replay_gain: reimplement as a filter plugin

Apply the replay gain in the output thread.  This means a new setting
will be active instantly, without going through the whole music pipe.
And we might have different replay gain settings for each audio output
device.

3 files changed, 34 insertions, 0 deletions

diff --git a/src/output_init.c b/src/output_init.c
index 2ce6b30f9..387915ddc 100644
--- a/src/output_init.c
+++ b/src/output_init.c
@@ -194,6 +194,17 @@ audio_output_init(struct audio_output *ao, const struct config_param *param,
 	ao->filter = filter_chain_new();
 	assert(ao->filter != NULL);
 
+	/* create the replay_gain filter */
+
+	ao->replay_gain_filter = filter_new(&replay_gain_filter_plugin,
+					    param, NULL);
+	assert(ao->replay_gain_filter != NULL);
+
+	filter_chain_append(ao->filter, ao->replay_gain_filter);
+	ao->replay_gain_serial = 0;
+
+	/* create the normalization filter (if configured) */
+
 	if (config_get_bool(CONF_VOLUME_NORMALIZATION, false)) {
 		struct filter *normalize_filter =
 			filter_new(&normalize_filter_plugin, NULL, NULL);
diff --git a/src/output_internal.h b/src/output_internal.h
index 804fd8cdc..2a438c62f 100644
--- a/src/output_internal.h
+++ b/src/output_internal.h
@@ -135,6 +135,18 @@ struct audio_output {
 	struct filter *filter;
 
 	/**
+	 * The replay_gain_filter_plugin instance of this audio
+	 * output.
+	 */
+	struct filter *replay_gain_filter;
+
+	/**
+	 * The serial number of the last replay gain info.  0 means no
+	 * replay gain info was available.
+	 */
+	unsigned replay_gain_serial;
+
+	/**
 	 * The convert_filter_plugin instance of this audio output.
 	 * It is the last item in the filter chain, and is responsible
 	 * for converting the input data into the appropriate format
diff --git a/src/output_thread.c b/src/output_thread.c
index eb44d4c87..0e34c64b7 100644
--- a/src/output_thread.c
+++ b/src/output_thread.c
@@ -26,6 +26,7 @@
 #include "player_control.h"
 #include "filter_plugin.h"
 #include "filter/convert_filter_plugin.h"
+#include "filter/replay_gain_filter_plugin.h"
 
 #include <glib.h>
 
@@ -261,6 +262,16 @@ ao_play_chunk(struct audio_output *ao, const struct music_chunk *chunk)
 		g_mutex_lock(ao->mutex);
 	}
 
+	/* update replay gain */
+
+	if (chunk->replay_gain_serial != ao->replay_gain_serial) {
+		replay_gain_filter_set_info(ao->replay_gain_filter,
+					    chunk->replay_gain_serial != 0
+					    ? &chunk->replay_gain_info
+					    : NULL);
+		ao->replay_gain_serial = chunk->replay_gain_serial;
+	}
+
 	if (size == 0)
 		return true;