 	KEY_CMD_EXEC10,
+	KEY_CMD_DELAY_LEFT,
+	KEY_CMD_DELAY_RIGHT,
 	KEY_CMD_WRONG
 };
 
Endast i moc-2.4.0-boost: moc-2.4.0.tar.bz2
Endast i moc-2.4.0: moc.spec
diff -ru moc-2.4.0/protocol.h moc-2.4.0-boost/protocol.h
--- moc-2.4.0/protocol.h	2006-02-12 12:55:10.000000000 +0100
+++ moc-2.4.0-boost/protocol.h	2006-03-12 01:19:53.000000000 +0100
@@ -119,6 +119,10 @@
 #define CMD_CLI_PLIST_MOVE	0x31	/* move an item */
 #define CMD_LIST_MOVE		0x32	/* move an item */
 
+#define CMD_GET_DELAY	0x033	/* Get delay value */
+#define CMD_SET_DELAY	0x034	/* Set delay value */
+#define CMD_GET_MM	0x035	/* Get delay value in millimeters */
+
 char *socket_name ();
 int get_int (int sock, int *i);
 enum noblock_io_status get_int_noblock (int sock, int *i);
diff -ru moc-2.4.0/server.c moc-2.4.0-boost/server.c
--- moc-2.4.0/server.c	2006-02-12 12:55:10.000000000 +0100
+++ moc-2.4.0-boost/server.c	2006-03-12 14:05:23.000000000 +0100
@@ -280,6 +280,38 @@
 		fatal ("dup2() failed: %s", strerror(errno));
 }
 
+static void audio_delay_load (char *filename)
+{
+	FILE *file=NULL;
+	int delay=0;
+	
+	asert (filename!=NULL);
+	asert (strlen(filename)>0);
+
+	if ( (file=fopen (filename,"r")) )
+	{
+		if (fscanf (file, "%d\n", &delay)>0)
+		{
+			audio_set_delay (delay);
+		}
+		fclose (fp);
+	}
+}
+
+static void audio_delay_save (char *filename)
+{
+	FILE *file=NULL;
+
+	asert (filename!=NULL);
+	asert (strlen(filename)>0);
+
+	if ( (file=fopen (filename,"w")) )
+	{
+		fprintf (file, "%d\n", audio_get_delay ());
+		fclose (fp);
+	}
+}
+
 /* Initialize the server - return fd of the listening socket or -1 on error */
 int server_init (int debug, int foreground)
 {
@@ -327,6 +359,7 @@
 	audio_initialize ();
 	tags_cache_init (&tags_cache, options_get_int("TagsCacheSize") * 1024);
 	tags_cache_load (&tags_cache, create_file_name("tags_cache"));
+	audio_delay_load (create_file_name ("audio_delay"));
 	clients_init ();
 
 	server_tid = pthread_self ();
@@ -446,6 +479,7 @@
 {
 	
 	logit ("Server exiting...");
+	audio_delay_save (create_file_name ("audio_delay"));
 	audio_exit ();
 	tags_cache_save (&tags_cache, create_file_name("tags_cache"));
 	tags_cache_destroy (&tags_cache);
@@ -604,6 +638,18 @@
 	return 1;
 }
 
+/* Set the delay to the value provided by the client. Return 0 on error. */
+static int set_delay (struct client *cli)
+{
+	int val;
+
+	if (!get_int(cli->socket, &val))
+		return 0;
+
+	audio_set_delay (val);
+	return 1;
+}
+
 /* Delete an item from the playlist. Return 0 on error. */
 static int delete_item (struct client *cli)
 {
@@ -1131,6 +1177,18 @@
 			if (!req_list_move(cli))
 				err = 1;
 			break;
+		case CMD_GET_DELAY:
+			if (!send_data_int(cli, audio_get_delay()))
+				err = 1;
+			break;
+		case CMD_SET_DELAY:
+			if (!set_delay(cli))
+				err = 1;
+			break;
+		case CMD_GET_MM:
+			if (!send_data_int(cli, audio_get_mm()))
+				err = 1;
+			break;
 		default:
 			logit ("Bad command (0x%x) from the client.", cmd);
 			err = 1;